RDCRIS

Who here has installed a c4 rear suspension? Also if you did how has it been holding up? Are still breaking parts?

I broke another u joint on the half shaft last night, over the twenty years I've owned this car I've broken 3 diffs, outer axles, 4 half shafts, and stub axles. Not mention broken battery box, bent strut rods, rear spring and shocks when the half shafts let go.

Just looking to know if the change would be worth it?

I know I would have to change my wheel combo also.

Thanks

jb78L-82

Just curious, how much power are you putting out and through auto or 4 speed? I am figuring you must be putting out some mega power levels for all that to happen.

69427

I've got a C4 suspension in mine, but I kept the C3 differential as they're strong, inexpensive, and I've got several different ratios sitting on the shelf.
I only do road course stuff with the car (no big clutch-dump shock loads).

RDCRIS

Motor is a 434 dart small block if the estimated power of 1.4hp per cube then it's 607hp. I'll guess a little lower maybe in the 550 range, cuz I run against my buddy that has a 2008 ZO6 and I pull on him up thru 4th gear. After 130mph he just keeps pulling. My car is certainly not a high speed car. Trans is a TKO 600. and a 3.55 rear gear. I had a TREMEC 3550 before and this motor stripped out 3rd gear not power shifting at all just full throttle applied. Trans lasted about month when I built this motor. What's seems a little strange is the drive shaft u joints are almost 20 years old never had a problem there, they are the LAKEWOOD brand solid cross ones. Had them in the half shafts too and they broke.

Bad Bird

Well the torque is much higher on the half shaft u-joints by a factor of 3.55:1. That explains why they break more readily.

Maybe it's time to upgrade to a super 10 or 12 bolt built by Mike or Gary?

RDCRIS

This last carrier has been in there for about 10 years recently broke the stub axle on the passenger side no big deal to fix. I searched the c4 forum and seems that they have the same problems we do. this is street car never goes to the track to hard to pass tech inspection, no roll bar, shoulder belts etc. Besides I know that it would break something out there anyway. Can't afford to spend thousands on the rear for a TOMS set-up anyway guess I'll just have to keep fixing it at a few hundred at a time. Just thought that maybe the c4 was stronger set-up. I know it mostly comes down to the shock load that's causing the problem, but I refuse to go to a Auto trans, just wouldn't be same car!

Bad Bird

Agreed on the transmission. My car just wouldn't be the same without the 4-speed. I just never could get into automatics, even if they are more consistent.

jb78L-82

Thanks. That's what I figured.

waljr

there was a dane 60 irs setup for sale on here a fair while ago, wish I had the cash at the time to snap it up

TheSkunkWorks

Are you sure the rear suspension isn't squatting enough to bind the half shaft u-joints? I don't recall ever breaking a LW solid one, and I've destroyed well more than my share of driveline components. ...so much so that I did the 12-bolt IRS conversion long ago.

RDCRIS

The car is lowered with longer bolts. At rest the diff is just below the center line. What's weird is the driver side inboard joint has broke 3 times and this last time it was at the wheel. I broke the passenger side stub axle and wheel axle in the past. I have a traction bar, offset t-arms and the cross member locked down. I don't get any wheel hop.

These last joints lasted about 10 years and they had the zerk fitting in the cap I would grease them once a year, I may do about 3to5 thousand a year also the car sat for 2 years when I broke the stub axle.

I thought it was the trans at that time because it had no 3rd gear, I didn't have the $$$ at the time for a new trans so I got fed-up with it and let it sit for two years.

So those last joints were in service for like 7 to 8 years and maybe 30 to 40 thousand miles on the high end. So maybe I just need to plan on changing them every 5 to 7 years or 30 thousand miles. Guess that's not too bad for a 500hp plus hotrod.

TheSkunkWorks

You might want to consider raising your diff in the chassis. Having the inner Us lower than the outers at static ride height not only puts you at additional exposure to damage from excessive squat, but also significantly increases adverse rear toe-steer geometry.

As for cycling parts out, I learned a long time ago that anything which improves performance usually comes at the price of shorter service life.

Rkreigh

from what we learned on c4s hopped up like ZR-1 and blower c4s as folks started going above 500 at the dana 44, half shafts, and especially the spindle axles started to break

running an auto will certainly help but at that hp level something stronger would be better

for the dana 44, we install the 3/8 bold Super Dana Viper gears which are MUCH stronger

for the spindles, we custom made some axles and rebroached the splines on the carrier hub but that is an engineer that has access to the high end equipment (he broke a few spindles and was tired of it!!)

I'd like to see what a lightweight modular 9 inch sheet metal rear could do!!

because of the thich sheet metal, it would be easier to weld custom brackets to and you could use the meaty DSS axles

thinking of "back halfing" a 68 vette to handle the HP from a build putting out about 900 hp,

like to use a modular 4 link ford, don't care about the IRS anymore, just want to hook and go!!

CaseyJones

From all I've read, u-joint/half shaft alignment and orientation is very important regarding driveline life. Raising the car up enough to have the half shafts parallel or slightly higher with the car at rest takes a bunch of strain off the drive components back there.