Upper control arm shaft tolerance.
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Joined: Apr 2016
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Upper control arm shaft tolerance.
Got new rubber control arm bushings ‘moog. Slid them on the shaft for the fun of it and to my surprise it seem to have a lot of movement. I know when installed they’ll be torqued down. Is the play normal? Seems it should be at lease a slide fit. This is on the shaft only not installed.
Melting Slicks
Joined: Nov 2006
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From: Apple Valley, MN
Where did you get the bushings from? Does each bushing exhibit the same amount of “looseness” on each of the shaft ends?
These are mass-produced parts and there are, unfortunately, manufacturing variations. While not designed to be a “machined fit”, they should not flop around like a carp on a hot sidewalk. Any visible wear on the shafts? Post a pic of the shafts
These are mass-produced parts and there are, unfortunately, manufacturing variations. While not designed to be a “machined fit”, they should not flop around like a carp on a hot sidewalk. Any visible wear on the shafts? Post a pic of the shafts
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From: New Or-leens Loo-z-anna
Apparently different companies sell bushings with different size internal diameters. I tried my new bushings on the shaft ends...the bushings would not slide on unless I tapped them with a hammer....not a good thing.
The outer sleeve on each bushing was also much too tight which required machining .005" from the outer diameter to have a decent press-fit that would not damage/seize-up while being pressed into the holes in the control arms.
I had to machine .005" out of the inner sleeve on all the bushings to get a slip-fit with grease applied to the shaft ends. Then I was able to assemble the shaft/bushings
The outer sleeve on each bushing was also much too tight which required machining .005" from the outer diameter to have a decent press-fit that would not damage/seize-up while being pressed into the holes in the control arms.
I had to machine .005" out of the inner sleeve on all the bushings to get a slip-fit with grease applied to the shaft ends. Then I was able to assemble the shaft/bushings
Race Director
Joined: Apr 2011
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From: North of Toronto - Ontario
When I did mine a handful of years ago I checked the sizes of new moog and prothane bushings and had someone (I can't recall who) check a set of new shafts
Upper shaft .670-.676, moog bushings .683-.687, prothane .685-.689
Lower shaft .738-.742, moog bushings .755-.758, Prothane .754-.758
FWIW, I was using my original shafts and just knurled the bushing area so that it had a "snug" fit that you could rotate by hand with a bit of effort. The inner sleeve locks onto the shaft shoulder with the serrations but having the sleeve fit better isn't hurting
M
Upper shaft .670-.676, moog bushings .683-.687, prothane .685-.689
Lower shaft .738-.742, moog bushings .755-.758, Prothane .754-.758
FWIW, I was using my original shafts and just knurled the bushing area so that it had a "snug" fit that you could rotate by hand with a bit of effort. The inner sleeve locks onto the shaft shoulder with the serrations but having the sleeve fit better isn't hurting
M
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From: New Or-leens Loo-z-anna
And as the members taught me...when installing the assembled upper and lower arms on the car....
Do Not torque the shaft bolts until the car is sitting on the garage floor and the car has been rolled forward/backward several feet so the arms will settle into position.
THEN torque the bolts to specs. so the serrations "bite" into the shaft. *The bushings rubber will rip themselves apart in a few weeks if the shaft bolts are torqued before the car is sitting on it's own weight*
Do Not torque the shaft bolts until the car is sitting on the garage floor and the car has been rolled forward/backward several feet so the arms will settle into position.
THEN torque the bolts to specs. so the serrations "bite" into the shaft. *The bushings rubber will rip themselves apart in a few weeks if the shaft bolts are torqued before the car is sitting on it's own weight*
Le Mans Master
Joined: Jun 2019
Posts: 7,649
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From: Indiana
hmmmmm weird.. all the same ? too small rods? no difference in size?
here was my thread
A 79 control arm bushing saga using the Lars method - CorvetteForum - Chevrolet Corvette Forum Discussion
here was my thread
A 79 control arm bushing saga using the Lars method - CorvetteForum - Chevrolet Corvette Forum Discussion
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Joined: Apr 2016
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Well I going to order new shafts. I think the play is a little excessive too. I did use the caliper that I saw on the other post / good info and one side one shaft was a little different / small. That’s the one on the video. Don’t know why maybe factory defect. I’m sure if I hit a bump it could shift and eventually loosen. Hopefully I’ll get something a little tighter. Just trying for snug. Thank you all for the help.
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