964 C4 wheel alignment
Discussion
After fitting a set of P-Zero Rossos to my C4, the steering feel changed completely. The steering was much lighter and with much less feel than on the old Contis, and initial understeer was much increased requiring far more lock to get into any bend, occasionally with quite alarming results as the front tyres just lost grip. Ultimate grip once in the bend was much higher though.
I was not at all comfortable with this so I had a full 4 wheel alignment done and this actually added to the problem. The steering vagueness was increased and initial turn in at any speed was a bit of a guess with more and more lock being required where previously very little would have been needed. Once into a bend it was OK and the inherenct understeer was well under control. The settings were not standard but as suggested by the workshop of a well known independent with considerable track car experience. The car is lowered too.
Unhappy still, I got the independent to have another look which they did. Now, the steering has no feel and is twice as heavy as before with all the other problems remaining. Seriously, a 50 mile drive through Essex into Kent in the pouring rain just wore me out, mentally and physically.
Where do I go from here? Obviously the tyres require a totally different setup to the Contis so should I go back to completely standard. Basically, I just don't want to drive the car at the moment as it is so s**t. Anyone got a good specialist tucked away or got magis settings to make me happy again. All suggestions welcomed.
Incidentally, the car is my daily driver but will also do half a dozen track days this year so I accept that some compromise is necessary but it was so much better before the change of tyres. (And yes they are well run in - 1500 miles+).
Thanks
I was not at all comfortable with this so I had a full 4 wheel alignment done and this actually added to the problem. The steering vagueness was increased and initial turn in at any speed was a bit of a guess with more and more lock being required where previously very little would have been needed. Once into a bend it was OK and the inherenct understeer was well under control. The settings were not standard but as suggested by the workshop of a well known independent with considerable track car experience. The car is lowered too.
Unhappy still, I got the independent to have another look which they did. Now, the steering has no feel and is twice as heavy as before with all the other problems remaining. Seriously, a 50 mile drive through Essex into Kent in the pouring rain just wore me out, mentally and physically.
Where do I go from here? Obviously the tyres require a totally different setup to the Contis so should I go back to completely standard. Basically, I just don't want to drive the car at the moment as it is so s**t. Anyone got a good specialist tucked away or got magis settings to make me happy again. All suggestions welcomed.
Incidentally, the car is my daily driver but will also do half a dozen track days this year so I accept that some compromise is necessary but it was so much better before the change of tyres. (And yes they are well run in - 1500 miles+).
Thanks
Probably stupid questions follow...but you didn't mention any of this in your post...
Are the tyres inflated correctly - what pressures are you using?
Are the tyres 'directional' and pointing in the right direction?
How many miles have you done on the new tyres, you should allow a few hundred miles before judging their effectiveness.
If it isn't any of the above then take the car to another indie and get them to drive it and give you their opinion.
Are the tyres inflated correctly - what pressures are you using?
Are the tyres 'directional' and pointing in the right direction?
How many miles have you done on the new tyres, you should allow a few hundred miles before judging their effectiveness.
If it isn't any of the above then take the car to another indie and get them to drive it and give you their opinion.
Hi
New tyres can feel very different for a quite a while- taller treads, stiffer sidewalls,(both of which will mean more initial understeer but good grip once the line is established) and the release compound, although you mentioned that they seem well bedded in.
Pressures? Sometimes a fitter will stick 40-odd in the front, that'd make things skittish.
Did you get a narrower front than before inadvertantly? Not implying that you don't know what you're doing of course..! Just looking for clues..
Some days my C4 feels like all it will do is understeer, but just those no-grip-after- first-rain days, perhaps with not much gas in the tank. Its difficult to know for certain, though, as you have now had the geometry changed from what you were used to..It sounds like they dialled in more than standard front negative camber, which sharpens turn in , but might make initial C4 understeer worse?
Might be worth borrowing a set of different brand tyres from an understanding mate to do a back to back, or pulling back the camber.
New tyres can feel very different for a quite a while- taller treads, stiffer sidewalls,(both of which will mean more initial understeer but good grip once the line is established) and the release compound, although you mentioned that they seem well bedded in.
Pressures? Sometimes a fitter will stick 40-odd in the front, that'd make things skittish.
Did you get a narrower front than before inadvertantly? Not implying that you don't know what you're doing of course..! Just looking for clues..
Some days my C4 feels like all it will do is understeer, but just those no-grip-after- first-rain days, perhaps with not much gas in the tank. Its difficult to know for certain, though, as you have now had the geometry changed from what you were used to..It sounds like they dialled in more than standard front negative camber, which sharpens turn in , but might make initial C4 understeer worse?
Might be worth borrowing a set of different brand tyres from an understanding mate to do a back to back, or pulling back the camber.
Tyres are the same - 205/50/17 & 255/40/17 - and the pressures are always 36 psi and checked weekly. The fronts now rub, which they never did, on full lock as the Rossos seem an awful lot wider than the Contis and this is on a wide bodied car.
The front camber has gone from -0*21' to -0*08'
The front caster has gone from 2*49' to 3*06 (sorry no degree sign here)
Do I assume that the column "specification" on the printout gives the standard settings. If so, then I do have slight negative camber but within spec. The caster is about 30% away from standard.
I don't want to change tyres but I do want to get the settings better.
The front camber has gone from -0*21' to -0*08'
The front caster has gone from 2*49' to 3*06 (sorry no degree sign here)
Do I assume that the column "specification" on the printout gives the standard settings. If so, then I do have slight negative camber but within spec. The caster is about 30% away from standard.
I don't want to change tyres but I do want to get the settings better.
I'm guessing it's the excessive castor that's causing the extra weight through the wheel. 30 % out of spec is a massive amount.
Are the tyres the correct (N rated) ones for the car ?
I'd set things (accurately) back to within the specified settings and try the car again, if it still feels "wrong" get your indy to swap the wheels and tyres off another car to see if this improves things.
Are the tyres the correct (N rated) ones for the car ?
I'd set things (accurately) back to within the specified settings and try the car again, if it still feels "wrong" get your indy to swap the wheels and tyres off another car to see if this improves things.
Richard,
According to the specs (and the alignment chart I sent you) the front castor angle for the 964 C2/C4 should be 4° 25' +15'/-30'. The settings you seem to have are WAY off. The camber setting is more according to taste but the standard spec for both narrow and wide bodied cars is 0° =/-10'.
I'm surprised that your indi has set it up so far off spec. If you can't get it sorted it might be worth a visit to JZ Machtech although they ain't cheap!!
Regards
Dave
According to the specs (and the alignment chart I sent you) the front castor angle for the 964 C2/C4 should be 4° 25' +15'/-30'. The settings you seem to have are WAY off. The camber setting is more according to taste but the standard spec for both narrow and wide bodied cars is 0° =/-10'.
I'm surprised that your indi has set it up so far off spec. If you can't get it sorted it might be worth a visit to JZ Machtech although they ain't cheap!!
Regards
Dave
Unless the car has been aligned using laser equipment by someone who knows what they're doing I personaly wouldn't have much faith in the outcome or numbers for castor, camber and toe.
Castor seems way out and I guess it would be nice to know the toe as well. I cant see the camber being the problem unless its well out of spec and IIRC you just don't have that degree of adjustment on a stock C4 to get it really "wrong"
Castor seems way out and I guess it would be nice to know the toe as well. I cant see the camber being the problem unless its well out of spec and IIRC you just don't have that degree of adjustment on a stock C4 to get it really "wrong"
Thanks for the respones and for the cart Dave.
The work was done by a firm with considerable experience, not the least of which came from a guy involved in the running a team at Le Mans for many years - certainly last year as well.
It may be that I can't get my point across to them very well as I am not too well versed in suspension settings. I think that I will ask them to set it back to standard and see how it feels.
The fact remains though that it was fine until the day the tyres were changed and then it just was so totally different - even after about 1000 miles which should be enough to bed the things in.
The work was done by a firm with considerable experience, not the least of which came from a guy involved in the running a team at Le Mans for many years - certainly last year as well.
It may be that I can't get my point across to them very well as I am not too well versed in suspension settings. I think that I will ask them to set it back to standard and see how it feels.
The fact remains though that it was fine until the day the tyres were changed and then it just was so totally different - even after about 1000 miles which should be enough to bed the things in.
Gassing Station | Porsche General | Top of Page | What's New | My Stuff