Fitting Wide Aftermarket Wheels

the green one did get a bumper tuck and lost the elephant ears since, and I'm cheating a bit, that pic was when I was setting the bump height on the coilovers so there are no springs installed sitting on the bump stops. any lower and I started having lots of tire to structure issues when turned. I didn't want to end up with tire rubbing at full bump.
 
bpimm said:
the green one did get a bumper tuck and lost the elephant ears since, and I'm cheating a bit, that pic was when I was setting the bump height on the coilovers so there are no springs installed sitting on the bump stops. any lower and I started having lots of tire to structure issues when turned. I didn't want to end up with tire rubbing at full bump.
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Did you roll your fenders? I haven't had any issues since I rolled mine. Before rolling them I had lots of rubbing at 3/4- full lock.
 
Throw in a bunch of negative camber on all four corners and you could be on the Vortex forum. ;)


Eastep said:
Did you roll your fenders? I haven't had any issues since I rolled mine. Before rolling them I had lots of rubbing at 3/4- full lock.
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Naturally it depends on the off-set, but when mocking-up my 7" rims I found the front fender lips will need to be rolled. The front lower corner is the worst spot.
 
Regarding the front lower corner rubbing wide tires:
On both of mine it appears the front wheels are not centered in the fender wheel openings, but are positioned forward some. This makes the tire interference much worse in that lower corner. I looked at the suspension geometry, steering alignment, fender fitment, etc and do not see any indication of damage or problems. So I assume that is how they were designed?
Looking at the suspension's front trailing arms (torque struts or radius rods), their length determines the position of the wheel in the fender opening. But lengthening the rod (to center the wheel) would effect caster, making the steering very nervous and difficult to keep tracking straight.
Anyone else look into this or have different experience?
 
Dr.Jeff said:
Regarding the front lower corner rubbing wide tires:
On both of mine it appears the front wheels are not centered in the fender wheel openings, but are positioned forward some. This makes the tire interference much worse in that lower corner. I looked at the suspension geometry, steering alignment, fender fitment, etc and do not see any indication of damage or problems. So I assume that is how they were designed?
Looking at the suspension's front trailing arms (torque struts or radius rods), their length determines the position of the wheel in the fender opening. But lengthening the rod (to center the wheel) would effect caster, making the steering very nervous and difficult to keep tracking straight.
Anyone else look into this or have different experience?
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I have tested a range of front end geometry in my X racecar. The factory spec for front caster is 6 deg 10'. The car likes 6 degrees of caster. Moving away from that in either direction isn't good. Note: If you lower the front end relative to the rear end (changing rake) you reduce caster. However, lowing the front end in general reduces the length of the side of the triangle opposite the apex of the caster angle and therefore increases caster.

You can easily use a spacer to lengthen the radius arm (track rod) to move the front wheels back some and then correct the caster using a camber/caster plate for the top strut mount. This will likely require the use of a coilover style spring with a 2.5" ID to provide the necessary clearance.

I would note that lowering the car excessively causes a number of geometry issues. The roll centers get too low, you loose suspension travel, both front and rear ends will suffer from excessive bump steer and you will likely damage there exhaust system. All things I learned through experience.
 
Steve Hoelscher said:
You can easily use a spacer to lengthen the radius arm (track rod) to move the front wheels back some and then correct the caster using a camber/caster plate for the top strut mount.
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Good idea. Possibly relocate the top mount rearward a little by elongating the holes on the towers? Assuming the springs/upper perches are small enough diameter to allow it as you say.
 
Yeah, you could do that but I prefer using a proper camber plate. Slotting the holes isn't terrible but its not the preferred method.
 
Sorry to whore out my car, some more, but....
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I was going to trim the front corner as well. But after reading the comments above I might try relocating the position of the wheel within the fender. Extending the trailing arm and repositioning the upper mounts back.
 
Dr.Jeff said:
I was going to trim the front corner as well. But after reading the comments above I might try relocating the position of the wheel within the fender. Extending the trailing arm and repositioning the upper mounts back.
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If you roll and flush the inner fender lip; the lip curve/line transitions into the lower rear corner. Continuing the lip rolling, will roll the lower corner, as well. The front corner does not interfere when turning. This is also do to the shape/ line of the inner fender lip.it also transitions to the exterior/ lower front corner. I'm sure 9.5-10 inch wheels up front would have interference issues, but my 8.25s are fine, lock to lock. I guess each application and vehicle may vary, so it's probably a trial & error approac.
 
Ya, mine is the opposite. Lots of clearance in the rear corner, no rolling required there. But severe contact in the front, beyond rolling to clear...like 10-12 mm. Actually tore a huge chunk out of a mock-up tire just turning the steering without any suspension movement or wheel rotating. But rather than cut the corner out, I'll see if the wheel can be centered better (see the picture of Eastep's X I noted above). Then rolling/flattening might be enough without cutting. I have a fender roller but for the most part the lip isn't an issue with the 7.5" wheels I'm going to use.
 
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