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-   -   How to reasemble rear hub.... need help (http://forums.pelicanparts.com/porsche-911-technical-forum/296002-how-reasemble-rear-hub-need-help.html)

herman maire 07-29-2006 03:04 PM

How to reasemble rear hub.... need help
 
Guys I could really use some help here before I loose my Mind:mad: :mad:

I am trying to reassemle my rear trailing arms after taking them apart (they are off the car)

I left the bearing installed and I am now trying to get my hub back in..... I started with a beautiful fresh zink hub and now it looks like s%$&....Sucks big time

I heated the hub and expected everything to just slide in.... I couldnt be more wrong.

Apreciate any responses.....

I will get a few pics to explain,

Thanks

Jim Sims 07-29-2006 03:20 PM

Heat things on the outside (hot air gun), cool things on the inside such as the hub (night in the freezer). Pull hub in through bearings by tightening nut. Do not pound in as this will ruin the bearings.

john walker's workshop 07-29-2006 03:21 PM

put the e brake stuff on first, along with the retainer plate. the tool to install the hub is basically a big fat all-thread, thick washers and a couple of nuts. cool the hub, or leave it room temp. tap it into the outer bearing race a bit and spin it to be sure it's going in straight. the main thing is to keep the inner bearing race from being pushed out while the hub is being pulled through it. that's what the fat, wide washers are for. hold the nut on one side and crank on the other. some lube helps both on the threads and on the hub.

goldgunner 07-29-2006 06:43 PM

If you took the hub out you probably have ruined the bearings.
You'll probably need to remove the bearings and the race that remained on the hub.

herman maire 07-29-2006 07:15 PM

Thanks for your help guys. I will get pics in the morning .... I had to get away from that thing for a few hours.

Quick question....I dont know if this is normal but the part of the bearing that the hub spins on, with a light tab in the middle (joint) they pop out...

Should I put those (bearing race) in the freezer or the Hub overnight?



Jim sims- wouldnt the hub expand in the freezer or am I thinking of water freezing?

Thanks again

CBRacerX 07-29-2006 07:29 PM

Metal shrinks when cold, expands when hot.

Zeke 07-29-2006 07:31 PM

Metal gets smaller when cold, expands when hot. Ice exapnds becasue of trapped air.

The other thing you said about the "part of the bearing that the hub spins on" is what is damaged now that the hub is out. The bearing needs to stay whole. It's done, stick a fork in it.

He heh, Chris and I typed almost the same words at the same time.

Jim Sims 07-29-2006 08:03 PM

Water and printing type alloy are the only compounds I can immedately think of, that expand when they freeze or solidify. Almost all engineering metals shrink when they are cooled and expand when heated. I agree that the bearing is typically ruined when the hub is removed.

CBRacerX 07-29-2006 08:08 PM

I've done this the DIY way and the "pro" way with a tool (not cheap, but I got it). either way works, but the DIY way is more difficult and nerve wracking. Get new bearing, install after freezing for a day. Then let sit for a day and freeze the hub. Rush out with the hub and install, using long bolts and washers to draw the hub into the bearing. Whew!

herman maire 07-30-2006 05:50 PM

Thanks a bunch guys for your help and suggestions.....

I am kinda bummed about the diagnosis for my bearings being wrecked I thought it was normal for them to seperate.

My initial attempt I was heating the hub and leaving the bearing cold... what a fuch up ...Complete opossite of what I should have been doing .


2 other questions-

-Do the 74-up rear bearing fit my 73 ? Is there any point getting the later 74 bearing? pelican shows a different part# for 73 and 74-up, the 74 bearing is cheaper also.

-Last question...Since my trailing arms are off the car would pressing in the bearing be a eazy job for a machine shop or do I really need the gear you guys are talking about.

Thanks again for taking the time to help me out.

Jim Sims 07-30-2006 06:50 PM

The rear suspension arms ("banana arms") through 1973 were fabricated from steel and were made from aluminum alloy in 1974 and afterward. I suspect the ball bearings are therefore different and hence different bearing numbers. I know the 1973 ball bearing number fits the 1973 arm - I've replaced them in a 1973. The bearing has to be pressed out of the arm using either a special tool or with a hydraulic shop press. One has to press or load through the inner race and this tends to jam the ball bearings into the races damaging them (brinneling them) hence removal is a destructive process. The new bearing is pressed into the arm using a pusher rod or cylinder that only loads the external race (so one doesn't brinnel the races). The steel arm is also heated to 250F prior to pressing in the bearing to make more clearance. I had a round bar of aluminum turned to fit and only load the outer race of the bearings. The arms were off the car so I used a 20-ton hydraulic shop press and the turned bar to install the bearings. The other retainer and trapped brake parts are installed and then the chilled hubs are pulled through the inner races as described above.

herman maire 07-30-2006 07:10 PM

Jim,
Do you think with a shop press I could get away without heating the arm to 250F? I ask because....I just painted the darn things but if its the only way I guess I will have to

Thanks

Jim Sims 07-30-2006 07:45 PM

Probably you could by chilling the bearing and only heating the arm to 120F. What kind of paint did you use? 250F isn't that hot - heat with a hot air gun and handle by the unpainted portions.


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