- Thread starter steveo3002
- Start date
normspanners
Member
- Messages
- 8,853
Yes pdg that is obviously correct
I was talking about my question in post 79 re
the comment that was made, that I was talking rubbish, in me stating that the slight extra torque applied to the hub nut would NOT damage the bearings in anyway, I said it would only damage the stub or the nut
I was asking a general question if anybody could explain HOW a bearing of the type in this thread COULD be damage with slightly over torquing the hub nut, when if a bearing is fitted on a shaft in a press they would normally be pressed together to 15-20 ton in the correct method that you explained to make sure they are seated and home and that force far outdoes the load imposed by the hub nut correctly torqued or even over torqued by the slight amount that the op was stating, the correct hub nut torque is just holding them together parallel and in seated position without spinning, and that figure is close to the fasteners correct torque for that size of nut/thread, (irrespective of it being a hub nut), the hub nut torque is not adjusting bearing load at all and all that over torqueing would achieve is to poss damage the stub or nut thread or the nuts inbuilt washer.
Steve please
as stated there is no need to over torque the nut, that is not going to achieve anything at all the correct torque is ALL that is required you need to check shaft and housing diameters as your first point of test. looking for any witness marks of any kind.
daedalusminos
Member
- Messages
- 2,250
- Location
- Norwich
Brakes binding leading to overheating, loss of lubricant?
Bill Edwards
Member
- Messages
- 4,959
- Location
- Scarborough, North Yorkshire
That's my adopted principle, though in practice you won't cause any problems with careful use of a press on the wrong part of a roller bearing - ball I'd be less happy about.
I have encountered bearing quite recently however where it simply wasn't possible to push on the correct part due to the overall design, made me cringe.
Question is, what do you do when a press is a tight fit in a housing and on a shaft at the same time...?
Seadog
Save the planet. It's the only one with rum!
- Messages
- 12,326
- Location
- NE London - UK
You use a flat faced tool that bears against both the inner and outer races. Relieved in the centre to clear the shaft if necessary.
Bill Edwards
Member
- Messages
- 4,959
- Location
- Scarborough, North Yorkshire
Yes, but even if there was a lathe at work the boss would whinge about the time taken to make the tool, given how much he whines about the time taken to do the job in the first place!
normspanners
Member
- Messages
- 8,853
Very unusual to have to do that in the case of wheel bearings though, more replacing bearings in a machine that has fixed shafts.
he would whinge even more if you damaged a new bearing or the machine itself though !!
Bill Edwards
Member
- Messages
- 4,959
- Location
- Scarborough, North Yorkshire
Yes farm stuff where I encounter two places it needs pushing on together, I can't recall having to do that on a wheel bearing (my memory isn't always great though!).
My boss is not known for having any grey matter whatsoever, so I'd say the chances of successfully justifying the need to spend precious time on such precautions are perhaps 40%
normspanners
Member
- Messages
- 8,853
Hum and 'WE' hope he isnt a member of a welding forum with a pseudonym either----- I believe.
not forgetting this is in a public domain !!
normspanners
Member
- Messages
- 8,853
A classic example of having to 'over torque' a wheel bearing was the MG METRO 6R4 we could NOT get the CV hub nuts to stay tight it was a constant battle, if and when they came loose, then the result would be damaged wheel bearings, they where being torqued to the 'manufacturers' setting but they would always slacken, so to combat this we worked out the 'MAX' that the fastener could stand, as a 10.9 bolt and nut, and used hard WASHERS also IIRC. The torque used was roughly DOUBLE the original setting something like 600ftlb s and we had to use a 3/4 drive torque wrench 2 meters long.
Still they would slacken so we ended up using some loctite that needed applying and then tightening so fast if on a hot shaft, we had to use a 3/4 nut gun and torque immediately otherwise the loctite would lock the nut on the thread, if we took our time running it up with a ratchet, it would lock so solidly we could end up torquing the nut up on the locktite itself, IE the nut had not gone fully home.
AT NO POINT was a wheel brg EVER damaged by this 'OVER' torquing only if the bearing became slack or was torqued up incorrectly on the loctite.
Still they would slacken so we ended up using some loctite that needed applying and then tightening so fast if on a hot shaft, we had to use a 3/4 nut gun and torque immediately otherwise the loctite would lock the nut on the thread, if we took our time running it up with a ratchet, it would lock so solidly we could end up torquing the nut up on the locktite itself, IE the nut had not gone fully home.
AT NO POINT was a wheel brg EVER damaged by this 'OVER' torquing only if the bearing became slack or was torqued up incorrectly on the loctite.
Last edited:
clift_d
Member
- Messages
- 571
- Location
- Hackney innit (UK)
She already knows what he's thinking and will be telling him what she thinks when he gets home.
steveo3002
Member
- Messages
- 7,531
right well things get stranger
the bearing arrived today , drum off and knocked the old one out with a hammer like normal ,cleaned it all up and got ready to push the new one in and sat it over the hole , the new bearing drops in and out with finger pressure now !! measure the 2 old bearings and the new one and yes theyre all the same , last one didnt fall in so somehow the drum hole is too big now, i dont have the gear to measure the hole accuratly but i guess no point so ive ordered up a new drum
fwiw the paint on the drum has started to blister so its got pretty hot
the bearing arrived today , drum off and knocked the old one out with a hammer like normal ,cleaned it all up and got ready to push the new one in and sat it over the hole , the new bearing drops in and out with finger pressure now !! measure the 2 old bearings and the new one and yes theyre all the same , last one didnt fall in so somehow the drum hole is too big now, i dont have the gear to measure the hole accuratly but i guess no point so ive ordered up a new drum
fwiw the paint on the drum has started to blister so its got pretty hot
normspanners
Member
- Messages
- 8,853
sounds like it has got a crack in it, maybe hold it up with a welding wire and tap it if, it doesnt ring it is cracked.
best idea they are not that dear anyway.
steveo3002
Member
- Messages
- 7,531
yeah dunno whats going on ...no signs the last bearing had span
if the drum openings were say slightly egg shapped woud the bearing still force in or what ? the outer shell is fairly hefty i cant see a slightly iffy opening deforming a bearing but then what do i know lol
if the drum openings were say slightly egg shapped woud the bearing still force in or what ? the outer shell is fairly hefty i cant see a slightly iffy opening deforming a bearing but then what do i know lol
steveo3002
Member
- Messages
- 7,531
yes new and 2 old bearings all drop in now , assume its deformed or cracked when i bashed out the old one, didnt go mad just knocked it out with a socket and ball pien hamy
rtbcomp
Moderator
- Messages
- 18,574
- Location
- Sheffield UK
+1 for the new drum. Next time just go round the block a couple of times and feel the temperature of the drum (compare it with the other side) just in case you've got a binding brake.
If you want to check for a crack soak the drum in paraffin overnight, wipe it completely dry and sprinkle some French chalk on it, you should see the chalk appear damp as the liquid seeps out any cracks.
If you want to check for a crack soak the drum in paraffin overnight, wipe it completely dry and sprinkle some French chalk on it, you should see the chalk appear damp as the liquid seeps out any cracks.
steveo3002
Member
- Messages
- 7,531
would there be a limit to how many bearings can be swapped into a drum before things go wrong , its had 3 fitted in it now
normspanners
Member
- Messages
- 8,853
the hole in the housing /drum will quite easily deform a bearing, the drum being much larger dia will try keep its shape even if that shape is now oval, so the round outer race of the bearing will now become oval the same as the disc, the outer race then will have highs and lows ie more load on bearing where it is forced inward.
just because the bearing race is made from hard metal that doesnt mean it will stay in shape, it WILL deform, it requires the housing to be the correct shape also and then the whole assembly is equal
if the housing for instance is too small it WILL reduce the bearing diameter slightly ( and expand the housing )
My gut feeling is the drum has been out of shape for awhile now, and now it has cracked and will not hold the bearing tight.
normspanners
Member
- Messages
- 8,853
No unless they have been fitted cocked over
