Composite rear leaf springs on an E-Body

[Brads70]

I've been doing some "research" on these. I asked a guy who just bought a set to weight them and his reply was 10 LBS each!  :2thumbs:  Great way to take 50-80LBS? of unsprung weight off a car and they are available in different rates!  I'm thinking the 175LBS rate would be good!
They are only available in superstock length  ( 2" shorter front segment) so you would need to get a commonly available relocation kit.
I'm liking this........


Pages 17-18  http://www.hypercoils.com/hyperco-catalog#Page10=undefined&page=18

I'm guessing 175LB because Hotchkis uses a 160LB in there kit?  But I'm no expert?   I have both front and rear Hotchis bars now.
I bought the 175lb rate  Hyperco composite rear leaf springs and installed them. I have found they react quicker than steel springs. While they are rated higher than anything stock the rear end really squats down when taking off from a stop during a hard launch!
I'm still tuning the new engine and tranny controller so I can't say how they reach during hard cornering. They do not feel too stiff or harsh over bumps.

[Brads70]

FYI... here is what I had to do to make them work/fit.
They are 20 1/2" front segment  so I had to rework the DrDiff offset SS hangers. I welded up the hole and redrilled it 1/2" forward. I also at that point welded in a plate to gusset the top of the hanger so it won't flex. I don't know if it will flex or not but now was the time to add it in anyways!



I assembled the rear end with the hangers as supplied and it pushed the rear end back that extra half inch..... and it bugged me so I fixed it!




I also had to "shim" up the srings width wise to make them fit the hanger. I made custom shim/spacers.



I also had to flip the socket head cap screws that hold the spring eye as it was too close to the body.


Then made these bushings  for the spring pins because it bugged me how the pin flopped around in the hole on the rear end.

[Brads70]

I found the 175# springs to not be enough spring for my set up so I Installed the 225# Hyperco composite leafs . Expensive mistake! I also machined up a pair of 3 deg shims to get the pinion pointing down. It was pretty close to level before. The parts on the side of the shim is so the u-bolts do not make contact with the composite parts. A big no no according to hyperco. Now I just need some nice weather and some rain to wash all the salt off the roads. I just snowed here this morning...5" worth! :stomp:

[Brads70]

Just a quick update..... 225 rate is much better than the 175. Keep in mind I'm using a 451" BB and a S-60 Dana . 175 with a small block combo I would guess? What you NEED to know with these springs is that you MUST run good shocks. The Bilstein RCD just could not keep up with how fast the composites react. I swapped in QA1 double adjustable shocks to take the bounce out.  I am using TD801 in the rear due to the lowered ride height( catalogue suggests TD901) and TD501 up front. I've been running this combo for 3 years now with no issues!
Hope that helps someone down the road?

[Cuda Cody]

You do awesome work!!!!   

[Spikedog08]

Nice job Brad!   

[Chryco Psycho]

Your car as come a long way , you are always pushing the envelope & making it work !!

[Brads70]

Thanks ! 25 years involved with circle track racing is bound to rub off here and there.......

[303 Mopar]

Those are really nice, and circle track racing does teach you a thing or two...   

[HP_Cuda]

Any long drives on those new springs Brad?

I have another ride which has 200lb rear springs and you cannot forcibly move the rear up and down without putting all your weight into it. Even then it barely moves, no wonder it's called stage III suspension.

[Brads70]

Any long drives on those new springs Brad?

I have another ride which has 200lb rear springs and you cannot forcibly move the rear up and down without putting all your weight into it. Even then it barely moves, no wonder it's called stage III suspension.

Yes I've driven to Carlisle 2x with those springs ( 7 1/2 hours each way) Ride is not that harsh at all I find?

[Moparman82]

Looks awesome brad, never get tired of seeing all the little things you build and fab for your car.  Off topic question, any future plans for a T/A style exhaust?

[Brads70]

Looks awesome brad, never get tired of seeing all the little things you build and fab for your car.  Off topic question, any future plans for a T/A style exhaust?

I was considering it with electric exhaust cut outs but when I researched electric cut outs I found they were not very reliable and didn't last very long. So I figured I didn't need the headache ( pardon the pun LOL )  Last year at Carlisle  I bought as new AMD rear valance with the cutouts as I'm sick of trying to keep the paint clean of exhaust stains.....  Likely get that painted and tip installed this spring?   

[ec_co]

have you looked into the Chrysler or (gasp!) Chevy factory cut outs (I believe they have them on the ZL1?)? I would think they would be much more reliable/durable since they have to warranty them for the Hellcat and ZL1

[Brads70]

have you looked into the Chrysler or (gasp!) Chevy factory cut outs (I believe they have them on the ZL1?)? I would think they would be much more reliable/durable since they have to warranty them for the Hellcat and ZL1

Never thought of that? I'll have to dig around and see how much they are?