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I've stripped down my steering box and the internals all look to be in good condition. The pitman shaft slides freely in the bushes and I can't feel any slop at all. Is there a way to measure whether the bushes need to be replaced?
I guess the question really is how much clearance is too much. I don't won't to replace the bushes (which doesn't look to be that easy) and then find I've made it worse.
I got out my unit repair manual. And although it does give a lot of spec's for settings. No actual spec for bushing to Pitman shaft.
My take on this is if there is no visible wear, zero shake that they are good. Practical experience would tell me to set it up new at about .001 clearance. It does get hot and expansion will happen. But how much? And those factory replacement bushings that are pre sized are likely no longer available. Replacing those bushings and then line reaming to size will be a bit of work. And if your at zero shake I can't see how you can make it better. DON'T FIX WHAT AIN'T BROKE!
There is no spec on the bushings that you will find in a manual. I always replace the bushings as part of the build process.
The kit bushings will vary, depending on the sector diameter and housing bore. I never use kit bushings. I have my own bushings, made to my spec and size them to the sector once it is checked and polished.
Now with that said, when I install my bushings, the sector will not fit, until I size them.
It depends on what level of build you want. Common kits will have the internal parts, less the cover bushing and gears. The new gears sold today may be questionable and will setup differently than yours. Centering means nothing with these boxes, you need to know where the high lash and arm positions are.
I got out my unit repair manual. And although it does give a lot of spec's for settings. No actual spec for bushing to Pitman shaft.
My take on this is if there is no visible wear, zero shake that they are good. Practical experience would tell me to set it up new at about .001 clearance. It does get hot and expansion will happen. But how much? And those factory replacement bushings that are pre sized are likely no longer available. Replacing those bushings and then line reaming to size will be a bit of work. And if your at zero shake I can't see how you can make it better. DON'T FIX WHAT AIN'T BROKE!
Thanks for digging this out, but as you say it doesn't give any definitive guidance
There is no spec on the bushings that you will find in a manual. I always replace the bushings as part of the build process.
The kit bushings will vary, depending on the sector diameter and housing bore. I never use kit bushings. I have my own bushings, made to my spec and size them to the sector once it is checked and polished.
Now with that said, when I install my bushings, the sector will not fit, until I size them.
It depends on what level of build you want. Common kits will have the internal parts, less the cover bushing and gears. The new gears sold today may be questionable and will setup differently than yours. Centering means nothing with these boxes, you need to know where the high lash and arm positions are.
I've seen you mention previously that the kit bushings don't meet your standards. Given this and the risk of damaging the new bushes by replacing them without the special tool, I think I'm best to leave as is.
I personally think your right here. Pretty hard to line ream and hone new bushings to size to achieve zero shake. But a slip fit. And when you are already there?
When I did valve guides in the machine shop, you would just shake the valve and decide if they were good to go, or not.
You can feel over ~1 to 1.5 thou, and that was the valve guide spec.
If you can feel "something" it was loose.
If you can not feel "anything" it was good.
I would expect a steering box should be roughly similar.
Or you could buy the inside & outside mics and try to measure it.
Or put a dial indicator on the end of the shaft as you shake it.
Just shake it, dry, in all 4 directions, on a clock face.
Bushings tend to wear oblong in only one direction.
If it is not loose, you will not gain anything by tearing into them.
Dial indicator method. If your shaft is 6" long, and your bushing is 1" wide, a bushing clearance of 1 thou will give you 6 thou of shake. You can measure that even if you can't feel it. Worn will give you a lot more.
Last edited by leigh1322; Jan 4, 2026 at 10:15 AM.
The condition of the gears is more important than using stock bushings. If your gears are worn out it won't matter. It doesn't matter if they are high or low mileage, only if the grease has become acidic or they have been incorrectly adjusted over their live. Correctly built with good parts, there is a smooth preload, defined high lash point, and arm location.
Good example, I have a new, knockoff box here. These are sold all over. The gears are so far out it can't be setup correctly and will always have play in the straight-ahead position. It makes you wonder if those making the gears know anything about how to dial - in these boxes? This is a throw away box and a loss of $400.
When a box is correctly built, there is -0- play in the straight-ahead position.
When I did valve guides in the machine shop, you would just shake the valve and decide if they were good to go, or not.
You can feel over ~1 to 1.5 thou, and that was the valve guide spec.
If you can feel "something" it was loose.
If you can not feel "anything" it was good.
I would expect a steering box should be roughly similar.
Or you could buy the inside & outside mics and try to measure it.
Or put a dial indicator on the end of the shaft as you shake it.
Just shake it, dry, in all 4 directions, on a clock face.
Bushings tend to wear oblong in only one direction.
If it is not loose, you will not gain anything by tearing into them.
Dial indicator method. If your shaft is 6" long, and your bushing is 1" wide, a bushing clearance of 1 thou will give you 6 thou of shake. You can measure that even if you can't feel it. Worn will give you a lot more.
This was the sort of thing I was thinking of doing Leigh, but I didn't know what would be an acceptable/non-acceptable amount of play. Having said that I've decided to leave the bushes as they are. If I put the box back and I'm not happy with the steering feel it's a fairly easy job to pull it back out again.
Like Gary said slop in the box goes way beyond slop in the bushings alone.
Bearings, bearing end-play, true surfaces, gear wear, gear mesh, gear high spot, top lash adjuster end-play, recirc ball looseness, etc.
There is only so much we can do at home.
Fresh grease and seals is a good thing.
If it still feels bad, despite your best efforts, send it to Gary.
There are several different lash adjustments when you set the box back up.
Make sure you have a GM Overhaul manual.
Best resource.
As it happens Leigh, I'm fairly confident that all my box really needs is just new grease and seals plus proper adjustment. When I removed it from the car it was running at 3.5 to 4 in lbs from end to end, but this was easily adjusted to 4 to 4.5 at the ends and 12 to 12.5 in the middle. Everything inside looks to be in good condition. I just wasn't sure if there was an old pro's method of measuring an acceptable/not acceptable amount of bush wear.
Thought I would just finish off this thread by saying that after careful inspection of the bearings and gears I decided I could re-use them all and the bushings. As I had already found, the box was easily adjusted to the correct figures and was very smooth in operation. Back in the car, the constant small adjustments to the steering, that I had previously needed in the straight ahead position, have now gone and all feels good. Most unusually for a Corvette, this even turned out to be a cheap job, just 2 seals, a gasket and some grease required.
Thought I would just finish off this thread by saying that after careful inspection of the bearings and gears I decided I could re-use them all and the bushings. As I had already found, the box was easily adjusted to the correct figures and was very smooth in operation. Back in the car, the constant small adjustments to the steering, that I had previously needed in the straight ahead position, have now gone and all feels good. Most unusually for a Corvette, this even turned out to be a cheap job, just 2 seals, a gasket and some grease required.
You must have had the stars align!
Time to go play the lottery.
Pitman Shaft Bushes
