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An unfortunate series of events will require that I remove and replace the differential on the ‘73. Currently have a replacement unit along with a replacement drive shaft. Have not done it before so I’m turning to the experts to guide me in the right direction for the process. Long story short (a separate thread) I have a side yoke pulling out and need to swap it out. So any insight on the best plan of attract would be appreciated. Basically just need to get it moving again. A restore could be in its future, but not right away. Thanks in advance for your input!
I just did this for the first time on my 66. Attached is the check list that I made up. I added a couple of things as I went that may not be reflected on this list but it should give you a basis to start.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I just swapped rear ends last weekend
remove the spare tire tube
remove the side shafts at the differential, push them up and tape the u jionts caps so they dont come off. You can push out on the trailing arms to aid in removal
remove the drive shaft at the front differential yoke, push it forward and tape the drive shaft yokes
remove the bolt holding the front snubber to the frame
unbolt the bottom bracket from the differential that hold the struts
remove the struts from the bracket
Count the threads below the nut that retains the spring to the trailing arms then remove the nuts
place a hydraulic jack up under the differential, a tranny jack works great to the differential after removal
unbolt the frame crossmember at the sombreros
use a py bar to help "pop" the sombreros loose, you may have to work each side repeatedly to get them loose. youmay have to slowly lower the jack to get room for them to pop loose. Be careful its gong to be heavy
Last edited by Rescue Rogers; Sep 29, 2020 at 01:13 PM.
Just now reviewed the attachment I posted, not sure what happened there sequence wise. Between the two responses you should have a clear vision to proceed. Sorry for any confusion.
use a pry bar to help "pop" the sombreros loose, you may have to work each side repeatedly to get them loose. youmay have to slowly lower the jack to get room for them to pop loose. Be careful its gong to be heavy
If doing this from the side of the car, use a long enough pry bar to keep your hands well clear of the wheel well. If you don't, when it "pops" loose, it could rebound and smash your fingers. I know this from experience. Nearly lost a finger nail over that one.
It is quite possible to take the differential out without "popping" the cross member. I've done it twice but you need the two tools in the picture. As I remember, you need to preinstall a couple of guide pins to help get things positioned during replacement. Also, if you don't have a drain plug in your replacement and you intend to keep it, put one in now. I didn't put a magnet in the socket, but thinking about this now, it's probably a good idea. I'd epoxy it in to make sure it stays there. Clearly you don't want to drop anything.
All, thanks for all the info. Some great advice and outlines. I will be doing this on a 4P lift, jacking the car at the rear outside rise section of the frame and then using smaller jacks to do the spring bolts and support the differential. Any thoughts on how to keep the side yoke in on the problem side while jacking the car? It will want to fall to the lift runway on that side. I plan to replace the spring bolts assemblies, the differential snubber, and the crossmember cushions. Any thing else?
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
Use a ratchet strap to hold it in. Just wrap it around the wheel and crank it to the other wheel. It will hold long enough to get it off the ground and then can start taking it apart. You can also run them from the end of the trailing arm to the other trailing arm
Last edited by Rescue Rogers; Sep 29, 2020 at 06:26 PM.
so I tried the ratchet strap on the wheels and the trailing arms just forward of the spring bolts. Went slowly with both set ups just to see what kind of response I’d get and it still wants to pull out. Can I do and damage to the trailing arms if I just go with it? I have to believe that at some point it can only come out so far, but wasn’t going to push it until I double checked. Thanks.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
While you are raising it they will only go out so far, and once you remove the straps from the yokes to free the u joints they are free to move out any way. I removed my half shafts at the yoke and just let them go. I had to push the trailing arms out further to get the u joints free too. You will be fine. theres nothing pushing them out once the weight is off of them and the rear spring will only let them go out so far as well. If you have the rear sway bar connected thats something else that limits movement and will have to be taken apart to let them move out as well
Last edited by Rescue Rogers; Oct 4, 2020 at 05:27 PM.
So I’m back on this, had an hour or so today and removed the spring. Surprisingly went well and the ratchet strap idea offered worked well as a safety precaution. Tomorrow is go time, removing the struts and the diff crossmember. A couple more questions as I complete my thought processes/planning for finishing. Do the trans yoke and differential yoke need to be 180 def when. Reinstalling the drive shaft? It’s a different shaft than I took out. I’ve read it doesn’t matter on the side yokes. I do not have a removal tool for the shock mount so I will be trying a couple different methods on that. Lastly, is it the full weight that needs to be on the spring before the final torque, or partial?
Thanks for all the help guiding me through the process. Invaluable!
Shock mount wise I spun a coupling nut on it so as to capture as many threads as I could. This protects the threads from the next step which is pounding it with a hammer. Mine came out pretty easily but were not crusty or rusted.
On the cross member I backed both bolts out about 3/8" so when successfully popping the sombreros loose, the unit would still be supported by those bolts. Then I placed a floor jack under the differential, cargo strapped the two together, removed the bolts completely and slowly lowered it while ensuring the half shafts (with taped universal caps) were clear. To break the sombreros loose I used both a pickle fork pounded in with a meaningful amount of oomph and a crow bar to lever downward.
On reassembly it is my understanding that torquing of the spring bolts occurs with the full weight of the car.
On the driveshaft I can not say with authority on that. When I disconnected the driveshaft universal at the differential I noticed that there was no phasing relative the to the transmission, something I thought was a no no. I had no driveline vibration prior to my project but I was going to ask advice on that myself. Hopefully others will advise.
On the struts, seems like it’s done a couple ways, do they need to come out totally or can the be taken apart by marking the camber and unbolting at the bracket? Might be an issue with the exhaust still in and working the diff out.
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
When I had mine shortened the front yoke was balanced with it and is marked that way. If its not original to your car its not going to matter how you install it unless you send it out to get balanced. I would install it and see if you get vibrations. I have never had any shaft vibrations on any vehicle i have owned so with I have just been lucky everytime or its not a very big deal due to the rotational mass and distance to center. You arent going to phase them as well as they will only bolt up one way. If you are concerned about the balance, it only took one day for my guy to balance mine, and this is sounding like its going to be a few days, just send the shaft and front yoke out to get balanced together. Its relatively inexpensive as well.
As for the rear spring, full weight to torque is what Ive always heard here. If you cant get under it, lowerr the tires onto some blocks and make sure the front wheels are chocked, its in gear or the parking brake is on so it doesnt roll off on you.
Good luck
My bad on that. I removed the struts because the strut bushings were shot. If yours are OK then you should be able to leave the outboard ends connected. I used a digital angle finder to measure the camber on my wheels prior to pulling things apart. Still will need an alignment when it all goes back together. Some say that if you mark the eccentric bolt at the differential you may not require an alignment.
I also pulled my under car exhaust off so as to have room to work (hardest part of the job for me). Some have done this job with the exhaust connected. If you use the floor jack/cargo strap method to lower the differential/cross member you may be able to rotate the unit as it descends to clear the pipes.
No bad, seems like replies here, everyone leaves the struts attached at the shock mount. My big drive here is to swap the bad differential for now, just to get it to storage, and deal with the rest when we tear it down. It could use all new bushings just about everywhere etc. I’m going the path of least resistance and develop the learning curve for next time. That said, looks like it’s mark and remove them at the bracket.
Yes, proving to be pretty straight forward. Been picking away at this morning and it’s going well. Down to just the crossmember and wrestle it out of there. Going to lower the lift this afternoon and get it finished. Can’t thank everyone enough for all the input.
Thought I would give a big thanks to all who provided input! It’s finally finished, and so far so good. Quite the learning curve, but have all the confidence to do it all over again to replace all the other parts next spring thanks to all the advice/help here. Did still struggle with the drive shaft install, but decided to attach it in the rear, remove the caps on the trans side, protect the ends with plastic battery terminal caps, work it into place, and put the caps back on. Next time, the shaft is going out to be shortened. We seem to be good for now. Am going to take a look inside the old differential this winter to see what exactly happened!
Differential Removal/Install
