Vette79C3

While my 79 was idling in my garage I was turning the steering wheel to the full turn position and the cotter pin and nut from shaft to the frame bracket popped/snapped off. Curious why something like this would happen. I'm assuming it makes no sense to continue to use this power steering cylinder since the threads on the shaft and not are most likely screwed. This power steering cylinder was a re-manufactured one installed just a few years ago.

Vette79C3

~bump~

MelWff

not clear what your question is, did you remove the cylinder and see if it moves freely? Have you looked at the threads and they are damaged?

TeaEye

As far as why it snapped off -- could be many reasons.

If you have a lot of $$$ and you really want to know, you can send the part off to a lab and get a formal root cause failure analysis.

What do I think? Not very much to go on............but its interesting that your post says that you had the steering wheel in the full turn position. Perhaps, if you do this very often, the metal could have fatigued and finally failed.

When I bought my vette a few years back, I noticed someone had welded a stud to the end of the steering cylinder. I didn't think much about it and just replaced it and never had any problem with the new one. But given what you have said, I go back to the initial comment. If the power steering pump is allowed to transfer all of its power/pressure when the steering wheel is in the full turn (lock position) something has to give--in this case the end of the steering cylinder.

Hope this helps.

Vette79C3

After further inspection today, the power steering cylinder shaft threads are fine. The nut is toast. Turns out I was using the standard nut that came with the re-manufactured power steering cylinder which according to all the documentation I have seen and read is the wrong nut. It should be a castle nut. Does not really explain why the standard nut failed but it does make sense as far as cotter pin use is concerned. In the process of purchasing new correct castle nut and cotter pin. Then I can go back to my initial issue of pulling to the right when moderately braking

johnmb

Castle nut/regular nut shouldn't make any difference if the nut was the correct thread pitch and the threads were not damaged. I'm not sure all of the replacement kits would come with the more expensive castle nut...but again, properly installed it shouldn't make a difference.

It does often seem the case that when you go out to fix problem "A", you discover problem "B" , "C" and "D" that need solutions before you can address the original issue! :-)

John

Jim Shea

Are you saying that the threaded part of the piston rod #15 or the threaded portion of the ball stud #6 snapped off?

The piston rod should be plated to prevent corrosion. There is a potential problem with plating procedures called "hydrogen embrittlement." As part of some plating operations a part needs to be heated after plating. (I am not a metallurgist so I am not real up on the exact type of plating and relieving procedures.)

Anyway, hydrogen embrittlement may weaken a part so that it will fail in a highly stressed area. The weakening of the part may take days, a week, or possibly years. My early 396 big block in my 1965 Impala had crimped, torque retention nuts on the rocker arm studs. After a couple years the nuts actually cracked in the crimped area of the nut(s) and they started to back off. I took one of the failed parts to Saginaw Steering Gear where a metallurgist indicated that hydrogen embrittlement was the culprit. I replaced all of the nuts since most likely they all came from the same batch of crimped and plated parts.

Jim

TeaEye

You ceratinly lucked out with just a bad nut!!!

Before we leave the power steering system, are you aware of a procedure called Control Valve Balancing? Might be a good thing to research on the Forum.

Also as far as the braking issue. Here is a data dump on things to check and pursue as required.

1. Check tire pressure
2. Jack up that part of the car and check the wheel for play. Holding the wheel at the 9 and 3 oclock position then 12 and 6.
3. Spin the wheel, does it turn easily?
4. Take wheel off and do visual inspection.
5. Note: Don't remove the disk/rotor without indexing it to the hub. Very Bad!!!
6. Check for play in the hub again.
7. Do the dial indicator procedure to check for rotor runout.
8. If you can barely turn the disk/rotor, the caliper probably needs to be rebuilt.
9. When was the last time you flushed the brake system with new brake fluid?
10. What is condition of the brake pads and wear pattern compatred to the other side?

Good Luck.

TeaEye

Jim brings up a good point!

I'm guessing the OP is talking about the nut in the first picture. We need to make sure

Vette79C3

Yes, the nut in the first picture. Shaft to frame braket nut. Basically I turned the steering wheel all the way in one direction and the cotter pin snapped off and the nut came off as well. Looking at the nut, the threads are destryed but on the shaft itself the threads appear to be fine. Obviously, I don't want to spend any more money then necessary so I'm purchasing a castle nut and cotter pin and re-installing. Think about this, if it is not a castle nut with a cotter pin to prevent it from backing off then why have a standard nut there that will back off? That cotter pin is not going to hold a standard nut from backing off during use and movement, correct?

As for the brakes, when I press on the brake pedal during movement quickly I can lock up both front wheels. When braking easily it pulls to the right. New rotors, pads, calipers, master cylinder, and rubber lines all within the past few years. Followed correct break-in procedure for rotors and pads. Bled the system three times. No bubbles and fluid is clear. No visual leaks at the caliper. Front suspension looks fine and there is no significant play at the wheel.

myoriginal77

If you had a standard nut was the cotter pin just pushed through the hole?
That for sure is not going to hold anything.

My other thought is, if the cotter pin was just though the hole the nut had to be tightened behind it so maybe was moving around, the shaft is harder than the nut, the nut threads got worn down from movement and finally let go.

Just a thought.

Frank

MelWff

concerning the pulling to the side under light braking, a visual inspection of the steering components is not going to tell you if you have play in a tie rod, idler arm, etc. Have the steering components checked for wear.

Vette79C3

I was basically comparing one side to the other looking for loose bolts, worn bushings, cracked welds, etc. It's probably going to go to the shop after the holidays.

TeaEye

Bite your tongue! You can fix it!!! Here are a few threads I found after doing a quick search "front brakes locking up".
I sure there are more.....

http://forums.corvetteforum.com/c3-t...ocking-up.html

http://forums.corvetteforum.com/c3-t...rakes-ugh.html

http://forums.corvetteforum.com/c3-t...taying-on.html

http://forums.corvetteforum.com/c3-t...erheating.html

http://forums.corvetteforum.com/c3-t...ocking-up.html

Consensus is Brake hoses or M/C.

Good Luck!

Vette79C3

The issue is not with the front brakes locking up. It's the pulling to the right when light to moderate braking. When I brake hard they lock up like they are suppose to.

Vette79C3

Purchased a new Power Steering Cylinder and will be installing it this weekend. Does anyone have a power steering fluid recommendation? Type, brand, etc.

Jim Shea

Genuine GM power steering fluid (available at most GM dealerships) is the only fluid that was specifically formulated to operate with the GM line of power steering pumps. This paper describes the fluid in more detail.

http://jimshea.corvettefaq.com/?p=861

jim

Vette79C3

Jim,

Are you saying I can go right to the GM parts department at the dealership and pick up a quart? Any special reminders when replacing the power steering cylinder? I understand bleeding the system by putting the front end in the air and with the engine off turning the steering lock to lock two dozen times. I also need to connect the lines in the same order as I removed them but other then that, anything else?

Jim Shea

The assist cylinder has the most air and is the furthest point from the power steering pump in the steering system. So it will be the most difficult part to eliminate the air from the system. So it just might take a bit longer to "get the air out."

I can't vouch that every dealer will have a can of fluid just sitting on the shelf. The entire Corvette steering system will hold a bit over 20 oz of fluid. GM 89020661 or 89021183.

Please make sure that you reconnect the hoses such that they criss-cross at the control valve and connect to the correct ports on the assist cylinder. Otherwise you will be in for a rude surprise.

Jim

Vette79C3

Thanks Jim. I purchased the fluid with no problem today at the dealership. Funny, once I get this problem resolved then I can move forward with the initial problem which were my brakes