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fossyant
Ride It Like You Stole It!
- Location
- South Manchester
Are you ready for this, whack it with a hammer
In seriousness, first job is to get the cassette off, then see if the freehub will slide off, or needs a large allen key !
Get googling the DT Swiss service instructions,
If you get the freehub off, then get a bit of wood cut to just a bit bigger than the axel, and tap one side out, then pop axel back in and tap the other side out.
Fitting is a little trickier - use of an appropriate sized 'socket' can help fit them.
What are you looking to do - if bearings just need a 'regrease', pop the covers off with an pin. Did my MTB's hubs - my freehub came off easily.
In seriousness, first job is to get the cassette off, then see if the freehub will slide off, or needs a large allen key !
Get googling the DT Swiss service instructions,
If you get the freehub off, then get a bit of wood cut to just a bit bigger than the axel, and tap one side out, then pop axel back in and tap the other side out.
Fitting is a little trickier - use of an appropriate sized 'socket' can help fit them.
What are you looking to do - if bearings just need a 'regrease', pop the covers off with an pin. Did my MTB's hubs - my freehub came off easily.
I had heard about the 'whack with hammer' method, but didn't want to go at it without confirmation!
New bearings are necessary, so I need them out to measure what size to order.
Thanks
Edit: Which side is best to start from, or doesn't it matter?
New bearings are necessary, so I need them out to measure what size to order.
Thanks
Edit: Which side is best to start from, or doesn't it matter?
Yellow Saddle
Guru
- Location
- Loch side.
Yes, do do whack it but not with a steel hammer. Best is a copper hammer or a hard rawhide hammer or, heavy nylon hammer. A steel hammer damages the aluminium axle.
By examining the exit path of the bearings, you'll figure out which way to knock it out. I can't remember which side, even though I've done zillions of them. I haven't done it in five years and unless I have it in my hand, I can't say for sure anymore.
You don't need fancy anvils or wooden blocks either. Simply grip the wheel by the hub, through the spokes (make an eagle claw and grip the hub) with your left hand. Now whack it with the other hand. In other words, you're banging it against yourself, not an external support. That way the axle pops neatly into your open hand.
Another tip, no matter what type of metal hammer you use, don't tap tap tap tap. Give it one mighty wack. Tap tap tapping just peens the axle.
When you whack it, the axle moves through the bearings on the hammer side. The opposite bearings come out with the axle. The hammer-side bearings now have to be drifted out from the inside. Use a pin punch and judicial, oppossite-opposite taps (now you tap, not whack) to drift the bearing out.
Take careful note of the axle orientation (mark it beforehand) and note how the spacers are located.
It doesn't pay to regrease the bearings. Once the grease is depleted, the seals are worn out. Worn seals and depleted grease go hand in hand. The one cannot happen without the other.
By examining the exit path of the bearings, you'll figure out which way to knock it out. I can't remember which side, even though I've done zillions of them. I haven't done it in five years and unless I have it in my hand, I can't say for sure anymore.
You don't need fancy anvils or wooden blocks either. Simply grip the wheel by the hub, through the spokes (make an eagle claw and grip the hub) with your left hand. Now whack it with the other hand. In other words, you're banging it against yourself, not an external support. That way the axle pops neatly into your open hand.
Another tip, no matter what type of metal hammer you use, don't tap tap tap tap. Give it one mighty wack. Tap tap tapping just peens the axle.
When you whack it, the axle moves through the bearings on the hammer side. The opposite bearings come out with the axle. The hammer-side bearings now have to be drifted out from the inside. Use a pin punch and judicial, oppossite-opposite taps (now you tap, not whack) to drift the bearing out.
Take careful note of the axle orientation (mark it beforehand) and note how the spacers are located.
It doesn't pay to regrease the bearings. Once the grease is depleted, the seals are worn out. Worn seals and depleted grease go hand in hand. The one cannot happen without the other.
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Levo-Lon
Guru
It will look like this, the axle and bearings.
I made up a refitting tool with a long bolt washers and a nut..
You use the axle to remove the first bearing, tap from hub side after removal.
Use axle to tap out other.
Use the bolt washer press to install.
Or whatever you can knock up.
You must only apply force to the outer race.. Installation, use old bearing for this if you dont have a big washer etc
Hth
I made up a refitting tool with a long bolt washers and a nut..
You use the axle to remove the first bearing, tap from hub side after removal.
Use axle to tap out other.
Use the bolt washer press to install.
Or whatever you can knock up.
You must only apply force to the outer race.. Installation, use old bearing for this if you dont have a big washer etc
Hth
Last edited:
Thanks for that
robgul
Legendary Member
I had heard about the 'whack with hammer' method, but didn't want to go at it without confirmation!
New bearings are necessary, so I need them out to measure what size to order.
Thanks
Edit: Which side is best to start from, or doesn't it matter?
When you get the bearings out you should be able to read the product code or size either on the metal itself or the plastic seal ring. Kintetic Bearings is a good site to see the sizes and buy online - various qualities of the same size etc.
Rob
Thanks. I've used SKF in the past and they've been good as well.
I worked with bearings on a daily basis, all types and sizes. We would use SKF / NSK / FAG bearings, not worth using cheap bearings and as we were routinely getting 80%+ discount the difference in cost was not worth the potential hassle of premature failure.
It is worth paying a little more for " 2RS " bearings. It is a doddle to flip the shields out by hooking the tip of a fine blade between the metal inner and the rubber of the shield. They can easily be popped back in by pressing with a couple of fingers and wiping round the face of the seal.
You can then add any grease you prefer ( waterproof/ high / low temperature etc) .
Be very frugal if you do add your own grease, the amount fitted by the manufacturer often appears too little, but the most common cause of premature bearing failure is over greasing.
@Tenkaykev good info, thanks.
Yellow Saddle
Guru
- Location
- Loch side.
Industrial bearings tend to have too much grease for some applications on a bicycle and too little for others.
Freehub bearings need a minimum of grease because the drag caused by the grease is enough to make the freewheel not settle when not pedaling. Instead, it keeps on moving and throws the chain onto the chainstay and pulls the jockey backwards. Sometimes with unwanted consequences.
On suspension pivots, industrial bearings are not suitable because they don't have enough grease. These bearings don't rotate, but oscillate and are therefore robbed of their method of recirculating grease. An oscillating bearing quickly runs dry, causing dimples in the races. In theory, the Big 5 bearing companies can supply bearings with different greasing levels but in reality, their suppliers don't know about it. and will fob you off with whatever they have in stock.
One company that does know its onions in this department is Enduro.
Freehub bearings need a minimum of grease because the drag caused by the grease is enough to make the freewheel not settle when not pedaling. Instead, it keeps on moving and throws the chain onto the chainstay and pulls the jockey backwards. Sometimes with unwanted consequences.
On suspension pivots, industrial bearings are not suitable because they don't have enough grease. These bearings don't rotate, but oscillate and are therefore robbed of their method of recirculating grease. An oscillating bearing quickly runs dry, causing dimples in the races. In theory, the Big 5 bearing companies can supply bearings with different greasing levels but in reality, their suppliers don't know about it. and will fob you off with whatever they have in stock.
One company that does know its onions in this department is Enduro.
Yellow Saddle
Guru
- Location
- Loch side.
The way it was explained to me is that if there is too much grease the individual balls can't roll inside their cages as they are meant to and start to bind up. The bearing still rotate as the cage with the individual balls slides round between the inner and outer races, causing heat, the grease gradually gets less " greasy " causing more heat etc.
When I was working a colleague and I were called out to a breakdown at a local factory ( Ryvita )
There were several very old cast iron frame motors in one particular location. The one that they were concerned about was quite big, about from the floor to my knee in height and we could hear that the drive end bearing was knocking quite loudly.
After we'd isolated the supply and removed the drive belts and pulleys we took off the drive end endshield.
Imagine a big dish at least a couple of feet in diameter, that's what we had, but it was filled to the brim with grease, we were scooping out handfuls of the stuff.
The maintenance man would go around the plant every Friday and grease everything with a grease nipple. Over the course of years the grease built up eventually fill up the end shield.
As I was writing this I realised that my experience with bearings was in an Industrial setting, the bearings typically rotating at several thousand RPM and usually at high temperatures. I can't imagine that bike bearings would experience anything like this, and contamination through the ingress of water / crud would pose a much greater problem.
When I was working a colleague and I were called out to a breakdown at a local factory ( Ryvita )
There were several very old cast iron frame motors in one particular location. The one that they were concerned about was quite big, about from the floor to my knee in height and we could hear that the drive end bearing was knocking quite loudly.
After we'd isolated the supply and removed the drive belts and pulleys we took off the drive end endshield.
Imagine a big dish at least a couple of feet in diameter, that's what we had, but it was filled to the brim with grease, we were scooping out handfuls of the stuff.
The maintenance man would go around the plant every Friday and grease everything with a grease nipple. Over the course of years the grease built up eventually fill up the end shield.
As I was writing this I realised that my experience with bearings was in an Industrial setting, the bearings typically rotating at several thousand RPM and usually at high temperatures. I can't imagine that bike bearings would experience anything like this, and contamination through the ingress of water / crud would pose a much greater problem.
Yellow Saddle
Guru
- Location
- Loch side.
I think something else was at play in that biscuit machine of yours. Ball bearing mechanism isn't affected by size, they all roll on a film of grease and there's nothing I can think of about over filling that would cause a knock. A boundary layer of grease sticks tenaciously to the race and ball, no matter what the pressure there, and prevent steel-on-steel contact. MOre pressure will only increase the boundary layer rather than decrease it. Overfilling the cartridge cavity will have no effect on the rolling of the ball although it will increase drag in the bearing. The only problem with over filling is that it forces the grease out between the seal lip and race groove. Very quickly an equilibrium is found and no more grease will pump out. It is simply a waste of grease.
It is a pity I got rid of my bearing textbooks. But, I sold them for beer money. They are extremely expensive and fetch good prices on the second-hand market.
Have a look here: Link
Bearings are damn complex.
I still have an SKF (free) handbook on bearing failure in my book boxes. I'll dig that up this afternoon and see if there is anything in there about over filling.
