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BC BR Series Coilovers
#1545283
23/07/2015 10:07
23/07/2015 10:07
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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I’ve just had the BC BR series Coilovers fitted to my car and it clearly needs to be set-up properly. I’m after what might be called a ‘fast road’ set-up and would like to get a better understanding of damper rates before taking it along and given it to someone else to sort out for me.
I have the 6kg/mm front and rear springs and have been trying to read up on what sport of damping level should be required to get the best level of comfort vs grip. I’d really rather not just keep experimenting with different settings, it’s too time consuming, costly and, frankly, it’s only maths and so should be pretty straightforward to calculate to a good starting point at the least.
As the ride height is mostly independent to the spring / damper rates, and the spring rate is fixed, I’d like to focus on the damper rates.
These coilovers have 30 clicks on both the front and rear (though it feels like 34 on the front adjuster?) – for starters, I don’t know what level of damping these correspond with, which I’m guessing is pretty fundamental!
The rears are tricky to get too and so not something I’ll be doing more than once if I can help it – do it once, do it right.
Now, given that each front corner is basically twice the weight of the rear corners, it would seem to me that the damping force would have to be a LOT more. I haven’t seen anyone going for this ratio on the ‘New make of coilovers’ thread – why is that?
At the moment, the rear dampers are set to 5 clicks from hard (so 25/30) and the fronts are set to 12 from hard (so 18/30). The tracking is so far out that it’s pretty impossible to work out how these coilovers perform because I just get rampant power on and lift off understeer (WTF is that about!?) at the moment. The new AD08Rs aren’t properly scrubbed in yet either.
One other question about these – do they permit corner weighting because this is something I know these cars really suffer from being a left hand drive design.
Any help on this would be greatly appreciated as I’m looking to get the work carried out within the next two weeks.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545287
23/07/2015 11:19
23/07/2015 11:19
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I thought the rear damping adjustment was at the bottom of the shock......
ISTR that its a single damping adjustment (ie not separate compression & rebound) - if so, the valving on the fronts versus the rears should already be set up to accommodate the difference in weight (ie you don't need to go twice as hard on the fronts, as it'll already be set up to be twice as hard anyway)
What you'll need to do is experiment on a favourite (and quiet...) piece of road, that has the required undulations and bumps
Set it up full soft and go for a drive - it'll wallow a bit and will tend to understeer
Then, set everything full hard and it'll bounce like Zebedee on speed and the back end will try to step out
now start to find a decent mid point setting, where the car absorbs bumps without pitching you into the scenery, but without more than once "bounce" before it settles
From experience, I'd suggest you start from the soft end of the scale, rather than the hard end, as I think you'll find your eventual settings are closer to the soft end if you're after "fast road", rather than "trackday"
I would suggest that the key attribute to aim for is the ability to hit the power fairly hard halfway round a corner and the only effect is the Quaife will pull you round, rather than tug you off-line. Also desirable is the ability to lift off part-way round a bend without the rear stepping out. A slight correction of line is OK, but you don't want to be adding opposite lock.
Finally, you need to be able to plant the throttle at any speed in any gear in a straight line and STAY in a straight line
If I can get all of this on Osravs and Toyo Proxes, you should definitely be able to achieve it on BCs and AD08s
FWIW, my "sweet spot" is about 20% from soft on the rear and 25% from soft on the front
I'm guessing that the lift off understeer is caused by the fact that you're way too hard at the rear (oooer missus...)
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545546
27/07/2015 11:33
27/07/2015 11:33
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Joined: Feb 2006
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Trappy
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I’ve now got the damper strength set to 12 clicks from soft. I haven’t been able to adjust it over the weekend as I’ve been away but I drive it shortly on Saturday morning and it is totally un-driveable. The geometry is so far out that I’m looking forward to seeing the results (you can literally see how far both front wheels are sticking out! On that note, it’ll be going in next Saturday for a full fast road set up.
At the moment, I know the following are adjustable on these coilovers: - Ride height - Bound and rebound (same setting) - Camber
The question for me is does it allow for corner weighting?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545547
27/07/2015 12:00
27/07/2015 12:00
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Joined: Dec 2005
Posts: 12,299 Sandhurst
Begbie
ex El Presidente
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I believe with corner weighting, that the car is measured at each corner (obviously) and the height, camber and rebound is adjusted to take account the weight over each corner, so the height might be slightly different on one side to the other, along with the rebound hardness.
Your car is Usain Bolt with wellies
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545554
27/07/2015 12:49
27/07/2015 12:49
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Joined: Oct 2008
Posts: 6,793 In the coupe.
magooagain
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In the coupe.
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I seem to remember that Kevin 20vt had a big problem with them at first fitting. He reckon the car nearly sent him into a ditch. He wrote about it on here I think on the bc coil over thread.
Edited to add that Kevin started to contribute to the thread at page 10. May be worth a read Trappy. Hope it helps.
Last edited by magooagain; 27/07/2015 12:52.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1545627
28/07/2015 10:20
28/07/2015 10:20
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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Jimbo, I’ve been searching through your old posts but can’t find what I’m looking for. I’m sure you once said that the Coupé should, in theory, handle better at standard ride hide than when lowered. I ask because it rubbed the rear wheel arch again and now I’m happier with the dampers set to 12/30, I’m going to increase the ride height to clear them. At least until I get the rear subframe refreshed anyway as it’s possibly something that worn that’s causing the wheel to protrude a few mill further on the right and so snag the wheel arch.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Begbie]
#1545628
28/07/2015 10:22
28/07/2015 10:22
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Joined: Feb 2006
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Trappy
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I've donme some reading and think I'll wait until I've had the suspension refreshed with poly bushes before having this done. Sounds like it'll be the icing on the cake but not something you can really do if you're going to be fiddling with it all in the near future.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: magooagain]
#1545629
28/07/2015 10:23
28/07/2015 10:23
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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Thanks Joe. I had a good read through before buying and so am aware of the problems a few people had that were later ironed out in the most part. It's really only the front end that's not up to snuff no and, before the tracking is done, I couldn't really say the coilovers are at fault.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545632
28/07/2015 12:34
28/07/2015 12:34
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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The reason that the Coupe handles better with standard ride height is the angle of the wishbones
At standard ride height, the wishbones should be angled very slightly downwards towards the wheel hub - this is so that when the suspension is compressed, the wishbone prescribes an arc, which actually moves the hub away from the centre line of the car, and thus increases the negative camber as the suspension compresses
On a lowered car, the wishbones are parallel to the ground, or even angled upwards at the hub. This means that when the suspension compresses, the camber moves towards positive, which isn't desirable
The answer (which is fudging the issue) is to beef up the anti-roll bars, but this has the undesirable effect that uprating the front ARB promotes understeer, so the rear has to be beefed up even more
Quite simply, the Coupe suffers from being derived from the Tipo - it was never meant to be a low-riding, sharp-handling sports car.
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545633
28/07/2015 12:46
28/07/2015 12:46
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Joined: Dec 2005
Posts: 9,706 Gone
Jimbo
Je suis un Coupé
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Yep, as Nigel said above, it's the angle of the wishbone that effects the geometry. That said, the movement is so small with uprated dampers and springs that you'll be lucky to see an inch of travel so the geometry won't be changing to dramatically.
One thing I like about these coilovers is the adjustment. The height adjustment on the front is done at the hub mounting so you aren't altering the pre-load on the springs when you change the ride height.
Get the wheel alignment done and set the camber, etc, it will feel a completely different car once that's done. It will be a game of tug-o-war on the steering wheel until it's all pointing in the right direction.
Last edited by Jimbo; 28/07/2015 12:46.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1545634
28/07/2015 13:04
28/07/2015 13:04
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Joined: Feb 2006
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Trappy
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Thanks Nigel / Jimbo. The car is currently sitting 10mm or so higher than it was on the Eibachs so I might go another 10mm higher for now. Nigel, I am thinking about upgrading both ARBs at some point too. I just want to see how nervous it is with all of the planned mods finished first. First impressions of the tyres and suspension at the rear is that it feels VERY planted but we'll have to see. A refurbished rear subframe with poly bushes is also on the list if it is still a bit vagued Jimbo, it's not so much a tug-o-war at the moment, the problem is that the car is VERY keen to steer itself. There is no self correcting what-so-ever. Instead, if it finds the slightest camber in the road, it will just veer off - makes for a very interesting drive!! I only wanted these coilovers because the pre-load was independant of the ride height. Time for a call to Elite then
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545635
28/07/2015 13:11
28/07/2015 13:11
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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Nigel, I am thinking about upgrading both ARBs at some point too. Definitely wait until the rest of the setup is done, as I suspect you won't need both, just a rear the problem is that the car is VERY keen to steer itself. There is no self correcting what-so-ever. What camber are you running? Sounds like a proper geo setup will work wonders - you should be able to get it so that its pointy into corners AND planted on long sweepers AND stable on straights
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545637
28/07/2015 13:49
28/07/2015 13:49
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Joined: Feb 2006
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Trappy
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I'll have a look tonight; both at the top mount and the reasoning behind your question in the thread!
Anything I should be worried about?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545640
28/07/2015 14:34
28/07/2015 14:34
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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Anything I should be worried about? LOL - if you have the asymmetrical top mounts AND you fitted them so that the centre of the shock was forward of the centre-line of the mount, you would have reduced caster quite significantly, which would reduce the self-centring effect of the steering
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545644
28/07/2015 15:04
28/07/2015 15:04
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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From memory (5 minutes last Wednesday) the L one has been installed on the left and the R on the right but I'll check tonight.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545645
28/07/2015 15:10
28/07/2015 15:10
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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the L one has been installed on the left and the R on the right Logical, I guess..... If they are "handed" I believe it means you have the asymmetrical versions, which is the version that gives you higher castor and stronger self-centring
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545646
28/07/2015 15:21
28/07/2015 15:21
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the L one has been installed on the left and the R on the right Logical, I guess..... Depends which way you're looking at the time... I get so sick of the looks I get at work when I ask for specifics that I give up when it comes to the hobby... to my detriment mostly... If they are "handed" I believe it means you have the asymmetrical versions, which is the version that gives you higher castor and stronger self-centring
So I have the ones that give more castor if installed correctly, but less if not? I'm Rog knows what he's doing.
Last edited by Trappy; 28/07/2015 15:22.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1545732
29/07/2015 12:16
29/07/2015 12:16
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I'm thinking there may be a cock-up with the labelling on the top mounts Firstly, you definitely have the asymmetrical mounts - you can clearly see that the opening for the shock is forward of the outer mounting, whereas on Begbie's, they are in line - see below However, the aspect that's throwing me is that SURELY, the idea of the asymmetrical mounts was to increase the castor, not decrease it.... I think a question needs to be asked of BC as to the reasons for the two versions of top mounts - if they say the asymmetrical versions are to give more castor, then they've got the labels on the wrong side of the mounts I wouldn't alert them to the fact there's a possible issue - just ask why some top mounts are symmetrical and some are asymmetrical
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1545738
29/07/2015 12:57
29/07/2015 12:57
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So it may just be that BC have labeled all of them the wrong way around? It isn't just light Jimbo, it turns itself. There's no weight to it at all! I'll have to have a word with Rog then as there's no way I can do this myself. I don't even have tools or a jack anymore
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545799
30/07/2015 08:22
30/07/2015 08:22
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Good stuff, Nigel, I look forward to the response!
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Nigel]
#1545806
30/07/2015 10:41
30/07/2015 10:41
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Trappy
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I also found a post from Kevin_20vt as follows… Castor... Looks like it was well know back then. I foolishly made an assumption that these were teething problems that were later resolved. Maybe I could get away with having them swapped over?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546192
04/08/2015 12:17
04/08/2015 12:17
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I've had an answer, and suspect that a) Apex don't know Coupes well enough to comment and b) the factory has made a mistake
Hi,
Please see below explanation from the factory:
We used to think that ZO-01 front top mounts were symmetrical, however, last year, there came a 93 coupe to our factory and we now know that the front left top mount is a tiny bit offset, so we modified the design of top mounts after then, hope this helps you clear things up.
Regards, James
Apex Performance Parts Ltd +44 (0)1274 683633
I don't accept this explanation, so I have replied with the following:-
Hi James
There are no ’93 Coupes in the UK – the earliest is May 1995. A 93 Coupe will be a very early LHD model (very few were registered in 93). In any event, the vast majority of your customers will own 20valve turbo Coupes, which are late 96 onwards.
The factory explanation doesn’t make sense, as on some of the kits you have supplied, the topmounts are symmetrical and on some kits BOTH topmounts are visibly offset (approx 1cm at a guess), not just the nearside. If it were the case that only one topmount is offset, then every kit you have supplied is incorrect.
I find it difficult to believe that the factory would amend its production specifications based on their findings from a single early left hand drive model, especially when the later 20v models account for about 90% of the Coupes still on the road in the UK.
Standard 20v / 20VT topmounts are ‘handed” with a slight offset to the REAR of the car.
The problem is that the offset on your “handed” topmounts has been set forwards, which is dramatically reducing castor and causing unusual handling characteristics – one customer is reporting zero self-centring effect. Even your symmetrical topmounts will be reducing castor over a standard car
For the record, I have no vested interest in this matter, as I haven’t purchased any BR coilovers for my own Coupe. I am merely getting involved as a Coupe enthusiast, in an attempt to assist those Coupe owners that have spent their money and are suffering handling issues.
Given the unusual handling traits experienced when castor is dramatically reduced, I would respectfully suggest that this matter is given the urgent attention is deserves, rather than wait for an owner to have an accident.
Regards
Nigel Ogram
I'll await their reply and post it back here, but I rather think that one of the current BC coilover customers needs to take this over from me.
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546196
04/08/2015 12:36
04/08/2015 12:36
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Joined: Dec 2005
Posts: 12,299 Sandhurst
Begbie
ex El Presidente
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Nigel,
Just a slight point to raise, Apex are the distributors for the kit. In the initial reply from James, he has forwarded on the reply from the factory which are based in Malaysia (IIRC), so there isn't much point stating about cars from the UK.
Your car is Usain Bolt with wellies
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Re: BC BR Series Coilovers
[Re: Nigel]
#1546622
08/08/2015 10:17
08/08/2015 10:17
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Joined: Feb 2006
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Having had the geometry sorted and been away for 5 days on holiday, it's time for an update. I took the car to Elite last Saturday and the geometry was checked - these are the BEFORE results. Camber Front left 0o 19' Front right 1o 07' Rear left -1o 16' Rear right -0o 44' Caster Front left 1o 54' Front right 1o 42' Toe Front left -1o 40' Front right -2o 37' Rear left 0o 10' Rear right 0o 25' Once he'd gotten over the results, I told them about the issues with Castor to date and the chap said that less castor can help with steering response. He said that they offer a 14 day free alignment if not happy and so it would make sense to get it done now anyway. If I'm not happy, I can have the top mounts switched myself and then return to have it done again. So I had the full tidy up completed, asking for 1 degree of Camber on the front. Front left -1o 01' Front right -1o 01' Rear left -1o 14' Rear right -0o 46' Caster Front left 1o 54' Front right 1o 42' Toe Front left 0o 08' Front right 0o 08' Rear left 0o 11' Rear right 0o 24' The rear settings are a bit wobbly, but will be fixed to a fair degree when I have the rear subframe refreshed, I'm sure. All finished, I took it for a spin and... it is transformed. It's now handling very well indeed. Straight line stability is much improved, even a fair degree of self alignment has returned at speed. But it still feels very nervous; too edgy at motorway speeds. I will be having the top mounts switched and then take it back for another alignment for the higher Castor. More stability at speed and more favourable camber in corners sounds very good. In terms of the car's ride, I'm pleased to report that it's actually rather good at 12/30 front and rear. Very composed over rough / jiggly surfaces on the sort of roads that sat navs love. On Motorways and flat A&B roads it feels amazing, save for the nervous steering. Really stable and planted. It's on bumpy b roads where it's suffered a little. Too bouncy for my liking, but they're hardly the roads you use for spirited driving. One other problem I have is caused by the 235 section tyres. With a fair dose of steering lock and a little speed, it rubs the inner arches at the front. I haven't been able to explore the levels of grip properly because of this but it's already far better than it ever has been before when it starts to rub. I'll have the ride height increased again to alleviate this. Would stronger ARBs front and rear help this? I have a 22mm whiteline on the rear but I'm thinking of going 24mm on the rear and 26mm on the front. Oh, now that the tyres are well scrubbed in, I have full grip in 1st and 2nd gear - which is nice
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Nigel]
#1546640
08/08/2015 14:45
08/08/2015 14:45
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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According to their machine's guidelines, the toe range for a Fiat: Coupé: Rest of World: 2.0 Turbo: 1994-2001 is 0o 13' to 0o 04'. I don't have Excel on my home laptop so can't work it out using formulae I've found on the internet.
It's more how responsive the steering is than the car wandering around on the motorway. It's too edgy.
Like you say, I'll get the top mounts switched before playing with anything else but the ride height will have to go up too - I can't have this rubbing any longer.
Once I have degrees converted to mm, what would you recommend I get them to set it too?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546644
08/08/2015 15:11
08/08/2015 15:11
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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I'd start at the most stable setting (full toe-in) and then work back from there
If its still turning in too rapidly and the back is feeling loose, you may have to back off the camber a bit
I spent ages trying to get the balance back on mine, before I twigged that it was a tyre mis-match, which clearly doesn't apply in your case
Before then though, try firming up the front damping a little (or softening the rear) - should help
If its still diving into corners, an ARB might be the only answer - suggest you search for a Lancia Dedra front ARB - slight upgrade on the OE 20vt
On another note, but related - keep a very close eye on your oil pressure gauge - I found that with trackday tyres on, it was easy to get enough lateral G through a roundabout to cause the oil pickup to starve - not a good idea, especially on an expensive forged build
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546660
08/08/2015 22:53
08/08/2015 22:53
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dlongstaff
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dlongstaff
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546923
12/08/2015 18:47
12/08/2015 18:47
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Joined: Feb 2006
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I took a few snaps this morning on my way out of the house. Quick snap of the same side now they've been swapped over. I'm off for a realignment on Saturday morning so will report on the Castor status then. No idea if it handles any better yet as the shoreline ARB has snapped a bracket bolt and that now needsremoving but has to wait until next week.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Nigel]
#1546943
12/08/2015 22:32
12/08/2015 22:32
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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I asked Rog to do that because the middle setting gave me 1o of positive camber on one side and half a degree of positive on the other side. 1o negative was 90% of the travel so I figured it's better in the short term. Clearly, BC didn't do a very good job on the top mount design with the asymmetric versions...
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546962
13/08/2015 07:26
13/08/2015 07:26
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mihai7645
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mihai7645
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So I'm assuming that when facing the engine of the car, the coilovers are labeled correctly? Like mine are overe here
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Re: BC BR Series Coilovers
[Re: ]
#1546969
13/08/2015 08:57
13/08/2015 08:57
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Joined: Feb 2006
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Trappy
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So I'm assuming that when facing the engine of the car, the coilovers are labeled correctly? Like mine are overe here Yes, that's how they should be fitted for more Castor.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1546984
13/08/2015 12:24
13/08/2015 12:24
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Joined: Dec 2005
Posts: 9,706 Gone
Jimbo
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I asked Rog to do that because the middle setting gave me 1o of positive camber on one side and half a degree of positive on the other side. 1o negative was 90% of the travel so I figured it's better in the short term. Clearly, BC didn't do a very good job on the top mount design with the asymmetric versions... I wouldn't worry too much about having less static camber, if you're running more positive caster then you will get extra camber as the wheel turns. That's exactly how you want it, full tyre contact with the wheels pointing straight ahead and negative camber as the wheel turns in so the body roll and suspension compression will still have full tyre contact in the turn. Should handle nicely.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547000
13/08/2015 16:46
13/08/2015 16:46
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Posts: 5,408 Essex
Trappy
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I wouldn't worry too much about having less static camber, if you're running more positive caster then you will get extra camber as the wheel turns. That's exactly how you want it, full tyre contact with the wheels pointing straight ahead and negative camber as the wheel turns in so the body roll and suspension compression will still have full tyre contact in the turn. Should handle nicely.
It's funny you should say that Jimbo, because I was thinking along the same lines yesterday. More specifically, I was considering asking the chaps in the alignment shop if they could measure the camber on full lock. Is that possible? If it was, then what sort of settings should I be looking at? If, say, 3 degrees was ideal in a corner and in a straight line that meant 1 degrees, would it still be worth backing off to 0 degrees and taking 2 degrees at full lock? As far as I know, it might increase it by a factor of two or more… In that case, you’d need some to get any increase! I have no idea how much extra camber I’ll get, but how much at full lock is good?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547062
14/08/2015 11:50
14/08/2015 11:50
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Posts: 5,408 Essex
Trappy
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It's way more complicated than just saying you'll have 3' of camber with the wheels turned Trappy. In a corner, the outside damper will be compressed so the geometry will change from the static condition. Just get them to measure the caster angle, if you're running a little more than standard then you'll be fine, if not then pull in some negative camber. Go on then Jimbo, what’s “a little more than standard”? Book would appear to say -0o13’ to -1o13’. Go for good old -1 degree?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547109
15/08/2015 09:43
15/08/2015 09:43
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Trappy
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Just got back from Elite. Settings are now the same as before but with 2o 47' of castor on the left and 2o 30' on the right.
Feels a lot more stable and surrfooted at speed but with the rear left ARB bracket not in place, I can't really push on yet.
Almost there!
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547216
16/08/2015 18:43
16/08/2015 18:43
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Posts: 17,370 Staffordshire
Nigel
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Hmmm, you're still almost 1 degree of positive caster short of a standard coupe. I've just checked one of my geometry printouts - with Osrav shocks and standard topmounts, I have 3.13 (L) and 3.37 (R) degrees of caster Either Trappy has something fundamentally different going on with his car (wishbones?) or the BC coilovers are all wrong somewhere
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547217
16/08/2015 18:44
16/08/2015 18:44
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Nigel
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PS - I'm only guessing, but with the BC top mounts on the other way, the caster must have been around 1 degree - no wonder it felt a bit weird to drive....
EDIT - just remembered that Trappy listed the caster earlier on - 1.50-ish - not sure I understand why flipping the mounts has added such a small amount
Last edited by Nigel; 16/08/2015 18:47.
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547227
16/08/2015 21:03
16/08/2015 21:03
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crazyf1
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On my report I have 2,55 and 2,54 (degrees of caster) on both sides and values should be between 2 and 3 degrees according to the report. I have aftermarket standard top mounts (febi bilstein).
EDIT : Fiat documentation says 3°30' +/-30' I have Eibach springs -30mm. Can this explain the difference?
Last edited by crazyf1; 16/08/2015 21:17. Reason: Comparison with Fiat data
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547250
17/08/2015 08:37
17/08/2015 08:37
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Nigel
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.
Last edited by Nigel; 17/08/2015 08:37. Reason: double-post
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547342
18/08/2015 08:31
18/08/2015 08:31
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Posts: 17,370 Staffordshire
Nigel
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Are you sure Nigel? Camber alters with lowering due to the suspension moving in an arc which is hinged inboard to outboard, I'm not sure the caster angle adjusts with lowering? No, I'm not 100% sure, but here's my rationale:- Let's say that the bottom ball joint is 25mm forward of the centre of the shock top mount (both are clearly fixed points, so cannot vary) At standard ride height, let's say there's 400mm (wild guess) between the bottom ball joint and the top mount - this creates an angle of (say) 3 degrees Now, we shorten the distance between the bottom ball joint and the top mount (by fitting lowered suspension). The fore and aft distance (25mm) cannot change, so the angle of the line between the bottom ball joint and the top mount MUST get a little steeper, as the vertical distance has shortened. The arc prescribed by the bottom ball joint with movement of the wishbone will make the bottom ball joint move away from, or closer to the centre line of the car (thus increasing or decreasing camber) but it cannot move the bottom ball joint fore and aft, so the arc will not affect caster EDIT - contrived diagram to explain my thoughs Left-hand line is the standard suspension (as viewed as though you're looking into the wheelarch with the wheel removed) Right hand line is lowered suspension - the fore and aft distance of the top and bottom points is the same, but the height is reduced, which increases the caster angle
Last edited by Nigel; 18/08/2015 08:40. Reason: added diagram
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547372
18/08/2015 13:18
18/08/2015 13:18
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Nigel
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Are there any piccies of the Gaz "max caster" topmounts that are available as an option on their coilovers? Edit - Gaz coilovers with Max-caster topmounts Just look at the extra offset on the topmounts to create the additional caster - its massively different to the BC topmounts
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547374
18/08/2015 13:38
18/08/2015 13:38
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Nigel
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Ok I agree there will be some altering but the ammount is minuscule in the 20mm of lowering we are talking about, certainly much less than he camber created by lowering so probably not enough to recover the 1' of caster we are missing here. I agree - any increase is there, but very minimal (and probably not detectable by the driver)
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Re: BC BR Series Coilovers
[Re: Nigel]
#1547377
18/08/2015 14:31
18/08/2015 14:31
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Joined: Dec 2005
Posts: 9,706 Gone
Jimbo
Je suis un Coupé
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Are there any piccies of the Gaz "max caster" topmounts that are available as an option on their coilovers? Edit - Gaz coilovers with Max-caster topmounts Just look at the extra offset on the topmounts to create the additional caster - its massively different to the BC topmounts Unfortunately that view seems to be looking at the front to rear view of the top mount so we don't see how far back they are, but to put it into perspective, to fit the Gaz max caster top mount, you had to shave metal from the rear of the suspension mounting top mount cut out in the chassis! I think Si (Suba) had them fitted to his coupe so could contribute to the mounting of them. I did a little calculation, you'd have to lower the suspension approximately 6" to get a 1' shift in caster. I'm no mafs eggspurt but I think I got it right. It would sure look bad ass but you'd be going through a new exhaust every day.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547393
18/08/2015 16:35
18/08/2015 16:35
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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Oh wait, the damper on the right has the other view, you can see the caster quite clearly. Agreed - the centre line of the damper rod is WAY behind the centre line of the topmount on the Gaz kit I've chased Balance Motorsport by email today to get them to chase the BC factory for an update In the meantime, I thought I'd do some more research to see if anyone else is having issues with BC Lancer boys aren't impressed - check out the photo part way down the page Sadly, it appears not to be an isolated incident.... Fairly old thread though, so I guess BC have sorted the issue by now?
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547540
20/08/2015 14:50
20/08/2015 14:50
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Posts: 17,370 Staffordshire
Nigel
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UPDATE - I've had a response from Balance - they have supplied me with a technical drawing of the BC topmounts and suggested that I should tell them what changes need to be made, and they will look into having some made.
I think this is a good point for me to hand this line of enquiry over to one of the BC coilover customers - I really don't want to be acting as middle-man if I can help it
Any volunteers?
DOH! - Not Balance - Apex
Last edited by Nigel; 21/08/2015 16:23. Reason: wrong company.....
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547626
21/08/2015 16:24
21/08/2015 16:24
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Posts: 17,370 Staffordshire
Nigel
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I thought you were interested in buying a set Nigel?
I was, but I'll wait until the issues have been addressed (or I'll bite the bullet and go for the Gaz setup)
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547631
21/08/2015 17:53
21/08/2015 17:53
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Joined: Dec 2007
Posts: 2,252 Windsor/ Reading
knight7660
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with the Gaz kit dont you have to modify the chassis at some point like the D" kit which is what put me off.
reading the evo post has made me think twice about ordering the fronts now
LE53 (452BHp & 389ftlb's with Quaife) Wine red VIS FOOFY Audi RS4 B7
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547659
22/08/2015 18:22
22/08/2015 18:22
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Joined: Dec 2007
Posts: 2,252 Windsor/ Reading
knight7660
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such a shame i dont want to cut mine if i can help it. Hope the issues with the BC's are solved
LE53 (452BHp & 389ftlb's with Quaife) Wine red VIS FOOFY Audi RS4 B7
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547712
24/08/2015 08:41
24/08/2015 08:41
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mihai7645
Unregistered
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mihai7645
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So what would the risk be if I mount the BC kit that I've recently got? I've posted a pic with the top mounts and they are asymmetrical.
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1547944
28/08/2015 10:02
28/08/2015 10:02
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Joined: Feb 2006
Posts: 5,408 Essex
Trappy
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Would less castor cause more torque steer?
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1547953
28/08/2015 11:41
28/08/2015 11:41
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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Would less castor cause more torque steer? I don't believe so, although less caster makes the self-centring effect less pronounced, which means you can FEEL the torque-steer more easily Torque steer is caused by many things, but is rooted in a difference of grip between the driven wheels (which could be tyre deflection, surface, driveshaft twisting, geometry etc) I guess the only time caster could affect torque-steer is if the caster was different on each side
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Re: BC BR Series Coilovers
[Re: Jimbo]
#1548007
28/08/2015 23:22
28/08/2015 23:22
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Trappy
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Confirmed then. It's definitely squirming and pulling on uneven surfaces now since fitting these coilovers.
F****** b****** thing...
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Re: BC BR Series Coilovers
[Re: Trappy]
#1548018
29/08/2015 06:14
29/08/2015 06:14
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Joined: Dec 2005
Posts: 17,370 Staffordshire
Nigel
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With Positive caster, road surface variations have a minimal effect on the tire, the tire will continue to go straight. When a tire has a Negative caster condition, where the projected steering axis point of load is behind the tire point of contact, a vehicle will have a tendency to be easier to steer but will lack directional stability. A vehicle with negative caster is affected by any road surface variation such as small road irregularities or bumps. You have about 2.5 degrees positive caster, so you shouldn't really be getting any caster-related squirming - does it happen on and off the power and on a steady throttle?
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