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Ground Control Coilovers

528
354
sfo
What's your definition of 'close'?


Norm

That's a good question. How many millimeters is the general consensus? 1? 3? 5?

And it is not the wheel that is the issue since that really does not move much but the tire. Tire are often wider than the bead on the sidewall. Take an A7 hoo hoo for example and it has that rib that sticks out.
 

Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
That's a good question. How many millimeters is the general consensus? 1? 3? 5?
I always ask this question because there is that much and more variation in what different people consider as being "too close". Some people feel that Ford's own 18x9.5 GT500 wheels are already too close (at about 1/2" strut-side clearance).

In my experience(s), 2 mm at the wheel flange should be plenty as long as your wheel bearings are in good condition. If they aren't, that's already a problem that needs fixing regardless of wheel clearances.

And it is not the wheel that is the issue since that really does not move much but the tire. Tire are often wider than the bead on the sidewall. Take an A7 hoo hoo for example and it has that rib that sticks out.
Tire clearance needs are going to differ. I suspect that tires fitted to max-recommended width wheels can get away with running tighter clearances than tires fitted to anything narrower.


My '08 GT has run without rubbing with both wheel and tire clearances being approximately 1.2 mm (measured with feeler gauges). One side required a DIY-fabbed 0.025" thick spacer to get that much and eliminate a light rub.

I had another car that never rubbed with about 1/32" tierod end to wheel flange clearance (car was autocrossed but not tracked).

285/35-18 MPSS on Forgestar 18x11 wheels, so not a lot of lateral tire flex happening up at the 12 o'clock position (looking in full-on side view). No rubbing included track time.


DSC03378-web.jpg

DSC03379-web.jpg


Norm
 
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JDee

Ancient Racer
1,327
1,239
Exp. Type
W2W Racing
Exp. Level
20+ Years
halfway between Mosport and Shannonville
Norm, those pics make me feel real good about my clearance!!!
I have about 4mm with a 20mm spacer and I thought that was as close as I'd be comfy with. With 305/30's that have a raised band on the sidewall that sticks out 1-2 mm or so I have seen a very light rub on occasion but that's all. That was on a track that was kind of rough, and it's since been repaved and no further rub has occurred since.
 

Grant 302

basic and well known psychic
And it is not the wheel that is the issue since that really does not move much but the tire. Tire are often wider than the bead on the sidewall. Take an A7 hoo hoo for example and it has that rib that sticks out.
I’ve tried to tell people. Top and sidewall of the tire moves more than many think.

With the angle and ‘stretch’ that Norm has - I don’t think that would be a problem even for a soft sidewall like on the Michelins.
 

Norm Peterson

Corner Barstool Sitter
939
709
Exp. Type
HPDE
Exp. Level
5-10 Years
a few miles east of Philly
I’ve tried to tell people. Top and sidewall of the tire moves more than many think.

With the angle and ‘stretch’ that Norm has - I don’t think that would be a problem even for a soft sidewall like on the Michelins.
I was only a little surprised, as I'd seen some almost end-on pictures of one of my other cars where tire distortion was getting pretty extreme. IIRC, that setup was 205/50s on 7" wide wheels. You may have to zoom in to see, but the rather large amount of tire distortion at the bottom has essentially tapered off to nothing at the top, and that's with a much more flexible tire to wheel combination.

85EP 4May08 4.jpg


One thing you can't count on getting away from when the clearance gets down to 'absolute bare minimum' is the possibility that your next replacement hub(s) or wheel bearings may not provide the same wheel and/or tire clearance. You might gain a little and be OK or you could lose a little and end up needing a thin spacer. Seen both sides of that matter.


Norm
 

Grant 302

basic and well known psychic
You may have to zoom in to see, but the rather large amount of tire distortion at the bottom has essentially tapered off to nothing at the top, and that's with a much more flexible tire to wheel combination.
Miscellaneous aspect ratios impact the relevance to this discussion, and I would expect little deflection at the top of the 205/50. Wether total deflection or relative/proportional to the contact patch deflection.
It would be difficult to make the cylindrical portion of that 205 stiff enough to be relevant.

This is not the case with most of the tires and sizes that we normally discuss here.
 
1
0
Exp. Type
W2W Racing
Exp. Level
20+ Years
San Jose, CA
Hi. Apologies for the noob question but when you guys refer to GC coilovers and the shocks, are you referring to the Konis in the standard packages described here:

I know GC used to have their own brand race shocks so making sure I understand the context of this thread.

Also, what is the difference from say... running the GC setup of Konis and let's say ~200# 2.5" race springs vs Konis and the Ford P or other lowering springs that are ~200#?

Thanks.
 

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