Tires Rubbing Front Fenders - ugh
#1
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Thread Starter
Tires Rubbing Front Fenders - ugh
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
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
#2
Rennlist Member
I hear the RE 11's run a bit wide. Which is great, so you have a larger contact patch. Are you running 225 40 18?
#3
Rennlist Member
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...
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...
#4
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Thread Starter
#6
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Thread Starter
Thanks again for the feedback,
Jim
#7
Rennlist Member
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.)
(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.)
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#8
Rennlist Member
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...
Tirerack has all the specs for all the tires.
I would not roll the fenders...
#9
Rennlist Member
Thread Starter
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.
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.
Last edited by Foxman; 06-23-2016 at 01:43 AM.
#10
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.)
(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.)
difference between the wheel backspacing and the centerline
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
#11
Rennlist Member
not quite, this part is correct
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
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
Totally blew it on the negative/positive offset.........
I'll go crawl back into my hole now.
#12
Rennlist Member
Thread Starter
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
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
#13
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.
#14
Rennlist Member
Thread Starter
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.
Modified suspension mounts
Modified suspension mounts
#15
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.
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.