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i have maxed my caster as much as I can. I got 4.6 degrees. My tire hits the fender liner so I am going to back it off to rs spec. I have seen the strut top plates made by ground control that also have a caster adjustment. Has anyone used these? Is it always better to get the most caster possible? I understand why more caster is a good thing for more camber on turn. But maybe it throws other geometry of the suspension off if you go beyond the rs specification for caster. Any advice would be great.
If you want to run tires- like 235- then the ground control plates might be useful in terms of keeping the tire out of the front fender liner. Clearance is tight on my car with 225’s with the stock equipment. If I was going to get camber plates anyway I’d probably opt for
the CG ones just to have that added ability.
I also wondered how much is too much. I think it also has to do with how fast you generally go around corners/ what your camber specs and tire pressures are and what kind of tire wear your getting.
i have maxed my caster as much as I can. I got 4.6 degrees. My tire hits the fender liner so I am going to back it off to rs spec. I have seen the strut top plates made by ground control that also have a caster adjustment. Has anyone used these? Is it always better to get the most caster possible? I understand why more caster is a good thing for more camber on turn. But maybe it throws other geometry of the suspension off if you go beyond the rs specification for caster. Any advice would be great.
caster has no effect until the steering wheel is turned, Then it tips the top of both tires toward the inside of the corner you are turning into, Think of it as dynamic camber which helps both front tires generate grip
KPI or king pin angle is a different kind of caster, it works differently to regular caster in that it tips the top of the outside tire out(bad) and the top of the inside wheel in(good)
caster offsets the bad KPI on the outer wheel and helps the good KPI on the inner wheel
KPI is not adjustable w/o changing the spindles
The caster spec for all 964 is 4°25'+15'-30', generally more to a point will be better for handling and feedback through the steering wheel, 993 caster spec was increased to 5°20'+15'-30' for that reason.
Why would someone want less caster?
the lower the caster used the faster that end of the car responds to steering input, the higher the caster used the slower that end of the car will respond, so it is not uncommon for a race 964/993 to use 4° 00'
Now as to hitting the liner, on a lowered car w/ taller tires the tire will often hit the liner at full bump, the Cups use modified liners to reduce that issue, alternately stiffen the springs or raise the car
Bill If the cup cars were using 4 degrees I am assuming they used a lot of camber instead to get the best of both worlds. Given that tire wear is not a massive concern.
For a a non dedicated track car that sees some track days and auto cross events in your opinion is more caster better. So there is more of that dynamic camber since setting camber aggressively wears tires very fast. I guess I am asking if for a non dedicated track car is the dynamic camber more important than the cars response to steering input. Or was Porsche bang on with that 4.25 setting and the RS camber setting to get the best of both worlds. If so why did the 993 and so on continued to increase their caster?
Bill If the cup cars were using 4 degrees I am assuming they used a lot of camber instead to get the best of both worlds. Given that tire wear is not a massive concern.
For a a non dedicated track car that sees some track days and auto cross events in your opinion is more caster better. So there is more of that dynamic camber since setting camber aggressively wears tires very fast. I guess I am asking if for a non dedicated track car is the dynamic camber more important than the cars response to steering input. Or was Porsche bang on with that 4.25 setting and the RS camber setting to get the best of both worlds. If so why did the 993 and so on continued to increase their caster?
You will be hard pressed to get more than ~4°30' of caster and yes I'd go for the max that you can get. Then depending on tires run Up to ~ -2° camber, spec is 0 but the more neg the more bite in corners w/ little sacrifice in wear, 0 toe
If you are more concerned w/ tire wear than turning then go back close to 0 camber, The oe style camber plates are designed to allow an owner to switch between more camber for track days and less for street by rotating the shock in the mount. No alignment needed. For oe RS camber plates the range of adjustment is 1°30'
Now as to hitting the liner, on a lowered car w/ taller tires the tire will often hit the liner at full bump, the Cups use modified liners to reduce that issue, alternately stiffen the springs or raise the car
Any more info on these modified cup liners please? Is there a part number or any pics available showing whats different - it could be a good mod for many?
Maybe Bill can chime in on this as well, I just replaced my struts with B6's with Eibach springs on my 1992 964 Turbo, I have the ride height set to RS spec's, The rear alignment came in perfect to RS spec's as did the right side front , caster set at 4.25 and there's room for more caster, but the drivers side cast wont go past 3.25 caster, if you turn the cam adjuster more it goes the opposite way. What could be the problem ? from what I can see, the control arms look the same and it's mounted the same. I confused. Please advise
I would pick a point on the front control arm mount (bushing) and then another point diagonally across the front of the underside of the car and measure the distance between the two points. Do the same on the opposite side of the car, if the measurements are different that will tell you if anything like your frame is bent. I would do the same thing on the control arm mount for the front and rear bushing.
I also would do the do the same thing from the front boot area from the top of the strut to a point diagonally to make sure nothing is out at the strut mounts.
Start there, that should point you in a direction to further investigate. I don’t have a turbo model. But getting 4.25 on both sides is not an issue at all on my 964 c4.
11-02-2018, 02:05 AM
Is more caster always better
