The Guide to UrS4 fender flares on a B3 Chassis...

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The Guide to UrS4 fender flares on a B3 Chassis...

Postby Audilard » Wed Apr 20, 2016 12:15 pm

I thought it would be useful for those who, like me, long to have Vomit Comet wide body UrS fenders on a B3 80/90, to have a place to read about how it is accomplished, issues to overcome, and other bits of information that might come in handy when undertaking such a project.

Posts to follow...
Darin
1989 80 20vt
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Re: The Guide to UrS4 fender flares on a B3 Chassis...

Postby Audilard » Wed Apr 20, 2016 12:35 pm

Location of the rear wheel within the rear arch.

The arch itself and the axle within the arch is too far forward to accommodate a larger wheel/tire combo. The stock wheel and tire combo is something like a 195/60/14 or 205/60/15. A 17 or 18x9 wheel with a 245/40 or 255/40 or even bigger like a 275/40 tire will be right up against the front of the fender.

This is a 17x8 245/40 wheel tire. (edit - a 235/40 tire and bat rolled stock fenders)
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This is a 225/45/17
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The b4 90 fender and the UrS fender is wider than the B3 arches, thus the axle/control arm will need to be centered within the new arch/door/bumper.

Enter adjustable control arms.
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These are the units that both my car and the Vomit Comet run in the rear. But you can't just install them as is. You have to modify the black spacers seen in the picture to move the ball joint point towards the rear of the subframe.

Carefully machine the spacer.
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And install as shown. (Notice the washer that replaces the material we lost when machining!)
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You gain more than half an inch by using these control arms.
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These aren't cheap, but get used to it. Neither is this project.

This is the best "after" picture I can find where this was done will the old fenders still in tact. About an 1.25" from tire to fender edge.
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Last edited by Audilard on Wed Apr 20, 2016 4:04 pm, edited 2 times in total.
Darin
1989 80 20vt
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Location: Draper, UT

Re: The Guide to UrS4 fender flares on a B3 Chassis...

Postby audifreakjim » Wed Apr 20, 2016 3:00 pm

Good idear, Darin. Thanks for doing this.
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Re: The Guide to UrS4 fender flares on a B3 Chassis...

Postby Audilard » Wed Apr 20, 2016 3:28 pm

Front wheel turning radius.

I won't go into the many various coilover, steering arm, control arm, brakes, wheels, offsets etc. configurations one might have on their car, but in all likelihood, if you are wanting to fit wide wheels and tires you will run into this problem one way or another. With the UrS fenders, you will want to fit a 9" wide or wider wheel underneath them. With a wide wheel and a 245+ tire, the lock to lock turn in/out will push into the fender liner on the back of the arch.

This is a 17x9, 255/40/17 wheel/tire combo. This is with the original 2 bolt stamped control arms from the 1989 90. This picture is dark, but you can see just how close it is to the rear of the arch. (These are b4 front fenders already)
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I have spent a lot of time corresponding back and forth with Jim Green regarding the Vomit's setup. Both of us elected to put cast B4 control arms on our cars, which gains some caster and put this combo less than 1.25" from the bottom of the car.

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Lock to lock in my car the tire was crushed up against the side skirt (more on those later) and the fender liner. So much that I'd have to modify those too much to mess with.

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The Comet has had many other things done to it, namely adjustable strut tower and camber/caster plates, different coilovers and steering arms, and his is a 1989 90, vs my 1989 80. Don't know how or why our cars are so different, but in the end, the best way to add room in both cars is to swap knuckles.

Right to left, left to right, this gains 3/4" more clearance, but you do have to put the calipers on the front instead of the rear.
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In the end, the difference between where my wheel sits and the VC (Vomit Comet) is different by about a 1/2". Neither of us know exactly why, but you'll mock up your fenders according to where yours line up.
Darin
1989 80 20vt
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Audilard
 
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Re: The Guide to UrS4 fender flares on a B3 Chassis...

Postby Audilard » Wed Apr 20, 2016 3:44 pm

Here is a comparison of the location of the strut mount in my car compared to the VC with adjustable strut mounts.

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Now once upon a time I used to know the math calculation to figure out how much further back the VC wheel center sits relative to my car based on pivot point, length of strut, something to do 3.14, blah, blah, blah, but based on crude measurements and a tape measure on the floor, there might be about 1/8" difference. I still want these for the positive caster!!!
Darin
1989 80 20vt
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Audilard
 
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Joined: Feb 27, 2013
Location: Draper, UT

Re: The Guide to UrS4 fender flares on a B3 Chassis...

Postby Audilard » Wed Apr 20, 2016 4:03 pm

Optional B5 S4 side skirts.

The beauty of this optional modification, is the precise fitment of the side skirts from a B5 Audi S4 from fender to fender. This is only true on the B3 80/90. The B4 90 is about 2" longer and the CQ is either longer or shorter, I don't remember.

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Depending on your skill or who you have do your body work, you'll have to figure out how to mount them. Sealant, screws, brackets, velcro, whatever it takes you can put these on flush, extend them out a bit if you want even wider fenders, under the trim piece, remove the trim pieces, however you want.

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Pic of my car with the S4 side skirts and B4 fenders all around. I elected to remove all upper and lower door trim. The VC is a completely shaved look.
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Darin
1989 80 20vt
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