rear stifness

Well as i have my coop dismantled waiting for the bits to arrive, im thinking of getting a upper and lower strut brace, but what about the back? Less weight and less stifness att the back = understear right? So if thats the case ( i imagine if not wrong) how would we get the rear stiffer to perform better? So much stifness in the front should cause the rear to bounce as ther is no weight or braces that can make it equal to the front?

I was thinking about it because the front is ok and there are loads of things to do to get better grip , but the rear?

the only real way to improve is by fitting a thicker rear ARB, anything else to prevent wandering at the rear is pointless, as the shell sits on a metalastic set of bushes which fit to the subframe.

You "could" replace the rearmost set of bushes with Alu' items as this makes a slight difference.

I do believe some others have fitted a cosmetic rear seatbelt ARB ( looks VERY OEM & well made ), some have commented that this has reduced rattles a bit... probably as the old seat belt bolts were loose

Stiffness in the chassis is a different thing to stiffness in the suspension. Strut braces should stiffen the chassis only. This does not change the balance of the car as such; it just stops the suspension points from moving relative to each other. This lets the suspension work better overall; not specifically give more or less grip.

Suspension changes with a stiffer chassis will have a more precise and predictable effect.

a 22mm whiteline ARB has helped mine quite a bit, the front braces are good too, and i added a dedra front ARB - feels quite flat and soilid to me, but i'm no expert

I've got upper/lower front braces and a 22mm whiteline rear ARB, roll is much reduced compared to OEM.

I've also got the upper rear brace, looks nice but I suspect it doesn't do a lot more!

Strut braces make no difference despite the hype,.
Although i am a fan that lots of little things make a big difference.
In relative terms the chassis wont twist to the extent where 1 single bar will help.Or you'll have the seem sealant cracking and the windows popping out.
A well engineered roll cage which acts as safety and as an aid to structural stability is noticeable.

Strut braces are literally cosmetic.



I run a Eibach rear roll bar,which seemed to make the front end more precise on turning.
The Whiteline is a little unpredictable.

I messed about quite alot around the track with my Gaz suspension and making the back too firm induced heavy overseer and issues with braking.
It also didn't inspire quick cornering as you get a feel for things after time.
I found the Eibach a good all round solution to the handling with very forgiving cornering no matter how much you get it wrong,.

trying to get the best stability on the car dosen´t mean have better grip, but it is asosiated. so where do we start from? as for all these facts what i can´t still understand is , why all this elements for the fornt and not for the back ? thats where the coop needs it right? geting all the weight and traction up in the fornt suerley we will need to get the rear sorted.what im trying to say is get it all balanced front+rear . i now weight problem is actually imposible unless we have the cash to make a RWD. getting all the cash spent on the fornt wont make us get more stability form the rear or will it?

"This does not change the balance of the car as such; it just stops the suspension points from moving relative to each other. This lets the suspension work better overall; not specifically give more or less grip"

wich means it won´t help on understeer or oversteer then?
as for the problem on the coop "in my case" is that understeer has been reduced by konis , new arms ,actually new everything, and i would like less. But oversteer is quite bad, so get that sorted if the rear is stiffer you get better stability wich means extra grip ??

I disagree with the comparison to Rwd,.
I outhandled a Porsche GT3 RS around Donington park and i run a FWD setup.
The coupe in stock form is not an agile car on the corners.
With money spent in the right places you escape the limitations of the FWD.
I dont suffer with oversteer unless heavy braking into a corner in the wet.
Under what circumstances does your oversteer typically appear?

I think there's a big difference between outhandling and having bigger balls through the corners.

A GT3 RS would show a coupe a clean set of heels every day of the week and if it was my GT3 RS, I'd be a little concerned about driving it on the ragged edge too, it would be a little more expensive to fix if you got it wrong.

The problem is i get big understeer in fast corners. Accelerating in th corners i get a loss of traction but quite normal for a 300hp fwd.

do you not mean oversteer?...understeer in fast corners sounds a little strange?
As people have said, there is a few ways to stiffen the rear of the car... rear arb, solid bushes, stiffer springs, harder dampers settings,tyre pressures etc will all change how the car feels and reacts.

The rear trailing arm bearings are one thing to replace, if there is play in them they effectively give you rear steering which means oversteer!

The coupe will always understeer if you enter a little too fast, it will give an initial turn in then just plough straight on.
Adapting driving to suit the chassis is probably the cheapest way of sorting the issue.

Thats true in low speed bends, but high speed?

Nop, the problem is understeer. As for the oversteer i get is quite normal.

Rear arb should be top priority then!

Been looking at recent BMW´s Audi´s etc, I will look into transverse stiffening brace over the "prop-tunnel", which many cars use nowadays (actually it's already on the Golf Mk3). Just in front of the rear axle.

Problem for my Coupe and many others might be the big exaust which is a bit in the way.

Top priority really ought to be an investigation into why the car is understeering in fast corners - it should be perfectly planted

My guess would be rear radius arm bushes, poor tracking setting, or incorrect camber

Is it the same for left AND right bends?

The same applies - a front heavy, FWD car is always going to understeer when on the power. Stiffening the rear and playing with alignment / suspension will result in lift off oversteer - so you can control what the car is doing with your right foot once it's pointing where you want it to.

Bang on Jim, I minced a GT3RS round Donny, but the driver did not have a clue and was cleary scared, a well driven GT3 would blow a coupe into the weeds. Outhandled JBT I dont think so, if you were driving the GT3 you would blow away your own coupe lap time for sure.

Actually never thought about that nigel , but when taking corners to the left it understeers more than to the right. I should get the rear checkd to see if everything is ok.

That confirms my theory that you have a fundamental geometry issue - you need to solve this before you start playing with suspension settings, otherwise you're just going to be masking the problem

Well ill have to eliminate, bearings, shocks and springs as they are new

When did you last have the tracking done? How did they set up the car?

i ve never had the rear tracked actually. i thought you couldn't track the rear wheels ?? only the front right?

This maybe technically true but I have never had understeer at speed?

Nigel is right you should get everything checked to make sure nothing is a miss....then put the rear arb on
The rear geometry is not adjustable, but in an ideal world you should set the front in line with the back, so four wheel alignment is better.

The correct geometry makes a big difference on my car, so its worth getting setup properly.

I have been trying to get my car to handle right for years and it is still not there, I have had my rear bearings checked and they have no play but they do have 4mm toe in on one side,I should have just changed them last time.....but I'm getting them changed soon and i'm hoping this will be the last piece in the jigsaw!

Try turning in hard at about 80 mph with no throttle on - I promise you the car will go straight on unless you are running some very severe negative camber on the front, and a very stiff rear - even then the weight will go on the front outside wheel, and you'll go sideways when it bites.

If you do the same in something mid engined the car will still go straight on, but either sideways or backwards.

Ill try that out suba in the next few days as ive got the coop in the garge with no cambelt busy waiting for the bits. On friday ill try it out. With no throttle ? Why ? To not oversteer i imagine?

I have a feeling suba was replying to jonone, and his comment wasn't directly aimed at you

Upsss didnt see jonone's post.

LOL!

I managed to get my coupe to handle as follows (with a lot of effort, and a lot of money):

turn in hard with no power on (or lightly on the brakes to provoke it), rear end goes 'light' - point where you want to go before any real opposite lock is needed and power out to pull the car straight through the corner. (with a shade over 300bhp - so the rear will always follow the front when power is on)

With the balance of the car and the power going through the front wheels it is very hard indeed to spin or oversteer when on the power, and understeer is inevitable.

I hasten to add that these antics were all on track, I would not want to mess about as above on the road at 80mph.

I'm so glad you said that! I kind of suspected that might be the case. Even so, I had a rear ARB and front strut brace on my list of things to get, but now I can save my money on the brace

I'm going to stick my neck out here and say that I did notice a difference with a top and lower brace fitted. Personally I noticed a sharper turn in and as such less understeer at low speed corners. I don't track my car so can't comment on that, only on road use. Any doubters are welcome to come and drive my standard car with and without the strut braces. Bring your own OEM lower wishbone bolts as i'm not sure what I've done with mine!

Front upper strut brace makes A LOT of difference...it very easy to test this with a back to back drive with one on and then it off.

I added a top brace and was impressed with the improvement in the feel of the front end.
I then added Nigels lower brace and was very very happy with the results.
One of the best improvements for the money spent.

This may go against most guys experiences, but I have now changed all 4 springs from eibach to the Group Buy CountryCrusing ones.. They are more progressive and I find the rear has better handling both in corners and over bumps.

You can call them progressive springs..and they thicker then Eibachs.. Its a cheap and simple change.

I know adjustable shocks may also improve things, but everyone has different opinions.

Theres something that i find a bit strange, why are there so many diferent opinions ? I thought that the struts improve alot the handling, but i see peopele saying that it dosent make any diference.

I can only guess that those who say they don't make a difference have either not tried them as a first modification on thier car becuase they thought it'd make no difference, or have done them after heavily modifying the rest of their suspension and as such when they were finally added didn't notice much of a difference. Or perhaps some other unknown reason?!

To be fair, there's only one or two people saying they make no difference and many, many people saying they've improved the handling of their car.

I've driven LOTS of Coupes, in many states of tune and chassis configuration. I think I'm well qualified to comment on what works and what doesn't.

In my humble opinion, the best handling mod you can do for a Coupe is shocks and springs, followed by an uprated rear ARB. Next comes a bit more negative camber at the front, followed closely by an upper strut brace and then my lower subframe brace. Personally, I wouldn't bother with an uprated front ARB unless you've already gone VERY stiff on the rear ARB and need to balance it up a bit.

As Gunzi suggests, I reckon if you stuck a pair of braces on a standard car, the difference would be very noticeable. Adding them to a car with a host of existing handling mods will be less noticeable.

...or any lower subframe brace..
Yes it does make a big difference, more so than the Sparco strutbrace I'd say.

Mmmmm i'm very interested to hear peoples views on handling and like Nigel i reckon i am pretty well placed to pass comment, all be it however on a pure race set-up. There are fundamental things that if done will improve the handling of your coupe or any car for that matter. What you then have to do is fettle your car to how you drive. Somoe people will not like a vervous and skittish rear end on a fwd, personally i quite like it as it's much faster on track but i certainly wouldn't want this in a road car where progressive handlig on the limit especially in a FWD car is absolutely a necessity otherwise you will find yourself backward into the scenery. However there is also a school of thought where some people have completely different set-ups yet are just the same on track, this is all down to the driver. However i emphasie this is on track only. On the road it needs to be a little supple. The roads in the UK are not smooth and always contain diesel, oil and other contaminents which make the road surface very slippery when wet. Unfortunately we don't have the luxury of dry weather predominently.

I agree that the strut braces will help on their own and if teamed up with better suspension and spring ratings you will get a road car handling pretty well. Everything is a compromise and the more you fettle the less time tyres, brakes and suspension lasts before it wears out. Making something stiffer will put pressure on something else further down the chain.

I'm now running 750lbs springs on the rear of my car and 850lbs on the front, with race spec dampers, every brace known to man and some serious geometry settings. My coupe is still not the best handling FWD car in the race as newer more advanced cars such as the Seat have a better foundation to begin with and more technolgy. You can only pee with the winkle you are given so to speak.

Very interesting and informed view Marco

I was a passenger around Curborough in a Clio 200 Cup and I was staggered at the precision of the steering AND the compliancy of the chassis (normally these are mutually exclusive on a FWD road car)

I wonder what it is about the Coupe that makes it such a poor starting point. Seeing as the vast majority of the geometry can be changed (albeit expensively, in some cases), there's no reason why it shouldn't be able to be as good as something like the Seat Leon you compete against.

I'm beginning to think its probably down the the iffy weight distribution. Great for traction off the line, but counter-productive almost everywhere else.

I know the Leon will have the benefit of several more years development and chassis knowledge, but should it really be THAT far ahead of the Coupe? What else does it have?

Just as a matter of interest, you say you're running 750/850 lb springs - do you know what standard is, or maybe what Eibachs run at?

Nigel recall the chassis is from the 1980's, recall what cad would have been back then and the effect that would have on iterations. The base car was not of a performance starting point, the earlier generation Leon Supercopa had custom uprights I'm darn sure the later version has even more custom items (One of these also one the eurosaloons championship a few years back), also we cannot be sure without looking what type of suspension method they are employing including the design (double wish bone perhaps) and the type of antiroll bar - bars which are far removed from the bits of wire used on our cars - I know the Alfa 156 ST has hollow bars in the 50+mm range, such that the roll resistance is mainly ARB and not springs.

The Tipo design of high outer wishbone position gives a poor force application point in regards to inner wish bone position. Also the upright will lack rigidity compared to modern designs - this is very apparent with the BMW mini such as the challenge version I picked up recently on behalf of my brother and took a look round) in the mini the lower ball joint is as low as it can be, enabling the wishbone to be far more level at ride height thus less angled in the roll.

McPherson struts may not be the worst part of the tipo design but the trailing arm might well be as there is no camber recovery in roll. I think the evolution to the 156/147 chassis shows the progression to what should be superior front double wish bone and rear McPherson struts, and if you look at those alfa you will still see the Tipo underpinnings albeit with added sections to accomodate the new suspension.

The tipo along with its coupe counterpart are very flexible chassis, with the coupe probably benefitting fromt its shape over the hatch back but they cannot be a patch on modern cars iterations between lancer evolutions show how rigidity can be increased substantially without noticably radiacally changing the shape.

The fiat is not a great place to start from or rather its original design was a mass market road car which then tried to become a sports car - fiat did do a few things Tipo to coupe like wider track, then the turbo models got substantially beefier uprights, but as you know alfa went further with the 916.

When they races the 155 d2 everything was custom, but they had to keep the same rear suspension configuration, a thorn in their side, but nothing was shared with the production vehicle aside from the chassis mounting points. This is not quite the same for the 156 ST where you can see a production front and rear sub frame (modiefed for a plate brace at the front) and modified production wish bones, the uprights again a near as custom as they can be. Although its unfair to compare home brews with factory challenge cars which the likes of the Clio cup and Leon supercopa are, developed on €100K+ budgets

850 fronts Marco!, maybe I can go stiffer! Currently 627 and tons of understeer, rear was wound up for Trevs last race still didnt seem to help.

I estimate eibachs to be 70Nmm so 400lb/ft as a guess.

This is why lowering a coupe does not help make it handle - nice description Rich!

The standard fronts are indeed about 400lbs and the rears 350 maybe. Not sure about the Eibachs Nigel and you know how secretive Eibach are when it comes to spring rates!

Very informed reply Rich and right on the money. Technological advances in chassis design make a world of difference and even a standard modern clio or the like will outhandle a well sorted coupe. Rich i have loads of springs if you need any to try mate.

That's why i love making my car go se well, it's bucks the trend and makes people see what it is really capapble of in the right hands and with the right set-up. Yes i do have to drive it like i've stolen it but is that not just more fun again. Come and watch me through the twisty section of knockhill and there is lterally nothing any quicker down through there. That's not my own opinion that's people standing watching. That makes me proud to be competeing in my old Fiat!

Is there anytrhing that can be done to increase the rigidity of the chassis aside from the usual bracing? For example the Nova crowd seam weld their engine bays before fitting the 2.0 engines. Is this something which you have done Sparco, or did Fiat provide a rigid engine bay to start with?

Suba -Well its is off set by the lower CofG, but when the angles get extreme its bad. I was upset by that mini, it had everything I wished the fiat had, no wonder they handle well.

Still the Stilo had rear beam suspension a totally retro grade step over the tipo based designs.

Marco, are they 60mm I'd like to give it a stab, I noted the lap time change you found on the front increase in rate.

Yes i have 60mm fronts, 650's 750's spare.

Std front springs are surely not 400lb?

The Gaz road/trackday kit was sold with 425lb front springs and that's rock solid on the road!

When I had the 8" 425lb springs on the front of my car all I got was a crashy ride and loads of wheel spin.

The problem with my Gaz setup is, if you use a tender spring the platform between the springs rubs against the body, so I have been forced to use one single rate spring, I have ended up with a 300lb front spring, which for me is about right on the road, I would like less body roll but when you up the poundage the ride goes to pot.
My only other option is to get a dual rate or progressive spring made so you still get a decent ride.

There is a debate if the eibachs are progressive or not, maybe this is how they hide there poundage? but i will be shocked if they are more than 300lb

Im swapping the rear suspension on my fiat tipo for a alfa gtv remove spare wheel well tank in boot powerflex bushes it can be done to a coupe aswell tipo