Neil B

I'm getting ready to do an in-car pinion seal replacement and it looks like time well spent to remove the front diff mount to gain better access. I plan to do this on my 4 post lift with the weight of the car on it's wheels. Can you remove the front diff mount with the suspension fully loaded or will the diff rotate up and possibly tweak the crossmember? Thanks.

gcusmano74

I would not.

CanadaGrant

I just did this on my 69 about 2 weeks ago. No problem whatsoever. Just make sure the car is out of gear with the wheels blocked so there is no pressure on anything and it doesn't move when you unbolt the driveshaft. The diff will not rotate at all.

Neil B

Thanks. If you had to do it again, would you remove the front mount to get better access to the yoke and seal or try to work around it? I've only done this on live axle cars with lots of room in that area.

69427

Why not just take a few minutes ahead of time and jack up the frame at the rear (just ahead of the wheel wells), and put some wood blocks there to take the weight (and twisting force) off the rear spring?

Neil B

It seems like the load would be on the crossmember, but I do agree that the crossmember is slightly behind the axle plane.

CanadaGrant

I was removing the driveshaft for balancing and u joints but the front diff mount should be removed. It is only a 10 min job and gives you easy access to everything. Check your rubber mount cushions for wear at the same time and don't forget a couple of new cotter pins for the 2 horizontal bolts.

Neil B

I'm on a 4 post lift with no good way to jack the rear and place jack stands. I really don't want to do this job off the lift if I can help it. I do have pole jacks but that seems like a Darwin award winning move.

69427

I currently have my '69 on my four post lift, on a couple 4x4s on the rear frame corners, and have the rear end out of the car for some repairs.

Did your C3 come without a scissor jack, cuz they're incredibly handy for lifting a Corvette up by the frame.

CanadaGrant

You have to block it up anyway to keep it from moving or rolling on your hoist when you disconnect the driveshaft so a couple of blocks at the rear frame pockets is a very good idea.

Neil B

On my Camaro, when I remove the driveshaft, I chock the wheels and set the parking brake. For the Corvette, I'm gonna take another look at how the frame aligns with the lift to see if I can get some jack stands under it.

CanadaGrant

The frame pockets just in front of the rear wheels line up with the tires so if the tires are on the lift, jack stands will fit no problem too.

69427

Your car, your labor, but you don't have to lift the car up as far if you use wooden blocks, and the stability and movement friction of the blocks are going to make the car more stable than taller jack stands.

But, your call.

lvmyvt76

I did it on my car, on jack stands, no problems.

Neil B

Thanks for talking me through it. Worked like a charm...

Stephen Irons

How can you work in such dirty conditions?

Just looks like a good excuse for some gratuitous photos of an unfeasibly clean Corvette underside and garage to me. I'm soooo envious!