Hi guys, I've searched some old posts and found good info on springs and ride height. I'd like to get new springs all around for my 1971 Skylark (all iron 350SBB). Before I start buying parts I just want to ask for confirmation/any new information you guys may have. I don't want to spend for adjustable coil overs. But I do want better rake than factory, which seems 1" lower in the rear. I also think that stiffer than OEM springs (new ones that aren't sagging) will improve the OEM handling. Step 1 is to install the Moog variable rate (cargo) springs, P/N cc501. After they settle out and I measure ride height, I'll have a better guess on front springs (that's step 2). FYI, step 3 may be a fatter front sway bar. My main concern is whether you all think those rear cargo springs will be TOO stiff? Seems like several posts talked about liking those springs, maybe one said too stiff...? If they don't raise the rear as much as I'd like, I can add a spacer OR use 1" lowering springs up front. I think the factory rate for rear is only 122#/in. where the Cargo shows 175#/in. Yikes! But if that 175# is at max compression/right before coil bind, and the first inch of travel is similar to the softer factory rate, maybe that's a good tradeoff for better performance. I do mostly cruising with some aggressive driving, no autocross or track time intended.
Hoping that LARRY70GS and eagleguy weigh in with ideas, seems like they have similar past experiences
I only have 100 miles or so on my car, but I haven’t had any noticeable amount of increased stiffness with the cc501s. I am a big fan of the stance it provides. For step 3: a 1.25” front sway bar out of an f-body will definitely improve your handling
What Louie said - I have the same on my 70 GS. I am using a 1"" bar on the back. To go big in the front you need a bar in the rear but not bigger than the front sway bar. I think the cc501's ride well.
Thanks Louie and Bill, glad to hear neither of you find your cc501 as too stiff a spring. That advertised rate of 175# looks so high vs. the OEM 122#. A tech guy at UMI Performance thought they'd be too stiff. So he suggested their rear springs 4049R (linear rate of 130#), and they're advertised as firmer, so I thought 175# might be nutty. But being a progressive rate must tame them for daily driving/cruising/etc. And no worries when I load up the trunk with beer coolers, or people in the back seats!
Matt - yes It will affect understeer/oversteer. You want as close to neutral as possible. Controlling the rate of roll with sway bars will affect how the weight settles across the tires, which ties into roll center, center of gravity, and suspension kinematics like camber, caster, and toe-steer. Oversteering happens when a vehicle excessively leans. This occurs when the rear wheels have less grip on the road compared to the front tires. On the other hand, understeering occurs when a vehicle turns less than expected. It happens when the front wheels lose their grip on the road compared to the rear wheels. Increase stiffness to a sway bar on one end, reduces the side grip of that axle, while increasing the side grip on the other end. As the rear sway gets thicker and thicker, body roll is reduced and the tire contact patch stays flatter & flatter until, snap! the rear end swings around w/o warning. A thinner rear sway allows more body roll, and makes it easier for the driver to sense when the limit is being approached. If it's true that a thicker rear sway promotes oversteer, then a thinner one promotes understeer which is easier to react to.
I have been running these springs for the last 4-5 years and she still rides great. I added Bilstein shocks as well.
UPDATE: For anyone searching these threads for Moog rear springs, I thought to update. I just installed mine yesterday, part CC501. The CC = Cargo Coil, they're progressively wound. They feel nicer than the old ones I removed, which is to say a bit more controlled going over bumps (like modest rail road tracks at 40mph). Seems like the first inch of travel is about the same, so the ride felt about the same on smooth roads. But maybe it's part imagination since I thought it may feel that way? Anyway I'd recommend them for what I think is a good ride, firmer & more controlled than old ones, but only noticeable over bumps and swales, and harder cornering, etc. Ride Height: In my case the new springs did raise my soggy bottom a little, as I hoped. Per tape measure, it raised the rear about 3/4" +. It also improved the lean it used to have on drivers side, now the rear sits level within 1/8" side to side (service manual allows 3/8" variation). So I'm now getting measurements of 25.625" to 25.75" at the fender well peak, where svc manual shows 25.125". Old springs it measured 24.75" +. Over time I wonder if the new springs will settle in a bit more, and lower the height any. New rate is 175# (but I assume that's at full compression) and wire diameter is .610", old springs were .540" wire dia. Now I'm really looking forward to new front springs with a little stiffer rates! I expect it'll improve the handling/cornering a bit more - I'm thinking the UMI 1" lower springs since I want a little forward rake, and the taller top ball joint (and then a badly needed front end alignment).
No good pics, let me try uploading what I do have… Boxed control arms didn’t allow the axel to drop down far enough for spring to escape, so I had to jack up the left side of axel housing to force the right side lower…repeat…then the old springs came out. Rubber brake line would’ve been the limiting factor otherwise, to get the axel low enough. I also disconnected drive shaft. Experienced mechanics out there prolly know these things but I shared for other newbies like me
These are all AFTER pics. I could see the 3/4” higher rear end but not dramatically noticeable, to my eye.
UPDATE: For anyone that's doing spring and things, and may be interested in other peoples experiences with aftermarket parts: I just completed my Steps 2&3 on the front end of my 1971 Skylark. I'll make a new post on UMI Front Springs next...
