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.

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...)

Some good reading and setup tips here:

http://www.bimmerhaus.com/tech/shocktuningTN.html

http://www.dtmpower.com/documents/howtosetupracecaradjustabledampers.pdf

Don't go too firm on the rear! I remember when I first had my Ledas fitted, I set the rear pretty firm for a track day at silverstone, corner one, turned in on a damp track and the car immediately went sideways

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?

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.

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.

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.

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.

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.

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.

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.

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

Definitely wait until the rest of the setup is done, as I suspect you won't need both, just a rear



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

Thinking about it some more - do you have the symmetrical or asymmetrical top mounts?

If asymmetrical, have you got the top of the shock behind the centre line of the top mount, or ahead of it?

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?

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

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.

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

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...



So I have the ones that give more castor if installed correctly, but less if not? I'm Rog knows what he's doing.

If it isn't self centering then the castor is not set correctly, get the top mounts pulled aft as much as possible if they are adjustable and you will feel the steering weight up immediately.

Take the ride height down to the same as the Eibachs, its perfectly safe at that height.
Once it's up on the ramps, view the wishbones from the front of the car, they should be ever so slightly angled down at the outboard point compared to the inboard, it doesn't have to be much at all, just ever so slightly, remember you don't have much travel now.

How much adjustment are in the top mounts on these?

I took a few snaps this morning on my way out of the house.

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

The second picture you posted seems to be incorrectly labeled too Nigel.

If that is a L/H top mount, then that too would give less castor angle.

I'd try swapping them over and see what castor angle you have, the change is steering weight should be immediately noticeable, it must be pretty light at the moment?

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

I have emailed BC to ask for the reason for the different types of top mount - I'll keep you posted

Good stuff, Nigel, I look forward to the response!

Note that early in the BC group buy thread, Barbz commented that the top mounts were "for a Bravo", which Jimbo (I think) agreed with as apparently, Bravo topmounts have less castor

Either way, I'd say that the current BC asymmetrical topmounts have less castor than the symmetrical version, which in turn is the same as the OE Coupe topmount

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?

You should simply be able to swap the entire assembly from left to right, although that may cause problems with the hose connector brackets

If not, you'll need to remove the top mounts and flip the plates over (assuming the underside of the plate is the same as the top side)

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



I don't accept this explanation, so I have replied with the following:-




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.