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My son and I have rebuilt the steering box/links, etc. on my 1959 Vette. I do have several questions I am hoping somebody may answer. Why is the worm/sector steering box designed so that there is no play when centered, but develops significant play at right and left extremes? I know this is normal, but does not seem logical.
We have the steering set so that the front tire immediately responds to turning the steering wheel slightly, but when we watch the linkage there is significant lost motion between the third arm and the third arm bracket--looks like from the bearing, which we replaced. When the steering wheel is turned one way the third arm raises a bit and when the wheel is turned in the opposite direction it falls a bit. Is this normal? It seems like removing the quick steering adaptor might reduce this problem.
I just want to optimize the steering before starting on another part of the project.
Thanks
I believe the high point steering gear design was a factor of the machining capabilities of the day....
And yes, if you remove the quick steering adapter, there will be less vertical motion at the tie rods, but it really points out that there should not be any noticeable vertical play in that bearing.......I would find another of better quality (if possible)....
Have you ever driven it with the quick steer adapter? I know some guys love it, but I can't imagine myself doing so........
Good luck,
Plasticman
Last edited by Plasticman; 08-17-2017 at 09:30 PM.
Ha ha ha Plasticman.. I removed my quick steering adapter sometime in 1980… Last week I had a customer complaining of how hard his car was to turn, and he too had the quick steering adapter. As far as handling, it’s great… but it makes the car so dang hard to turn without moving it’s like driving an old dump truck without power steering... I removed it for him and he's extremely happy with it being gone.
If you have rebuilt the gear box the high point is supposed to be on center and have less resistance as you travel the throw of the hour glass worm gear. One main issue is the reproduction steering worm gear wasn’t made correctly and the high spot is not on center. If you follow the GM instructions from the ST-12 Service manual (or the instructions that come with the gear set) and find center by turning left to right you won’t be on the high spot and then when you run in the lash it’s too tight and you cook the new sector bearing.
The reproduction gears are very usable and work great if you know this and why they don’t put something in the package that tells customer about this issue is a mystery to me.
Normally I’ve found the high spot to be anywhere from 1/2 to 3/4 turn off from true center. Don’t worry though, you can make this up on the pitman arm.
What you have to do is move the lash adjustment inward slightly until you find the high spot. Once you find the high spot, then (and mark your new shaft at this time) you do the pull test for the lash. I use a trigger pull tester to do this; some use a fish scale or the original GM tool.
I’m not sure if you’ve watched Joe Calcagno’s video, but I believe he shot this before the worm gears were made incorrectly. I spent the better part of an hour talking to him about this two years ago and you might give him a call too, he's a very nice guy and always willing to chat.
If you have not watched his video here is the link…
Thanks to both of you fine gentlemen. I may take off the quick steering adaptor, as I would guess it also adds to the stresses on the system.
Wilcox--Joe is really great. Followed his instructions. Also gave him a call and he is very gracious and full of knowledge. Fortunately, it appears as I have purchased a NOS sector roller and an excellent used worm gear shaft. I used the trigger pull scale like Joe said for adjustment after finding center bu going half way between right and left soft stops. Then I removed side cover and the sector was hitting the worm at center point.
Again, thanks guys. You are great.
Guys, I still have the QS adapter on my BB FI car and have no complaints on the steering. It too, is a 59. I'm 64 years young and can still turn the wheel. It's the bad knees and clutch pedal pressure that's starting to become an issue for me. Glad to hear that you got it worked out Larphred. Now get out and enjoy!!!
Regarding your third arm vertical movement, I discovered the same thing on mine years ago when I was trying to eliminate all lost movement in the system. The problem was that the bearing was not a press fit in the housing. The slightest bit of looseness at the bearing-housing interface translates into quite a bit of vertical movement at the end of the arm. you can look for a different housing which has an interference fit with the bearing or what I did was drill and tap 4 equally spaced set screw holes in the top of the housing so that the set screws bear straight down on the outer bearing race and presses it tight against the snap ring. This eliminated all of the vertical movement in the third arm. If you do this, seal the set screws holes with some silicone sealant when done to keep any water from migrating down into the bearing. Did mine about 15 years ago and still tight.
Regarding your third arm vertical movement, I discovered the same thing on mine years ago when I was trying to eliminate all lost movement in the system. The problem was that the bearing was not a press fit in the housing. The slightest bit of looseness at the bearing-housing interface translates into quite a bit of vertical movement at the end of the arm. you can look for a different housing which has an interference fit with the bearing or what I did was drill and tap 4 equally spaced set screw holes in the top of the housing so that the set screws bear straight down on the outer bearing race and presses it tight against the snap ring. This eliminated all of the vertical movement in the third arm. If you do this, seal the set screws holes with some silicone sealant when done to keep any water from migrating down into the bearing. Did mine about 15 years ago and still tight.
Klaus,
Great idea!
Do you remember what size set screws (I am thinking 1/4-20 should work)?
Could also use blue threadlocker to seal the set screw threads, and it would be a little better at preventing them from moving.
Plasticman
Last edited by Plasticman; 08-18-2017 at 04:06 PM.
Excellent feedback. Thank you all for your helpfulness. I will remove the bearing housing and check the fit. When I installed it I put the bearing in the freezer and the third arm bracket in the oven. Under those conditions the bearing just dropped in.
I think we'll remove the quick steering adaptor and see how that works.
I have been considering conversion to a hydraulic clutch later down the road, but haven't had time to research it yet.
Thanks again.
Why is the worm/sector steering box designed so that there is no play when centered, but develops significant play at right and left extremes? I know this is normal, but does not seem logical. Thanks
Here is my take on your question.
When you are traveling straight you do not want any play in the steering wheel to keep the car from wandering.
But when you are turning you do not want any 'binding' of the sector/worm which will make turning easier. The play, when off center, doesn't matter when turning.
Joe
On the green bean we restored a few years back, the third arm bearing housing was trashed. The bearing was being held in by three Allen screws... So we machined out the third arm bearing housing and make a zero clearance insert for it. Once we did this we pressed the original bearing in place and the movement was gone. If your third arm bearing housing is bad I can fix it.
On the green bean we restored a few years back, the third arm bearing housing was trashed. The bearing was being held in by three Allen screws... So we machined out the third arm bearing housing and make a zero clearance insert for it. Once we did this we pressed the original bearing in place and the movement was gone. If your third arm bearing housing is bad I can fix it.
Willcox
Thanks. We will pull thenbearing and mic. The housing. 😊😊
Do you remember what size set screws (I am thinking 1/4-20 should work)?
Could also use blue threadlocker to seal the set screw threads, and it would be a little better at preventing them from moving.
Plasticman
John;
Yes I used 1/2-20 set screws installed from the top, not the sides. I'm not a fan of sleeving the housing as it is a highly stressed part and machining and sleeving the housing will weaken it. Set screws from the top do not. The idea is to trap the bearing against the snap ring so that it always remains perpendicular to the bore and removes all clearance between the bearing and the snap ring.
I didn't take any pics when I did it but I have a bent one here somewhere that I can do the modification on to demonstrate. Will try to find it this weekend.
I performed the modification, on an old third arm I had, and took pictures to illustrate the procedure. Took me about 1 hour to perform.
Third arm with bearing removed.
Layout of drill template cut to fit bore diameter.. Hole centerlines 1/8" from edge of template and 90 deg. apart.
Center punch through layout pattern
pilot drill holes with 1/8" High speed steel drill.
Follow with #7 drill.
View of holes as drilled from top side of arm..
Tap holes from inside using 1/4-20 High speed steel tap. Suggest purchasing new tap for this procedure as this is a high strength steel forging.
Go slowly an back off tap and clean chips frequently. I've found Rapid Tap cutting fluid to be excellent for all drilling and tapping operations.
4 holes as tapped and after cleaning and deburring,.
Install 1/4-20 x 1/4 set screws with thread sealer from top side. Install bearing, stud, and snap-ring and then tighten setscrews to force bearing against snap ring. Finally seal tops of holes with RTV.
08-17-2017, 04:21 PM
C1 Corvette Steering Questions
