Rear suspension - Performance leaf springs

mrmustangman357 · Nov 28, 2008

After suffering from crippling wheelhop after my 5 speed and 8.8 conversion, I decided to redo the completely stock rear suspension. My goal is to simply do what I want it to: Drag race on sunday, street manners on monday, handling on tuesday, and drift on wednesday. So far I decided to go with a set of global west leaf springs:

Global West Suspension L-10 - Global West Suspension Category 5 Leaf Springs - summitracing.com

They are 140 lb/in springs. 5 spring leaf pack designed not to wrap up on acceleration (so after all I may not need to build a set of caltracs). They say it lowers the car approx 1.5" so I may need a small spacer in there to get the desired ride height I'm looking for. They also say the springs are so stiff laterally that a sway bar is not necessary. at $300 I think they are a bargain for what they promise.

After talking with global west about my plans and my slight curiosity with drifting, they recommended a single adjustable shock for the rear to lock out the suspension movement and make the rear more predictable.
For shocks I am thinking of using the summit brand rear drag shocks:
Summit SUM-G7704 - Summit® Drag Racing Shocks - summitracing.com
They are 3 way adjustable and I hope the extra firm setting (70/30) can accomplish this same thing. What sucks is that the shock has to be removed to adjust it Of course, they are $50 per pair as opposed to $300 for QA1 or another full racing shock. What are your guy's setups for springs/shocks?

SNAKEPILOT · Nov 29, 2008

mrmustangman357 said:
They also say the springs are so stiff laterally that a sway bar is not necessary.

Sway bars don't control lateral flex, they control roll...

Springs can control body lean and eliminate the need for a sway bar but that is because of the spring rate. The lateral flex in a leaf spring suspension is not from the springs but from the spring bushings and/or shackles.

Rubber spring bushings flex in roll and laterally. You can use Global West's recommended Del-alum bushings and heavy duty shackles which will control both axis' or use a panhard/watts set-up to eliminate lateral movement in conjunction with a sway bar to eliminate roll.

It is interesting that Summit calls them "Cat 5" springs. Global West Cat 5 springs use special spherical bushings (not Del-alum) and they are quite pricey, about $900/pr. The springs listed are NOT Cat 5.

10secgoal · Nov 29, 2008

I'd skip the summit adjustables and get the Rancho's. The summit's are are a pain and kinda confusing to adjust. If your stuck on them you can pay to ship the ones I just took out.

mrmustangman357 · Nov 29, 2008

do you have a part number on rancho's?

mrmustangman357 · Nov 30, 2008

are they the RS99204 ranchos? I heard on another forum that they can bottom out on the shock before the suspension bottoms out. is this correct?

rbohm · Dec 1, 2008

for what you want i would go with flex a form fiberglass leaf springs with koni shocks instead. the konis are adjustable in the car, and the fiberglass springs dont wrap up, and you wont need the heavier rate spring as you would with steel springs since you dont have to control as much weight, thus you will get the handling you want, and a better ride as well. i would also run a 3/4" rear antiroll bar to help control body roll.

SNAKEPILOT · Dec 1, 2008

I have Flex-a-form springs and I am very happy with them. Smooth ride and zero wheel hop (and I am running an FE stroker).

I am using Global West Del-alum bushings that control body roll so I didn't need a sway bar but a side benefit is wheel hop control.

The mono-leaf design of the fiberglass springs resists wheel hop but if you look at the Cal-Tracs and Slide-a-Links, they all use a solid front spring eye bushing. Eliminating vertical movement at the front spring mount helps control wheel hop.

mrmustangman357 · Dec 2, 2008

I'm not too keen on the fiberglass leaf springs. I understand the weight savings but for cost and simplicity sake, I'll stay with metal leafs.

SNAKEPILOT · Dec 2, 2008

Whichever spring you use, the bushings will have a significant role in handling (roll) and straight line (wheel hop) performance.

SoCalCruising · Dec 2, 2008

I use the GW springs you mention, their del-alums and hd shackles. The rear is firm, little flex or roll and no wrap up, at all, when I jump on it (400+hp stroker). Simple and effective.

rbohm · Dec 2, 2008

mrmustangman357 said:
I'm not too keen on the fiberglass leaf springs. I understand the weight savings but for cost and simplicity sake, I'll stay with metal leafs.

i will agree with the cost, but you cant get any simpler than a mono leaf spring, metal or fiberglass.

mrmustangman357 · Dec 11, 2008

global west 5 leaf with reverse eye L-10R ordered through summit, $261 shipped thanks to my discount code and some cannodling with the sales rep.

I might hold off on the shocks for now since the economy is in the rut and I'm unemployed.

madbrad · Dec 11, 2008

Where do you get the mono fiberglass springs from?

Hack · Dec 11, 2008

SNAKEPILOT said:
Sway bars don't control lateral flex, they control roll...

Springs can control body lean and eliminate the need for a sway bar but that is because of the spring rate. The lateral flex in a leaf spring suspension is not from the springs but from the spring bushings and/or shackles.

Rubber spring bushings flex in roll and laterally. You can use Global West's recommended Del-alum bushings and heavy duty shackles which will control both axis' or use a panhard/watts set-up to eliminate lateral movement in conjunction with a sway bar to eliminate roll.

It is interesting that Summit calls them "Cat 5" springs. Global West Cat 5 springs use special spherical bushings (not Del-alum) and they are quite pricey, about $900/pr. The springs listed are NOT Cat 5.

Rear leafs don't control body lean only by spring rate. When the body rolls, the bushings deform and/or the leaf springs must twist. It takes a significant amount of force to twist a rear leaf spring! The bushings only allow the body to move a small amount, then the spring must twist for the body to roll.

SNAKEPILOT · Dec 11, 2008

madbrad said:
Where do you get the mono fiberglass springs from?

Flex-Form Fiberglass Leaf Springs replace Steel Leaf Springs

jerry S · Dec 12, 2008

SNAKEPILOT said:
It is interesting that Summit calls them "Cat 5" springs. Global West Cat 5 springs use special spherical bushings (not Del-alum) and they are quite pricey, about $900/pr. The springs listed are NOT Cat 5.

I have the L11-cat 5 springs from GW and I paid about $900 for them. If you go to summit and select either the L11s or the L10s, these are indicated as having the spherical bearings. I am pretty perturbed at the price difference.

SNAKEPILOT · Dec 12, 2008

jerry S said:
I have the L11-cat 5 springs from GW and I paid about $900 for them. If you go to summit and select either the L11s or the L10s, these are indicated as having the spherical bearings. I am pretty perturbed at the price difference.

I don't understand what you are perturbed about. Summit is NOT selling Cat-5 springs for $300. They are selling regular L-10 and L-11 springs for about 10% less than Global West's retail price.

If you search for L-11CAT5 at Summit you will get:

Global West Suspension L-11CAT5 - Global West Suspension Category 5 Leaf Springs - summitracing.com

Which are $760, about 10% less than Global West retail.

The CAT5 springs come with the special spherical bushings for the leaf eyes and the Delalum frame bushings and shackles. With the regular "L-11" springs you would have to purchase the bushings and shackles separately for $210 (or $190 at Summit).

Now, if you paid $900 and don't have spherical bearings and didn't get the frame bushings and shackles, then you should be perturbed.

jerry S · Dec 12, 2008

SNAKEPILOT said:
I don't understand what you are perturbed about. Summit is NOT selling Cat-5 springs for $300. They are selling regular L-10 and L-11 springs for about 10% less than Global West's retail price.

Now, if you paid $900 and don't have spherical bearings and didn't get the frame bushings and shackles, then you should be perturbed.

The summit description for the sub-$300 stuff says that they have spherical bearings. That is what the spendy GW L11-Cat 5s have. Perhaps the summit product description is wrong. I hope so.

Rear suspension - Performance leaf springs

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