Rubbing issues
Thread Starter
Member
Joined: May 2006
Posts: 264
Likes: 1
From: UK
Car: 1984 Firebird S/E
Engine: 1985 2.8 MPFI
Transmission: 1985 T5 5 speed manual
Axle/Gears: 3.42/4.03
Rubbing issues
Hey guys and girls, hope you’re all well and Merry Christmas 🎄
I have these fitted to my car which has a stock 3rd gen rear end:
2x 18x8.5 23mm adaptor 255/45/18
2x 18x9.5 23mm adaptor 285/40/18
The car has been lowered 2” from stock and every suspension components is new. (Restoration)
The driver side rear wheel hits the arch when it hits a pot hole or while I corner and the road undulates beneath it and it’s sliced the tyre tread a good 5mm and of course it going to damage my arch.
Any suggestions other than decrease the tyre width?
I have these fitted to my car which has a stock 3rd gen rear end:
2x 18x8.5 23mm adaptor 255/45/18
2x 18x9.5 23mm adaptor 285/40/18
The car has been lowered 2” from stock and every suspension components is new. (Restoration)
The driver side rear wheel hits the arch when it hits a pot hole or while I corner and the road undulates beneath it and it’s sliced the tyre tread a good 5mm and of course it going to damage my arch.
Any suggestions other than decrease the tyre width?
Joined: Feb 2001
Posts: 8,494
Likes: 411
From: Sophia, NC
Car: 2016 Camaro SS + 1986 Z28
Re: Rubbing issues
Run a 35 series tire instead of a 40.
285/40/18 is 27" tall
285/35/18 is 25.9" tall,
MUCH closer to (at least my) stock 245/50/16, which is 25.6" tall. Obviously width would help too, but width is COOL!!!!! -plust dropping an inch in diameter overall should give you a half inch (radius) of clearance, and it sounds like that should be enough.
285/40/18 is 27" tall
285/35/18 is 25.9" tall,
MUCH closer to (at least my) stock 245/50/16, which is 25.6" tall. Obviously width would help too, but width is COOL!!!!! -plust dropping an inch in diameter overall should give you a half inch (radius) of clearance, and it sounds like that should be enough.
Joined: Feb 2001
Posts: 8,494
Likes: 411
From: Sophia, NC
Car: 2016 Camaro SS + 1986 Z28
Thread Starter
Member
Joined: May 2006
Posts: 264
Likes: 1
From: UK
Car: 1984 Firebird S/E
Engine: 1985 2.8 MPFI
Transmission: 1985 T5 5 speed manual
Axle/Gears: 3.42/4.03
Re: Rubbing issues
Run a 35 series tire instead of a 40.
285/40/18 is 27" tall
285/35/18 is 25.9" tall,
MUCH closer to (at least my) stock 245/50/16, which is 25.6" tall. Obviously width would help too, but width is COOL!!!!! -plust dropping an inch in diameter overall should give you a half inch (radius) of clearance, and it sounds like that should be enough.
285/40/18 is 27" tall
285/35/18 is 25.9" tall,
MUCH closer to (at least my) stock 245/50/16, which is 25.6" tall. Obviously width would help too, but width is COOL!!!!! -plust dropping an inch in diameter overall should give you a half inch (radius) of clearance, and it sounds like that should be enough.
Joined: Feb 2001
Posts: 8,494
Likes: 411
From: Sophia, NC
Car: 2016 Camaro SS + 1986 Z28
Re: Rubbing issues
2x 18x8.5 23mm adaptor 255/45/18
2x 18x9.5 23mm adaptor 285/40/18
2x 18x9.5 23mm adaptor 285/40/18
Thread Starter
Member
Joined: May 2006
Posts: 264
Likes: 1
From: UK
Car: 1984 Firebird S/E
Engine: 1985 2.8 MPFI
Transmission: 1985 T5 5 speed manual
Axle/Gears: 3.42/4.03
Re: Rubbing issues
Of course you’re right. The 285’s are on the back. Ok so basically knock it down 5% on the side wall. I’ll have to wait until the next tyre change as these are very expensive tyres!
Would rolling the arches help in this situation because the 35 profile tyres I had these wheels first looked ridiculous!
Joined: Feb 2001
Posts: 8,494
Likes: 411
From: Sophia, NC
Car: 2016 Camaro SS + 1986 Z28
Re: Rubbing issues
Im sorry! I’ve had a beer this afternoon.
I've never had to roll a fender/lip, and without really seeing the issue, it's hard to say if that'd help, but it certainly might.
As for the difference in size, I too prefer the look of a little more sidewall, but I plan on going with a 35 simply for fit when my new 18" wheels come in.
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Joined: Sep 2005
Posts: 1,125
Likes: 55
From: PA
Car: 92 camaro RS
Engine: LSA
Transmission: Magnum F
Axle/Gears: TNT 8.8 wavetrac 3.31
Re: Rubbing issues
Did you recenter the rear axle with a adjustable panhard bar? Could be why your rubbing on the driver side
Joined: Sep 2005
Posts: 1,125
Likes: 55
From: PA
Car: 92 camaro RS
Engine: LSA
Transmission: Magnum F
Axle/Gears: TNT 8.8 wavetrac 3.31
Thread Starter
Member
Joined: May 2006
Posts: 264
Likes: 1
From: UK
Car: 1984 Firebird S/E
Engine: 1985 2.8 MPFI
Transmission: 1985 T5 5 speed manual
Axle/Gears: 3.42/4.03
Senior Member
Joined: Aug 2004
Posts: 991
Likes: 24
From: Peoria, AZ
Re: Rubbing issues
The other option that hasn't been mentioned is go to a 255/45/18 on all 4 corners. Unless you have modified the engine from the 2.8L listed on your profile, you really don't need 285's on the rear.
Joined: Aug 2006
Posts: 12,804
Likes: 103
From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: Rubbing issues
Not entirely true, just depends what you want the car to do. I ran 295/35/18 on all four corners of my 92 bird with a stock 3.1. Wanted the car to stick to the road and handle extremely well, and it did
For the OP
what shocks are you using? Larger and heavier wheels and tires need stronger shocks. If you still bottom out on the fender lip, the metal can be rolled, or consider raising the car some.
Last edited by //<86TA>\\; Dec 22, 2017 at 08:47 PM.
Senior Member
Joined: Aug 2004
Posts: 991
Likes: 24
From: Peoria, AZ
Re: Rubbing issues
If the car is just a cruiser, moving down in size with proper tire selection won't impact handling and might even make it better.
Thread Starter
Member
Joined: May 2006
Posts: 264
Likes: 1
From: UK
Car: 1984 Firebird S/E
Engine: 1985 2.8 MPFI
Transmission: 1985 T5 5 speed manual
Axle/Gears: 3.42/4.03
Re: Rubbing issues
Thanks for tall the advice guys. Turns out when I hit a MAHOOSIVE pothole, the shocker bent on the mount flange and the shaft and it's movement is a bit out of whack. Gonna swap it out, fix anything else thats bent and roll the arches. Will report back after that!
Thread Starter
Member
Joined: May 2006
Posts: 264
Likes: 1
From: UK
Car: 1984 Firebird S/E
Engine: 1985 2.8 MPFI
Transmission: 1985 T5 5 speed manual
Axle/Gears: 3.42/4.03
Re: Rubbing issues
Well I swapped out the shocker and put the car through an alignment and is all good. Except it still rubs the arch lip going over dips and bumps.
Looking from the rear of the car it’s leaning 1/2” to the left (drivers) side. WTF? I’ve checked front spring isolators and indexing and it’s all fine, and done the same on the rear. Added the heater hose mod to the rear left spring and it’s made about 2mm difference which is obviously the thickness of the tube wall.
Any ideas? I’m thinking of adding a 1/2” isolator to the spring to level it up. I’m NOT buying weight jacks and any more new stuff, it’s getting real expensive!!
Looking from the rear of the car it’s leaning 1/2” to the left (drivers) side. WTF? I’ve checked front spring isolators and indexing and it’s all fine, and done the same on the rear. Added the heater hose mod to the rear left spring and it’s made about 2mm difference which is obviously the thickness of the tube wall.
Any ideas? I’m thinking of adding a 1/2” isolator to the spring to level it up. I’m NOT buying weight jacks and any more new stuff, it’s getting real expensive!!
Joined: Aug 2006
Posts: 12,804
Likes: 103
From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: Rubbing issues
If they rub the arch, you can roll the lip, use better shocks, or use different spacers to move the wheels in a little more.
As for the lean, for some reasons some cars do that some don't. Try the spacer, or maybe swap the springs to opposite sides.
As for the lean, for some reasons some cars do that some don't. Try the spacer, or maybe swap the springs to opposite sides.
Senior Member
Joined: Mar 2002
Posts: 998
Likes: 19
From: Ontario, California
Car: 1992 Z28
Engine: 383
Transmission: 700R4
Re: Rubbing issues
I bet you have a t-top car. If so then the chassis is flexed/twisted and theres no way to fix it. Best to put subframe connectors in and space up the low side and change to narrower rear spacers.
Joined: Aug 2006
Posts: 12,804
Likes: 103
From: Central NJ
Car: 86 Trans Am
Engine: 408 stroker sbc
Transmission: TKO600
Axle/Gears: Moser full floater m9, 3:70 trutrac
Re: Rubbing issues
Unlikely. Is quite common for these cars to be lower on one side in the rear, someone made a comment years ago that it was an issue with assembly and the quarters were set lower sometimes and gave the illusion the car was sitting crooked. My 86 for instance looks to be lower on the passenger side rear, but measurements from the suspension pickup points shows the car is level and square.
Senior Member
Joined: Mar 2002
Posts: 998
Likes: 19
From: Ontario, California
Car: 1992 Z28
Engine: 383
Transmission: 700R4
Re: Rubbing issues
Where was your car built?
I have owned over 11 of these cars and the t-top cars and verts tend to be tweaked. Some of the hardtops as well but not as much. I steer away from the hard top with the cracks in the upper rear corner of the door/roof connection. Clear sign of chassis stress.
I have owned over 11 of these cars and the t-top cars and verts tend to be tweaked. Some of the hardtops as well but not as much. I steer away from the hard top with the cracks in the upper rear corner of the door/roof connection. Clear sign of chassis stress.
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