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View Full Version : 69 Chevelle SPC Rear Spring issues



nitetrain4590
06-06-2011, 10:05 PM
I might be overreacting, but I need some help figuring out a problem with my rear suspension setup. I've got SC&C Stage II plus set up on my SBC 69 Chevelle....front looks great and sits well. The rear is a pain in the a$$. After getting the Spohn Rear adjustable upper and lower control arms set to give the rear diff a 2.9* pinion angle to match my transmission, it looks like the rear suspension is lifted more than lowered. I've got SPC springs front and rear, and the rears are supposed to be 1.2" lower than stock. Here are the pics of what it looked stock, and what it looks like now with the body back on it.

Before:

https://static1.pt-content.com/images/pt/2011/06/IMG_0422-1.jpg?psid=1

After: with SPC Springs and Spohn Rear upper and lower control arms

https://static1.pt-content.com/images/pt/2011/06/IMG_0674-1.jpg?psid=1

I did have to take in my lower control arms a bit to make the pinion angle work since I had to take in my uppers so much, the springs were leaning significantly in their perches. Is that supposed to happen and do I need to leave the lower control arms at stock length? I don't buy that my "springs will settle" that much. On top of it, I'm running 305/35R18s that are over an inch taller than the rollers that are on it now.

Does anyone else run these SPC Rear springs on their A Body? What rear springs are guys running that give a more even ride height compared to the front... aka 11" 175lb/in spring????

nitetrain4590
06-06-2011, 10:20 PM
Okay, I realized that those were horrible comparison photos. Here is a before pic with no weight in the rear...no gas tank or an interior...

https://static1.pt-content.com/images/pt/2011/06/IMG_0031-1.jpg?psid=1

gearbanger
06-09-2011, 04:51 PM
Hey Man, I am glad I found this thread. I am dealing with the rear suspension issues on my 67 GTO. I talked to Marcus the other day about the SPC springs. I was very very specific about what I wanted as far as ride height, and after about an hour of suspension talk I realized that he really had no idea what the ride height would be and there was no way he was going to let me try the springs to find out. So I am steering away from the SPC package. I guess I will just give the information to either Eaton or Coil Spring Specialties on what I want and let them make the springs for me.

mplecha
06-11-2011, 05:25 AM
My 64 has SPC springs front and rear. I also have SPC upper and lower A arms. My car dropped quite a bit when I put them on. Marcus told me the rear would come down abouyt 1.5 inches and the front would depend on the spacers I put in.

https://static1.pt-content.com/images/pt/2011/06/5761032357_94931e1170_b-1.jpg

gearbanger
06-12-2011, 10:24 AM
Hey mplecha,

Nice car! Do you think you could get a measurement on the height of that spring at ride height?

wmhjr
06-12-2011, 10:53 AM
Interesting. I got my SPC springs from Marcus on my '66 Pontiac A-Body. Currie Currectrac and Moser bolt in rear end. Nothing else modified in the geometry. I am quite happy about where my height ended up.

https://static1.pt-content.com/images/pt/2011/06/DSC_4653-1.jpg

https://static1.pt-content.com/images/pt/2011/03/DSC_4651-1.jpg

gearbanger
06-12-2011, 11:14 AM
Hey wmhjr!

Good pics. I am glad you posted. I am looking for something lower in the rear, but I like the height of the front perfect. As far a spring rates, do you like the way your takes bumps? How would you compare it to a modern sports car like a camaro or a corvette?

wmhjr
06-12-2011, 01:25 PM
Hey Alex, Actually if anything I may slightly increase the height in the front. For the rear, anything lower would create some problems for me. Don't forget all of the other complications that start to occur. It'll be harder to set pinion angle, have driveshaft clearance, etc. My first pic above is a little misleading. I took it from low on the ground and it makes the rear end look higher than it is. The second pic is pretty accurate.

Anyway, I'm pretty darned happy so far with the spring rate. I just switched to Varishock double adjustables and the Hellwig rear sway bar so I'm still getting used to that. Very little miles since that change (almost no miles). I'm going to be at Motor State next week where I'll really find out how well it works together.

Bill

gearbanger
06-13-2011, 09:58 AM
Are you having dragging issues in the front? I have had my front end at different ride heights and have found that 5" under the center cross member eliminates about all the issues I have. Lower than that and the tires can get into the fenders when you have the wheels cut alot and are traveling on uneven ground. Also, low hangin headers are more of a pain.

As far as the rear goes, my car hits the bump stops just before the driveshaft contacts the tunnel and I have a 3.5" driveshaft with no step in the rear portion so it is pretty much a worst case scenario unless you have a 4" aluminum tube.

With my car at ride height, it has 2" travel to the bump stops. My problem is when the car gets loaded down, I have about 1/2" to the bump stops. Not good. I am looking for more spring rate but I dont want it to be a really rough ride. I am just learning about this suspension tuning stuff.

nitetrain4590
07-02-2011, 01:33 PM
Man mplecha,

That ride height is awesome. I've seen a few 64-67 A-Bodies that look great with the SPC setup, it just seems that the 68-72's have a taller rear spring setup. As for now, I'm gonna stick with the SPC rear springs and see what it looks like when the car is put back together....hopefully that's sooner rather than later.

mplecha
07-03-2011, 03:02 AM
Thanks! I'm pretty happy with the whole setup. Do you still need the ride height? I missed this post earlier.

gearbanger
07-04-2011, 06:12 PM
No thanks mplecha, I got what I needed from wmhjr.