Opps Gearbox bearings to hot...

[lebochet9]

So I'm now trying to put the 5 speed box back together. Got myself a set of new bearings and tried to fit them. Lacking a suitable press, I had a good idea: Shaft in the freezer, bearings in the oven @250C. Still too tight for the layshaft, so I heated them further on the gas hob. Except, I think I got them too hot, and now a couple of the needles have a nice blue colour (Like I rmeber motorbike exhausts used to go...) and some an equally nice straw colour.

Question is: Is this serious damage, meaning I should throw these away and start again? I seem to remember some metalurgy classes a long time ago, where this was called annealing and will have made the metal softer...

Any informed opinions?

1980 DHC TR7-V8 (was an 8V, then a Sprint)
Back on the road after 3 years restoring...

[Odd]

You've fried them. I wouldn't use them in a gearbox I was rebuilding
- but I'm kind of an anorak in matters like this...
/Odd

[Rayjones]

You will need to replace these bearings without a doubt, the fact that they have changed colour indicates that the hardening/tempering process has changed. Not worth the risk!

Ray

1980 UK BRG 2L DHC

[john 215]

Hi,
Sorry Lebochet [:(] way to hot for a bearing would'nt risk it myself, At work we quite often have lads and the odd lass come in and ask for this or that to be pushed on or off,will normaly do at dinner time when boss not around as a favour or at the most the price of a drink or 6 [;)] . Worth asking at local garage or engineering shop you never know [?]
Cheers John

LIVE LIFE A QUARTER OF A MILE AT A TIME!
1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6 WILL BE ON THE ROAD VERY SOON!
Read My Blog http://www.waringstowntr7s.co.uk/blogs/ ... hp/John215

[flynns tr 7]

If they have gone blue you have now destroyed the case hardening bearings are now scrap.

[Underdog]

I agree that they are now junk. I'm not sure which brg you speak of. I have rebuilt three of these boxes and don't recall useing a press. From memory, I was able to use a suitable size pipe or socket and a hammer to drive them home. It needs to be of the correct size as to only apply force to the inner race. Perhaps not the most elegant way of doing it but it has worked for me.

72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

[lebochet9]

[:(][:(] Thanks for the input. I think deep down I thought as much. There is nothing like the joy of chucking $100 down the drain!! Still, better than getting it all back together then having to pull the box out again...

Got flashed by a Radar on the motorway yesterday, so thats more money wasted.....its been a bad week....[B)]

1980 DHC TR7-V8 (was an 8V, then a Sprint)
Back on the road after 3 years restoring...