Rear Strut symmetry???

[cwerve74]

New to this and need a little help. Bought a 1974-BB conv and in my firts pass on what do I need to do right away came up with brakes. While I was replaceing the e-Brakes I noticed the rear spring attachment to the ditterential was broken(crack). When I got all of the parts out, I was looking at the rear struts and not sure of what I am seeing. I would expect to see symmetry between the left side and right side. Not the case----Both have a bend in them about 75% of the way from an end. The one on the driver side has the bend close to the differential and the strut on the passengers side has the bend near the wheel attachment. Both bends are uniform and look OK but I would have expected to see both with the bend at the same place. Either close to the differnetial of near the wheel. I found a good picture of a 80 vette and it had straight struts(differnet spring and differential attachment). Need help understanding what I have hear on my 1974. I can work on a picture if my description was not clear. Thanks

 

[MaineShark]

Are you talking about the camber struts? If so, some people bend them to align the car. Not a good thing. Most of the major vendors have replacement struts that offer more accurate adjustment than is available with the stock cam system.

Joe

 

[MidShark]

cwerve74
Welcome to the CAC! Your rear struts are supposed to be straight. In this all too common scenario, a shop trying to do a rearend alignment has purposely bent the struts because they couldn't get enough camber adjustment. That is usually an indication of worn out parts (such as the strut rod bushings). A Corvette oriented shop would know better (I hope). My '71 had the struts bent also at some point in time (although they were symetric :L ) I ended up installing the poly-bushed adjustable ones, which were cheaper than stock replacements. I have since found out that the bent ones can be straightened and re-used, though.

Dick

 

[ChuckG]

After years of driving, the ends of the stub axles that come out of the differential wear on the ends. This wear causes the camber to become more negative.

You can reach a point where you have so much wear that you cannot compensate by adjusting the strut rods. To get more adjustment, shops often bend them.

Think of it this way....the stub axles and half shafts are both a suspension and a driveline component. Think of the stub axles and half shafts as the "upper A frame" of your rear suspension, while the strut rods are the "lower A frame".

The cure to your problem MIGHT be rebuilding the differential with new stub axles which will re-establish the correct upper geometry.

Chuck

 

[cwerve74]

Ok I got it. ...Straight.... is the only answer for rear camber struts.

Since both have a very uniform bend I tend to discount the damage option and lean toward the alignment shop bend to get the proper alignmant. The problem here is If a I install straight struts I have not solved the root cause. I studied the ChuckG response and this might be a contributing factor I can't get all of the missalignment from that cause. About .332 inch difference in lower strut length over straight. Plus the half shaft yoke is connected to the stub axile with a c-clip and it looks to be in the orginal position. The camber strut bushings are bad so some of it is there. But -- Let me try out this posibility and you can comment. After I looked at the geometry of the suspention it looks like:
---Speculation on my part---
if the car sits lower due to a soft spring the top of the wheels move toward the center. See attached picture. The two links, half shaft and camber strut are of different lengths and ends are not on the same plain. If you bend the camber strut you pull the bottom of the wheel in correcting the out of alignment condition. Put in a new spring car sits tall & proud plus the alignment is now in spec.

Comments please.

 

[Vettehead Mikey]

By Jove I think you've got it! Are you sure your car sits too low? Have you measured how much end play you have on your side yokes? Anything much past 1/8" (some opinions may differ) indicates it's time for some internal work.

 

[cwerve74]

Measures the stub axle end play it was .050 Drivers side .005 passenger side. Well within the 1/8 number. Did not measure ride hight and now with up on stands not a praticle option. I just can up with the ride hight as a possible problem that I could fix. I will be putting straight stutsand new spring on and will discover if the theory was right. Everything on this car is orginal and the spring has 30 years of gravity working on it. We will see. While I was measuring ghe end play I discovered s slight movment in one of the U-Joints. I think I know what that means. ... More parts. After a Fosters moment I decided to freshen up all moving parts less the differential. Half shatfs done in my garage and I am going to send the Trailing arms to Vtech for rebuild. Any opinions on there rebuild service?