Is it OK to trim inner fender "lip" to avoid tire rubbing?

[beeman]

Haven't seen anything about this with the GTM, is it safe to "shave" the inner fender lip up front to avoid tire rubbing over bumps? Or would it weaken the area too much?
I'm getting ready to put together my front end, and currently have the ability to widen the front hood (and thus the fenders) to give me a little more overhang- should I go an inch or 2 wider? I'd like the tire to sit closer to the bodywork if possible, not have a big gap between tire and fender to avoid rubbing over bumps.
More like this:



The tire tucks into the arch



Interestingly, here is the GT at full suspension droop!

[crash]

Remember, there is virtually no travel on the Ford GT as compared to our GTMs. It will not look like that when jacked up. That said, I don't think there will be any issues with body strength if your FFR body looks anything like mine. It is THICK. If you do experience any unwanted flex after trimming, then a lip made of glassed in rope around the underside of the wheel arch will fix the issue. I wouldn't hesitate to trim a little. Just remember that you can always cut more off, but adding it back presents a whole bunch of issues.

[beeman]

I agree it's pretty thick Mike, I think I'll shave them back to a minimal lip, leaving a little bit for strength and to allow a nice rolled edge.
What do you think about widening the front bodywork? I don't think it would look bad to have an inch or so of fender overhanging the tire vs deal with rubbing issues.

[crash]

Both the front and particularly the rear have tons of room for the tire to travel up into the fender. Probably a good 2-3" even when the front is lowered. I think it really has more to do with what shocks and shock settings you use as opposed to how you trim up the fenders. Of course you could always go crazy on the trimming, but still, if you leave three inches for compression and another three inches for rebound, then you are working with a total of 6" of travel, which should be plenty for a cushy street car ride. Our race suspension, I am guessing, compresses about 2" and has about 2-3" of droop. Of course a lot has to do with the dynamics of the shocks as opposed to overall travel ability, but really I think you could compress the suspension 3 inches from ride height with the shock off and if the tire is not hitting the fiberglass, then all should be well. I think you will probably find that there are more issues with turning than with wheel straight compression. On the FFR PDG GTM race car the tires stay pretty far inside the outer fender lips and we have not had rubbing issues. As far as I recall, we have not done any major trimming to the front. The rear is another story, but that was only in the rear part of the fender to fit the 345 X 710s.

I tried to upload a picture of the FFR PDG GTM under cornering load in a high speed corner, but this site will not allow big pictures.

Here's a link to some good photos though...

http://headonphotos.net/gallery/NASA...6/4/index.html

[beeman]

OK, I'm confused. I see some completed cars that have the appearance I'm looking for, with the tire tucked right up to the fender. But I also have seen quite a few where there's a big gap between the tire and wheel arch. I assumed that this gap was deliberate to prevent rubbing issues, maybe it could have been improved with more hood bodywork? Like this example :



Or this

[crash]

Both those pictures look like there is a YUGE gap between the wheel and the fender. I believe the right front has a bigger problem than the left and is also out of round, which obviously can be addressed. But the biggest issue is that this body was designed to be run low and it had to be brought up to meet the road car standards for clearance. There is no easier way to get the look you are after than to lower the car. It just "looks right" on the GTM. Unfortunately it also leads to a lot of splitter replacement issues. The suspension lifting system is probably one of the best answers for this issue. Alternatively, the shocks on the FFR PDG GTM race car dynamically lower the car so that it not only "looks right" but helps with performance. As you suggest, and I have mentioned elsewhere, a lot can be done by properly fitting the nose on the car. This includes lifting the front of the nose, fitting the rear properly, and then lowering the entire front end via the suspension. In order to get the rear of my nose to fit properly on my stock GTM bodywork I had to lift the nose 1" higher than the rest of the body.

[Roger Reid]

I had Shane (who finished off my car) widen the front and rear to properly clear the 345/19 rear and 315/19 front. On the rear I took the spring off the shock and adjusted the wheel spacer at full compression for clearance. Then we know how much to widen the rear fenders. On the front the clearance issues were related to the inside tire contacting my sway bar. Then adjust the spacer and fender width accordingly. My goal was tire choice, not just to make it wider. So the fenders were widened just enough to fit my tire choice.
Also keep in mind the camber increase during travel helps keep the tire from contacting the inner fender lip's.

[beeman]

Wow, I currently have 245/35-18 fronts on my CCW wheels, maybe I should leave room for more?
Looking at your pics, how did Shane widen you? Doesn't look like he added flares, I know he has done that on other projects.

[Roger Reid]

I asked Shane to do a subtle widening. If you look at the pictures, you can see how the fenders were split, widened, and re-glassed. It was a lot of work $$. Inspired by Pandora herself. Maybe Shane can share a few pics of the glass work before paint.

[beeman]

That's definitely a clean way of doing it Roger. Thanks for the pics.
Mike - I haven't seen a pic of the VBM 4000 GTC in quite a while!

[VRaptor SpeedWorks, LLC]

There are a ton of variables that we're looking at here. Like that yellow car and the red car photos above. What are they running for ride height? What are the front wheel sizes?....are they running aftermarket C5 wheels...which would mean that the front wheels are only 17's? Compare that to Roger's car where he is running 19's. The 19's are going to fill up that wheel opening a lot better than stock 17's.

As for tire clearance, the only problem we've ever encountered here is not the wheel arch in front, but the main body in front of the hood latches. That always needs to be trimmed back substantially to clear the tire.

As for widening the hood on Roger's car, I have the moulds here to make the parts needed to do that. There is a significant amount of work that goes into doing this since the main body behind the front wheels needs to be widened also.......it's not as simple as just sticking a new moulded part onto your hood.

[mlkwd1]

You can get 285-18 front and 335-18 rears (no spacer installed) on the factory five wheels with very minor mods. The Proxess are slightly rounded on the outside edge and it helps. My tightest spot was where Shane mentioned by the hood latch. That section can be removed and provide plenty of clearance. I did have to trim the inner fender lip about and 1/8" to stop a slight rub.

As far as wheel well space, if you run the car low (3.5") the spacing is perfect. I had Shane make a splitter out of 1/8 aluminum and then I added some polyethylene skid strips to protect the underside of the splitter for driveway entrances but you can forget doing speedbumps or a steep entrance at heights make the wheel well look right. Side rockers are even a bigger challenge for clearance but it does look good.

Michael

[carbon fiber]

You need the Ramlift system for the front end. Then you can run at the lower height and still have clearance when you need it. Check out the Stig's build page, he has it on his car.

[beeman]

That's interesting, I believe my chassis was the one it was developed on? I bought the kit from Fran at RCR, someone had traded it in I believe towards an SLC. When I received the kit, it had a custom lift system included. I was contacted by the original owner of the kit who wanted it back. I shipped it to him on my own dime and never received anything in return for it.
Ha, just found this thread, it was JCHRacer. Someone tell him he owes me a grand.
http://www.ffcars.com/forums/42-fact...some-help.html