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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.
I would jack up the car so it is level to a height that you can get under the car.
Make sure the car is well supported.
Measure each frame to level ground to make sure it's level.
Now check the spring mount on the rear differential cover to see if it is level. If not check the diff mount and cross brace.
You should see something out of whack in that area.
Just remember if a front spring is bad it will affect the rear also. To test this jack up the car from the front just off the ground and measure the frame to ground under the front door as a reference. Both sides equal.
If the spring mount is tilted the car will tilt. If the diff is tilted - same. Check all mounts and bushings.
If you drop the spare tire tub it may reveal some issues and make life easier.
We have a 4 post lift, so I’m doing all these measurements from under the car. So, the rear diff can be mounted out of level? That’s what it “feels” like in my mind with what I had to do to fix it.
Also, the diff bolts to the cross frame as I call it. That is now level that the body is level. I measured the rear diff spring bracket 3 times sure it was casted out of level
First if you have a new spring in the rear. I would remove the two front springs and make sure there is identical , or preferably replace with a known set of springs .
If one side of the rear Is down the the opposite side front has to be up . If the chassis is not bent.
measure chassis to ground on a level surface , before measuring body.
bfit
So, while rear was out of level-frontwas level. After rear is level-front is still level. I have assumed frame bent also, but since my car is now level and crossframeabove diff side to side is also level, I’m baffled as to what could be put.
I think ill put car back on lift and support frame level. Then remove spring and put level on axle diff. It has to be out, but I don’t see how it could be out. Doesn’t iount directly to frame which sits against body?
Make sure the front springs are both properly mounted and the spring ends are locked into the spring pockets.
If one of the spring ends is not resting in the pocket it will throw everything out.
The spring mount had 2 " tabs" that extend out from the diff cover which is the spring mount. If these are out of level even a slight amount - it will show up as a much larger deviation at the frame rail. due to the length away from the center of the car. I would take the spare tire tub out and double check the area.
If you can :
Jack up the car in the rear.
Remove both spring to trailing arm bolts.
Measure how far down the spring drops on both sides - should be the same.
Measure to the trailing arm spring mount hole both sides to the frame.- should be the same.
The only other variable is the shock. If a shock is bad it can upset the car. to test - set spring as normal - equal length both sides - remove the shocks, put the car on the ground and see if the car is level.
Also, the diff bolts to the cross frame as I call it. That is now level that the body is level. I measured the rear diff spring bracket 3 times sure it was casted out of level
Bob, correct me if I'm hearing you wrong, but it sounds as if you are thinking your rear differential cover was cast incorrectly?
In other words, the two red lines (on your rear cover) are not parallel.
If that's the case, it should be easy to verify by just comparing the two measurements at A and B. If the two measurements are the same, the rear cover is probably cast correctly, but if the rear cross member is bent, that could cause the rear to shift and create the same effect/result.
Would front springs not make care out of level in front if one front spring was my issue? I need to remove to check?
You have to think of the car as a 4 legged stool. If one leg is "off", it affects the other 3. My suggestion, so you don't have to do a lot of disassembly, and especially since you have the advantage of a 4 post lift (I'm extremely jealous!!), is to measure from the inner pivot bolts, of the lower a-arms, to the ramps of the lift, on both sides, in the front of the car. If this distance is equal, then your issue is most likely in the rear of the car. If the front isn't level, side to side, I'd recommend you attack that first, so you're not chasing your tail. And secondly, using the height of the fender openings, while frequently used, isn't always accurate, as the body panels aren't always attached in a uniform manner.
Originally Posted by OldCarBum
Make sure the front springs are both properly mounted and the spring ends are locked into the spring pockets.
If one of the spring ends is not resting in the pocket it will throw everything out.
This is a good idea, too, and easy to check. Just look in the lower a-arm, and see if the spring indexes FULLY in the recess of the arm. This USUALLY is a proper check, HOWEVER, if you're not the original owner of the car, and know it's previous history, you won't know if a previous owner replaced the springs, and in doing so, installed proper springs.
Would front springs not make care out of level in front if one front spring was my issue? I need to remove to check?
That is what was wrong with my '70. it sat low on the drivers side. PO had the rear spring reset by a local spring making company but it made no difference so he gave up, I replaced the front springs and the car sits level now. FWIW both the original springs were the same length when I removed them.
I measured the front and it is dead level from control arms and any other points I can find to ground.
The rear casting is cast straight.
It must be in rear. I’m starting to wonder if cross brace is bent. Even a couple degrees might do this I would guess.
Wed ill I’ll be back in shop to look at. I think I’ll jack car on 4 post rolling jack( jealousy is really abound by now) 😂 then remove spring from both sides and hopefully I can see what part is out of level. I’ll take pics. Thanks everyone for the help.
This is the car I’ve wanted since HS, I’m 52 now. Finally money, time, the right car, and all other things in the universe have lined up.
Can you show me what this looks like? My new spring bolted to diff and I don’t think there was anything but a rectangle shaped pad
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.
12-23-2018, 10:57 PM
C3 1976 Rear spring help please
