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.