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Excessive stubshaft endplay w/ new bearings?


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As the title says I just replaced by wheel bearings because the left sides felt a little loose. Even with new bearings the left rear stub shaft would not build proper preload to ever achieve the spec force to spin it. The right worked fine and was good at about 200 ft-lb. Spec says start at 180 ft-lb and go up to as high as 250 or until you get a certain pull force to spin the shaft. On the left I went to 250 ft-lb and the force never changed and there is still excessive play similar to the old bearings. Spec says 0.0057" end play and I'm between 0.008 and 0.009" and you can feel it when you try to rock the wheel back and forth. So any ideas what could be wrong? I used good quality Timkin (spel?) bearings.

 

Thanks

Cameron

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Already tried adding a shim in there. The right (good) side already had a copper looking shim and after the left would not preload I had a shim sitting around so tried it. The shim made no difference. Maybe two shims?

 

Cameron

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It sounds to me like the spacer is too long. Does the spacer match the spindle?

 

You could try another spacer or have that one shortened. Problem is, how much? Maybe 0.010" at a time.

 

jt

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I was wondering the same thing. If the spacer is too short, your preload should come in too soon (before a safe amount of torque has been placed on the nut). If the spacer is too long, then the outer race has not been set against the shoulder (which causes the preload as the nut causes the inner race) to set preload against a fixed outer race, resulting in no significant preloading. Does this sound reasonable?

 

With that said, if you could get a shim that would sit between the outer bearing race and the bearing shoulder (effectively spacing the bearing outward), this then provides the same effect as shortening the OEM bearing spacer if indeed it is too long. Did you verify the boss and the spacer have the same letter stamp?

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You guys are right, my shim suggestion is the wrong solution. As stated, check the letter stamped on the outside of the hub and the letter stamped on the "disnace peice" (spacer) between the bearings. They must match (A to A, B to B, C to C).

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Those copper washers are washers, not spacers. They are supposed to go under the stub axle nut. Zcarnut has posted about them before: http://forums.hybridz.org/showthread.php?p=546309#post546309. I'd remove them entirely.

 

As these are ball bearings, you really don't want a lot of preload on them. Changing the torque on the nut in theory should not change the preload, as there is no mechanism for changing the torque to shorten the distance between the inner bearing and the outer bearing. You'd need thousands of pounds of torque to crush that spacer. I know John and I have disagreed on this issue before and the FSM seems to support him, but I just don't see how changing the torque affects the preload at all (once things are tight).

 

You obviously don't want excessive endplay either. I would not take .010" off of the spacer. I'd start with .001 or .002 and work your way up. The one issue I can see is damaging the hub taking the stub axle in and out to get everything fitted up correctly.

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but I just don't see how changing the torque affects the preload at all (once things are tight).

 

You're right in that once things are tight, additional torque won't change things. But what's "tight"? There are 9 parts in this assembly: hub, two bearings, spacer, companion flange, stub axle, nut, and washer. Bearings are being pulled into their seats in the hub, the spacer is being loaded, a washer and the new stub axle nut are being tightened together for the first time, the stub axle is being stretched, etc. It may take 180 ft. lbs. to make things tight in one assembly and 240 ft. lbs. in another.

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You're right in that once things are tight, additional torque won't change things. But what's "tight"? There are 9 parts in this assembly: hub, two bearings, spacer, companion flange, stub axle, nut, and washer. Bearings are being pulled into their seats in the hub, the spacer is being loaded, a washer and the new stub axle nut are being tightened together for the first time, the stub axle is being stretched, etc. It may take 180 ft. lbs. to make things tight in one assembly and 240 ft. lbs. in another.

OK, that sounds reasonable to me.

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  • 5 weeks later...

OK this is an exercise in extreme frustration!!! Could not find the mark on the upright. Took it apart and the spacer is a 'B'. My thinking is the spacer is too long. If is't way too long it would still tighten up but then you could risk the outer race walking out - not good because then it would loosen up over time. If it's a little long which is what I have then the bearings will not get preloaded and it will be sloppy. Anyway so I ground a bit off the end and it tightened up a little. So I'm thinking I'm getting somewhere so I ground a little bit more off and then it's WAYY tight. Dammit. I cannot believe how sensitive it is. I'm taking it real easy with a 12" disk sander so I didn't take much off at all. So I added a shim but it's too thick. Now I'm working on grinding the spacer down some more to make the shim work. This is just temporary to hopefully get me through an autox tomorrow. I really need the next shorter spacer from a "B". Anyone have one I can buy or know where I can get one?

 

Thanks

Cameron

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I don't have it with me, but the specific length of the spacers, A - B -C, are in the FSM. I would pit it in an end mill and have it reduced it to the exact length. No point in eyeballing it imho. As to where to find one... well you should probably first find that letter on the strut. The B spacer and strut combos are pretty common from what I have read. You might have to go yard to yard to find it. I can't exactly remember where it is myself, but you should be able to find it if you clean the strut. It is somewhere on the "barrel" that houses the stub.

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  • 5 years later...

I am having the exact same problem with  left  rear wheel bearing free play.   I thought replacing the bearings would fix the problem, but the left stub axle still has latteral slop.  That is, grabbing the stub axle flnage at 1 o'clock and 7 o'clock I can rock the flange while pushing at 1 o'clock and pulling at 7 o'clock.

 

I measured the "B"  spacer and it is within spec per the FSM.

Edited by Miles
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