I pulled apart my dax Gen4 this morning due to a bad leak on the case gasket. While I had it apart I planned on replacing all four of the case bearings. The small gear side case bearing was stuck on the crank shaft. I removed the bearing by squeezing the bearing in a vise until it broke and then grinding the inner race off with my cut off wheel. I've done this one other time very successfully only gouging the crank a tiny bit. This time I got carried away and I am using my dirty safety glasses as my excuse for grinding the crank so badly. My question is this crank useable? I cleaned up the burrs and the new bearing fits like a glove. Will this throw the balance of the crank way out of wack?
In need of your 2 cents
- Thread starter chris8686
- Start date
I am going to go ahead and throw it back in. I talked to DAX and he said that he is 8 weeks out from having any more cranks. After pressing in the new bearings i test fitted the crank in the case halves and there is a tiny bit of side to side play in the crank. Any thoughts on that?
PIGEONHAWK
New Member
they are buggers to get off. doesnt look good for holding a bearing now sorry/ thats sucks.
l8r
l8r
what method do you use to remove a stuck bearing? It still holds a bearing quite well. The bearing on the magnet side sides on and off the crank with little force and the gear side prior to a lot of force to drive the bearing on. Now the bearings slide on and off about the same
PIGEONHAWK
New Member
the bearings work fine. the bearing races/outer and inner shells are a little thin and soft but so are the cases holding them in. they work ok.
plus the cases dont bolt together perfectly aligned as there is nothing to align it but bolts and bearing shafts.
plus the cases dont bolt together perfectly aligned as there is nothing to align it but bolts and bearing shafts.
crassius
Well-Known Member
it depends on whether the crank is sliding in the bearing inner or the bearing outer is sliding in the case - the steel to steel fitting will take much more abuse than the steel to aluminum fitting
also, to get it off the crank, I go thru the big end journal from the other side & hammer it off (not suitable if bearing is to be reused) - this is harder with the newer small bearing cases than when the mains were much larger in outer shell size - I may have to soon get a piece of pipe that fits around the bearing & weld a washer to its end (creating a bit of an inner lip) then splitting the pipe lengthwise to fit the 2 halves over the bearing so the pipe can be pulled with a standard puller
also, to get it off the crank, I go thru the big end journal from the other side & hammer it off (not suitable if bearing is to be reused) - this is harder with the newer small bearing cases than when the mains were much larger in outer shell size - I may have to soon get a piece of pipe that fits around the bearing & weld a washer to its end (creating a bit of an inner lip) then splitting the pipe lengthwise to fit the 2 halves over the bearing so the pipe can be pulled with a standard puller
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Crank should be a tight slide fit into bearing.
Bearing should be an interference fit into case. Cases should be heated before fitting bearings.
If crank does not slide nicely into bearing use sand paper or fine file till it does.
Crank should slide freely side to side through 360 deg of crank rotation.
30 to 40 thou is good side float, as crank will expand with heat.
I install seals last, to be sure crank is rotating and sliding smoothly you may need to tap the cases before tensioning case bolts, with a jug lightly bolted down to insure flat mating surface.
The cut you have in your crank journal is unfortunate, and may weaken the crank, but looks to still be usable.
Heating inner bearing race may have been better way of getting it off.
Bearing should be an interference fit into case. Cases should be heated before fitting bearings.
If crank does not slide nicely into bearing use sand paper or fine file till it does.
Crank should slide freely side to side through 360 deg of crank rotation.
30 to 40 thou is good side float, as crank will expand with heat.
I install seals last, to be sure crank is rotating and sliding smoothly you may need to tap the cases before tensioning case bolts, with a jug lightly bolted down to insure flat mating surface.
The cut you have in your crank journal is unfortunate, and may weaken the crank, but looks to still be usable.
Heating inner bearing race may have been better way of getting it off.
maniac57
Old, Fat, and still faster than you
I agree. All movement should be bearing on crank journal. The mains should be a press fit in the cases. Shim the crank PROPERLY by being sure both mains are fully seated before taking sideplay measurement.
I usually set the cases out in the sun to heat and chunk the bearings in the freezer.
Makes assembly a LOT easier.
I usually set the cases out in the sun to heat and chunk the bearings in the freezer.
Makes assembly a LOT easier.
I use the oven while the missus is out.
I only install main bearings this way.
The clutch shaft I leave out until I'm happy with the rest of the bottom end.
Usually installing clutch side bearing last.
Clutch shaft should also be made to be a snug slide fit on the bearing, making disassembly/reassembly later, much easier.
Then seals I install last, after I'm happy that every thing is spinning freely.
Be sure to remove any burrs/sharp edges that may damage seal.
I only install main bearings this way.
The clutch shaft I leave out until I'm happy with the rest of the bottom end.
Usually installing clutch side bearing last.
Clutch shaft should also be made to be a snug slide fit on the bearing, making disassembly/reassembly later, much easier.
Then seals I install last, after I'm happy that every thing is spinning freely.
Be sure to remove any burrs/sharp edges that may damage seal.
Thank you guys very much for your input. I put the bottom end back together last night using the damaged crank. The side to side play in the crankshaft was lessened a lot when the case halves found there sweet spot and were snugged down. I am sure that the play was there before I tore it down. Something like that doesn't pop up out of nowhere. I wanted to shim the play out of it but I started grabbing the other bottoms off the shelf to give them a shake and one of them also had a tiny bit of side to side play. I hope I get a few more miles out of this one and it doesn't find it's way onto my shelf.
Hey guys! Just took my bike for a few rides using the damaged crank and it was a success! The new Fastenal 6202's really helped quiet down my ride. The air leak coming from the bottom of the case was due to a casting burr around the bottom bolt hole making the gasket not sit flush with the other case halve. I filed down the burr and used copper gasket spray to help seal up the case. This China girl has a lot of miles left in her. Don't chuck your motors in the trash! Fix'em!
