I have some play in the front wheel bearings on my '74 vette (right and left about the same). I've replaced the inner and outer wheel bearing set twice and still have the problem. The ball joints, although original, seem fine. If I overtighten the wheel bearings the play goes away. I suspect that the spindle on the knuckle is worn and the inner race of the inner bearing fits over the spindle too loosely. Is there a way I can determine if the knuckles are worn? Will it be evident with a visual inspection? What should the dimensions of these parts be? I'd like to confirm this before buying new knuckles and another set of bearings. Any input is appreciated.
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Re: 1974 front wheel bearings
Todd-----
First off, how do you know that the "looseness" which you describe is excessive. Front wheel bearings, when properly adjusted according to the procedure described in your Chevrolet Service Manual, SHOULD evidence a small amount of play or "looseness". When properly adjusted the end-play should be in the range of .001" and .006". The way this system is designed there is no way to control where in this range that your particular car is going to fall. That's because there are only so many positions in which to insert the nut retainer and cotter pin. So, if you fall at the high-limit spec, you will notice "considerable" looseness. But, that's how tapered roller bearings are supposed to be adjusted. The fact that the "looseness" disappears when you put the bearings into pre-load tells me that this is probably all that you're experiencing here. If the spindles were worn, the "looseness" would not disappear when you tightened the spindle nut beyond spec.
In any event, I do not have the spindle dimensional specs handy here. However, you really should not need them to further check for this problem. Simply install new bearings on the spindle bearing surfaces and check them for "play". The bearing inner race should fit over the spindle bearing surface snuggly, but not tightly. Most important, you should not be able to "rock" the inner race on the spindle bearing surface. If you can, then you probably have worn spindles and you will need to replace them or repair by having the spindle hard-chromed and re-machined.
Make sure that you follow the bearing adjustment procedure found in the Chevrolet Service Manual TO THE LETTER.In Appreciation of John Hinckley -
Blue printing wheel bearings
As Joe says, when properly adjusted the wheel bearing end play is in the range of .001"- .006". I've always found that having the wheel bearings on the tight end of the clearance range yields more precise on center steering. If you're on the high end, just take a couple or three thou off the washer by dressing it with a piece of 280 or so grit paper on a flat surface. It's best to have a mike to measure the thickness of the washer so you know how much to take off. It's also handy to have a dial indicator to measure the clearance, but I've learned to do it by "feel" by wobbling the tire. The final check is to see if I can turn the washer with my fingers. With .001" clearance, you should be just barely able to turn the washer with your fingers.
Duke
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Re: Blue printing wheel bearings
Duke-----
I think that you must have your Cosworth Vega "thinking cap" on or something. On a Corvette, the front wheel bearing washer is keyed to the groove on the spindle shaft and can't be rotated. I suppose that a non-keyed washer could be used, but I'd probably be reluctant to do so, myself. Although I've never really understood the rationale for it, I'm sure that GM had a very good reason for going through the trouble (and expense) of machining the groove in the spindles to retain the keyed washer.In Appreciation of John HinckleyComment
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Oops!
Actually, Joe, it was my "Mercedes hat" as I just snugged up the left front wheel bearing on the '88 190E in an attempt to exorcise a low amplitude high frequecy vibration in the steering wheel in the 37-43 MPH range. The left side was a little loose. Snugging it helped, but did not completely eliminate the vibration. The Merc has a spindle nut with a pinch bolt on it, so it's infinitesimally adjustable, and the washer isn't keyed. The Cosworth has the same arrangement as the Corvette. When I did the Cosworth I ground the washer until the nut snugged just past one of the twelve possible cotter key positions (cross-drilled spindle with six slots on the nut). It took a couple of fittings and wiggling the wheel (top to bottom) just produces and audible "click" but there was no perceptable movement. The steering really tightened up, and this procedure should work on any GM car with this wheel bearing retention arrangement. I actually haven't done this to the SWC as other resto activity has higher priority, but it will be part of my final chassis check.
DukeComment
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Re: 1974 front wheel bearings
I should have provided a little more detail. When I went to have the car aligned last summer, the mechanic thought the play was excessive. I had just replaced the bearings, so I told him that I still wanted the alignment done. I wanted to explore the bearing play regardless.
When I mentioned overtightening the bearing, I mean applying more torque to the nut than to just take up the play (in and out). If I tighten the nut gradually, I can feel the end-play (in and out) decrease to essentially zero. After this, I can alternately tug on the top & bottom (or left & right) of the tire and feel this play. I wish I could quantify this, but all I can say is I feel the motion. 0.010" to 0.020" at the outside diameter of the tire maybe?
I suspect that when I apply even more pressure that the inboard vertical side of the inner race is held in place by friction with the vertical edge of the knuckle. This is when my play disappears. The wheel does not turn very smoothly at this point, as you might imagine.
I also applied a "liquid shim" (loctite sleeve retainer product) to the inside on the inner race to attempt to take up the play. I was hoping to identify the problem this way. This did not work.
I will try just checking the fit of the inner races as you suggested. If I recall correctly, there may have been some rocking. If so, do you have any suggestions on who can do this "hard chrome/re-machine" job.
Thanks alot
ToddComment
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Re: 1974 front wheel bearings
Todd-----
As far as a source for hard chrome/re-machining goes, your best bet would be to check with a heavy duty truck or construction equipment repair shop in your area. Although they probably won't perform this operation themselves, they will be able to advise you as to who does it for them. This operation is common in heavy duty truck and construction equipment industry since some parts are very expensive and worth repairing in this manner. Usually, as far as automobiles go, such a repair is cost ineffective unless a required part is discontinued and/or otherwise difficult to obtain.
In that regards, the spindles for your car are still available from GM under part number GM #3953416. Currently, these spindles carry a GM list price of $189.07 each, but you should be able to purchase them from a competitive GM dealer for less than that----perhaps $140, or so. I doubt that you'll find the cost of the repair that I mentioned to be less than that, but it may be worth looking into, especially if you want to retain your original spindles. The hard chroming/re-machining will produce a repaired part as good or BETTER than the original. That's because the hard chromed surface will be more wear resistant than the original hardened steel surface.In Appreciation of John HinckleyComment
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Re: Blue printing wheel bearings
Joe, or Duke -- Many years ago, there used to be a product known as "Micro-Nut" (I believe) that gave nearly infinately adjustable positioning when used in place of the standard castellated nut. Provided quite precise adjustment of the play in the front spindles. Do these still exist?
New MachineryComment
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Re: Blue printing wheel bearings
"Ol' Geezer"-----
I've never seen them, but they might be out there. Actually, I'm sure that a self-locking "Nylock" type nut (if available in this odd-ball thread size) would work to provide infinitely adjustable bearing end play. It's just that without the cotter pin for "security", I'd be reluctant to use it.
Actually, the best solution would probably be a set of 6 wheel bearing washers which are surface ground in increments of stock thickness - .001", -.002", -.003", -.004, -.005", -.006". Using such washers you could set the end-play precisely to the low limit.
In fact, now that I think about it, I've got a friend with a surface grinder. I think, maybe, I'll finally just make myself up such a set. Actually, I've been thinking about doing this for years, but just never got around to it. 2 sets (one for each side) would be a lifetime supply.In Appreciation of John HinckleyComment
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Re: Blue printing wheel bearings
Actually, Joe, you can probably dial in the clearance by grinding your existing washers with a piece of 280 wet paper on the garage floor with mineral spirits in less time than it would take to drive down to and back from the grinder's shop. I believe the nut is 20 threads per in, so each half flat is about ,004". You can use how far you have to back off the nut to the next key slot as a guide. The clearance on the Merc is speced at .01 to .02 mm (.0004 to .0008"), so I bet you could run a GM car at as little as half a thou.Comment
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