rearend broken in my c3

ok i have been fighting a transmission leak in my vette for a little while now fixed a few things and found more things leaking. i pull it on the rack today and replace the o-ring on the vacuum modulator and put a little bit of rtv around it no big deal. issue is the trans usually leaks a lot when i drive the car not so much just sitting on the rack. so i start the car up and put it in drive and shift through the gears. right when i am ready to back off the throttle to shut the car off and raise the car back up to see if anything else is leaking i hear a loud bang. i hit the breaks and try to put it into park and i heard the parking pawl grinding...my wheels were not moving. shut the car off and the diff is well broke. don't know what all happened at this point i have to tear into the car this weekend. i am guessing it has something to do with the c-clips and that i should not have been running it with the wheels off the ground. so going off worse case scenario and saying everything is destroyed what are some decent upgrades that could be done as far as aftermarket vs oem. best u-joints for my axles any type of c-clip eliminator kit ( don't know if they make one i don't see how they could) and rec. any particular limited slip for it. i also plan on rebuilding the rear suspension while it is apart but that would be a different section. on by the way my car is a 76

if this makes you feel any better (hope so). I had a 82 GMC 4x4 truck, locker both ends, new 35" mudder tires, 3/4 ton running gear.... had a snowfall of 36" in one night - no problem, I think, I'll just bust the road out with my trusty steed... I backed 10' and realized the front wheels weren't helping me. I looked under my truck and saw that the driveshaft was spinning inside the splined yoke.... no problem, I think, I still have the back, a locker and mudders. Another 10' back (now on the road), I hear a "bang" - it at the ring gear (knocked 2 teeth out)... I managed to get it back in my driveway.... I went from 4 wheel drive to no wheel drive in 10'

probably a ring gear for you as well.... you were planning on upgrading your gears anyway? :confused2:

actually no out of everything i wanted to do to the car i had not even considered that. and on another note i'm trying to buy a house and i got a kid on the way. really didn't feel like anything breaking on the vette right now. and thats funny about your 4 wheel drive. i had a blazer and tried pulling a truck up over a hill in 4LO in reverse with chains on the front tires.....the diff lasted about 10 seconds lol.

At least they're cheap on Craigslist? - where I'm at $400 is the going rate for a good differential.

I have an H3 as my DD, and I have chains for all four wheels, I'm wondering how long before the t-case goes boom in it.... (everyone wheels their DD, right?:3rd

You can always look at it this way, at least you broke at home. If you're going to break, that's the place to do it.
As for the rear, we have a couple members here that build diffs for our cars. I'm sure others will step in and add some info but I know Gary (GTR-something) builds Danas as does Mike(?) but I don't recall his screenname.

well didn't break at home. i happen to be a race car mechanic and keep my vette stored at work. i put it up on my rack when i punched out for the day. so still it broke where i keep it. only thing i had to do was tow it back over to the garage where it goes with the our pit cart this morning. and ya i may need some input on this diff. i have messed around with ford diffs and old english p.o.s. diffs but never had a vette apart. it should be a good learning experience for me and my wallet.

hopefully you'll post up lots of pictures, I think my posi clutches are about done; and I need to be done with the 3.08 (or worse) gearing - so a tutorial from a noob would be really helpful (okay, a 'vette diff noob)

I've gotten the impression that these C3 diffs are inherently weak? Or weaker than others anyway?

What's the way forward when replacement time comes? Mine makes some suspicious noises now and then...:huh2:

"that i should not have been running it with the wheels off the ground"


This will surely put things in a bind.

well hey i understand how that could possibly have killed it. but that is total b/s. i run cars on the rack everyday for different issues. if this diff. is going to explode by doing that then there has to be something better.

When the rear is hanging (like on a rack), the trailing arms are down, pulling on the halfshafts, binding the u-joints from too much angle, loading the stub axles and the side gears in the differential case. Lot more going on there than just wheels going around.

As Tim mentioned, if you ran the car with the IRS hanging down the 1/2 shafts will bind up and you may have issue.
If you turn the pinion yoke and the side yokes don't move you probably broke the posi case in 1/2.
You will have to drop the diff and pull the cover to see. If the posi is broken then everything inside may be shot, it can be rebuilt but you would be better off finding a good used one to rebuild. Check out every used diff, just about all of them need attention.
The iron diff's are plentiful out there. They can be built to handle up to 1000hp but the quality 30 spline spiders are nearly gone now and those I use in the 500-1000hp builds.
You can run the diff in the air but you have to block up the arms to keep them at ride height.
Gary

as said above.... hanging half shafts are binding the Ujoints and also you put quiet a pull on the side yokes and the small C clips holding might have broken....
pull the diff and take the cover off, maybe all you need is two yokes and four new Ujoints.....

and a good cleaning of the diff... make sure you get all the debris out

MYBAD79 said:

as said above.... hanging half shafts are binding the Ujoints and also you put quiet a pull on the side yokes and the small C clips holding might have broken....
pull the diff and take the cover off, maybe all you need is two yokes and four new Ujoints.....

and a good cleaning of the diff... make sure you get all the debris out

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the more I read, the best thing to do to a stock rear is cut the c-clips off and replace that link with an arm across the top. No offense to TT's amazing set up, for DD/autoX duties a simply tie rod across the top so the drive shafts can move freely would be the 90% I shoot for in my builds (it is my firm belief you can achieve 90% of the top with 10% of the effort or outlay - thus, I build my cars to that rule and rely on blind luck, occasional talent, and acts of God to cover whatever part above 90% that I didn't build into the car).

well i will have to do a little bit of looking on my car. i can't imagine it would be to difficult to make an upper control arm. and we use a driveline shop that may be able to make me up some cv axles for it. wouldn't that solve alot of issues??

fastcompany2 said:

well didn't break at home. i happen to be a race car mechanic and keep my vette stored at work. i put it up on my rack when i punched out for the day. so still it broke where i keep it. only thing i had to do was tow it back over to the garage where it goes with the our pit cart this morning. and ya i may need some input on this diff. i have messed around with ford diffs and old english p.o.s. diffs but never had a vette apart. it should be a good learning experience for me and my wallet.

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Lots of good info in the Tech section on diff inspection and rebuild. Here is one on rebuilding:

http://www.vettemod.com/forum/showthread.php?t=167

here's some info on my rear suspension mod:
http://www.vettemod.com/forum/showthread.php?t=7894

now that I installed the telescoping half shafts I have the 3" half shafts with solid Spicers for sale ..... brand new, zero miles.....

well not interested in putting the same style axles back on the car. but they actually sell those half shafts?? i mean they were not custom made? i was going to see if my driveline shop could work me up a set of cv axles for it. i still may try going that route just because cv axles are current technology. they are the best thats out there at this point.

fastcompany2 said:

well not interested in putting the same style axles back on the car. but they actually sell those half shafts?? i mean they were not custom made? i was going to see if my driveline shop could work me up a set of cv axles for it. i still may try going that route just because cv axles are current technology. they are the best thats out there at this point.

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I hope you find them and post them up; they'd be expensive to manufacture.

wow i just read through your 11 page thread on your suspension. nice work. that was exactly what i thought about doing as far as the rod ends go for an upper control arm. and my boss looked at your pictures of your slip shafts. we think our driveline shop could build me a set of those and they treat us pretty good as far as prices go. thanks for the info and pics..