C3 Steering Box Rebuild

[John S.]

So after 45 years of Corvette ownership I decided it was time to rebuild my first steering box. No particular complaints or problems with the box other than a minor seepage of grease out of the input shaft. I had also read quite a bit about old grease breaking down and causing internal corrosion if the car had sat for a long periods of time and my car was non-op from 1991 until I bought it in 2014.

On the back yard mechanic scale of 1 to 10, I’d rate the rebuild a 6-7. Specialty tools required included a bushing install tool, a bearing race install tool, an in/lb torque wrench to set the gear preload and lash. A ft/lb torque wrench was also required to tighten the pitman arm nut.

Overall a greasy mess but not too bad.

The original grease was still present but had clearly broken down to a brown goopy mess.

F85A6FE3-0FDE-4652-932C-FEF9D3928DAB.jpg

Here the pitman arm shaft/gear was starting to show signs of corrosion at the upper bushing. I was able to clean it up and reuse with a bit of polishing.

583CC1FB-2167-4721-8305-0A72489BFED3.jpg

Cleaned up and ready for the rebuild kit, I purchased the deluxe rebuild kit from CC that included new bushings.

14C70B83-86B0-4535-AC58-51E2F11CE5AC.jpg

Back together and ready to install with cleaned up original rag joint.

A9A2BE35-8554-4873-8FE5-12AF7B63206B.jpg

Installation and road test sometime later this week.

A special thanks to Gary R., for his posts on CF and Digital Corvette. Very helpful and made the job much easier. I would highly recommend this rebuild to anyone who has not had their box recently serviced or if the car has been inactive for an extended period of time.

[Jimmy P.]

Re: C3 Steering Box Rebuild

Great job John ! Looks like it came out very nice.
Thank you for sharing

[Joe L.]

Re: C3 Steering Box Rebuild

So after 45 years of Corvette ownership I decided it was time to rebuild my first steering box. No particular complaints or problems with the box other than a minor seepage of grease out of the input shaft. I had also read quite a bit about old grease breaking down and causing internal corrosion if the car had sat for a long periods of time and my car was non-op from 1991 until I bought it in 2014.

On the back yard mechanic scale of 1 to 10, I’d rate the rebuild a 6-7. Specialty tools required included a bushing install tool, a bearing race install tool, an in/lb torque wrench to set the gear preload and lash. A ft/lb torque wrench was also required to tighten the pitman arm nut.

Overall a greasy mess but not too bad.

The original grease was still present but had clearly broken down to a brown goopy mess.

[ATTACH=CONFIG]105217[/ATTACH]

Here the pitman arm shaft/gear was starting to show signs of corrosion at the upper bushing. I was able to clean it up and reuse with a bit of polishing.

[ATTACH=CONFIG]105218[/ATTACH]

Cleaned up and ready for the rebuild kit, I purchased the deluxe rebuild kit from CC that included new bushings.

[ATTACH=CONFIG]105219[/ATTACH]

Back together and ready to install with cleaned up original rag joint.

[ATTACH=CONFIG]105220[/ATTACH]

Installation and road test sometime later this week.

A special thanks to Gary R., for his posts on CF and Digital Corvette. Very helpful and made the job much easier. I would highly recommend this rebuild to anyone who has not had their box recently serviced or if the car has been inactive for an extended period of time.

John-------


I don't think the oily mess you found was a result of the grease breaking down. For one thing, the grease does not break down to the sort of lubricant you found. Much more likely is that someone once filled the box with the much lower viscosity gear lube which a lot of people think is what's used in all GM manual steering boxes of the period. Most of the steering boxes did use a lubricant of about this viscosity. But NOT Corvette. Corvette used a much higher viscosity lubricant akin to chassis grease.

[Jerome P.]

Re: C3 Steering Box Rebuild

I just had my 72's steering box rebuilt. Hopefully, and I will ask if they used the higher viscosity lubricant Joe mentioned.

Thanks, Joe.

[Gary R.]

Re: C3 Steering Box Rebuild

John looks like you did a nice job. Glad my old threads helped you.

What you found for sludge is very common, I find it a lot. Often the ball screw ends are affected and you won't get a smooth bearing preload- some will say 3-5 in/lb is ok, it is not. You need a steady and smooth 5 in/lb for the correct preload. Sometimes the box is empty leaving behind a dry rust grit.

Also did you check the D-Flat for positioning of center and the high lash? The misconception with these boxes is the D-Flat or earlier Chisel mark on the input indicated true center and high lash. Most times they are not even close resulting in a box with high lash off center. If there is a choice to be made in that situation always go for the high lash, true center isn't going to mean much. Some marks are dead on, some off up to 90*.

How was the fit of the kit bushings? I haven't a vendors kit in 15 years and used to machine my own bushings, now I have them made to my spec , then polish the sector and fit the bushings to it.

When all done once on high lash if you move the input the output moves at the same time, no lost motion. That combined with fit bushings and couple of other blueprinting tricks will give you a box better then it ever was from Saginaw and will compete with some of the most expensive aftermarket options.

Good job.

[Richard G.]

Re: C3 Steering Box Rebuild

I agree with Gary on the bushings. GM bushing can be found on Ebay as they were used for many years and applications.
The bushings I received where junk. Wall thickness varied by almost .003. They were not concentric. I.e. the inside bore and outside diameter were not bored on the same setup. When the shaft was installed it would bind on the bushings. That's how I found the lack of concentricity.
On a scale of 1 to 10, I’d rate the rebuild a 8. I would rate it lower maybe a 6-7 if you don't mess with the bushing.
Rick

[John S.]

[Gary R.]

Re: C3 Steering Box Rebuild

Sounds good John. As long as you got a steady preload with the new bearings and the lash is dialed in you should see a big improvement. Many times with a box in sludge like that the new bearing preload is very choppy, jumping 2-3 in/lb.

Glad the bushings fit well too, they will compress when installed. One reason I stopped using vendor rebuild kits many years ago was due to poor bushing fit, many were loose. Tom Reina had the best kits and I still have them. Did you get a cover bushing too, I see many kits today have dropped them all together.

[John S.]