Rubbed down a bit of front fenders with tire..what causes??

[Silver Bullet]

Both front fenders on the outer part lip have some wear down where they rubbed down. But tire looks fine so must not have been a lot of rubbing but constant enough.
I run 18x11's in the front with 295/30/18's that stick out just a tad.
My guess is either one of two things:
To Much body roll or too much dive under braking.

Now my penske's are full stiff in front and car doesn't feel like it dives at all so my guess is body roll as I still have stock sway bars.

Is that probably the case??

[seege]

This has happened on my car as well. If your shocks are full stiff(and working correctly) then ride height is your only adjustment left to make it stop(aside from bigger sways). The cause may be both issues - diving and body roll. Heavy trailbraking would cause this. Mine doesnt bother me but I did have to smooth the sharp outer edge because it was really sharp.

[No Doubt]

Is the car lowered? If so how much?

Are your Penske shocks the shorter bodied versions in order to permit lowering without bottoming them out?

What are the tire specs? For example 275/35, etc. From this you can determine sidewall height as compared to stock.

What springs are you running: stock, aftermarket leaf or coilover?

You said full stiff. Is that compression or rebound? Although I would assume you mean compression. If so that is likely going to result in untoward side effects such as understeer and other undesirable characteristics.

[DJWorm]

If the rub is on the underside of the top of the lip (12 o'clock position)you are making contact under either hard braking (Dive) or cornering (excessive Roll) or both. This will eventually crack the fender. If it's on the 9-10 and/or 2-3 o'clock position then it is under full lock and can be either a rim size, positive offset or a Roll problem.

Running Full Stiff ,#6 position, on the Penske's Bump is appropriate in some situations (High speed, smooth tracks, high Aero downforce) but not all. The fact that you need this and are using the shocks to adjust for clearance indicates you need to address other parameter(s). You may be inducing other untoward effects by running the shocks too stiff all the time and may not be getting the full benefit of the shocks (or the shocks are under valved) .

NOTE: Suspension Rules of Thumb:
1. Shocks should be used to control Spring oscillations, only
2. Sway Bars should be used to control Roll
3. Spring rate should be tailored to individual corner weights
4. Ride Height should be as low as possible within suspension parameters.

An easy solution is to set the Ride height a little higher, but this may not be optimum.

A better solution is to:
- Consider increasing the front spring rate first. For example using a VB&P Extreme front spring will allow you to run lower ride heights with less deflexion and Roll with out making contact. (Coil Overs are the ultimate solution)
- Consider running a T1 Sway bar if excessive Roll is still present after increasing spring rate.

Note: I recommend and I run a larger tire than you with a more positive offset with NO rubbing problems or the tire sticking out:
305/30x18 on 10.5x18 with a +0.25" offset.

Are you running the correct offset or are you running a rear rim or one set up for some other car? Why are you running an 11" on the front ??





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[RocketSled]

Originally Posted by Silver Bullet

I run 18x11's in the front with 295/30/18's that stick out just a tad.

My guess is either one of two things:
To Much body roll or too much dive under braking.

Both guesses are wrong. You clearly state the problem:

295/35-18s on 11 inch rims that "stick out just a little".

If you don't want the wheel to rub, it has to fit *inside* the wheel well opening.

You could "doctor" the problem with stiffer shocks or springs or with adjustments to ride height or even by adding more positive camber, but the real fix is a wheel/tire that doesn't protrude outside the wheel well.

[robiferretti]

widebody kit

[Silver Bullet]

It's the CCW's with the right offset as they don't rub anything under full lock in normal driving.
Penske's running full stiff udner compression and like a 19 on rebound in the front.
Looking at it like a clock it rubbed at 10 all the way across top of fender to the 2.
I thought about it and my car is still riding fairly high as it's only mildly lowered. These also aren't the super lower penske shocks.
I think I actually know where this was happening. Bottom of roller coaster (hog pen) at VIR.
Car bottom's, hard turn under throttle and coming down a hill with ton's of body roll.

But it is on both sides the exact same so that doesn't make sense unless it is under braking.

Would that not be the case if both sides are worn evenly??

[Silver Bullet]

Ok further inspection.
Front measures 26 1/4 on each side ground to wheel well center point. Tires are 25 inch tall. (rear 26 3/4 and 25.5 inch tall tires but no rub). So 1.25 inch clearance till it would rub.
Wheel well has more rub at 10 o'clock than at 2 but only barely.

So where do I invest to fix. VBP spring or T1 bars or both.

[DJWorm]

Cheapest solution is to install Front T1 Bar only 1st but you may also need to install Rear T1 bar as well to balance the car. You may have to add preload on all corners but then run risk of "picking up" an outside wheel if the rates are too high

Best solution is to increase the Spring rate in the front with a VB&P Extreme front spring. You may need to add a rear T1 bar to balance the car (This is run by a few top national drivers).

Be advised that you may end up adding BOTH Front & Rear VB&P springs and T1 front and rear bars

[Silver Bullet]

Probably not a bad overall combo but more than I want to spend right now.
Once I make it through summer heat I can't run Cup tires anyway as they don't get up to temps in cold weather. So may just bolt back on stock rims with the Toyo RA1's and then should have no rub issue anyway.

I will post a seperate message about what spring rates,etc.. for my combo on the VBP option.

[speedpup]

I have a set of VBP springs forsale they are 796 rear and 900 front. I was having similar problems. I went to 1200 and 900 because of the body downforce. your car needs to be higher or stiffer springs. I cut 3/8"+ off the fenders and it was still not enough. I ruined a few sets of slicks before I figured it was the fenders after seeing rubber threads hanging from them.

[Silver Bullet]

Sp speedpup it sounds like those other springs weren't stiff enough even huh.

Those are some pretty stiff spring rates you went to.

I may just hold out for this year and figure it all out in a winter mod fest game plan.

Springs and T1 bars would certainly complete the suspension setup but I would want to get a good combo with the shocks I have, tires, etc..

[speedpup]

The harder you push the more weakness you find. Watch the C6R in a corner or LGM's car, look at the splitter to ground clearance it doesn't vary hardly at all in a corner. Coilovers would have been 900/800 if I went with them.