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Front hub balance problem

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TR3driver

TR3driver

Great Pumpkin - R.I.P
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Arggh! I just spent most of an hour turning a tool on the lathe, only to find out I mis-read the calipers and worked to the wrong measurement!

Anyway, both of the apparently original front hubs/rotor assemblies on TS13571L are significantly out of balance. If you turn them 1/4 turn and release, they will turn back under their own imbalance. Not a big deal as I've got other hubs; but I'm curious as to how this happened.

Has anyone else found apparently undamaged hubs that are out of balance?

So far I've only checked the rotor runout on one of them, it's about .005" TIR. I'll check the hub face runout as soon as I finish that tool I mentioned (a longer shaft to mount the dial indicator to the magnetic base, so it can reach out to the face of the hub).
 
Randall, what was the problem you noted? Were you examining the wheel play, or were you noticing some issues while driving. What part were you shaving on the lathe?
 
Kentvillehound said:
Randall, what was the problem you noted? Were you examining the wheel play, or were you noticing some issues while driving.
Click to expand...
I originally noticed the balance problem while servicing the brakes; but it did seem that the car vibrated rather more at freeway speeds than it should. Not sure how much of that was due to hubs, since at that point I still had the old tires from the wrecked car and they were well past their "best before" date. But I swapped the front hubs from the wrecked car when I put the new tires on; and the vibration seemed to get better. Still seems high, though, plus other problems are apparent (the left front lug nuts have come loose twice now, once on the way to TRfest and once during the Fun Rallye @ TRfest), so clearly the hubs are not the only problem and may not have been a contributing factor at all. It's an ongoing process.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]What part were you shaving on the lathe?[/QUOTE]Perhaps the following photos will make it clearer.
DSCF0001_crop.jpg

Highspot.jpg

Lowspot.jpg

Note the rod that the dial indicator is mounted on; with the horrible surface finish.

Good thing there are no grades in my self-taught machining course, as that assignment would certainly earn an 'F'! I've already ordered a suitable sized rod (25/64" or .390") with a smooth finish from MMC (and hopefully learned something from the experience).
 
Andrew Mace said:
Is there any chance that whatever "imbalance" is primarily in the rotors and not the hubs themselves?
Click to expand...
Could be, but finding almost .010" runout at the hub face would seem to indicate some problem with the hubs.

At this point, I think I'm going to abandon this investigation for now, and concentrate on changing the damaged studs & wheel on the car.
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Has anyone else found apparently undamaged hubs that are out of balance?[/QUOTE]

I'm not sure I would have noticed. I've spent so much time over the years trying to keep the play out of front hubs (solved only with the "Uncle Jack" stub axle kit), that I've never given any thought to hubs' balance. I can't even imagine how to test that balance, other than spinning it on the car, and this seems a bit subjective.

By the way, I can't seem to load your photos.
 
I fouund the same imbalance on my 62 TR4. Have'nt yet investigated the cause.
 
Well, I pulled the LF hub & rotor from the car; it has even more runout at the hub face than the other one. Doesn't seem as badly out of balance, but of course I've not found a way to quantify it yet, beyond being bad enough to turn the bearing. Pulled the rotor off and the heavy side changed about 60 degrees, so the problem appears to mostly be the rotor.

Thought I had a NOS front hub, but it turned out to be a rear hub. Oh well!

Now I'm looking at another hub & rotor from the parts bin; runout at the hub face is only about .004" TIR, so I think I'll use it. Gonna try machining away a bit of the rotor edge to balance it and see what happens.
 
Can there be "hub" runout? I can understand rotor runout, but what could cause hub runout? Nothing rubs on it, right?

I'm sure I'm missing something. If so, sorry.
 
Kentvillehound said:
what could cause hub runout?
Click to expand...
I can think of several possibilities, but at this point I don't know which one(s) is correct:

1) Machined wrong at factory
2) Bent/damaged in use
3) Warped due to heat and/or old age
4) Defective (not centered) bearings
5) Burr or grit between a bearing race and hub bore.
6) Broken (cracked) bearing race.

#2 and #3 seem most likely to me, I guess, followed by #5.

Sorry about the photos, Perry. I resized them a bit smaller, but I doubt that is the problem. They show up for me in both IE and FireFox.
 
Any chance that it's the axle or associated parts that aren't as heavy construction as the hub or rotor.
 
ekamm said:
Any chance that it's the axle or associated parts that aren't as heavy construction as the hub or rotor.
Click to expand...
Nope. Front hubs: axle doesn't turn, so it can't be out of balance.

On the third hub & rotor (the one I'm going to try to correct the balance on), I spun it up until it shook the entire workbench. Seems to indicate that the balance problem is significant.
 
First, run-out, on the hub should be less than .001", preferrably less than .0005" , on the wheel face, and the rotor mounting face. I would look at making sure there is not a problem with the bearings, first. Then i would have the hub faces machined, before having the hub (only) balanced. Then put the rotor on and check the run out and balance again. If it went bad when you put on the rotor, i would send the rotor back or get a new one and try it again. The rotor should not have more than .001" runout on the outermost diameter.
Good luck
Rob
 
trfourtune said:
The rotor should not have more than .001" runout on the outermost diameter.
Click to expand...
Just for clarity, the factory spec is .004" for the rotor. If there was a spec given for the hub, I missed it.
 
yes, i know what the "factory" spec is. Do as you like. I'm just very picky.
R
 
No problem, Rob, just trying to be clear for others.

At this point, I've found a newer hub with less runout that I'm going to try on the car. Got the rotor down to about .002" as well; but now that I think about it, I may try taking just a wee bit more off the rotor's mounting surface on the low side, and see what that does to the balance. Besides, I meant to put some Loctite on the bolts, and I think I forgot it.
 
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