C4 rear axle problem
#1
03-19-2015, 04:35 PM
C4 rear axle problem
Hello guys, my name is Miroslav, I come from Czech Republic. I would like to ask you for help with my 1984 C4. My car hit the concrete wall with rear right rim, which did some bad stuff to the rear axle. Below please see exact video of what happened. The worst is that I'm the guy watching behind that white board at the video 
https://www.youtube.com/watch?v=ZxnT...ature=youtu.be
Now the rear right wheel has positive camber and little bit more toe-in then it should. The biggest trouble seems to be the fact that whole axle moved little bit left in the car. Not much, but it is noticeable when you are walking around the car. The worst is that everything seems to be straight and correct, nothing is obviously bent or cracked. After very very careful examination it seems that right camber rod (bottom arm) might be very slightly bent close to the mounting point at the differential, and perhaps the steel mounting point is also little bit bent towards front of the car. Both would explain the camber and toe-in, but not the movement of the whole axle!
We tried to set up the rear right wheel alignment. We set the right wheel alignment regarding the left wheel, which alignment seems to be good. We had adjusted a camber and toe in little bit. Now the rear right wheel is standing straight as well as the left one, but the whole axle is still moved left in the vehicle.
Now the worst part. If I measure distance from rear wheel disc to the chassis of the car (or to the center of the car), the distance is the same at both sides!! But when I hang a plummet from the edge of rear fenders, at right side I measure 10 mm gap between the rope and the wheel disc. But at the left side the rope is touching the tire, causing plummet not even to hang straight! So it means, that bodywork had to move somehow at the chassis. But this is not very much possible at our C4s, right?
I naturally suspected the two mounting points at the chassis where the rear axle is hanged for. But those holders are solid pieces of aluminum, the axle would have to fall apart first before such a piece of material would bend! Everything seems to be in correct shape and I'm desperate now. It was not that big hit to suspect the chassis to be bend, right?
I found whole rear axle from 85 Vette in Poland for good money, with brakes and everything. But I'm afraid that after I will drive 400 km to Poland and back and install it, it will be also moved left against the bodywork.
Do you guys have some experience with hitting something with rear wheels of your C4 when power-sliding? Where are some fixed points at the bottom of the car against which I could measure the position of the rear axle in the car? How to change position of the rear axle in the C4? Thank you very much for any advice!
https://www.youtube.com/watch?v=ZxnT...ature=youtu.be
Now the rear right wheel has positive camber and little bit more toe-in then it should. The biggest trouble seems to be the fact that whole axle moved little bit left in the car. Not much, but it is noticeable when you are walking around the car. The worst is that everything seems to be straight and correct, nothing is obviously bent or cracked. After very very careful examination it seems that right camber rod (bottom arm) might be very slightly bent close to the mounting point at the differential, and perhaps the steel mounting point is also little bit bent towards front of the car. Both would explain the camber and toe-in, but not the movement of the whole axle!
We tried to set up the rear right wheel alignment. We set the right wheel alignment regarding the left wheel, which alignment seems to be good. We had adjusted a camber and toe in little bit. Now the rear right wheel is standing straight as well as the left one, but the whole axle is still moved left in the vehicle.
Now the worst part. If I measure distance from rear wheel disc to the chassis of the car (or to the center of the car), the distance is the same at both sides!! But when I hang a plummet from the edge of rear fenders, at right side I measure 10 mm gap between the rope and the wheel disc. But at the left side the rope is touching the tire, causing plummet not even to hang straight! So it means, that bodywork had to move somehow at the chassis. But this is not very much possible at our C4s, right?
I naturally suspected the two mounting points at the chassis where the rear axle is hanged for. But those holders are solid pieces of aluminum, the axle would have to fall apart first before such a piece of material would bend! Everything seems to be in correct shape and I'm desperate now. It was not that big hit to suspect the chassis to be bend, right?
I found whole rear axle from 85 Vette in Poland for good money, with brakes and everything. But I'm afraid that after I will drive 400 km to Poland and back and install it, it will be also moved left against the bodywork.
Do you guys have some experience with hitting something with rear wheels of your C4 when power-sliding? Where are some fixed points at the bottom of the car against which I could measure the position of the rear axle in the car? How to change position of the rear axle in the C4? Thank you very much for any advice!
#3
03-21-2015, 04:17 AM
This spot I have watched most carefully many times. Also the proof that this spot is ok I think is that the distance from wheel disc to chassis is the same at both sides. The axle seats good at the chassis, but it seems that the bodywork moved at the chassis. Is this possible?
#4
03-21-2015, 07:12 PM
I'm no bodyman but I did do a number of changes when I was younger. If it was my car here's what I would check.
Before doing anything else, I'd get it on a hoist and get the frame measurements and check it for square. Insure it's not damaged.
Next I'd mark the centerline of the differential and measure from that line to either side of the frame, the same point on each side. Also check to Insure the mount points etc are square in the frame.
If everything checks out frame wise then start checking things like from the center line to various mount bolts for the body and see if they check out.
On the older body-on-frame cars, it was possible to shift the body on the frame especially if things were dried out. I'm not so sure it can happen on a Vette, but best to start with the basics.
Good luck, hope it's an easy fix.
Before doing anything else, I'd get it on a hoist and get the frame measurements and check it for square. Insure it's not damaged.
Next I'd mark the centerline of the differential and measure from that line to either side of the frame, the same point on each side. Also check to Insure the mount points etc are square in the frame.
If everything checks out frame wise then start checking things like from the center line to various mount bolts for the body and see if they check out.
On the older body-on-frame cars, it was possible to shift the body on the frame especially if things were dried out. I'm not so sure it can happen on a Vette, but best to start with the basics.
Good luck, hope it's an easy fix.
#5
03-27-2015, 09:15 AM
I'm no bodyman but I did do a number of changes when I was younger. If it was my car here's what I would check.
Before doing anything else, I'd get it on a hoist and get the frame measurements and check it for square. Insure it's not damaged.
Next I'd mark the centerline of the differential and measure from that line to either side of the frame, the same point on each side. Also check to Insure the mount points etc are square in the frame.
If everything checks out frame wise then start checking things like from the center line to various mount bolts for the body and see if they check out.
On the older body-on-frame cars, it was possible to shift the body on the frame especially if things were dried out. I'm not so sure it can happen on a Vette, but best to start with the basics. Good luck, hope it's an easy fix.
Before doing anything else, I'd get it on a hoist and get the frame measurements and check it for square. Insure it's not damaged.
Next I'd mark the centerline of the differential and measure from that line to either side of the frame, the same point on each side. Also check to Insure the mount points etc are square in the frame.
If everything checks out frame wise then start checking things like from the center line to various mount bolts for the body and see if they check out.
On the older body-on-frame cars, it was possible to shift the body on the frame especially if things were dried out. I'm not so sure it can happen on a Vette, but best to start with the basics. Good luck, hope it's an easy fix.
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