|
Sponsored Links (Register now to hide all advertisements) |
|
|
Thread Tools | Display Modes |
03-01-2024, 11:46 PM | #1 |
Member
Join Date: Nov 2018
Location: Kansas City
Posts: 64
|
Rear Hub Wobble/Drum turning?
So I was going to turn some new cast drums on rear hubs to true them. While apart I quickly checked them on a lathe for excessive hub warpage but didn't detect any(using an old axle taper). After swaging the drums on, one has a wobble(about .015"). Checked a third hub with old drum and it was fine.
I was indexing off the hub bearing race/rear hub(with bearings removed) and a small cone on the outer, small end. it's one of the new drums that wobbles(measured at the face about where wheel touches). When indexed off the taper using the same small outer cone, it's pretty darned true for turning as are the others using the bearing race and small cone. To me, the issue is the bearing is what the unit will use when on the car but the axle taper will then be off and the current drum wobble will remain. Truing the drum by indexing off the taper would fix the wobble but the drum would then not be concentric to the bearing. Hope this makes sense as it took me a while to trouble shoot. Have you guys seen bad rear hubs where the taper and the bearing race are machined not concentric? |
03-02-2024, 10:22 AM | #2 |
Senior Member
Join Date: Jun 2015
Location: Red Deer, Alberta
Posts: 5,057
|
Re: Rear Hub Wobble/Drum turning?
Is the "hub bearing race/rear hub" within spec? Old hubs are typically worn.
__________________
If you don't hear a rumor by 10 AM, start one!. Got my education out behind the barn! |
Sponsored Links (Register now to hide all advertisements) |
|
03-02-2024, 11:05 AM | #3 | |
Senior Member
Join Date: May 2010
Location: Eastern Tennessee
Posts: 11,537
|
Re: Rear Hub Wobble/Drum turning?
Quote:
When the hub was manufactured, there was a reamer that brought the taper and the bearing race to final size as a simultaneous op. This would have ensured they were in alignment. Think about this. When new, if the hub race and axle taper had been out of alignment, it would have broken the axle due to the constant flexing since the weight of the vehicle would have been on the bearing and the axle shaft was floating. FWIW, I have an aluminum plug that I made that I insert into the hub bearing race area. Then with my finger plugging the axle nut end, I quickly pull the plug out while listening for a vacuum 'popping' noise. If it doesn't 'pop', then I know that hub bearing race area is excessively worn and not worth reusing. Many hubs are worn beyond their serviceable life. |
|
03-02-2024, 05:26 PM | #4 |
Member
Join Date: Nov 2018
Location: Kansas City
Posts: 64
|
Re: Rear Hub Wobble/Drum turning?
I'll have to look again. It didn't appear too worn but nothing I own is beautiful and much of it is worn out old stuff("ran when parked" type stuff). I think one was off a spare rear and one was off a running car. I wanted them to match, early vs late style. I tended to choose the matching hubs that exhibited the least amount of taper wear and thus fit further out on the axle.
What you guys say makes sense. I need to explore why it runs without wobbling on the taper but wobbles when on the bearing(that slight chamfer). I suppose either one or the other surface is damaged/worn. I just might have fallen for the vary assumptions/issues I tend to rant about. Thanks for the ideas. Dave |
03-03-2024, 01:30 PM | #5 |
Senior Member
Join Date: Jun 2010
Location: San Antonio, Texas
Posts: 16,466
|
Re: Rear Hub Wobble/Drum turning?
I true wire wheels for the Harley Davidson motorcycles. I shoot for .010" rim bead side clearance and get it with quality OEM parts. Aftermarket rims not so much. OEM specs were 1/32" or .032". I can get the Aftermarket rims to within that spec but just. I mount a tire and install them and they go down the road fine.
A lot boils down to the drum lathe when truing a brake drum. The bearing, the journal, and the hub inner race may have an issue with any one item and get some wobble or eccentricity from it. The taper really doesn't affect that all that much since the axles float and flex. I'm not saying the tapers aren't important but they should be good enough to function properly or better parts should be sourced for replacements and same with the hub bearing components. Worn parts wear on the good ones so get the best you can. |
03-04-2024, 01:07 PM | #6 |
Member
Join Date: Nov 2018
Location: Kansas City
Posts: 64
|
Re: Rear Hub Wobble/Drum turning?
Sponsored Links (Register now to hide all advertisements)
I am using a DIY jig similar to what Vince Falter shows (https://www.fordgarage.com/pages/swaging.htm) and a 32 ton air over hyd jack in a 20 ton frame. This was my first time so I'll need to get better but not sure how to get that hub to hug the drum while in the press. Dave Last edited by dmar836; 03-04-2024 at 01:46 PM. |
03-04-2024, 06:08 PM | #7 |
Member
Join Date: Nov 2018
Location: Kansas City
Posts: 64
|
Re: Rear Hub Wobble/Drum turning?
Interesting. I mounted the offending drum/hub on a wheel - in this case a '32 wheel and torqued the nuts to 50ft/lbs. The gaps drew up with no measurable gap between hub and drum. They are clearly not "loose" as the sheared part of the shoulder is 3/32"+ and sits below the face of the drum.
I am actually growing confident to add nuts and washers and go ahead and true the drums. I know some say they tack their studs to the hubs and run the drums as slide-on style but I do not agree with that at all. That's not how the engineers did it. I digress. Any thoughts? Dave |
|
|
Sponsored Links (Register now to hide all advertisements) |
|