cheesenr7

I have a 1976 Corvette telescoping and tilt column. I recently bought this car and went to test out the telescoping feature and to my surprise I was holding the steering wheel in my lap

There is a shaft coming out the back of the wheel and i tried to slide it back into the column but the steering wheel is not engaging and is spining freely. (Steering wheel was working fine before i pulled it off) I am not to familiar with steering columns. Any help?

Thanks
Nick

RodgerF

Many many years ago I was a mechanic in the USMC. As my Gunny would say, "obviously there's something wrong that ain't right!" Beyond that I can't be of much help. I just had mine apart and put it back together for a color change but can't quite get how the whole thing just came apart like that.

The shop manual shows how to service the steering column. If you don't have it, you'll need it. Can you post a pic of what all came off of the column? That may help in the diagnosis. Also, Jim Shea would be the one to contact for this. He is the guru for all things steering column related.

Good luck

Rodger

cheesenr7

Haha yea i dont think that is the way gm intended it to work. I have spent all night searching. From what I can tell from what I read tonight is the part of the upper shaft that slides for the telescoping pulled out with my steering wheel. I believe usually that when dissembling the steering wheel this is the piece that would still be in the steering column that you would bolt the steering wheel hub onto. I read some of the papers from jim shea but am still having a hard time figuring out what to do. I know ill have to separate the shaft from the hub. I am still not sure how to reinstall the shaft (the correct way so it doesnt pull out again)

LudemJo

Thankfully, you weren't out somewhere...or worse yet, driving...when it happened! Holy cow, that is insane. Unfortunately, I can't help you either, but am looking forward to the pictures and the diagnosis. All I can say is WOW!

John

Jim Shea

You have a very serious safety situation on your hands. The following is a bit complicated but you need to understand how they go back together from a safety standpoint.

The upper steering shaft (that is still attached to the steering wheel hub) must have a semi circular wedge in place. That wedge must also slide in a keyway that is machined into the yoke steering shaft that is sticking out of the steering column. (You can see the keyway in the second picture below.)

Here is a sectional view of your T&T column head. You can see the locking wedge and the locking rod. When you rotate the round telescope lever that is attached to the special "star" screw, the star screw pushes the locking rod into the wedge. The wedge tips and secures the upper steering shaft to the yoke shaft.

You must have the locking wedge in place (in the upper shaft and in the keyway) otherwise the upper shaft will rotate freely in the yoke shaft. The wedge must have been in place originally, otherwise the upper shaft would have been free to spin from the start. However, once you were able to pull the steering wheel and upper shaft out from the yoke shaft, you must have dropped or somehow lost the locking wedge and possibly the locking rod.

Now the next critical parts that you are missing are the c-clip and the plastic retainer. If the wedge is in place and the c-clip installed, the wedge will hit the ear of the c-clip and the upper shaft CANNOT be pulled from the yoke shaft. You must find a replacement c-clip. The
following picture shows how the upper shaft, yoke shaft and keyway, locking plate and c-clip go together.

Lastly, you need to obtain a plastic retainer that will do two things. One it will fit snugly over the c-clip and prevent it from working loose from the yoke shaft. Second the plastic retainer will insulate that big telescope spring so that it is only touching the brass horn contacts and not any other metal steering column surfaces since that would cause your horn to blow continuously.

I will be in and out the rest of the day but will provide any more information that you might require.

Jim

cheesenr7

Jim, thank you for the detailed response. that is a big help and i defiantly have a better understanding now. I went looking in my floor boards and found the wedge and I see how it is installed. There is a C Clip still installed but it is not in all the way so there was nothing to stop the upper shaft from coming out. Compared the the c Clip in that picture it actually looks like more of an L. Maybe its possible that part of it broke off at some point and it worked its self out a little bit? I will order a new one to be on the safe side. I did not find a c clip retainer so I will order that to.

How is the tool used to install the retainer? I see how it is used to press the plate down so the c clip can be installed but if it connects to the upper shaft which at this point can slide in and out freely how is it secured to press the plate down?

cheesenr7

And yes, I am very happy and lucky this happened in my garage and not on the street.

Jim Shea

You need to temporarily install a 5/16-18 set screw (or a #20 Allen screw) in the end of the upper steering shaft (where the star screw normally goes). Turn it in until it presses against the locking rod and prevents the upper shaft from telescoping. Then you will be able to use the special tool to compress the locking plate. Just be sure to remove the set screw when you are done, otherwise, you will have permanently locked the telescope feature.

I was able to find both the clip and the plastic retainer at the Zip Products website. (I am sure that they should also be available at other suppliers as well.)

SC-757 Plate Retainer (c-clip)
SC-517 Plastic Retainer

The plastic retainer was only listed in the 1984-96 Zip Products Steering section. It should be in the 1969 through 1982 section as well.

Good luck,
Jim

Jim

cheesenr7

Thanks alot Jim. I appreciate the help.

-Nick

cheesenr7

Ran into a road block today. I went to a couple different hardware and could not match the thread on the upper shaft. It seamed pretty close to 5/16-18 but maybe the thread pitch is different? I brought the start screw and the upper shaft with. Neither appear to be stripped as they screw together nicely but the hardware store couldn't match them.

Jim Shea

The internal female thread in the upper steering column shaft and the male thread for the star screw was always 5/16-18 UNC from 1969 through 1982.

The engineering drawings of the C3 Corvette T&T steering columns all reflect the above thread information. In all my years of suggesting that you lock the telescope feature by temporarily replacing the star screw with a 5/16-18 set screw or a #20 allen screw, nobody has ever mentioned that information to be incorrect.

I can't explain your problem with the treads.

BTW (And this should not have any relationship to your problem.) The external male thread on the upper steering shaft (for the steering wheel nut) was 9/16-18 UNF from 1969 through 1977. In 1978 the male upper steering shaft thread for the steering wheel nut was changed to metric M14x1.5. It remained that way through 1982.

Jim

Jim

cheesenr7

Thanks Jim. I will take another look tomorrow.

cheesenr7

Im still stumped. I tried to run a 5/16-18 tap down the shaft and it would not start. I didnt force it. I also tried to use 5/16-18 tap on the star screw and it wouldnt start. Again I didnt force it. The start screw still threads into the upper shaft with ease. When the start screw is lined up next to a 5/16-18 bolt the threads seamed to be spaced out the same but the threads them self look different. I am no expert so here is a picture of what the threads look like if someone can identify if they look different.



Is it possible that at some point someone would have been able to use a upper shaft from a different gm column or a different column all together?

If i cant come up with an answer im going to try an muscle the new C-Clip in when I get it in the mail and hope for the best.

Jim Shea

You photo of the star screw isn't the sharpest but the threads appear to be distorted and all rounded (as if it had been screwed into a part with a close but different thread.)

I don't have much information on Corvette T&T steering columns after 1982. I do have one drawing of a 1989 Corvette T&T column and it still has the same 5/16-18 thread in the upper steering shaft. I guess it is possible that the upper steering shaft thread was changed to metric further down the road.

It doesn't make much sense to me that both your upper steering shaft and your star screw have damaged threads (since your male and female 5/16-18 taps won't thread on either of your two parts.)

It seems to me that you don't have much to lose by trying to work your male and female taps onto your mating star screw and upper steering shaft threads and try to correct the damaged threads back to compliance with 5/16-18 dimensions.

You could also purchase a new star screw and just "rework" your upper steering shaft threads.

Jim

cheesenr7

Thanks Jim. That is what i was trying to show in the close up picture is that the treads looked rounded. I tried to match it up to a metric bolt also when i was at the hardware store with no luck. It just seems odd that the star screw and upper shaft screw together so nicely. I would think if the threads were damaged on either one it would be hard to screw in the star screw.

LudemJo

Those threads definitely looked stripped. I wonder if someone tried to fix this before and ran the wrong tap and the threads and messed them up, but they threaded together, so they figured it was good enough. Looks like Bubba strikes again. Steering is too critical to take any shortcuts...I would be researching the cost of a new steering column personally...

John

cheesenr7

Im not sure if I will replace the whole column just because the star screw threads are stripped. Its only purpose is to control the telescopic feature which works fine. Now the problem I had with the steering wheel coming off I defiantly agree is a big safety issue and ill make sure that is corrected the proper way. That was not an issue with the star screw though, that was an issue with the c-clip not being installed correctly. I have a new C-clip as well as the c-clip retainer and I wont be taking any short cuts here.

Jim Shea

Sounds like a plan. Most people set the telescope length of the steering column once and for the most part don't move it again. The only other thing you need is to lock the telescope feature while compressing the locking plate to install the c-clip when you work on the column. You might try taking just the "U" part of the compressor tool (without the center screw) and have someone use it to press down on the locking plate as you reach into housing to install the c-clip. It would most likely be a friendly two person operation.

I also seem to remember someone using a piece of PVC pipe with a section cut out. That person pressed on the pipe with his chest and compressed the locking plate as he installed the c-clip through the cut out section. However, you might have to be a contortionist to do it yourself.

Jim

cheesenr7

Thanks for all the help!