mike1969

Had an issue this morning with binding and had to get towed home. When it was being loaded the differential drained onto the flatbed. Found a hole in the body looks like something punched through due to the binding. I will drop the differential and assess it. Have not had to work on these before so any suggestions are appreciated. I have some skill but have never had to work on these. I have a good idea on how to drop it, etc. Now to research costs associated with replacement. I am expecting another case is needed and new some internals. Not a good start to the day...

MISTERZ06

hope this helps
............................ tom

mike1969

Thanks MISTERZ06 - I have those two videos saved for reference. Glad to know I am on the right track.

Wee

I fabbed up a piece of aluminum flat plate so I could bolt it to my floor jack and then bolt that to the bottom of the differential for easy removal....It weighs about 90 lbs.




Brian

ddawson

It's not hard to remove just time consuming.

I too used a floor jack with straps to hold it in place. I keep a few threads on the cross member bolts to keep it from dropping until I'm ready to lower it.

When mine comes back from tracdogg2 I'm going to use a trans jack to hold it in place.

MelWff

I had the same thing happen to me at about 60 mph on the Long Island Expressway. What fun! At the time I had been doing a lot of autocross and HPDE events. The bolts holding the ring gear had loosened and apparently one of the bolt heads sheared and went through the case. It became an excuse to go from a 3:55 to a 3:70.

LS4 PILOT

Dang .... your lucky to be alive to tell about that ....wonder people did not just drive right over top of you ......

doorgunner

"While you are at it"..........post a couple pics of the spring assembly.......my rookie eyes think it looks "flat".

mike1969

Here's the photo of my spring. It is on the list of to do's.

doorgunner

Good idea about the To-Do List.

L-46man

Yup the diffy died.

The rear spring is not far behind.

While I'd love to sell you my old 7 leaf 45 lbs lump....the slick replacement is the 360 in. lbs fiberglas spring.

You'll be amazed.

Ps they make upgraded cases now in aluminum for the diffy.

mike1969

Thanks for the information... I'll be sure to look into those options....👍

mike1969

Getting parts ready to put the rear end back together. Was wondering if anyone knows what this silvery grease is on the cross member bushings? I checked in the AIM but wasn't able to find anything on it. Thanks

ddawson

Looks like anti seize.

L-46man

The 'silvery grease' is MOLYBENDUM DI-SULPHIDE....this is an extreme high pressure grease that 'plates' itself to moving parts.

those of us that have 'funny furrin cars' are very familiar with this, in that All EURO cars have this in the C.V. joints....from the factory.

Pronounced mol-ib-denim.

unkahal

mike1969

I have another question about C3 differentials. I see some differentials state 63-79 but others state 63-77 and 78-79. My question is: I have a '78 differential but the cover is from a '69 - should the '69 cover fit on the '78 differential - what are the differences? If I stick with the '78 what will I need to change? Will I need to change something else out? I am not worried about matching since this is a driver. Thanks everyone. BTW - the issue was that three bolts sheared off the ring gear mount.

MISTERZ06

WOW
somebody did not use RED Lock-Tite
............................. tom n carol

mike1969

I hope that is not the case. It was done by a qualified Corvette shop in April '95. Of course it sat from '99-'16 - but I did replace the diff fluid and limited slip fluid last fall (about 500 miles ago).

resdoggie

The '78-'79 cover is for a rear spring width of 2-1/2" vice a 2-1/4" spring width for prior years. All '63-'79 covers will fit afaik.

mike1969

Would I be right to say that I would be able to use the 2 1/2" spring on the '69 Vette then (If I purchased one along with the bracket)? Otherwise I would need to find a pre-78 differential case?