Need advice on my rear suspension set up

[johnnycarlo]

OK this is what I have. 80 Monte 454 TH350 Best ET 11.77 @ 113 on motor 10.99 @ 122 on a 150 shot.I built my own 8 3/4 Dodge diff using a homemade jig.It has 3.55 gears and a spool I run 275 50 R15 MT ET Street radials.For the upper links I welded two brackets on the diff on each side and made my own adjustable links with heim joints.The lowers were the south side machine boxed arms with the drop bracket but I just took them off and put the Ice man double adjustable lowers on , but I left the SSM lowering bracket on.The rear coils are stock and the shocks are just cheap NAPA units.The front end has stock small block coils and 90/10 shocks I also welded in control arm travel limiters. Last night at the track the best 60 ft I could muster was a 1.68.Last year I got a 1.59 on spray.It was very inconsistent off the line and had massive wheel hop or shake.
I see in the FAQ is says that with the solids bushing my pinion angle should be about 1 1/2 degrees down, I'm running at 4.5 degrees down so I will adjust that.
Should I remove the SSM lowering brackets and just bolt the iceman lowers into the stock location? My upper mount holes are 7.5 inches above axle center line.Maybe my instant center is too short?What about rear springs and shocks I don't want to spend a bunch of money but I want it to work good.Should I adjust my front control arm limiters? Right now I have them through the control arm about an inch.I am going to build my own rear anti roll bar that uses bearings on the frame ends instead of bushings.I might swap in some 4.10s and go with a 28x 10 slick. I also need to put in a roll bar now. That may also help with the wheel hop I was getting.Do G-bodys sometimes need weight in the trunk to hook up?Sorry for the long question, but I may take it back to the track once more if I get the rear suspension sorted out.Thanks for any help guys.

 

[Hiway]

Since your upper arms are 7 plus inches above the axle, I'd remove the SSM brackets on the lowers.

 

[johnnycarlo]

Thanks Hiway I will take out the SSM lowering brackets and try it that way next trip to the track.Anyone else have any advice for me?

 

[johnnycarlo]

So it ended up being easier for me to lower the top rear links than to raise my lowers.My lower brackets are welded onto the Dodge diff at a bit of a forward angle compared to stock, so when I try to put the lower links back in the original hole it moves my diff back and the lowers don't have enough adjustment to bring it forward enough.Anyway the uppers were 8.5 inches above centerline and I dropped them to 6 inches above centerline.I checked a stock diff and the uppers were about 5.25" above centerline.So hopefully this adjustment puts my I/C out far enough that it doesn't hit the tire so hard.I also set my pinion angle to 1 degree down.I hope I can get my 60fts at least into the 1.5 area.I will find out on Sat.

 

[racecar77]

Not to put a dark cloud over your situation, but you messed with perfection. The rear suspension geometry on these cars works perfectly as designed by GM. They basically need only adjustable uppers and lowers for tuneability and an anti-roll bar to limit the twist that G-bodies are known for. Unless you are making 1000 HP to the wheels this setup will dead hook the car. Mine 60 foots @ 1.40 pretty consistently and has no traction problems. There are many more G-bodies that 60 ft. much better than that using this setup. That being said, it doesn't solve your problem because you're committed to the Dodge rearend. By doing that you have changed the geometry and pickup points for the suspension. You may be able to play with it and get it dialed in, maybe not. My suggestion would be to try to duplicate the pickup points and angles of the stock geometry. I don't think the car will ever know what type of rearend is in it as long as you get it in there right. I ran Mopars for years and understand you using the Dodge rearend, it's a good piece. I hope you get it to work, keep us posted. P.S. There is a guy on this site named Norm, I think last name might be Peterson. He is the suspension guru. Maybe he can help. Lee

 

[johnnycarlo]

I welded the stock brackets off the 7.5 on my Dodge 8.75.And on the upper links I welded 2 plates per side so that a double adjustable link with heims would fit in between.They have 2 holes in each side one was way high around 8" above axle centerline and the other is 6" above centerline.Which is only a little higher than stock.So basically it has stock geometry other than the SSM lowering brackets.I think the aftermarket 9" diffs have the uper mount points higher too because of the size of the pumpkin they have to.I even used stock boxed lowers before I bought the SSM bars.I only removed those bars now so that I could put on double adjustable lowers with heims because they are freer moving and allowed me to pull my diff ahead a bit.All the mounts on the frame side are still in the stock locations.The only deviation is that when I welded the original lower brackets to this housing I got them both tipped ahead a bit.This caused my diff to sit an inch further back than stock.That is all fixed because I mounted the SSM lower brackets tipped back to bring it ahead, plus now with the double adjustables I can put it where ever I want to.I tried it tonight with my 275 50R15 ET street radials, it doesn't jump like it used to so I think it isn't shocking the tires like it was. It has 60 footed a 1.59 on a crappy track with the upper really high up and the lowers on the SSM lowering brackets so it can't be that awfull.Hopefully it will pull consistant 1.5s and that is good enough for the power I'm making.Thanks for any other tips you guys have.If this doesn't work I will raise the lowers to the factory point and make one more hole in the top bracket to drop the uppers to the factory height and start from there.I'm going to build a antiroll bar over the winter.This Sat trip to the strip is the last one of the year at my local track.racecar77 I didn't think the G-bodys hooked good with the stock 4 link locations because the instant center is so far forward, but by the sounds of yours and your 60 foot time there is nothing wrong with it.What do you run for rear shocks and coil springs?Thanks again
By the way sweet Malibu racecar77 I brought one home to be a racecar project.
John

 

[racecar77]

Rear shocks are just Competition Engineering 3-way adjustables, springs are stock V-6.

 

[wicked406]

Alot of times with the SSM bars or lowering the rear of the bottom bar it will make the car hit the tires to hard. the stock mounting pionts are more than enough "hit" to hook a small tire. if possible raise the mounting piont on the rearend. If you have ever seen the "anti hop" bars that is basic what they do. They some hit away so the car doesn't try to bounce the tire off the ground.

 

[wicked406]

Lowering the rear of the car also helps.