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Discussion Starter #1
Like lots of us, funds dictated the purchase of budget-friendly leaf springs many years ago.

I purchased the Grabatrack 5 leaf reverse eye springs. As the car evolved, especially the front suspension, the stiffness of the rear suspension is noteable.

So there are two things I want when I change out the rear springs. Day to day driveability (a little less harshness) and better overall handling. (more compliant)

I don't want to lose any ride height and I have caltracs that fit the reverse eye springs. I think I can get a different front bracket, from calvert if I want a pair, butI'm not sure that's necessary yet.

In reading the 5 leaf springs that I have now are rated at 195 lb/in
TCP claims their 5 leaf is 140 lb/in
or 4 leaf at 112 lb/in

So if those numbers are correct, what do you think, is the 195 to 140 enough of a change?
 

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Discussion Starter #3

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I have the global west L-11 rear springs which I think are 165#
Its stiff but not super stiff....
What is your front setup?
 

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I just went from 4 leaf standard eye Grab-A-Trak (with KYBs) to 5 leaf reverse eye TCP (with Bilsteins). Other than lowering the rear a good 2", the ride is only a bit stiffer...but I need the control for the track. My car also has a Watts link that controls the rear end to the 9s...so you need to add that to the equation.


I'm of the belief that each vintage car reacts differently to identical setups, but that's just me (and my car is possessed, so take that with a grain of salt lol). You may just have to bite the bullet and buy a new set of 4 leafs and see if you like the difference.
 

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Discussion Starter #6
I have the global west L-11 rear springs which I think are 165#
Its stiff but not super stiff....
What is your front setup?
Front is a Hybrid, started with TCP UCA's and LCA's then Shaun came out with his system, so it's his coil-overs and Bilstein shocks, The front is about 1 3/4"-2" lowered, quite firm, It's necessary as with that much lowering, one does not to be bouncy. The front shocks make the difference there. TCP R&P



I just went from 4 leaf standard eye Grab-A-Trak (with KYBs) to 5 leaf reverse eye TCP (with Bilsteins). Other than lowering the rear a good 2", the ride is only a bit stiffer...but I need the control for the track. My car also has a Watts link that controls the rear end to the 9s...so you need to add that to the equation.


I'm of the belief that each vintage car reacts differently to identical setups, but that's just me (and my car is possessed, so take that with a grain of salt lol). You may just have to bite the bullet and buy a new set of 4 leafs and see if you like the difference.
After having had my car on the track and street, it's demonstrated a noteable enough oversteer to try and look at options. The other issue is day to day driveabliity.

You mentioned Watts link etc. I am not ruling that out, but want to get the right balance with the rear spring. I'd guess with the 5 leafs that I have now, they are about the stiffest that I can get, and contributing to the jumpiness of the rear set up
 

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Leaf Springs are really a crap shoot. I have 5 leafs that really are not that stiff at all. In fact I clamped the front half of the spring and that didn't really change the spring rate that much surprisingly. It did make the car handle fantastic especially noticeable under trail-braking into a turn.



If you spend any time on the hairy edge of traction (autocross or track), a watts link is game changing in terms of letting you know exactly what is going on back there and if you break loose, you can gather it up without any drama. Its easy to find and hang on the hairy edge of traction. If not, you probably won't really notice its there unless you jerk the wheel from side to side quickly to wag the tail so-to-speak.
 

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If you spend any time on the hairy edge of traction (autocross or track), a watts link is game changing in terms of letting you know exactly what is going on back there and if you break loose, you can gather it up without any drama. Its easy to find and hang on the hairy edge of traction. If not, you probably won't really notice its there unless you jerk the wheel from side to side quickly to wag the tail so-to-speak.

Game changer indeed. The Watts (Fays2, in case you're wondering) *completely* changed the driving attitude of my car. It's scary how much that rear end used to move left & right. Now it stays centered, where it's supposed to be. Nice and predictable, like dobrostang said. It has little effect on "up/down" though, so it doesn't stiffen the rear. It just makes it behave lol.
 

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Yes, thanks, Global is good stuff as well. I guess I am asking if the rate difference will be that significant, or what rate I should be shooting for?
The rear is light. It responds well to something a bit stiffer than the "GT"
spec rear spring rate. We ran a 150# rate in 65-68's.
In direct answer to your question, a 10-15# change in the back is a
significant one. I think you'll find 160's are absolutely the stiffest rate
you would EVER want to run in the back.

ex-Global West GM
1991-1995
 

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I have the global west L-11 rear springs which I think are 165#
Its stiff but not super stiff....
What is your front setup?
L-10 are 150#
L-11 are 160#
L-12 are 170#
These rates aren't posted anywhere that I'm aware and not widely discussed.
150's are the ones generally recommended unless you're talking purpose-built
race car. The 170's are really not intended for 65-68's. We used them on the
later cars that were like B302 race cars and 71-up race applications.
They're super stiff, even with a low-drag bushing like a del-a-lum.

ex-Global West GM
1991-1995
 

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Discussion Starter #12
I have the global west L-11 rear springs which I think are 165#
Its stiff but not super stiff....
What is your front setup?
Thanks

Leaf Springs are really a crap shoot. I have 5 leafs that really are not that stiff at all. In fact I clamped the front half of the spring and that didn't really change the spring rate that much surprisingly. It did make the car handle fantastic especially noticeable under trail-braking into a turn.



If you spend any time on the hairy edge of traction (autocross or track), a watts link is game changing in terms of letting you know exactly what is going on back there and if you break loose, you can gather it up without any drama. Its easy to find and hang on the hairy edge of traction. If not, you probably won't really notice its there unless you jerk the wheel from side to side quickly to wag the tail so-to-speak.
I've looked at quite a few different iterations but am leaning to making the leaf spring suspension as good as I can, including looking at a watts link (if I can get the tailpipes past it)

Game changer indeed. The Watts (Fays2, in case you're wondering) *completely* changed the driving attitude of my car. It's scary how much that rear end used to move left & right. Now it stays centered, where it's supposed to be. Nice and predictable, like dobrostang said. It has little effect on "up/down" though, so it doesn't stiffen the rear. It just makes it behave lol.
Thanks

The rear is light. It responds well to something a bit stiffer than the "GT"
spec rear spring rate. We ran a 150# rate in 65-68's.
In direct answer to your question, a 10-15# change in the back is a
significant one. I think you'll find 160's are absolutely the stiffest rate
you would EVER want to run in the back.

ex-Global West GM
1991-1995
Thanks that's helpful
 

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(if I can get the tailpipes past it)

Thanks that's helpful

That's a big if, most of them I looked at recommend dumps. I designed and fabricated my own WL in such a way to make room for the exhaust.


BTW, are you sure its not your shocks driving the stiffness? Try backing off if they are adjustable or if they are airshocks dump em...
 

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My exhaust guy hates me, as he had to custom route my exhaust over/around the Watts. But the Fays2 isn't terribly obstructive, IMHO.
 

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Discussion Starter #15
That's a big if, most of them I looked at recommend dumps. I designed and fabricated my own WL in such a way to make room for the exhaust.


BTW, are you sure its not your shocks driving the stiffness? Try backing off if they are adjustable or if they are airshocks dump em...
I just have the very stock generic hydraulic shocks on there right now. I broke one of the bilstien rear shocks about a year and a half ago, so the remaining shock was taken off.
Due to the lowered stance there is quite an angle on the shock, so I wanted to rethink the mount before replacing them.
The car is so hideously loud that I would not be able to just dump the pipes. I need the tailpipes and resonators to help keep my sanity.

My exhaust guy hates me, as he had to custom route my exhaust over/around the Watts. But the Fays2 isn't terribly obstructive, IMHO.
Sounds promising. I'll definitely look at that once I decide on springs.
 

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If you are not doing a watts link or panhard, look at the del alum bushings. I think the ease of motion makes things feel a little less harsh.
 

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Discussion Starter #17
If you are not doing a watts link or panhard, look at the del alum bushings. I think the ease of motion makes things feel a little less harsh.
Thanks, I think that's worth looking at, and easy to do. Keeping in mind that I already have the aluminum bushing that comes with the Caltrac's in the front. Adding the del alum bushings, isn't going to make any noticeable change to the road noise that exists now.

I was researching the Cat5 springs, but I think the consensus is that they are a very stiff and a race only spring.
 

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Thanks, I think that's worth looking at, and easy to do. Keeping in mind that I already have the aluminum bushing that comes with the Caltrac's in the front. Adding the del alum bushings, isn't going to make any noticeable change to the road noise that exists now.

I was researching the Cat5 springs, but I think the consensus is that they are a very stiff and a race only spring.
Im reasonably sure you can get an L-11 in a cat 5.
I think the cat 5 is about as advanced as a leaf spring can get...
Mary Pozzi ran then for years in her camaro
 

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Given you don’t have a sway bar, Watts Link, or Panhard Link, I guess I’m a little surprised it oversteers. But that’s a more comfortable way around the corner provided it’s not acting like a drift car. My personal favorite is the adjustable Watts Link since moving CG (Center of Gravity) is a simple ten minute adjustment, a tight car that refuses to rotate can quickly be loosened up to rotate easily. And you don’t really need to understand anything but the very basics.

The Fays unit has proven to work and to last. Some good quality, round, short, mufflers and side exhaust is an easy way and it does not have to be harsh. You can get the exhaust out the back, I ran mine that way for a couple of years, but it takes a muffler shop with a guy willing to get it done. And a big tip when he does.

Back in the early seventies the general idea was to spring it hard and dampen it hard, not a very compliant suspension. That thinking has evolved to spring it soft(er) and dampen it hard(ish). Or dampen it to the needs of the track. So softer springs will allow the suspension to work and follow the bumps and dips, dampen with adjustable shocks to the needs of the track, add the Watts, and you’ll find you can fly. Or just do the softer spring that you want, a Watts Link, and you’ll still enjoy a car that’s easily adjustable for the conditions.

Small changes in spring numbers is hard to feel, big changes may get you in territory you find too soft. If your current spring is too harsh, maybe it’s the damper (or lack of) that’s the real issue? You know your setup far better than me, I guess I’m just voting for the Watts. :).

They do have a composite single leaf (sort of like on C5 and later Vetts), it knocks off some sixty or more pounds. Just a thought.
 

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Discussion Starter #20
Im reasonably sure you can get an L-11 in a cat 5.
I think the cat 5 is about as advanced as a leaf spring can get...
Mary Pozzi ran then for years in her camaro
Thanks, I used the GW contact form, but no one responded. Probably a tech issue. I'll call them when I cat my car back from the paint shop.

Given you don’t have a sway bar, Watts Link, or Panhard Link, I guess I’m a little surprised it oversteers. But that’s a more comfortable way around the corner provided it’s not acting like a drift car. My personal favorite is the adjustable Watts Link since moving CG (Center of Gravity) is a simple ten minute adjustment, a tight car that refuses to rotate can quickly be loosened up to rotate easily. And you don’t really need to understand anything but the very basics.

The Fays unit has proven to work and to last. Some good quality, round, short, mufflers and side exhaust is an easy way and it does not have to be harsh. You can get the exhaust out the back, I ran mine that way for a couple of years, but it takes a muffler shop with a guy willing to get it done. And a big tip when he does.

Back in the early seventies the general idea was to spring it hard and dampen it hard, not a very compliant suspension. That thinking has evolved to spring it soft(er) and dampen it hard(ish). Or dampen it to the needs of the track. So softer springs will allow the suspension to work and follow the bumps and dips, dampen with adjustable shocks to the needs of the track, add the Watts, and you’ll find you can fly. Or just do the softer spring that you want, a Watts Link, and you’ll still enjoy a car that’s easily adjustable for the conditions.

Small changes in spring numbers is hard to feel, big changes may get you in territory you find too soft. If your current spring is too harsh, maybe it’s the damper (or lack of) that’s the real issue? You know your setup far better than me, I guess I’m just voting for the Watts. :).

They do have a composite single leaf (sort of like on C5 and later Vetts), it knocks off some sixty or more pounds. Just a thought.
Thanks a lot for your feedback. I do tend to agree with you, and was planning on approaching it little by little. I think getting the springs correct is where I need to start.
The watts link is also on the radar.

The other issue I have, is that the lowered nature of the car, causes the rear shocks to be at a pretty extreme angle at times under compression. I l already snapped a Bilstien shock. I want to conceive a more freely articulating shock absorber mount, maybe similar to the Mair setup. Until I have that, I have just the generic econo hydraulic shocks.

I found out yesterday when I was at the paint shop, their mechanic stated there was a crack in a weld where the strut rod bracket attaches to the frame. When it gets back, I'll also look into that, to see if that's the case or not.
 
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