964 understeer
Discussion
I get understeer in pretty much any power-on situation with my C2 Targa and want to reduce this. I need my rear tyres replaced soon and was going to get the alignment done at the same time.
Is this likely to cure it or can the set up be changed to dial it out a bit (without me having to opposite lock round every roundabout)?
I'm running with:
205/50/17
255/40/17
Is this likely to cure it or can the set up be changed to dial it out a bit (without me having to opposite lock round every roundabout)?
I'm running with:
205/50/17
255/40/17
hey domster...you not often wrong but in this case if he has 17inch wheels then 205/50 fronts and 255/40 rears are the recommended tyres....for 16 inch wheels then yeah..205/55 and 225/50 
Basic check should be on tracking+alignment to be within factory spec, then can play with tyre pressure , then can play with roll bars and moving outside factory spec to customise.
I'd get someone else to drive it and confirm whether this was a real issue, 911's generally understeer as the weight distribution favours rear end traction, but you can trick them into doing a bit more up front
Basic check should be on tracking+alignment to be within factory spec, then can play with tyre pressure , then can play with roll bars and moving outside factory spec to customise.
I'd get someone else to drive it and confirm whether this was a real issue, 911's generally understeer as the weight distribution favours rear end traction, but you can trick them into doing a bit more up front
Hmm in what situations are you getting understeer ? If you are just pootling around and it happens get the geometry checked. If you are on track it may be because you are simply getting the power on too early, remember the 911 - 964 has a light nose and will push wide if you'r timing of the throttle is off.
TBH its hard to give specific advice without experiencing first hand you'r car.
TBH its hard to give specific advice without experiencing first hand you'r car.
Standard C2 understeer badly ( never mind, the C4's are worse)
You can try 225/45 up front but I suspect the understeer will still be there.
To cure the problem you need to adress the built in suspension geometry factors that lead to the understeer; new and uprated springs/dampers with lower ride height and its's a go-kart.
50+ rwbhp extra helps with the oversteer
You can try 225/45 up front but I suspect the understeer will still be there.
To cure the problem you need to adress the built in suspension geometry factors that lead to the understeer; new and uprated springs/dampers with lower ride height and its's a go-kart.
50+ rwbhp extra helps with the oversteer
I haven't tracked the car but the understeer is most noticeable when exiting roundabouts under power. Even before the exit I don't feel like the fronts are gripping at all unless I lift off. Very safe I guess but not much fun. It may just be my lack of experience or I'm still too used to fwd / front engine cars.
Oldtimer I'll follow your advice and get the garage to drive and then tracking and alignment checked.
Cheers.
Oldtimer I'll follow your advice and get the garage to drive and then tracking and alignment checked.
Cheers.
oldtimer said:
hey domster...you not often wrong but in this case if he has 17inch wheels then 205/50 fronts and 255/40 rears are the recommended tyres....for 16 inch wheels then yeah..205/55 and 225/50
And my point was that 16 inch 225 rears were (I checked) the recommended wheel and tyre for a 964 C2 Targa when it left Stuttgart.
Putting blinging 17s (or larger) on without changing suspension settings etc is bound to cause more understeer.
The car would be set up at the factory to handle 'properly' with 16 inch 225 rears (albeit even then there would be a little understeer in there).
So Clubsport, you can eat your hat, and Morgan pipe and slippers in the remainder of the boxed set
scottster said:
Certainly had no understeer issues with 17s on my C2 (and I was running 205/255s of course) - I'd suggest it's more of a camber/tyre choice issue. I always ran Continentals and it felt perfectly balanced.
Look guys, this is where it gets silly.
IIRC Dave's old C2 was running uprated/lowered suspension. This isn't standard on a C2 Targa. If you stiffen up the rear suspension of course you can run on 255 width rears and keep it more or less balanced.
The 255 width rear is what they put on the 964RS, which had much stiffer rear shocks at the back than the standard model. You can't just put fatter rubber on a car with standard suspension and expect it to handle the same, even if everything is all aligned.
Of course, you can always fiddle with stuff - why not chuck in 45psi in the rears and run Colway remoulds to get things a little more neutral?
I think I'll ask my garage for advice (I'm booked in with JZM at the beginning of July).
If there's no way to optimise the alignment for my 17inchers then I'll look into uprated suspension but don't want anything much stiffer than I've already got - not sure if the targa shell could stand it.
If there's no way to optimise the alignment for my 17inchers then I'll look into uprated suspension but don't want anything much stiffer than I've already got - not sure if the targa shell could stand it.
JZM should be able to help and have some ideas. As has been said, 911s naturally understeer in the dry in tight corners anyway - not much weight on the front end. I wouldn't really advise making 911s more twitchy at the back - stickier rubber or softer damper settings at the front could be a better route. Also make sure you don't have a front strut brace, as these tend to induce understeer in isolation.
ContiSports front and rear, although the fronts only have 2000 miles on them but the rears will need replacing soon.
I use 36 psi front and rear, which I understand is the correct setting for my wheel/tyre combination.
It's possible that the dampers and springs are the originals - I'll check the sh tonight. I guess 14 year old springs and dampers with 94000 miler on them aren't going to behave like new.
The car does have a high front, low rear stance btw.
I use 36 psi front and rear, which I understand is the correct setting for my wheel/tyre combination.
It's possible that the dampers and springs are the originals - I'll check the sh tonight. I guess 14 year old springs and dampers with 94000 miler on them aren't going to behave like new.
The car does have a high front, low rear stance btw.
High front, low rear does indicate standard set up.
36psi is quite low for your rear tyre pressures - this is what is recommended for the 964RS. This is on the same 255 rears but remember the suspension is harder than a gent on the door of a Macclesfield working mens' club.
From memory, the standard rear psi is in the 40s, so this could be a good start. Check your original handbook for pressures. The tyres should be set according to the application not the specification, as far as I'm aware - although a lower sidewall will give the 17s a slightly 'stiffer' character.
36psi is quite low for your rear tyre pressures - this is what is recommended for the 964RS. This is on the same 255 rears but remember the suspension is harder than a gent on the door of a Macclesfield working mens' club.
From memory, the standard rear psi is in the 40s, so this could be a good start. Check your original handbook for pressures. The tyres should be set according to the application not the specification, as far as I'm aware - although a lower sidewall will give the 17s a slightly 'stiffer' character.
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