Adjustable spring perches

west coast · 12-31-2008, 04:02 PM

Are adjustable spring perches on a coil spring car on the rear legal in nhra stock. The rule book is vague about this and does anybody run them for the ease of ride hieght adjustment.

Jeff Lee · 01-01-2009, 11:13 PM

In stock all traction devices need to be a bolt-on part. I'm not quite sure what you have here but I would think it could be argued it is a traction device as ride height can affect traction?

west coast · 01-02-2009, 01:38 PM

I would think what they mean by traction device is some that is not already part of the suspension but some thing you are adding to it and must be bolted on as under the rule book part about traction bars. It does not say you can but it does not say you can not. It says you can change springs so why not run a 2 1/2 inch style coil over spring to get your right spring rate plus now days they make allot of different lengths of springs. Any Chevelle, Malibu or 5.0 Mustang are rear coil spring cars have input? Or is this a kept secret.

Jeff Lee · 01-02-2009, 07:00 PM

If your talking converting a coil sprung rear suspension (like an A-Body GM) to a coil-over suspension, that is definetly not allowed.
Food for thought: A coil-over suspension is not nearly as effective at an OEM installed angle; in other words you can't make the shocks vertical.

Earle Holt · 01-02-2009, 07:52 PM

I've seen two types of lower arms with adjustable perches. (they are both on 5.0 Mustangs)

1- Lakewood makes one that is adjustable, but the spring perch is bolted to the arm. It is only way to adjust it is to remove the spring, move the perch to the next level, re-bolt it, then re-install the sping. This one I believe is permissable.

2- Steeda and a couple other companies make a lower arm that is adjustable as well. This one adjusts with a 1/2 drive ratchet and can be adjusted easily while installed on the car. This type I believe is not permissable.

west coast · 01-03-2009, 12:18 AM

I know coil over are not legal but just using the spring in the stock location with an adjustable spring perch for the assortment of spring weights. I have seen the adjustable ones on the lower control arms but was thinking more on the lines of circle track style with the top of the spring being adjustable which could be made to bolt on. In the rule book it says rear control arms maybe replaced with NHRA accepted OEM type after market units. So I would assume that the spring perches would not be on their list and I would assume there is not a list and would have to call NHRA with a manufacture and part# and they would get back to me in their speedy way.

12-31-2008, 04:02 PM	#1
west coast Senior Member Join Date: Dec 2008 Location: Rainy Washington Posts: 604 Likes: 12 Liked 215 Times in 69 Posts	Adjustable spring perches Are adjustable spring perches on a coil spring car on the rear legal in nhra stock. The rule book is vague about this and does anybody run them for the ease of ride hieght adjustment.

01-01-2009, 11:13 PM	#2
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Adjustable spring perches In stock all traction devices need to be a bolt-on part. I'm not quite sure what you have here but I would think it could be argued it is a traction device as ride height can affect traction? __________________ Jeff Lee 7494 D/S '70 AMX

01-02-2009, 01:38 PM	#3
west coast Senior Member Join Date: Dec 2008 Location: Rainy Washington Posts: 604 Likes: 12 Liked 215 Times in 69 Posts	Re: Adjustable spring perches I would think what they mean by traction device is some that is not already part of the suspension but some thing you are adding to it and must be bolted on as under the rule book part about traction bars. It does not say you can but it does not say you can not. It says you can change springs so why not run a 2 1/2 inch style coil over spring to get your right spring rate plus now days they make allot of different lengths of springs. Any Chevelle, Malibu or 5.0 Mustang are rear coil spring cars have input? Or is this a kept secret.

01-02-2009, 07:00 PM	#4
Jeff Lee VIP Member Join Date: Jul 2007 Location: Anthem, Arizona Posts: 2,766 Likes: 0 Liked 3 Times in 3 Posts	Re: Adjustable spring perches If your talking converting a coil sprung rear suspension (like an A-Body GM) to a coil-over suspension, that is definetly not allowed. Food for thought: A coil-over suspension is not nearly as effective at an OEM installed angle; in other words you can't make the shocks vertical. __________________ Jeff Lee 7494 D/S '70 AMX

01-02-2009, 07:52 PM	#5
Earle Holt Member Join Date: Nov 2001 Posts: 194 Likes: 1 Liked 4 Times in 1 Post	Re: Adjustable spring perches I've seen two types of lower arms with adjustable perches. (they are both on 5.0 Mustangs) 1- Lakewood makes one that is adjustable, but the spring perch is bolted to the arm. It is only way to adjust it is to remove the spring, move the perch to the next level, re-bolt it, then re-install the sping. This one I believe is permissable. 2- Steeda and a couple other companies make a lower arm that is adjustable as well. This one adjusts with a 1/2 drive ratchet and can be adjusted easily while installed on the car. This type I believe is not permissable. __________________ Earle Holt 1055 Stock

01-03-2009, 12:18 AM	#6
west coast Senior Member Join Date: Dec 2008 Location: Rainy Washington Posts: 604 Likes: 12 Liked 215 Times in 69 Posts	Re: Adjustable spring perches I know coil over are not legal but just using the spring in the stock location with an adjustable spring perch for the assortment of spring weights. I have seen the adjustable ones on the lower control arms but was thinking more on the lines of circle track style with the top of the spring being adjustable which could be made to bolt on. In the rule book it says rear control arms maybe replaced with NHRA accepted OEM type after market units. So I would assume that the spring perches would not be on their list and I would assume there is not a list and would have to call NHRA with a manufacture and part# and they would get back to me in their speedy way.