BarryK - I think I have your 2004 issue!

[twoseater]

Hey Guys - my 65 is causing me some concern and its now off the road until its resolved. While searching I found BarryK's post:

http://www.corvetteactioncenter.com/forums/showthread.php?t=51999

Describes my problem pretty accurately and better than I could have

Barry - can you confirm that the bearings resolved the issue? I'm going to follow this advise given in tracking it down, starting with the bearings. I think I'll need some hand holding as I don't have a mechanic that would know these cars and I like to do the work myself. I'm sure some questions will be forthcoming as I begin to take it apart and track it down.

The banging sound is really pronounced if I'm turning into the garage at very low speed. Its a single loud bang. This sound familiar to anyone?

Last night while driving home, I felt a distinct lateral shift when driving which means it needs to be fixed. Made me feel way to uneasy to trust it on the road.

And a thanks to all who posted back in '04 - your advise and recommendations are still going strong 4 years later!

 

[JohnZ]

Check the shim packs for the trailing arm front bushings first. If they're OK and it turns out to be bearings, that's NOT a job for a home mechanic - it requires expensive special puller and bearing setup tools, a press, dial indicators, and work that's done in thousandths of an inch. Remove the trailing arm assembly and send it to Bair's or Van Steel; they do this work every day, and do it right.

 

[BarryK]

wow, that thread brought back memories.........

Yes, at the time replacing the rear bearings solved the problem. Another issue that did crop up anther time that caused very similar symptoms (and was suggested within that thread as an area to look at) would be the shim pack on the trailing arms.
At one point after this thread I did lose the shim pack on one side and during turns you could feel the whole thing shift as the t-arm would move and you could hear a nice banging sound from the t-arm hitting the mount in the frame.

I'd jack up the rear of your car to get the rear wheels off the ground. Grab one of the wheels in the 12:00 and 6:00 positions and see if you can feel the wheel move any. It shouldn't. If it does you may have an issue with the bearings.
Than grab the wheel again in the 3:00 and 9:00 positions and see if you can move either wheel and the whole trailing arm in or out. If you can look at the shims where the t-arm bolts to the frame. The shims should be easily seen and tight in there. If they are missing or if they are loose you will need to get new shims and have the rear of the car re-aligned.

 

[Chainshot]

I've read that the clutches in the posi unit can also CAUSE the lat. movement. Not the loud bang though... I don't mean to hi-jack your thread. But, does anyone know for sure about a posi rear with lack of or bad additive causing the shifting movement while turning ? It is a VERY quick jerk of the r/e in the same direction as you are turning. Also check all of your u-joints closely.

 

[twoseater]

Thanks guys. Barry - Sorry I brought that thread back on ya. However, you should take satisfaction that you are now giving the advise rather than asking for it. Guess you've come a long way since you decided to do you own work.

I think we are similair in some regards - I have a '65 and an '80. The '80 I've done a lot of work to. (Cam, lifters, rocker arms, intake, carb, brakes, power streering rebuild, tie rods, etc etc). Been a good time learning, and since there is no rust, its been fairly painless. The '65 I haven't had to do a lot of work on - very clean car and in great shape. I've had it for a couple years now and this is really the first major issue - which probably makes me over due

I will jack the rear end up (once I figure out a good way without damaging the frame paint etc.) After re-reading this thread and the old one, I'm optimistic (er hopeful) that its the shims. I did jack the passenger side and didn't get movement on the 12-6. I couldn't really see the shims with the tire on, so once I get the entire rear end up, I'll give it a good check. I think my biggest concern now is how to prevent my jackstands from doing damage to the frame rails. Definately got some dings/scratches on the '80 from them. I, like many, won't poke my head under a jacked up car unless there are jack stands in place.

JohnZ - thank you for setting me straight on the work required to do the bearings. Fingers crossed I won't need it!

Chainshot - Thanks for the alternative suggestion - we'll see if it generates any responses. The bang didn't happen when the lat. shift occurred (or at least I couldn't hear it). I was doing 50mph or so. I only hear it when I'm parking or turning around. So, in theory I could have multiple issues.

Time to start the process of elimination game!

 

[BarryK]

i use cut pieces of old carpet on the jack stands as "pads" to keep from scratching the frames on my cars.
once you get the car up on stands it will be much easier to see the shim packs although even easier of course with the wheels off.

Hope it's only the shims as thats only the expense of new shims and alignment. Replacing the bearings is much more costly.

 

[Tom Bryant]

Posi clutches sticking will cause a jerking during low speed turning. What you discribed doesn't sound like posi clutches to me. Take it for a drive in your neighborhood or in a parking lot and turn some slow circles. If all is quiet and you can't feel any jerking or catching then the posi is not conributing to your problem. If you do, you can add a bottle of the GM Posi Additive or change your lubericant and add a bottle with the change.

Tom

 

[twoseater]

Not seeing a problem

OK, so I took off the tires and got a good look at the shim packs. Pictures attached. Hopefully, these look right. I can't feel or see any play.

I pulled off the tire and and brakes and got a better look at things. Everything looks great and I couldn't feel any play when trying to move the spindle assembly (granted I have little leverage).

I still need to do some parking lot tests, but not sure where to go now.

The only weird thing I see is the cover plate (see bottom picture) that is on the brake disk. My Chilton Manual doesn't show such a cover and I do see marks in it where the lug nuts were driven into the plate as opposed to through it. Is that plate standard?

Any ideas/comments on where to look next?

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[SMOKINGJOE]

OK, so I took off the tires and got a good look at the shim packs. Pictures attached. Hopefully, these look right. I can't feel or see any play.

I pulled off the tire and and brakes and got a better look at things. Everything looks great and I couldn't feel any play when trying to move the spindle assembly (granted I have little leverage).

I still need to do some parking lot tests, but not sure where to go now.

The only weird thing I see is the cover plate (see bottom picture) that is on the brake disk. My Chilton Manual doesn't show such a cover and I do see marks in it where the lug nuts were driven into the plate as opposed to through it. Is that plate standard?
Any ideas/comments on where to look next?

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Looks like a wheel spacer for the backspacing of your wheels.

 

[Toms007]

Looks like a wheel spacer for the backspacing of your wheels.

Yea, that's what that looks like! Someone has put those on to space out the wheels. If you have stock wheels you should be able to remove them.

 

[Tom Bryant]

I agree. Looks like a standard wheel spacer to gain a little extra clearance on the inside of the tire to the body or frame. What wheels and tires are you running?

Tom

 

[twoseater]

I agree. Looks like a standard wheel spacer to gain a little extra clearance on the inside of the tire to the body or frame. What wheels and tires are you running?

Tom

Hi Tom - running 205/75/15 all around. Seems obvious as to what they are now They do cover the holes in the brake spindle which I guess might provide some protection? Perhaps the rims would do the same thing when mounted....

I'm at a loss as the original issue of lateral movement. I think I'll put it back on the road and see if I can reproduce it. Everything looks clean and tight. I'll also investigate the front end just case what I feel is really just originating from some place else.

 

[Tom Bryant]

With 205/75s you should not need any spacers as that's the radial replacement for the original tires. I wonder if someone had something wide on the rear at one time and needed the extra clearance. If they replaced the stock wheel studs with longer ones to accommadate the spacers they may be needed now just so you don't run out of threads before the wheels are tight. Have you tried to mount them without the spacers? If not needed I would not run them.

Tom