Holding hub stationary for bearing replacement


#1

Working on the front hub of a '87 Porsche 944. The hub needs to be held stationary in order to replace the races and bearings. In particular the hub will be hot and the race cold, to aid in fitting them, so I think speed and stability are important factors.

What ways can the hub be held to do this that is better than simply squeezing naked vise jaws on either side, or even soft-jaw pads or wrapping it with something? I imagine a jig could be manufactured that the wheel studs bolt into, and I also imagine there could be vise adapters that squeeze a ring around the hub as the vise tightens, but these might be stupid ideas for all I know.

UPDATE : though I appreciate debate of hot/cold or room-temp parts, the essence of the question is how to hold the hub in the vise.


#2

I would not heat the hub unless absolutely necessary. I have replaced many bearing races with out heat. I pretty much just used a piece of 2x12 on the floor, put the hub on the board, and used the right size bearing/race driver.


#3

If the interference of the fit is so extreme as to require chilling the race and heating the hub attempting to force the fit otherwise will damage one or both pieces. My greatest experience with such a tight fit is on flywheel starter rings and chilling the flywheel greatly reduces the heat needed on the ring to get it to drop into place. The races are small enough that chilling should be no problem. If the races are left overnight in the freezer(0F) and the hubs warmed in an over to 300 prior to assembly a race driver should easily get the job done. But I can’t imagine the need for such a tight fit on a hub race… I would suggest checking some Porsche enthusiasts forums before getting out the hammer.


#4

I have to agree with @PvtPublic on this

I have replaced tapered roller bearings and their races, and I didn’t heat anything up

I’d hate for somebody to get burnt doing this repair


#5

Maybe this will help

http://www.924board.org/viewtopic.php?t=35149


#6

I wouldn’t want to eat anything cooked in that oven after the hub got heated in there . . .


#7

Possible alternative to using an oven is to heat up a pan of transmission fluid on a camp stove and put the hub in that. I have done that to Toyota rear axle bearing retainers as recommended in the FSM. Not sure you can get it to 450 though, I think the bearing retainers were heated to about 350 as I recall, maybe a little lower. Not sure ATF will go to 450, but some synthetic oils will.


#8

I usually appreciate off-topic comments as they broaden discussion.

however, heating the hub and chilling the race are what the shop manual states in this case. Some say they can skip the chilling, some use different methods.

notwithstanding, the question is about holding the hub in the vise.


#9

Why do you need to hold it in a vise, just set it on the bench.


#10

@keith wrote “Why do you need to hold it in a vise,…”

because I want to get a vise (I don’t have one) - ha ha.

but seriously, I have held things with my feet enough to know I don’t want to do it anymore if I can help it, especially with important things, and given my limited working conditions.

… HOWEVER, since there’s not a single mention of some contraption, it seems such a thing really is in my imagination only!


#11

How did you remove the old bearing races from the hub?

Tester


#12

OK, if you want to do something, take a piece of 2x6 or 2x8, set the hub on top, studs down and give it a light tap with a rubber hammer. Then drill 1/2 holes, 3/4" deep where each stud made a mark. If you don’t want to hit the hub, then put a little grease on the end of each one.

Measure the diameter of the smallest protruding section on the other side and get a spade drill bit or hole saw that size and cut a shallow hole in the center of the stud hole pattern. Now nail or clamp the board to a table and your all set.

Find another project to do for an excuse to get a vise.

You can make a lot of useful jigs and tools out of scrap wood and misc hardware if you want. I recently made a tool to hold the harmonic balance while removing the crankshaft nut for a Toyota out of a scrap 1x4. It worked and was a lot cheaper than the recommended tool.


#13

@Tester didn’t do it yet - all in theory now - however, I think they get brass-punched out. Not sure.

@keith cool - I know jigs are handy, however, the fundamental problem is what it attaches to. Theres a nice oak in my yard…


#14

A wheel with the same lug pattern makes a good bench top rest for such work.


#15

@Rod_Knox brilliant!

how do I put spaces in the user name when using the @ command?


#16

Call me anything, @JuniorMint. Just don’t be late when you call me to dinner.


#17

The only thing that I will add is that I’ve often had better luck applying cold to something rather than heat.
All depending on the procedure, I’ve frozen parts in the freezer or hit them (very carefully) with a shot of A/C refrigerant to shrink the part being removed or installed.


#18

You don’t need a brass punch to remove the old races. If you’re replacing them it doesn’t matter if they’re damaged using a steel punch or anything else made of steel.

To install the races you can get them started in their bores by using a plastic head hammer, and them finish seating them in their bores using a brass punch. Or you can use something like this.

http://www.harborfreight.com/10-piece-bearing-race-and-seal-driver-set-95853.html

You can’t buy a good vise for that price.

Tester