I am having trouble nailing the handling of my coupe,i have spent lots of time and money trying to get it right.
The problem i'm getting is the rear "moves" a lot, if you pretend your warming up the tyres on a gp circuit the rear of the car "moves" and "squirms" almost like its trying to "oversteer".
So it turns in very sharp but you have to be quite sensitive with your steering inputs otherwise you get the rear moving around which is unsettling in high speed bends,its never let go but for me it does not inspire confidence.

The car "handles" as demonstrated by my friend (a bit of a wheel man) who took me to the notorious perbright bends in surrey and (a) scared the life out of me and (b) said it probably carried a similar speed to his e46 m3 down the same stretch of very twisty road, helped by the mobile rear end adding turn-in and helping the front resist understeer.

I thought it may have been a trailing arm problem and have only recently got round to changing them, which has not cured it.
I also have solid rear subframe bushes so they should be good, playing with the dampers helps as it slows the movement of the rear but ultimately feels the same.

so this leaves my 25lb rear spring bias will this lead to a mobile rear end? or do people think there could be still problems with the trailing arms/bushes?

To be honest if your Coupe still has original rear subframe bushes fitted I wouldn't be surprised if this is causing rear end steer, if it has either look at changing them for solid mounts (noisy ) or replace them for genuine new replacements.

The rear trailing arm bearings have been changed and I have the solid subframe mounts joe, the mounts were second hand but i figured there only metal so cant go to far wrong?......could there still be play in the mounts/bearings? is there anyway to check this?

Also might try putting in std rear springs.

What dampers are you using Jonone? Also what wheel/tyre combination are you running?

gaz dampers, std 20vt wheels, falken 452 tyres.

It could well be the tyres shifting around then, try a lower profile tyre and see how it feels then, I notice a huge difference switching from the 18"s to a standard wheel and tyre, the car really feels like it's shifting around on the standard 16"s.

See if you can borrow some 17"s and give them a try!

hmmm not saying your wrong but does anyone else get this on std wheels/ 225 45 16 tyres?

If you've got solid mounts fitted and you've replaced the trailing arm bearings the only other movement is going to be from the tyres, what pressures are you running the 225's at?

32psi

Going back to the springs they are a std style spring but they have two sections a 325lb main section and a 190lb section that runs fully compressed to stop the spring from dislodging on full droop, even though it should be fully compressed with the weight of the car on it, it might be the transition when in a bend switching between the 190lb and the 325lb section?

the other thing is it maybe just the effect of running a harder spring in the rear?

I don't think so, for one, as you say the lower rate is compressed and is only there to prevent dislodging on full droop which you will never have on the road unless you are jumping hump back bridges.

These springs don't just switch rates, it acts as one rate which is a bit of maths between the two which combines to give you an initial spring rate.
Main spring x tender spring divided by main spring + tender spring = initial spring rate (I believe that's the correct formula) So you have an initial spring rate of 119Lbs.

The coupe is very light at the rear anyway with a huge fwd weight bias so the rear will always feel a little unsettled, maybe add some ballast to the rear and try again.

Oh and with regards to the tyres, you've fitted solid bushes to the rear and have the Gaz dampers, the only give in your rear suspension is now the tyres, there is nothing else that can flex or move so the tyres are now taking up all that energy.

32psi will make the rear end "mobile" - drop it to about 29psi and you'll get some of your stability back

Also, a stiffly-sprung rear will reduce understeer (up to the point of oversteer if you go too far).

Do you have adjustable damping? If so, firm up the fronts or slightly soften the rears.

It sounds to me like you have too much of a track bias on the car and it needs to go softer for quick road use.

playing with the dampers has little effect,my fronts are already stiff and it does not feel any better stiffer i just get bad ride and more understeer but the back feels the same.
the back actually feels a little better with the dampers harder as it "slows" the roll, if that makes sense?
Im not actually getting oversteer and it has never really bitten but at speed it turns in very fast and its a split second before the rear follows and then it follows with "jink"..if that makes sense.

Yes - makes a lot of sense and it must be disconcerting when it's being driven hard

My first guess would be tyres - a soft-sidewalled tyre might cause the behaviour you describe. The front tyre will always use up its sidewall deflection first, due the the extra weight and the fact the the front wheels are doing the steering. The (much) lighter rear end will then fall onto its tyre sidewalls a little later.

I would try to borrow a set of wheels and (good) low-sidewalled tyres to see if it makes a difference.

If it doesn't, you have something flexing or moving. Whilst it would be logical to suspect the rear radius arms or subframe mounts, I would have a close look at the front subframe and the wishbone mounts.

You know what, i think you guys maybe on to something....I also spoke to my friend who drove the car and he agrees as he had the same thing on his e30 m3 and said tyre choice made a huge difference to how it felt giving the feeling described.

falken 452 are 89y and toyo t1r are 93w in the same size.

Well - an easy test will be to do a front to rear wheel swap (not forgetting to change the pressures of course) - see if this alters the car's behaviour

i have falken 452 all round, just noting sidewall stiffness on websites!

ah - sorry - I misread your last post - thought you had a pair of Toyos in there

We aren't just pretty faces you know.........And Nigel's not even that pretty!

well i have been looking around the net and few people have had noted the same rolling/double bite at speed putting it down to the 452's tread movement/sidewall stiffness, but it gets complicated because tyre sizes come into it and 17s and above will have stiffer sidewalls and xl ratings so many do not mention this.

if its as simple as this i will be pleased as punch and be very happy with my car as this will be the final piece to my coupe puzzle...just need to find another £1000 now!

p.s im sure your both stunners

Only when it's very dark.....



I had a very similar experience when I fitted a set of four Toyo Proxies PX4 - the Toyo website listed them as "the new Ultra-high performance tyre", but the car was terrible. read my thread about awful Toyos well worth reading, just to hear how the tyre problems manifested themselves. Note that halfway down the page, DaveT recalls having a similar problem with some Falkens.

Quite simply, the tread blocks were moving around, causing all sorts of steering and stability problems. I could even make the car turn by booting it hard in a straight line

By far the simplest way to confirm or eliminate this hypothesis is to fit another set of wheels and tyres. If you weren't so far away, I'd offer to lend you mine to try out.

thanks for the offer nigel,funny enough i have always wanted you to drive my car to steer me in the right direction (no pun intended) but as you say we to far apart.

out of interest is there still a gb on the prorace 1.2 that need no spigot rings/right offset etc, where do i get them from and what do i ask for etc?

after today at oulton park doing a track day tires can make a massive difference to a car if you were close to me i would borrow you a set of wheels with TR1 tires
i spent a day tring to set up a pug 205 with toyo px4 tires in the wet......... the only tire with built in oil slicks..... try different tires thats all that can be left

Jon - I'm in Horsham next Wednesday for a couple of hours - happy to meet up if it's anywhere near you. I'd certainly be happy to drive your car if you want me to.

The ProRace 1.2 deal never took off, although I reckon they will still do you a good price - speak with Andy Williams at Rimstock in Birmingham

next wednesday could work, its a little drive to horsham but would be interesting to see what you think! pm me the details of when and where!

apart from 17's I was thinking of trying some 16" trackday tyres on the spare set of wheels i have, I have been looking at the federal 595RS-R as there cheap and seem to get fairly good reviews on the net and a few people have run them on here.
I am slightly worried that there load rating is 87w so less than the falken but does that mean in the real world they will be softer? being a track tyre they should have strong sidewalls and tread blocks?
I am attending the trackday this sunday so mind is split what to do, the federals are only £320 for four....but then that money could be put towards 17's if i decide to go that route

nigel did you find a change in feel from running your 17's with t1r and 16's with the trackday tyres on?

Yes - the 16" trackday tyres were firmer than the 17" T1Rs (and of course they gave much more grip). However, this was partly because I chose to fit the stiff-sidewalled Dunlops on the front and the soft-sidewalled Yoko AO48s on the rear. The handling was very pointy, with the back end getting quite loose, but that's what you want on a tight handling circuit like they run at TOTB

Hopefully this thread will make life easier for other Coupe owners when setting up the rear end as I spent ages getting mine right and had to try different setups until I was happy, there is one item I haven't read or I've missed it in this thread, rear anti roll bar, is yours standard jonone?

I tried several different conponents, solid rear mounts first which were too noisy so I've changed back to new OEM rubber mounts, new trailing arm bearings, hubs, 16"-17" and finally 18" rims but the biggest difference I noted with the lively rear end steer and weight transfer was an uprated 22mm ARB, I even tried a 24mm but found this too stiff so changed it back, now mine is really quite planted and I can predict it's movement dependant on road condition and speed.

full list is:
22mm whiteline rear arb.
dedra front arb.
gaz dampers.
300lb front springs.
190/325lb rear springs.
solid rear bushes.
new trailing arm bearings.
increased caster top mounts.
barbz hub centric washers for camber.
poly bushed wish bones.
16vt upper strut brace.
omp lower brace.
16" 20vt wheels
225/45/16 falken 452 tyres.

geometry is: 1 degree camber , 2mm total toe in.