lt1bird Posted November 4, 2009 Report Share Posted November 4, 2009 aftermarket cranks with orings! Machine some groves in the center bearing area to accept the orings for better alignmet? Im chatting with a company who wants these groves machined into the cases.... even my matoon cases dont have this. What would be the real reason to have these? Would the groves really hurt? Anyone ever hear about folks doing this? Thanks! Quote Link to comment Share on other sites More sharing options...
87sheerips Posted November 4, 2009 Report Share Posted November 4, 2009 aftermarket cranks with orings! Machine some groves in the center bearing area to accept the orings for better alignmet? Im chatting with a company who wants these groves machined into the cases.... even my matoon cases dont have this. What would be the real reason to have these? Would the groves really hurt? Anyone ever hear about folks doing this? Thanks! As far as I understand it, the o-rings replace the stock "stopper" pins that are usually in the bearings. Aftermarket bearings have o-rings to keep the outer portion of the bearing in place. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 4, 2009 Author Report Share Posted November 4, 2009 Yes, they definatly serve that purpose but, would mating machined groves in the cases maybe help keep the bearings in place better? Quote Link to comment Share on other sites More sharing options...
crustydemon Posted November 4, 2009 Report Share Posted November 4, 2009 Yes, they definatly serve that purpose but, would mating machined groves in the cases maybe help keep the bearings in place better? Were are the bearings going to go? I would think that is totally unnecessary. And besides the point, if you did machine grooves in the case halves the orings would not be able to do their job. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 4, 2009 Author Report Share Posted November 4, 2009 They will still do the job...The orings will simply sit 1/2 in the grove but still extend outward. They would still be compressed, maybe hold even tighter. This way larger berings might be able to be used? I have not measued the opening where the bearings fit. I wonder how much over sized is the case hole where the beraings fit so it leaves room for the orings?? The bearings must be a tad smaller than the opening...maybe a tad smaller on the aftermarket cranks than oem bearings? Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted November 4, 2009 Report Share Posted November 4, 2009 The O-rings are to keep the bearings from spinning in the cases, therefore you want the tightest squeeze possible. This is going to come from not maching a groove in the case, the O-rings will simply be squeezed down when the case bolts and nuts are tightened. The aftermarket bearings are the same size as OEM, they just don't have the stopper pins to keep the bearings from spinning. I don't see how the O-ring would be squeezed tighter if 1/2 is in a groove in the case instead of squished flat in the bearing bore. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 4, 2009 Author Report Share Posted November 4, 2009 I know what you mean....... Thanks for the opinions....Ill let you know what the manufature says... Quote Link to comment Share on other sites More sharing options...
toolucky Posted November 5, 2009 Report Share Posted November 5, 2009 I know what you mean....... Thanks for the opinions....Ill let you know what the manufature says... If someone tells you that you need these grooves machined into your cases then they just dont have a clue or they are trying to get money out of you. Quote Link to comment Share on other sites More sharing options...
AKheathen Posted November 5, 2009 Report Share Posted November 5, 2009 the main piont that they use the oring is so that the can run the same genaric bearing with the snapring groove on all 4, instead of having the aplication specific bearings manufactured with the locating pin. you can get the snaprring, and plain bearings @ a real good discount since they are made in mass quantities for hundreds of aplications @ once. it's safe to say that they are paying $3 or less for them, as opposed to at leas 2x as much just for the pin style. the o-ring is just there to help keep it from spinning and wearing the case. Quote Link to comment Share on other sites More sharing options...
bansheesandrider Posted November 5, 2009 Report Share Posted November 5, 2009 I know what you mean....... Thanks for the opinions....Ill let you know what the manufature says... By manufacturer I hope you mean Wiseco, HotRods or whoever made the crank and not some local yokel who is misinformed! Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 5, 2009 Author Report Share Posted November 5, 2009 Interesting idea about the big c clip. Guess that would not work well in holding the bearing tight...Hmmm....Ill let you know what they say... Quote Link to comment Share on other sites More sharing options...
rubberneck Posted November 5, 2009 Report Share Posted November 5, 2009 I would want an extremely good explanaiton from them before buying into that. All 3 of my bikes have aftermarket cranks in them and just built another for a cousin. None of them are machined, nor have i ever heard anybody else talk about it. I think they are selling you BS Quote Link to comment Share on other sites More sharing options...
AKheathen Posted November 5, 2009 Report Share Posted November 5, 2009 not sure you would gain anything by placing c-clips and grooves on the bearing, as they are intended for side loading, like the pto bearing. if you want a tighter fit, simply apply a light film of retaining compound to the bearings, so nothing squeezes out. the o-rings are soft and the little groove would not produce the desired results like something solid would, and only relieve pressure. i was just explaining why the orings are used. Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 5, 2009 Author Report Share Posted November 5, 2009 (edited) Hey, im with you guys...Ive never done it, but Im still waiting for a response from the engineer at the company. The company is the Two stroke shop in austrailia. The crank is for a 485, 90 degree firing order ,custom balanced with weights. Im still waiting to hear back from them. Origially I thought they said something about the grooves for keepting the bearings and everything from moving around. It looks like another grove for a 1/2 moon clip. This would help keep the bearing in location and give more side thrust retention, not all the pressure on the clip on the flywheel bearing. Lets see what they say... Edited November 5, 2009 by lt1bird Quote Link to comment Share on other sites More sharing options...
lt1bird Posted November 5, 2009 Author Report Share Posted November 5, 2009 ok, got a email back from them, seems to make sense.... The center half-circlip groove is there to locate the crank axially. It takes the place of the usual drive side retaining groove/circlip. We have to do this when running roller outer mains; because these are no good at coping with any side loads. They are designed to have double the radial load-carrying capacity of ball bearings though; so what we do is we have a hybrid crank with balls for the two center mains, one of which is used to locate the crank axially - and then rollers at the ignition and drive sides ... and hey presto, we have the strongest possible crank that can be built. And then we have an o-ring on the other center main. The two outer mains don't have circlip grooves or o-rings and they don't need them. This is because the crank is what is called a 'floating crank' whereby the outer two mains are a hand slide fit; the same as the main countershaft bearing. And so these bearings are not fixed to the crank the same as a conventional crank, and this prevents binding between the bearings, which otherwise would impose side loads on each other - thus robbing the engine of horsepower. All GP engines run floating cranks. It all sounds reasonable, maybe a hair nuerotic but they are really looking for every HP they can with the lightest rotating mass.... checkout their webpage at www.twostrokeshop.com Cheers Quote Link to comment Share on other sites More sharing options...
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