loggyboy
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| posted on 28/8/13 at 11:28 AM |
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The freezing alone trick didnt work, they must not have shrunk by much, if at all, in my domestic freezer. Didnt try the heating. at the mo ive
tapped them in a mm or 2, stopped going further till i decide to continue hammering, remove and try heat for hubs AND freezing of shells, or to take
them to my mates garage and press them.
I found the rear steels ones very easy (see the build thread update).
The old ones came out with a drift and hammer, and the new ones when it with a small hammering to get them started and pressed them the rest of the
way with a vice.
I think alot depends on the type of bearing. Tapered go in easier as you only have to be rough with the shell.
Mistral Motorsport
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Mr Whippy
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| posted on 28/8/13 at 12:02 PM |
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So are the bearings in yet????
Freezing the steel is a waste of time anyway unless you have liquid nitrogen at hand as they shrink a tiny amount. Heating the hubs up in the oven is
the correct way as the aluminium expands a lot. The shell would then just drop in.
Can't believe how many comments there were about the mysterious if not mystical changing of the metals property in a domestic oven, seriously
it's just a car wheel hub
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Litemoth
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| posted on 28/8/13 at 02:14 PM |
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Press them in.
As I said, heating and cooling will often stress-relieve bearings (especially cheap Chinese ones). Bearings are ground to microns (0.001mm) accuracy
and any upset (thermal or impact shock) will cause them to change shape and fail sooner than necessary...as will bearing housings that are out of
shape or too tight.
There are stories that some of the alloy hubs being way out of tolerance though (often oversize)
Mine took about 3-4 Tonne to push into my alloy housing. A Fiesta rear (double bearing) I did recently took 10 tonne to push out and about 6 to push
back in (std road car with steel bearing housing)
Driving them in with a hammer and a drift wouldn't have been an option
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britishtrident
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| posted on 28/8/13 at 03:47 PM |
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quote:
Originally posted by Litemoth
Press them in.
As I said, heating and cooling will often stress-relieve bearings (especially cheap Chinese ones). Bearings are ground to microns (0.001mm) accuracy
and any upset (thermal or impact shock) will cause them to change shape and fail sooner than necessary...as will bearing housings that are out of
shape or too tight.
There are stories that some of the alloy hubs being way out of tolerance though (often oversize)
Mine took about 3-4 Tonne to push into my alloy housing. A Fiesta rear (double bearing) I did recently took 10 tonne to push out and about 6 to push
back in (std road car with steel bearing housing)
Driving them in with a hammer and a drift wouldn't have been an option
.
If you seriously think heating any steel to sub-200c temperatures will stress relieve or make any other difference to any steel you are pretty wide
of the mark For the types of steel used for bearings (istr 1% Carbon + 0.45% Mn + 1.4%Cr) once it has been heat treated hardening by quenching from
850c then tempered by reheating to a lower temperature and slow cooling nothing short of 500c will have any effect, the stress relief temperature
would be in the order of 650c held for along period.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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loggyboy
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| posted on 28/8/13 at 09:27 PM |
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All done, heated the hubs and they did almost fall in, just the lightest of persuasion. I didn't heat the bearings anyway, although the shells
would have had some heat transferred to them but I'm sure they will be fine.
Mistral Motorsport
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