Ok, here's the question, I have Ground Control Coil Overs and adjustable rear spring perches. I'm getting ready to take the car to Balanced Performance Motorsports here in Atlanta to get it on 4 scales and get it balanced out. But when I do it, I want to keep it as low as I can. (FYI, these wheels and tires are just for autocross.... for now )

I'm going to be running 17x11 50mm offset with 315's in the rear and 17x11 36mm offset with 275's (to start with, I already had them) in the front.

My question is, how low can I go before I have rubbing problems.

I measured

LF - 25 3/4
RF - 25 7/8
LR - 26 5/8
RR - 26 3/4

This is before we do the balancing. I'm just curious how low others have gone with 17x11's.

Run get the yard stick!!!!

 

My 1994 Z28M6 rides at 26.25" in the rear with 315mm Kumhos on 17x11 AFS ZR1 replica wheels with 50mm offset. I am running soft Global West rear springs at 100 - 120 lb rate on Global West rear adjustable spring perches. The car is currently using HD Bilsteins. I had to hammer and undercoat the inner wheel wells and roll the lips past 30degrees up. I have no problems at all on hard dips and bumps with only me driving and only get rubbing with about 300lbs of additional passengers on moderate to hard bumps.

I have used Camaro SS 9"x17 wheels and AFS 9.5"x17 56mm offset wheels with 275mm Nitto 555RIIs, Advan AO32Rs, Yoko AVSs, Dunlop SP8000s absolutely no problems ever on the front. I use HD Bilsteins with Eiback Pros springs on the front. The car uses LG lower control arms with rod-ends, Global West upper control arms with del-A-lum bushings with -1.5 camber, 4.5 castor, and 0 toe.

 

Thanks! That's good news! Sounds like we have close to the same setup!

 

Ok either no one uses 17x11's or no one has a yardstick.....
Anyone else????

 

Steve,

Do some searches and email some of the folks. I know that Lonnie Bright uses 315s on all 4's on his Z28. Mike Taylor uses 315's all around with 36mm offset 17x11's on his 1994 Formula Firebird. His ride height looks slightly lower than mine with 500lb front springs. Note rear fenderwells are larger on birds, but the front fenders openings should be very close.

Good Luck.

 

Thanks Corner. I appreciate your help.

I think I saw Mike's pictures with 36mm offset wheels?? I saw Chuck's red TA (looked great Chuck!). I think no matter the car or what, it just takes a little work to get them to fit just right.

We'll see in a week or so. I'm going to have my rear bump stop mount trimmed (or removed) to make inboard room in the back. I can do the lip rolling myself.

 

Steve I have the same setup.

It is tire dependant. Hoosier autox tires are a little wider than Kumhos

I know of someone who uses 36mm offset wheels on the front of his camaro. He does not have to use a spacer. You shouldnt either even when you go to the 315's on that wheel.

W/ hoosiers you may need a very thin spacer in back. Even pounding wont get you out of pretty heavy rubbing. You will rub the LCA and that is the main rub problem. Even after pounding in the inner fenders.

W/ Kumhos at your ride height in front and lower than that in the rear I had no rubbing w/kumhos. In anticipation of Hoosiers (plus the car works better) I raised it up to 26" in front and 26.5" in back. I also went to a wider spacer in front (w/50mm offset wheels) and am going to a thin spacer in back.

I know of a car w/26 1/4" all around w/53mm (I think) CCW wheels and 315 Hoosiers and he uses 1/4" spacers at all four corners.



Lonnie


ESPFABRICATING.com

 

Thanks Lonnie! That's good info.

 

Mine's riding at 25.75" in front right now with 36mm offset wheels and it did rub some using 500 lb/in front springs and a 1LE swaybar. All I had to do was cut out the top part of the inner fender liner (plastic) and hammer flat the vertical rib that was underneath. You can't tell from outside the car.

On the rear I'm at about 26.25" ride height and have no rubbing issues with the same offset. I have rolled my fender lips but I did it well before fitting the 11" wheels because I used to ride lower back there. That's all I've done to the rear. Well, I removed my bump stops, but that was because the wheel lips would catch on the bump stops when lifting the rear of the car up with a jack.

This is all using Kumho 315 tires.

 

Steve,

I would NOT recommend totally removing the rear bump stops. You NEVER want to bottom out without one on that 1-in-10,000 unexpected pothole or bump. It would cause serious damage.

I had the problem of the wheel lip catching the bump stop (& bump stop bracket) with the car on a lift (50mm offset 17x11 AFS wheels), but the suspension would never droop that low during driving/racing. I trimmed the bump stop bracket with a grinder and installed straps to limit the suspension droop so that the wheel and bump stop would not interfere.

As far as tire contact to the rear lower control arms, I use Global West LCAs and my Kumhos are are still an inch away. The GW LCAs are large diameter steel though (approx 2 inches). With thinner, a rod-end aluminum or steel LCAs, there would never be a tire clearance problem at that location.

Remember to use an adjustable Panhard rod bar so you can locate the rear evenly, as you lower (or raise) it. I like the rod-end style as it further limits any play that poly bushings might have from cold-flow deformation.

Mike - I am surprised that your bump stop still contacted the edge of the wheel with 36mm offset 17x11 wheels. Mine just catch with the 50mm offset and I assumed that the extra 1/2" offset would clear it.

Rick Raldiris

Rick R

 

I know. I didn't want to have to remove them. How much did you take off?

Unfortunately, I can't change my LCA's due to class rules so I'm stuck with the stock ones.

 

Steve,

By take off, I assume you are addressing the grinding that I did to the bump stop and bracket. I ground off enough of the bump stop metal edges and bump stop bracket without weakening the load points. It was mostly to round it off and blend it in. This did not eliminate the wheel lip to bump stop contact with the car on a lift (50mm offset 17x11 AFS wheels), so I added straps between the frame and the axle to limit suspension droop. I don't recall the exact lengths, but they were between 9" to 12" to tie to available bolt connections. Just cut the cable and press on lugs to the length that prevents wheel to bump stop contact. No more contact.

As far as the bump stop itself, I did not trim it with my ride height at 26.25". In fact I installed fresh units. The only time the car touches the bump stop, is on very hard bumps or if I load the car down with 2 heavy passengers or 3 passengers (on moderate to hard bumps). With lower ride heights, I touched the bump stop too often. If you go any lower than 26.25", I would trim the bump stop by an equal amount. However, in my opinion, you are going to get an unacceptable amount of tire rubbing with 315 tires dependent on the specific tire model that you use.

And definitely stay away from the bump stop extensions that SLP sells with the SS style wheels. If your car is lowered at all, the car will always be on the bump stop. If this is the part used on the SS's, it is no wonder they appear squirrely at the limit coming out of turns.

Rick R

 

Exactly where did your rub? That will help me to go ahead and start working on that area first.
If I use 1/4" spacers will I need different length studs?

 

Steve,

To be absolutely conservative and safe, Yes.

However, AFS now sells a unique conical style lug nut that has an extended reach. It fits just like a factory conical style lug, but the base is extended about 1/4 inch to go nearly flush with the wheel flange. This will give you about 1/4" additional thread engagement for use with small spacers. I use them, but do not currently use any spacers. I have checked the lugs against my 1997 Camaro SS 17x9 wheels and my 2 sets of AFS 17x9.5/17x11 wheels and they are just long enough to be nearly flush, but not too long as to bottom out without torquing down the wheel against the hub. This may be an acceptable alternative to replacing studs for less than 1/4" width spacers, but it is clearly up to the user's comfort-safety level.

I don't need spacers in the rear. I would not to space out the tire any further on my 94Z28, as it would reduce the clearance to the outer fender lip. On Birds, this is not a problem, with the larger rear fender wells.

In the future (I am still recovering from a couple of kidney cancer surgeries), I am going to trial drive one of my 315mm/17x11 wheels on the front before, I decide on spacer need, thickness and whether I want to change studs or rely on the extended-reach lugs. I have ground the bump off the spindle (where the top of the wheel comes the closest) and my 17x11/315mm 50mm offset wheels fit on the front with about 1/8th inch clearance from wheel to spindle. Then there is the upper plastic wheel well interference and metal lip, that others on this post have mentioned. From what I am reading the 36mm offset 17x11 wheels would not require a spacer up front.

Rick R

Update:
Prior to installing the rear wheels, I used a 5lb mini sledge to round out the bumps in the inner wheel well. The most work was required directly in front of the tire with some minor work on the arc from the front to the top. Basically, you want the most clearance you can get that the frame will allow. I have heard some claim that they did the mistake of doing this work with the rear seat belts out, and they had trouble getting them back in. Then undercoat. Likewise, the LCA comes closest in the front of the wheel. I have never had any rubbing on the inside. area.

I had some rubbing on the fender lip with Eiback Pros in the rear, but rare and not too bad. However, when I went to soft Global West springs, I had to roll the fender lips. It was pretty easy to bend them up to 30 degrees and took a little more work to get them past 45degrees just above the wheel. Just use a large diameter pipe with duct tape wrapped around it and hammer away carefully.

Have fun.

Rick R

 

Rick, I'm sorry to hear about your cancer, I hope you're doing ok.

Thanks for your helpful information.

Sounds like the rear is a PITA to make fit properly. It also sounds like there is no "perfect" offset in fitting an 11" wheel, either front or rear.

Sounds like to me a 10" or maybe 10.5" wheel might be a better fit for F-Body's (at least with minimal fitting effort) .