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In those two pictures, it certainly looks like there's an issue with your rear crossmember. It's been a long time since I had one of those out of a C-3, but I seem to recall that the crossmember bolts that pass through the rubber bushing, pretty much seat flat to the frame rails. Meaning that something might be bent on the frame, causing that "out of level" condition, which won't be good. From what I recall, the big rubber biscuits in that crossmember, aren't available as replacements, either, if that's part of the problem....at least they weren't a while back, when I had one of those crossmembers out of the '79 that my wife used to own.
Bob, I believe these are the tabs he's referring to. One on each side, which are two of the four that hold the spring to the differential.
I've personally never seen a casting that appeared to have been incorrectly cast, but one person here who might have is Gary Ramadi, (GTR1999) who's probably looked at as many different castings as anyone here. He may stop by this post and comment, or you could send him a PM and ask him. I would be more inclined to think the cross-member or one of the sombrero's that attach it to the frame is at fault first.
Again, good luck... GUSTO
Old time racers would machine the housing with a slight angle to "pre-load" the car when drag racing. To try to pass tech inspection in the stock classes. I did a lot of drag racing in the late 60's.
Post 18 photo
It’s hard to tell what’s adrift here , I see the rubber in the RH trailing arm is compressed more so than the LH side.
interesting as both sides of the spring look to be disconnected.
The diff cross member looks low on the LH side at frame mount .
i have seen the centre section where the diff bolts to the member cracked and bent up .
bfit
From everything I have seen pics of, the crossmember attaches on both ends to the frame with bushings. The passenger side is definitely compressed more than drivers side. I ordered bushings to drop crossmember and replace. Am I looking at this wrong? https://www.corvettemods.com/C3-Corv...gs_p_9077.html this what I ordered. If I pull all this out and new bushings can’t fix, I have a machine shop with mills and a lathe. I’m sure I can “adjust” something to bring axle back to level. Hopefully it will be clear when the rear end is out.
Can i I just remove sway bar and lower rear end with Driveshaft’s all still attached? Just need to get low enough to get to diff bolts in top of crossmember.
Last edited by BobRiley; Dec 25, 2018 at 10:37 PM.
You have the correct bushings,
getting the cross member down can be a real task .
leave the diff attached until member is lose.
spray the top of bush with penetrating oil loosen the bolts in centre of bush three turns with a decent lenth pry bar leaver the member down , I have not seen one come off with a lot of #@$% effort .
while you have some room under their check the trailing arms to see if they look even both sides.
bfit
So, what all do I have to remove? Obviously the sway bar and snubber and crossmember bushing bolts. I have read a few notes and I have a ram with wedge spreader that ought to make easy work of separating.
So, can I just hang from driveshaft and swing. Arms?
When I remove the cross member . I do it this way.
chock front wheels to prevent vehicle rolling forward or backward.
Jack up rear of vehicle, support the car on the chassis just in front of rear wheel arch both sides, remove the wheels.
fit a stand under each trailing arm at the spring mount with about an inch clearance.
I leave the drive shaft attached loosen the snubber bush blot about 3/8’’ leave everything else attached loosen the two diff member bolts ,
pry the member loose . When it is loose remove the 4 bolts holding diff to cross member then remove member form the car .
remember always think about safety before working underneath a car.
Be VERY careful, when loosening the bolts that attach the differential rear cover to the crossmember, and also the bolts that hold the spring to the differential cover. The diff cover is cast iron, and the tabs are somewhat "fragile". The bolts are notorious for rusting in place.
The new penetrating oil FREEZ-OFF spray works well. If you can soak the bolts for a day or so it really helps. Sometimes tightening the bolt a touch will help - not much, turn a just a degree or so .
I like to chase the threads with a tap before re-assembly.
If you use the hydraulic pry - be careful the parts you are prying may be "weak" due to internal rusting.
I usually use a piece of wood and a 10# hammer and work around the cross member.
If you are not removing the spring - be sure to support the rear diff as hanging on a single bolt can snap the mounting tab. Even with the spring removed be careful not to side load the mountings .
Sometimes to help re- assembly , Put on one part in the Freezer and the other in the sun. One will expand and the other shrink - goes together easier.
here’s an interesting shot. The car is lifted forward of rear tires and frame is level. Spring is unbolted from diff and not touching. Sway bar is off. Car axle assembly is leaning heavy to passenger side which is same side as is low when weight is on it. Really baffled now.
Hows the TA bushing on the pass side? Looks as though the TA is contacting frame pocket. I'd be looking at a bent TA and/or missing ,destroyed bushing.What rear sway bar are you using?
Last edited by gjohnson; Dec 28, 2018 at 07:17 PM.
TA wasn’t hitting. Bushings look like someone already replaced recently. Stock sway bar. It’s just removed for bushing replacement and diagnosing this issue.
I have new crossmember bushings on the way, but I really don’t see anything out that far or anywhere close enough to lean the car this far.
I know this may sound off the wall? Have you checked the half shaft u-joints? When I recently replaced mine, I found when I removed the axle shaft, the trailing arm, and wheel dropped down. it looked just like your picture! Yours isn't as pronounced as mine was, but it was very similar in the looks of things. The trailing arm on mine was down so far that that I had to use a jack under the trailing arm itself to close up the gap in order to get everything lined back up and into a position so the new u-joint cups could be bolted into place.
My thinking is maybe one of the half shaft u-joints are so worn that it causes the whole assembly to be out of whack? Easy enough to check. Put the transmission in neutral with the rear wheels up off of the ground and turn the wheel assembly to get the half shaft on the passenger side turning. Watch the u-joints on the passenger side to see if there is any play? Another way to check the driveline ls to check and see if the bottom of the tire gains or looses clearance on the frame rack as it spins 360 degrees?
I know this may sound off the wall? Have you checked the half shaft u-joints? When I recently replaced mine, I found when I removed the axle shaft, the trailing arm, and wheel dropped down. it looked just like your picture! Yours isn't as pronounced as mine was, but it was very similar in the looks of things. The trailing arm on mine was down so far that that I had to use a jack under the trailing arm itself to close up the gap in order to get everything lined back up and into a position so the new u-joint cups could be bolted into place.
My thinking is maybe one of the half shaft u-joints are so worn that it causes the whole assembly to be out of whack? Easy enough to check. Put the transmission in neutral with the rear wheels up off of the ground and turn the wheel assembly to get the half shaft on the passenger side turning. Watch the u-joints on the passenger side to see if there is any play? Another way to check the driveline ls to check and see if the bottom of the tire gains or looses clearance on the frame rack as it spins 360 degrees?
Good Luck,
White One
Good response!
Funny thing you mention this. I typed up a similar response, yesterday, but got distracted, didn't hit "submit", and when I came back to the laptop, I just hit "log off" and walked away....
Hope you guys can help. I have read countless threads on this, but nothing seems to match what I have going on. The car is new to me with no history of its past. The passenger side rear sits 1.5" low as measured from the ground to top of fender well opening. Tires inflated the same and measured to make sure. It had a 8 leaf, so I hoped wrong or worn spring was the issue. Bought new 9 leaf. Ride height increased about 1", but still had over a 1" difference. I have measured front- all good. Body bushing measure same compression. Frame crossframe to ground measurement follows ride height sloping to passenger.
What I did- feel very bad about this, but to prove to myself what is happening- I installed 14 grade 8 washers (about 1.5") between castle nut and large bushing washer to effectively shorten passenger side bolt. This brought car to withing 1/4" level. So closer that if you measure ground to crossframe now it is dead on. Everything looks perfect - except you can see the obvious difference in spring deflection to hold the car level.
What I feel it needs is a pinion shim like you would use on standard style springs but in my case a 2-3 degree angle that the spring is mounted to axle housing. Then spring tension would be good side to side.
Again, front end is dead level. Body is level to frame. rear wheel centers to frame were all that was out. It was even obvious in driveshaft angle.
I know something very obvious to one of you guys will scream at you, but it is alluding me.
