badshee Posted February 25, 2007 Report Share Posted February 25, 2007 do the main crank bearings have to be pressed on and also just wondering how to get them off without messin anything up> thanks for any help.... Quote Link to comment Share on other sites More sharing options...
JET 99 Posted February 25, 2007 Report Share Posted February 25, 2007 do the main crank bearings have to be pressed on and also just wondering how to get them off without messin anything up> thanks for any help.... not being a prick but wrong forum......... repair and modification would be the correct place to ask this question and to answer question pulling bearings off with pullers is best.. heating bearings and cooling crank off having arbor press ready to seat bearings would be best. but if you feel comfortable hammering on bearings.... you could beat with hammer and center punch i guess ???? Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 25, 2007 Report Share Posted February 25, 2007 heating bearings and cooling crank off having arbor press ready to seat bearings would be best.but if you feel comfortable hammering on bearings.... you could beat with hammer and center punch i guess ???? Make sure that you do not heat and cool the bearings. For any type of ball or roller bearings, this ruins them. A set of bearing collars and a press are the best way to get the job done. :thumbsup: Quote Link to comment Share on other sites More sharing options...
JET 99 Posted February 25, 2007 Report Share Posted February 25, 2007 Make sure that you do not heat and cool the bearings. For any type of ball or roller bearings, this ruins them. A set of bearing collars and a press are the best way to get the job done. :thumbsup: i am not talking about using a blow torch( setting bearings on drop light or oven at 200deg) just enough to open i.d. of bearing even (.0005 of a inch)can help i do this all the time at work. precision cnc machinery. even the manufacturers of tool machinery do it. i have been to a few maintenance classes at the machine tool builders facilties.. sorry i have never experianced a faliure because of installation... just my .02cents Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 25, 2007 Report Share Posted February 25, 2007 i am not talking about using a blow torch( setting bearings on drop light or oven at 200deg)just enough to open i.d. of bearing even (.0005 of a inch)can help i do this all the time at work. precision cnc machinery. even the manufacturers of tool machinery do it. i have been to a few maintenance classes at the machine tool builders facilties.. sorry i have never experianced a faliure because of installation... just my .02cents Are you then cooling the crank with liquid nitrogen before you put the 200 degree F bearing on? If not I have a hard time seeing how you get enough expansion to over come the 20 micron interference fit..................... If someone was really in a bind can think of whay to get the job done with acomewhat large diameter, extra deep socket and a bench vise. :shrug: Quote Link to comment Share on other sites More sharing options...
JET 99 Posted February 25, 2007 Report Share Posted February 25, 2007 Are you then cooling the crank with liquid nitrogen before you put the 200 degree F bearing on? If not I have a hard time seeing how you get enough expansion to over come the 20 micron interference fit..................... If someone was really in a bind can think of whay to get the job done with acomewhat large diameter, extra deep socket and a bench vise. :shrug: nope just a deep freeze.....it only shrinks and expands so far..(i agree) its not the majic cure. but it does help... wasnt trying to steal the thread sorry... guess i will shut the f... up since i have no clue what i am talking about ...... :: :: :: :: hopefully some one will chime in and help you out :beer: Quote Link to comment Share on other sites More sharing options...
RNBRAD Posted February 25, 2007 Report Share Posted February 25, 2007 The temperature differential method is actually recommended for bearing installation on most if not all spherical bearings. I heated the inner race of the bearing about 6 or so seconds with a micro torch. Then they slide on and off like butter. :thumbsup: Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 25, 2007 Report Share Posted February 25, 2007 The temperature differential method is actually recommended for bearing installation on most if not all spherical bearings. I heated the inner race of the bearing about 6 or so seconds with a micro torch. Then they slide on and off like butter. :thumbsup: Temperature differential is almost always the best way to assemble an interference fit. If you can isolate the heat to the the part of the bearingeffecting the fit than fine, but it can't be done in may situations. If the bearing happen to be sealed or have the bearings controlled by a plastic cage, then you are hurting the bearing by heating it. The way to get around all of this is by heating or cooling the part the bearing is going on so that you don't have to do anything to the bearing. :thumbsup: Quote Link to comment Share on other sites More sharing options...
jeepman380 Posted February 26, 2007 Report Share Posted February 26, 2007 Just heat up the inner race of the bearing on both sides with a little propane torch for about 10 seconds on each side and it should just slide right on. Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 26, 2007 Report Share Posted February 26, 2007 Just heat up the inner race of the bearing on both sides with a little propane torch for about 10 seconds on each side and it should just slide right on. I am not going to recommend taking a flame based heat directly to the bearing. I would just assume that a press was used to install the bearing, or put liquid nitrogen on the crankshaft, beofre you resorted to heating the bearing. The 200 degree F temp at which to heat the bearing to is b.s. as the CTE of the material does nmot allow for a for any measureable expansion at that temperature. If the bearing was made of aluminum, then you might be a little closer to being accurate. :thumbsup: Quote Link to comment Share on other sites More sharing options...
badshee Posted February 26, 2007 Author Report Share Posted February 26, 2007 thanks for all the help guys, i was just trying to get some pointers because i bought a used 4 mill and i decided to put new bearings on... but after reading all of that ill prob just let my local shop do them for me...thanks for all the input.. Quote Link to comment Share on other sites More sharing options...
FireHead Posted February 26, 2007 Report Share Posted February 26, 2007 thanks for all the help guys, i was just trying to get some pointers because i bought a used 4 mill and i decided to put new bearings on... but after reading all of that ill prob just let my local shop do them for me...thanks for all the input.. I certainly don't want to dissuade someone from doing work on their bike themselves. I just want to give you the best chance at not screwing something up the firsttime you try it. :thumbsup: Quote Link to comment Share on other sites More sharing options...
Animalman294 Posted February 26, 2007 Report Share Posted February 26, 2007 Yeah, that was my suggestion - go to your local shop and pay the ten bucks for them to do it right........... :thumbsup: Quote Link to comment Share on other sites More sharing options...
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