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Putting in new bearings,


MTBmofo
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Any help would be appreciated, i have removed four bearings from my bike, i have sourced new bearings (correct size) from Bearing Man. Will i be able to put these back myself, or should i go to a bike shop? I don't have a bearing press, would i need one?

 

Thank!

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Any help would be appreciated, i have removed four bearings from my bike, i have sourced new bearings (correct size) from Bearing Man. Will i be able to put these back myself, or should i go to a bike shop? I don't have a bearing press, would i need one?

 

Thank!

 

You don't need a bearing press. However, you need to learn a new skill.

 

The easiest way to insert a new bearing is by using a pin punch - a 5mm pin punch should do, and a ball-peen hammer.

 

However, you need to learn how to hold the punch and place its tip (at an angle pointing the hammer end of the punch away from the wheel centre) and where to place it (only on the outside race).

 

Then you need to learn how to listen to the bearing as you drift it in.

 

Some rules:

 

1) Never smack any one position more than once.

2) Work only on two opposite ends of the bearing race.

3) Listen to the change in sound as the bearing reaches its seat.

4) Never hit the inner race.

 

If you are in Jhb, I'll gladly show you how. It is a very useful skill but it isn't intuitive.

 

Edit: I just saw you reside in another planet, not Jhb. Maybe one of the okes from one of my Cape Town courses can help you.

Edited by Johan Bornman
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I use a socket that fits onto the outer race(well actually just a tad smaller than the diameter of the race) of the bearing to wack it in.

Edited by Goodbadugly
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Thanks for the advice, it is for the suspension, where the suspension meets the frame, not sure if that makes any difference. But from What Johan says, it seems as if that would apply to inserting all bearings. I'm buying the bearings tomorrow and will try this then.

 

Thanks again for the tips.

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The 'socket' idea sounds like a winner! This is how i assumed the pros do it. (Then again i learnt a long time ago not to assume much!)

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A socket makes a good drift (a drift is something that you use to press something in, like a bearing) but.... on miniature bearings like those used on bikes, they seldom work.

 

Firstly, you are limited in their sizes. A good drift will not touch the seal and only contact the outer race. The chance that you find a socket that fits the bill is slim. Secondly, sockets are usually not flat-faced but the faces are champhered at both the inner and outer edge. This often causes it to miss the outer race and press onto the seal.

 

Secondly, a drift requires equal skill to hammer in. If your hammer is hammering off-centre, you have problems. With a punch you can spot the skew entry quicker.

 

But...whatever floats your boat.

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Thanks again for the advice Johan, i'll use a pin punch (if i can find one).

 

but i think you mean what ever floats you 'float'.

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Copper paste is your friend!!!!

 

Helps glide the bearing in smoothly as well as taking it out later if you need.

 

3 tubs you should always have close - Deep heat, Lube, Copper paste!

 

Foot note - they are NOT interchangeable!

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If space permits, try placing the old bearing on top of the new, and gently striking the old/top one with hammer. Seems the external ring/shell of the old bearing puts even pressure on the new bearing's external ring/shell without touching the seal. Just don't knock the old bearing in too deep or it might get stuck.

 

Also try cooling (i.e. stick it in the freezer for 20mins) the bearing and/or heating the receiving component (not if painted finish). Worked for me over the weekend when replacing cartridge bearings on an old square taper White Industries Ti bb.

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Is there anything as a cheap bearing press? Ive heard of using a drill press but im not convinced

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If space permits, try placing the old bearing on top of the new, and gently striking the old/top one with hammer. Seems the external ring/shell of the old bearing puts even pressure on the new bearing's external ring/shell without touching the seal. Just don't knock the old bearing in too deep or it might get stuck.

 

Also try cooling (i.e. stick it in the freezer for 20mins) the bearing and/or heating the receiving component (not if painted finish). Worked for me over the weekend when replacing cartridge bearings on an old square taper White Industries Ti bb.

 

No, don't do that. The old bearing will press on the new one's inner race and damage the balls. However, if you could butcher the old bearing, remove the inner race and balls, then you have a plan.

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I normally use the old bearing as a drift in a bearing press , but make sure that the drift bearing does not go to far in as you wont get it out ( if that is the case then use a socket as a drift ). Make sure it is only touching the outside race and that you push it in square.

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No, don't do that. The old bearing will press on the new one's inner race and damage the balls. However, if you could butcher the old bearing, remove the inner race and balls, then you have a plan.

 

i have put in thousands of bearing this way from bikes to Cat diesel engines with out ever having a problem , if you do it right and straight then you fine.

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No, don't do that. The old bearing will press on the new one's inner race and damage the balls. However, if you could butcher the old bearing, remove the inner race and balls, then you have a plan.

Thanks JB. Luckily for me the old bearings were opened and stripped. Will remember this in future though.

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i have put in thousands of bearing this way from bikes to Cat diesel engines with out ever having a problem , if you do it right and straight then you fine.

In that case, you've ruined or damaged hundreds of bearings without noticing. Deep-groove bearings don't take kindly to side forces on the inner race. Draw yourself a diagram of a cut-through of a deep groove bearing and see what effect it has when you apply pressure to the inner race whist restraining the outer race.

 

It is quite easy to demonstrate as well. Do as you say and turn the inner race with your finger. 3 times out of ten you'll feel a notchiness from the operation.

 

This type of mistake is very common in the bike industry where mechanics use the axle as a drift. The practice is to reverse the axle (if it has a bearing seat on it) and knock the bearing in with that. Most of them don't know what they've just done.

 

This is the reason that the drifts in a bearing press will have a cut-out to avoid pressing on the inner race.

 

And as someone pointed out, if you use the old bearing as a drift, it invariably sticks in the hole in anyway, bringing with it a new problem.

 

Just cause it seems to work doesn't make it best practice.

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