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My silver 993 came equipped with an Uwe Gemballa suspension, and the car's ride height is a bit lower than RS. Not ideal for daily driving, but the car rides exceptionally well on the track so I really don't want to change a thing.
The trouble is, after switching to Bridgstone RE 11's and driving a bit more aggressively at the AX, I discovered that the front tires have been rubbing my front fenders. Ugh! Not an issue at the track mind you, just AX. I took the car in reluctantly today to try and raise the front end a half inch or so, but I'm told it can't go any higher unless I change the coils or insert shims, neither of which I want to do. So I'm adjusting the camber a bit, and will likely roll the fenders (AFTER I get the fender straightened and repainted on the inside, doh!). I'm hoping this will do the trick and allow me to keep auto crossing with the existing Uwe Gemballa suspension. If not, I may need to run smaller tires in front for AX.
Here's a recent photo depicting ride height.
Low ride height
If you look just above the R (RE 11) you can see where the fender got pushed out a smidge
Nice car... I never understood why here is so much of a lip on the front of these cars... If you are open to rolling the fender it will buy you a bunch of clearance.
You don't need an special tools either... A plastic deadblow hammer is all you need (in the summer). Set the car outside and let the paint warm up and plan on taking 1000 small taps working your way back and forth gently easing the metal into shape rather than 10 gorilla strikes.
One thing to consider that most don't: When you roll it you want to make sure you form it so water and grit can flow out and don't get trapped. With a hammer and gentle touch, you can form the metal to your liking... With one of those DIY roller thingy's, most people don't pay attention to the shape they are creating... they just blindly work it back and forth...
The big lip is to retain theedge of the wheel well liners
It's not so much a height problem as a wheel problem
These tires & wheels are wider and the car is lower
Very good point, thanks Bill - I'm very happy with the light weight Fikse wheels, but they were purchased by the PO and the offsets may be creating a little more poke. I will reach out Fikse to try and determine what the offsets are.
Easy enough to measure yourself. Just the difference between the wheel backspacing and the centerline. For example, if you have an 8" wide wheel, the centerline is 4". If you have 6" backspacing, then the offset is negative 2" (~50mm).
(Those massive 11" rears we used to run on the widebody torsion bar chassis cars actually had about 1" positive offset. And that's where the wheel bearing damage overhype some may reacall reading about came from.)
I replaced my rear Bridgestones' Re050as with some Yokohamas AD08Rs for the very same reason. The minor difference in section and thread width did the trick for me. No more rubbing.
Tirerack has all the specs for all the tires.
I would not roll the fenders...
Looks like the fronts have a 50mm offset or so. The wheels come within a 1/4" of the suspension, and there's really no room to go further inboard. That leaves camber, tires and fender roll. Bill, you must run with some pretty stiff coils. I was fine at the track, but the twisting and contorting at the AX clearly taxes the limits.
Johan, great input on the tires. I've already been researching specs on tire rack, but what a shame that I can't run some of the best AX tires on the market like Bridgestone and even Dunlop. I'm equally reluctant to go rolling the fenders, but no way do I want to risk a repeat of this. Going to the body shop is no fun.
Easy enough to measure yourself. Just the difference between the wheel backspacing and the centerline. For example, if you have an 8" wide wheel, the centerline is 4". If you have 6" backspacing, then the offset is negative 2" (~50mm).
(Those massive 11" rears we used to run on the widebody torsion bar chassis cars actually had about 1" positive offset. And that's where the wheel bearing damage overhype some may reacall reading about came from.)
not quite, this part is correct
difference between the wheel backspacing and the centerline
but the rest is in error
an 8" wheel usually is 9" wide, exceptions are BBS and Fuchs, there may be others
backspace includes the additional flange width
ET =Backspace - .5 x Overall width or .5 x Overall - Frontspace
for you example an 8" wheel measures 9" overall(unless it's a BBS or Fuch)
so
ET = 6 - .5 x 9 = 1.5
The sign of the ET is important, when it is + it means the mounting face of the wheel is outboard 1/2 way point of the wheel aka shallow dish, when it is - it means the mounting face of the wheel is inboard 1/2 way point of the wheel aka deep dish
but the rest is in error
an 8" wheel usually is 9" wide, exceptions are BBS and Fuchs, there may be others
backspace includes the additional flange width
ET =Backspace - .5 x Overall width or .5 x Overall - Frontspace
for you example an 8" wheel measures 9" overall(unless it's a BBS or Fuch)
so
ET = 6 - .5 x 9 = 1.5
The sign of the ET is important, when it is + it means the mounting face of the wheel is outboard 1/2 way point of the wheel aka shallow dish, when it is - it means the mounting face of the wheel is inboard 1/2 way point of the wheel aka deep dish
Lastly in the real world all measures are in mm
Silly me for not accounting for nominal bead width. When I was schooled on this stuff for the formula car and sports racer world, it was more of a rounding error, given how thin the rim halves were/are. As you mention with the BBS, etc. competition end of the spectrum. And we did everything in inches (one of those guys I was hanging around being a Euro who later ran a fledgling Indy Car team), so I've just stuck with that. Even with all the Fuchs floating around in the '80s, it was easier to comprehend that an 8 had an inch of offset.
Totally blew it on the negative/positive offset.........
The rabbit hole gets deeper. After a thorough evaluation of the car, it looks like it's time for a new suspension. The coils and shocks are both showing signs of age, and the coils just aren't stiff enough to do the job. The ride height and wheels/tires are all doable, but not with 200 lb. coils.
The car is predominantly for AX and tracking, and my mechanic was recommended racing coils. I'm leaning toward a more conventional setup that will run well both on and off the track. Thinking about a set of H&R lowering springs with Bilstein B6XT's. Any feedback or advise is most appreciated. http://www.carnewal.com/products/P93...wering-Springs
Would need to understand the effective spring rate better of H&Rs. As I recall, they use a variable spring rate for most of their street lowering springs compared to a standard linear coil with X lbs of spring In a 60mm coil etc.
I should also mention that the rear suspension mounts were modified in conjunction with the Uwe Gemballa suspension work, and the whole rear sits about an inch lower. The front cross brace is distinctly the low point in the car - it's like having a a cow catcher in the rear.
looks like the tilt kit was installed on your subframe(rather than suspension mounts).
you can remount the front cross member to the top of the subframe to get rid of the cow catcher effect. there are pics on here someplace.
thought I saw some used jrz suspension listed, can't find it right now.
but cruise the for sale section, nice suspension comes up for sale quite often.
06-22-2016, 03:50 PM
Tires Rubbing Front Fenders - ugh
- I'm very happy with the light weight Fikse wheels, but they were purchased by the PO and the offsets may be creating a little more poke. I will reach out Fikse to try and determine what the offsets are.
