OK, how do you get the bearing off the shaft?

[Moody Blue]

Working on a '71 Merc 800, doing the crankshaft seals and both upper and lower bearings.

Lower bearing was completely shot and the outer race and balls just fell off when I pulled the end cap off. Can't get a puller between the inner race and crankshaft jounal.

Upper bearing was not in much better shape. Bearing cage came out in 9 pieces but the outer race and balls are still "attached" to the inner race. Again, can't get a puller between the bearing and the crankshaft journal.

Was thinking about heating the bearing and hoping it will slide off the shaft. Short of that, maybe cut them off with a dremel and cutoff disk.

Any other ideas?

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

Get A HAMMER! Just kidding Heat at 350 degrees will expand the bearing to slide off the shaft. YES True to fact I used a metal shaft and a hamer to tap away and remove mine. I did it on several engines. This is not recommeneded as if you miss you just screwed your CS. Removal of the bearigns and alot of slow concentrated attention to what came from where and where it goes back needs to be taken into consideration and careful marking of the conecting rods and the way they came off needs to be undertaken. If this is your first time removing Crank Shaft. The caps must be removed and replaced in the same exact order they came off. When replacing you must use your fingernail to assure there is no play between upper and lower connecting rod cap to rod. No bearings must be lost inside the engine as I already posted in this matter. After removing the crakshaft (patients and a superb understanding that you don,t want to mess up is essential) take nessecary mesures to get them off. When you have the parts all lined up for re assenbly and all marked as if even one bearing is out of place it is suggesed to replace the whole set and your sure you have it licked get a puller or like me use a shaft and a hammer and pound that piece of crap off and then heat the new bearing and slip it on goood as new. Now carefully check every step to be certain that #1 isnt #3 and #2 don.t wind up in #1 you get the point. Good Luck PS Take your time be patient and you will succeed. Don,t be too alarmed You can put the neeles back in any position of the same rod and journal but you cannot move from #1 to #3 or #2 they must remain as a set worn alike

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

Best bet is to get a gear puller and cover the splined area with a piece of metal to remove the lower If you choose like me to be neanderthal be sure to take your 7/16th steel rod and put it in the crook or the couterwieght and work both sides of both crooks and tap back and forth until the bearing falls off. Easy with the hammer. Patience is a vertue.

 

[Texasmark]

Re: OK, how do you get the bearing off the shaft?

They make and maybe auto parts stores rent them in your area, that are made for zero gap (essentially) installations. They are circular and in two halves (obviously) but the part that contacts the bearing is wedged shaped and allows you to "wedge" the bearing out before you start the actual pull.

Mark

 

[ENSIGN]

Re: OK, how do you get the bearing off the shaft?

Heat the bearing race and it should fall off,then allow things to cool slowly.

 

[Moody Blue]

Re: OK, how do you get the bearing off the shaft?

They make and maybe auto parts stores rent them in your area, that are made for zero gap (essentially) installations. They are circular and in two halves (obviously) but the part that contacts the bearing is wedged shaped and allows you to "wedge" the bearing out before you start the actual pull.

Mark

I've seen pictues of them and wondered how/where they were used. Now I know, thanks. I'm hoping not to remove the crankshaft if I don't have to, but as a last resort I will.

 

[Moody Blue]

Re: OK, how do you get the bearing off the shaft?

Heat the bearing race and it should fall off,then allow things to cool slowly.

Originally thought about doing just that, but after a bit more thought, I am concerned about the residual gasoline/vapours in the crankcase. When I split the block there was quite a bit of oil/gas mixture soaking the inside of the block.

If I do try that approach, it will be done outside with a face shield in place and a fire extinguisher nearby.

 

[buzzm19]

Re: OK, how do you get the bearing off the shaft?

MB, If you decide to use heat and have a fire extinguisher near by I would recommend using a co2 one(a friend may have a beer mister). I have used those powdered ones and if you have to use the fire extinguisher co2 doesn't leave any residue behind, If you have to use the powdered one then you will be taking the engine apart for clean up. When you read my last post and I told you about taking the rod caps off without removing the crank and me finding the problems with the bearing cages being cracked. I know it is a lot of extra work and the use of vaseline on reassembly. In your case and as me basically you are already there and the fact of the age of the motor? Remember that you won't know if there is a problem till after all the work on putting everything together in order to fire it up. Buz

 

[Texasmark]

Re: OK, how do you get the bearing off the shaft?

Heat the bearing race and it should fall off,then allow things to cool slowly.

The slow cooling process is necessary to keep from possibly tempering the shaft which would make it hard yes, but brittle also. Slow cooling keeps it ductile steel and the slower the more ductile.

Funny I was just reading a book about working with metal today and came across that. Twas very interesting the different ways you could cool metals to obtain a desired outcome.

Mark

 

[Texasmark]

Re: OK, how do you get the bearing off the shaft?

I forgot yesterday, the other thing I have done is to take a cold chisel and hammer and find one spot and repeatedly strike it over and over and over and over......at some point the race will fracture and crack open. Something about cast/compressed power metallic objects is that they work just fine, but when subject to compressive forces repeatedly the atoms break loose and they crack wide open.

I had a friend with a dump truck that had a "pup" trailer making it an 80,000 GVW rated vehicle. The pup was attached to the truck with a pintle hook, a steel casting. One afternoon he came over and showed me his connector which had sheared, just as if a giant gorilla or something took the front (attached to the truck) and the rear (hook the pup connected to) and just broke it in half. Amazing and scary for that. That's why the TX. DOT requires safety chains on every combination.

The failure mechanism was the constant pounding that the tongue of the pup placed on the tow hook, just like you constantly pound on your race and it will yield. Doesn't take all that long.

Mark

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

I have had alot of luck chiseling through metal. The bearing has enough room at the counter weight sides to get a knocking shaft in there and hiting it from side to side will slowly wiggle the bearing off, but be sure to put protection on the shaft end and sleeve as not to damge it. And do not hit the counter weights or you,could see something crack in half and it won,t be the bearing. JMO

 

[Moody Blue]

Re: OK, how do you get the bearing off the shaft?

I bought some 2" cutoff disks for the die grinder and tried cutting the outer race off the one bearing. Piece of cake. Took about 30 seconds.

My plan now is to carefully cut the inner race off the shaft but cutting it diagonally as much as possible then smacking the cut with a cold chisel. I expect it will snap pretty readily.

Buzzm19, which cracked bearing races are you referring to? I see your point about taking it completely apart to check everything now that I'm at this point.

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

Good call on the angle cut I expect you will be able to remove it fairly easily after the angle cut is made but the problem lies in the final area where the cutting disc cannot get to thats gonna be the problem. If you can S it enough without hitting the crank it should be good to go.

 

[Texasmark]

Re: OK, how do you get the bearing off the shaft?

I bought some 2" cutoff disks for the die grinder and tried cutting the outer race off the one bearing. Piece of cake. Took about 30 seconds.

My plan now is to carefully cut the inner race off the shaft but cutting it diagonally as much as possible then smacking the cut with a cold chisel. I expect it will snap pretty readily.

Buzzm19, which cracked bearing races are you referring to? I see your point about taking it completely apart to check everything now that I'm at this point.

Sounds like a plan.

Mark

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

Better yet make two cuts one on each side should do the trick

 

[Texasmark]

Re: OK, how do you get the bearing off the shaft?

Better yet make two cuts one on each side should do the trick

Once you cut it, a screw driver wedged in the slot will free it. The fewer the cuts the fewer the opportunities for a slip up.

My 2c,
Mark

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

This is not true by making 2 cuts it gives way to the chisel and splices the metal easily as it has little to no hinderance.

 

[Moody Blue]

Re: OK, how do you get the bearing off the shaft?

Once you cut it, a screw driver wedged in the slot will free it. The fewer the cuts the fewer the opportunities for a slip up.

My 2c,
Mark

Got to agree. The fewer cuts I make the fewer chances of me screwing something up. I'll have a go at it tomorrow.

 

[Moody Blue]

Re: OK, how do you get the bearing off the shaft?

Went ahead and covered everything up very well to keep the grit out of the block.

Chucked up the cutoff disk and had at it. I made a diagonal cut in each race about 3/4 of the material thickness and about 2/3 of the way across. Wedged a large flatblade screwdriver into the cut and smacked it with a hammer. The races cracked very easily and I was able to slide the race off the crank without trouble.

Now, to decide whether or not to further disassemble the motor or just put it back together.

 

[Maxz695]

Re: OK, how do you get the bearing off the shaft?

Due to the bearing condition I suspect there may be Main bearing wear on the races and needle bearings in the center if reeds the blocks should be fine. I had knocking and when I removed the races found indents from excessive play. I had 2 more sets and replced them. If you do decide to remove the rod caps bearings center mains etc look fo blueing in excess a sign of overheating nd replace all nesecary parts. Could get expensive. You could take your chances but to know what you have at this point is comforting when Full throttle in the middle of nowhere. JMO