car/wheel gap
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
car/wheel gap
3 years ago I installed 8" bolts to close the rear end gap between the car and the top of tire. I didn't want to buy bigger wheels at the time. Yes I know a bigger tire would close the space. Is that the only answer? Everybody said that installing longer bolts would do it and drive the car a while and it will settle. Well here we are and it hasn't dropped any. I have unscrewed the nut until I have about 3 to 5 threads left before it coming off. It seems to me that unscrewing that bottom nut would be backwards. Seems to me you would tighten it to pull the car down to close the gap. Am I looking at this wrong? I did remove the spare tire so maybe that didn't help with closing the gap because of removing the extra weight. Any thoughts?
Last edited by 7T3stinger; Jun 24, 2021 at 02:55 PM.
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,597
Likes: 7,046
From: New Or-leens Loo-z-anna
I removed my spare tire also before lowering the rear.
I installed 8" long bolts (upside down because it looked better that way).
It still had too much gap between the tire and the wheel arch.
I can't advise you to do this: I removed the thick top spacer on the springpack and installed a new bolt & nut to hold the springpack together which lowered the car more.(the threads were badly rusted on the original OEM bolt---do not use a standard bolt--they will snap in half)
I also made sure my tires were at least 28" in diameter...to "fill up" the wheel well better.
Smaller diameter tires make the rear of the car appear to be "Jacked-up".
NOTE: you can buy larger rims 16"/17"/18"/etc.....but you have to install a tire that is at least 28" in diameter on the larger rims or the tires will appear "Too Small" in the wheel well.
I installed 8" long bolts (upside down because it looked better that way).
It still had too much gap between the tire and the wheel arch.
I can't advise you to do this: I removed the thick top spacer on the springpack and installed a new bolt & nut to hold the springpack together which lowered the car more.(the threads were badly rusted on the original OEM bolt---do not use a standard bolt--they will snap in half)
I also made sure my tires were at least 28" in diameter...to "fill up" the wheel well better.
Smaller diameter tires make the rear of the car appear to be "Jacked-up".
NOTE: you can buy larger rims 16"/17"/18"/etc.....but you have to install a tire that is at least 28" in diameter on the larger rims or the tires will appear "Too Small" in the wheel well.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
I removed my spare tire also before lowering the rear.
I installed 8" long bolts (upside down because it looked better that way).
It still had too much gap between the tire and the wheel arch.
I can't advise you to do this: I removed the thick top spacer on the springpack and installed a new bolt & nut to hold the springpack together which lowered the car more.(the threads were badly rusted on the original OEM bolt---do not use a standard bolt--they will snap in half)
I also made sure my tires were at least 28" in diameter...to "fill up" the wheel well better.
Smaller diameter tires make the rear of the car appear to be "Jacked-up".
NOTE: you can buy larger rims 16"/17"/18"/etc.....but you have to install a tire that is at least 28" in diameter on the larger rims or the tires will appear "Too Small" in the wheel well.
I installed 8" long bolts (upside down because it looked better that way).
It still had too much gap between the tire and the wheel arch.
I can't advise you to do this: I removed the thick top spacer on the springpack and installed a new bolt & nut to hold the springpack together which lowered the car more.(the threads were badly rusted on the original OEM bolt---do not use a standard bolt--they will snap in half)
I also made sure my tires were at least 28" in diameter...to "fill up" the wheel well better.
Smaller diameter tires make the rear of the car appear to be "Jacked-up".
NOTE: you can buy larger rims 16"/17"/18"/etc.....but you have to install a tire that is at least 28" in diameter on the larger rims or the tires will appear "Too Small" in the wheel well.
Melting Slicks
Joined: Dec 2015
Posts: 3,181
Likes: 732
From: Texas City, TX Texas
Raise the car 1"
Fill the wheelwell 1"
Loosening the bolt-i.e. less threads showing- will lower the car. You are effectively letting the spring hang down more and it lowers the car. Was kinda hard to wrap my head around it at first. I'm sure someone else can explain better.
Can't safely use any longer bolts with 15" wheels or the bolt will hang below the rim-not good if you have a flat.
I am dealing with the same issue. I will be doing a combination of removing a leaf as mentioned above, and using a taller tire. When the next batch of composite springs hits the market I'm getting one.
Last edited by Richard Daugird; Jun 24, 2021 at 06:28 PM.
Race Director
Joined: Mar 2016
Posts: 14,402
Likes: 8,211
From: Napa Valley California
There are several different composite springs available on the market that will improve the ride and lower the rear end, without having to use longer spring bolts.
Some springs are made shorter with less arch to avoid any contact between the spring ends and the tire.
Contact Van Steel and ask their representatives about which spring rate will give you the ride, handling and stance you are looking for.
Van Steel also has a Derlin bushing kit for the rear crossmember that pulls the rear differential assembly up into the frame while lowering the rear end another 3/4" without effecting the suspension geometry.
Depending on your budget, you can also look at swapping to a coil over type suspension, which will allow you to set up the spring rate for your driving style and use of your car while setting the stance exactly where you want it.
Some springs are made shorter with less arch to avoid any contact between the spring ends and the tire.
Contact Van Steel and ask their representatives about which spring rate will give you the ride, handling and stance you are looking for.
Van Steel also has a Derlin bushing kit for the rear crossmember that pulls the rear differential assembly up into the frame while lowering the rear end another 3/4" without effecting the suspension geometry.
Depending on your budget, you can also look at swapping to a coil over type suspension, which will allow you to set up the spring rate for your driving style and use of your car while setting the stance exactly where you want it.
Last edited by OldCarBum; Jun 24, 2021 at 07:04 PM.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
A 2" taller tire will-
Raise the car 1"
Fill the wheelwell 1"
Loosening the bolt-i.e. less threads showing- will lower the car. You are effectively letting the spring hang down more and it lowers the car. Was kinda hard to wrap my head around it at first. I'm sure someone else can explain better.
Can't safely use any longer bolts with 15" wheels or the bolt will hang below the rim-not good if you have a flat.
I am dealing with the same issue. I will be doing a combination of removing a leaf as mentioned above, and using a taller tire. When the next batch of composite springs hits the market I'm getting one.
Raise the car 1"
Fill the wheelwell 1"
Loosening the bolt-i.e. less threads showing- will lower the car. You are effectively letting the spring hang down more and it lowers the car. Was kinda hard to wrap my head around it at first. I'm sure someone else can explain better.
Can't safely use any longer bolts with 15" wheels or the bolt will hang below the rim-not good if you have a flat.
I am dealing with the same issue. I will be doing a combination of removing a leaf as mentioned above, and using a taller tire. When the next batch of composite springs hits the market I'm getting one.
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Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
There are several different composite springs available on the market that will improve the ride and lower the rear end, without having to use longer spring bolts.
Some springs are made shorter with less arch to avoid any contact between the spring ends and the tire.
Contact Van Steel and ask their representatives about which spring rate will give you the ride, handling and stance you are looking for.
Van Steel also has a Derlin bushing kit for the rear crossmember that pulls the rear differential assembly up into the frame while lowering the rear end another 3/4" without effecting the suspension geometry.
Depending on your budget, you can also look at swapping to a coil over type suspension, which will allow you to set up the spring rate for your driving style and use of your car while setting the stance exactly where you want it.
Some springs are made shorter with less arch to avoid any contact between the spring ends and the tire.
Contact Van Steel and ask their representatives about which spring rate will give you the ride, handling and stance you are looking for.
Van Steel also has a Derlin bushing kit for the rear crossmember that pulls the rear differential assembly up into the frame while lowering the rear end another 3/4" without effecting the suspension geometry.
Depending on your budget, you can also look at swapping to a coil over type suspension, which will allow you to set up the spring rate for your driving style and use of your car while setting the stance exactly where you want it.
Le Mans Master
Joined: Jun 2019
Posts: 5,481
Likes: 2,190
From: Loveland
What spring are you using? It must be to stiff. Spring stiffness + bolt length = ride height. I would look very close at removing a leaf from your spring. It could make the spring package to weak and could bottom out. As the spring compresses the smaller spring come into play to progressively get stiffer. GM did have a design team.
Last edited by kodpkd; Jun 24, 2021 at 08:56 PM.
2026 Loser of the Year
Joined: Sep 2013
Posts: 36,597
Likes: 7,046
From: New Or-leens Loo-z-anna
A 2" taller tire will-
Raise the car 1"
Fill the wheelwell 1"
Loosening the bolt-i.e. less threads showing- will lower the car. You are effectively letting the spring hang down more and it lowers the car. Was kinda hard to wrap my head around it at first. I'm sure someone else can explain better.
Can't safely use any longer bolts with 15" wheels or the bolt will hang below the rim-not good if you have a flat.
I am dealing with the same issue. I will be doing a combination of removing a leaf as mentioned above, and using a taller tire. When the next batch of composite springs hits the market I'm getting one.
Raise the car 1"
Fill the wheelwell 1"
Loosening the bolt-i.e. less threads showing- will lower the car. You are effectively letting the spring hang down more and it lowers the car. Was kinda hard to wrap my head around it at first. I'm sure someone else can explain better.
Can't safely use any longer bolts with 15" wheels or the bolt will hang below the rim-not good if you have a flat.
I am dealing with the same issue. I will be doing a combination of removing a leaf as mentioned above, and using a taller tire. When the next batch of composite springs hits the market I'm getting one.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Do you have a stock spring in the rear? Or have you converted to a monoleaf spring? Some of the [stiffer] monoleaf springs are formed with too much arc and cause the car to sit too high in the rear. If that is the problem, longer bolts will not totally correct the problem.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
What spring are you using? It must be to stiff. Spring stiffness + bolt length = ride height. I would look very close at removing a leaf from your spring. It could make the spring package to weak and could bottom out. As the spring compresses the smaller spring come into play to progressively get stiffer. GM did have a design team.
Thread Starter
Racer
Joined: Dec 2020
Posts: 277
Likes: 57
From: Va.
Do you have a stock spring in the rear? Or have you converted to a monoleaf spring? Some of the [stiffer] monoleaf springs are formed with too much arc and cause the car to sit too high in the rear. If that is the problem, longer bolts will not totally correct the problem.
