Rear suspension upgrade advice

[UNGN]

275/60's will fit fine on a lowered car if the offset is right (probably around -7mm). Zero offset puts the tire too close to the frame. A 15X8 with a 4" BS would be close to -7mm offset.

 

[gbodytoys]

I went with the UMI Stage 1 Kit and it made a big difference. However, we have to be careful when comparing worn out stock parts vs new aftermarket stuff. I think that the G-Body community as a whole could benefit from some standards when it comes to suspensions, or even some sort of track testing. Something like "G-Body Proving Grounds"...start with baseline replacement parts from RockAuto and go up from there.

If I ever hit the lottery, I'll fund the entire thing. Parts, professional drivers, and track time. lol.

 

[buzz77]

That's the thing. To me a 1.5 inch drop seems like alot but how much will I notice it, if my springs are sagging 40 year olds?

How about my front springs . They are 40 year old and instead of the lighter 301 v8 I have a pontiac 400. I imagine it already sits lower than it did in 1979 when it rolled off the showroom floor.

 

[buzz77]

If the rear of the car looks low vs the front, you can install Tall lower ball joints on the car in a couple hours, using one of those C-clamp removal tools you rent at autozone. The shock captures the spring during the whole procedure. Tall (.5" taller) balljoints will lower the front about 3/4" and improve handling. Tall balljoints are about $100/pr shipped from Summit and will should work with whatever suspension you eventually go with.

Before doing anything, I eyeball the starting toe (with the front of the car on ramps, sight down the outside face of each front tire, mid tire, to see where the sight line - that touches the outside face of the front and back of the front tire, intersects the tread of the back tire) and note this. Tall ball joints will change the toe slightly, so it is good to know where you are so you can tweak the toe back into spec after the swap. Checking this on ramps allows for easy adjustment. Wider tires really help when eyeballing the toe, because the body doesn't get in the way.

Using parallel strings also works, but the eyeball method is faster if you are just trying to put things back where they were and basically works the same way, but without math.

Thanks Ungn. A few more things about rear components before I start a new thread on front suspension. Are the trailing arms like the ones sold by UMI neccesary for our cars? Are the stock good enough to keep?
Also if I go with a 1.5 inch drop in the rear what shock would I go with. The bilsteins I was going to go with says it's for stock ride height.

 

[Gremlinsteve]

Wow I have alot to learn about setting up a suspension. So far I've ordered the Umi lower rear tubular control arms. The hellwig rear swaybar. Will get the adjustable umi upper control arms with rotojoint.
Coil springs I'm still baffled with. How is it moog springs are 40 bucks a pair while the lowering springs are over 160? The Bmr 1.5 inch lowering springs for $109 maybe a good option but will my 275x60x15 tires hit the fender?
I personally am not into lowered cars I like the rake on moog 5379's. But I know if I want the handling I have to lower.

Bmr rear springs with a 275/45/17

 

[buzz77]

Bmr rear springs with a 275/45/17

Thanks Steve. Looks pretty good. What shock are you running in the rear? And what kind of set up are you running on the front end?

 

[el camino ss 84]

Umi suspension setups are what I used for my Malibu and El Camino. Definitely worth it and the improvement are good to compared to worn out 80's parts that need to be replaced.