C3 Tech/Performance V8 Technical Info, Internal Engine, External Engine, Basic Tech and Maintenance for the C3 Corvette

Differential Crossmember Removal

 
Old 02-16-2019, 10:22 AM
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Default Differential Crossmember Removal

For those who have done it, I ask this question:
What is the minimum disassembly of adjoining subunits in order to remove that cross member. I must replace the two bushings/cushions in it, as well as the Differential's front mount bushing/cushion.

Thanks much.
Steve
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Old 02-16-2019, 01:00 PM
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The front snubber bushing is pretty easy and can be done in place with only the retaining bolt removed.

The crossmember is a little more involved. You’ll have to remove the rear spring, disconnect the differential from half shafts and the drive shaft. Make sure that you tape the U+joints so that the caps don’t come off. Remove the snubber bracket. Soak the crossmember bushings with the penetrating fluid of your choice for at least a week. Partially remove the tw bolts holding the crossmember in place and start prying until it “pops” off.

Its nice to have a transmission jack or something similar to lower it. Shockingly heavy and awkward.
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Old 02-16-2019, 01:36 PM
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Two items I forgot to add.

The above assumes your spare tire carrier is off. I don’t think you could do the job with it in place. In any case, you wouldn’t want to.

if you don’t have an appropriate jack to raise and lower the crossmember and differential, you can replace the retaining bolts with threaded rods. You can then lower and raise it by wrenching on the nuts. Even with a ratcheting wrench, this is tedious but very effective.

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Old 02-16-2019, 02:56 PM
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I very much appreciate the descriptions and motivation they provide.
I'm thinking about maybe removing the exhaust pipes as well, for they're of the 2.5" variety. I'd of course rather not.
Can the "propeller" shaft stay on? I only need to lower the Differential enough to get to the two Crossmember attaching bolts from the top, correct (how tight are those mothers anyway)?

Steve
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Old 02-16-2019, 03:11 PM
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Originally Posted by Cavu2u View Post
I very much appreciate the descriptions and motivation they provide.
I'm thinking about maybe removing the exhaust pipes as well, for they're of the 2.5" variety. I'd of course rather not.
Can the "propeller" shaft stay on? I only need to lower the Differential enough to get to the two Crossmember attaching bolts from the top, correct (how tight are those mothers anyway)?

Steve
The rear struts will need to be removed as well.

Be aware that the cross member cushions don't just "pop out".
You'll need to entirely remove the cross member from the car.
Once you have it on the floor you'll likely need a BFH to knock out the retaining tabs and even then the old cushions will put up a fight.

Last edited by Hammerhead Fred; 02-16-2019 at 03:15 PM.
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Old 02-16-2019, 05:17 PM
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I just did this procedure a few weeks ago. I found that the best way to do the job is to just disconnect everything attached to unit and suspension from the get go. I used a floor jack right in front of the cover and balanced out very well. You can try to use some straps if you feel better about it! The hardest part was prying the crossmember away from mounts which really wasn't too hard with a oversize screwdriver!





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Old 02-16-2019, 06:26 PM
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Originally Posted by Hammerhead Fred View Post
The rear struts will need to be removed as well.
Fred,
You're referring to the Wheel Camber Adjusting Rods as the struts, right?
I've seen a pickle fork in use to separate the Crossmember from the Frame, using the weight of the Differential as an advantage. I am also prepared for a fight in removing the old bushings. Is the Crossmember weak to the point of having to take care in how much force can be used in removing them, to prevent crossmember bending/damage?

Thanks Fred

Steve
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Old 02-16-2019, 06:30 PM
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RedC,
I really appreciate those pictures! Thanks much.

Steve
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Old 02-16-2019, 07:13 PM
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Originally Posted by Cavu2u View Post
Fred,
You're referring to the Wheel Camber Adjusting Rods as the struts, right?
Correct
I've seen a pickle fork in use to separate the Crossmember from the Frame, using the weight of the Differential as an advantage.
Anything is possible with cross member removal: for some it pops right off with a short pry bar (me ; for others it's a 6 foot cheater bar; and others have resorted to 2-jaw pullers
I am also prepared for a fight in removing the old bushings.
You may need a press to get them out - I beat mine out.
Is the Crossmember weak to the point of having to take care in how much force can be used in removing them, to prevent crossmember bending/damage?
Probably the strongest part of the car - wouldn't worry about bending it

Thanks Fred

Steve
response above in BOLD
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Old 02-16-2019, 07:21 PM
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Thanks Fred, and all you other folks, for giving me an idea of what I'm going to be facing once started.


Steve
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Old 02-16-2019, 09:50 PM
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One of the few Harbor freight tools I really like

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Old 02-16-2019, 10:17 PM
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Be very careful with any bolts that screw into the "ears" on the diff housing, its a good idea to make sure they screw in ok before putting things together. The ears are cast iron and have been known to snap off if everything isn't put together correctly.
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Old 02-16-2019, 10:44 PM
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Originally Posted by GTR1999 View Post
One of the few Harbor freight tools I really like




Not particularly stable, nor very well made, but it’s cheap and I use it for a shocking number of things.
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Old 02-16-2019, 11:44 PM
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[QUOTE=Ed T;1598892497]Here is the bare minimum disassembly, most guys here hate on my method but can be done as shown. Work safe. Slow and steady wins the race.

remove tire tub & rear exh hangers, let the exhaust float. Remove spring, crack diff cover bolts and drain into a pan overnite






you will need a pry bar or 2/3 jaw puller to pop xmember aloose



pop both sides off and pull the xmember/diff cover out to the side of the car over top of the exhaust





to do it this way you need 2 jacks, one to support the diff and another to lower and push the refurbed xmember back into place if you are working alone. Not the recommended way, but your Q was what is the minimum disassembly. Plenty of good replies here as always, I left out some of the basic disassembly stuff, just think it thru before you start, not an awful hard job.


[QUOTE]

Ed,
That's exactly what I was looking for. Why would folks hate this method? No touching the U-Joints, camber Struts, or inner Wheel/Hub/Shock stuff. Marvelous. Oh I'll take the Wheels off, to get a good look/angle to maybe pry on and free the crossmember. But this is a pretty brilliant idea.

Thank you Sir!
Steve
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Old 02-16-2019, 11:56 PM
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Originally Posted by Haggisbash View Post
Be very careful with any bolts that screw into the "ears" on the diff housing, its a good idea to make sure they screw in ok before putting things together. The ears are cast iron and have been known to snap off if everything isn't put together correctly.
That's a very valuable piece of information I'll take to the bank.
Thanks Mate!

Steve
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Old 02-17-2019, 12:02 AM
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Originally Posted by Cavu2u View Post
Ed,
That's exactly what I was looking for. Why would folks hate this method? No touching the U-Joints, camber Struts, or inner Wheel/Hub/Shock stuff. Marvelous. Oh I'll take the Wheels off, to get a good look/angle to maybe pry on and free the crossmember. But this is a pretty brilliant idea.

Thank you Sir!
Steve
Not hate exactly, but there are a few reasons that this isn’t the preferred method. It requires you to drain and replace the diff fluid in an awkward manner. Getting a good seal on the diff gasket will be awkward too. You won’t be able to put a torque wrench on the top two casing bolts. Speaking of those top two bolts. They’ll be a bitch to remove and replace.
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Old 02-17-2019, 12:07 AM
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Originally Posted by CA-Legal-Vette View Post


Not particularly stable, nor very well made, but it’s cheap and I use it for a shocking number of things.


I ended up making a mobile unit .......


.... out of one of these. I originally made it for R&R'ing motorcycle engines, but looks like it may work here (IF it needn't go any higher than 16" off the floor).

Steve
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Old 02-17-2019, 01:10 AM
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Originally Posted by Cavu2u View Post


I ended up making a mobile unit .......


.... out of one of these. I originally made it for R&R'ing motorcycle engines, but looks like it may work here (IF it needn't go any higher than 16" off the floor).

Steve
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Old 02-17-2019, 08:49 AM
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Originally Posted by CA-Legal-Vette View Post
Not hate exactly, but there are a few reasons that this isn’t the preferred method. It requires you to drain and replace the diff fluid in an awkward manner. Getting a good seal on the diff gasket will be awkward too. You won’t be able to put a torque wrench on the top two casing bolts. Speaking of those top two bolts. They’ll be a bitch to remove and replace.
Gotcha.
Too bad there aren't studs on the Differential instead of bolts.
Would removing the Camber Struts at some point in the process help in reaching those upper dudes?

Guess I'll find out.

Steve

Last edited by Cavu2u; 02-17-2019 at 08:56 AM.
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Old 02-17-2019, 07:04 PM
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Originally Posted by CA-Legal-Vette View Post
You won’t be able to put a torque wrench on the top two casing bolts. Speaking of those top two bolts. They’ll be a bitch to remove and replace.
There is truth in what you say.

If the bolts weren't torqued to 60 ft/lbs, it wouldn't quite be so bad. But they have to. Gotta hand it to those engineers; combining a load bearing structure in a lubricated gear case with no drain. No wonder the GM shop manual states "The rear axle lubricant does not normally require changing for the life of the vehicle."
Lowering the entire works gives a little more room to reach those two upper cover bolts. But it is so difficult a chore to get a wrench on AND loosen them, that the disassembly of the U-joints & struts now seem not so big a deal. Right end Crossmember/Cushion dropped down easily. Left end hasn't budged.
Yet.
Removing the Leaf Spring was difficult because this heavy duty exhaust system was installed 2 years ago and the 9-leaf spring was already in. Those 2.5" pipes are so thick a gauge, they hardly droop a half inch with the muffler hangers off. And with a crossover pipe on it, that exhaust plumbing is tough to move.
I put almost 5 hours on it, knockin off for the day, and gonna sleep on the idea of maybe removing the entire Differential next. It was a good try, but I'm not quite done trying to get to those two top bolts yet.

Steve

Last edited by Cavu2u; 02-18-2019 at 05:03 AM.
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