Whittie Posted May 4, 2009 Share Posted May 4, 2009 G'day, I'm in the process of putting an nissan 'C' box in my car and I have had the counter shaft bearing hole of the 'B' bellhousing bored out to fit the larger bearing in the C boxes. I just picked it up from the machine shop and it seems like it has a LOT of play for a gearbox bearing. It slides easily in and out of the hole, you can wobble it slightly, however there is no visible verticle movement. Comparing this to the main shaft bearing (not bored) that has to be tapped in and is a PAIN to remove, I am not confident that the work is any good. However, I am not an expert on this and would like some advice. Do I continue and use this bellhousing, or do I have to get the work re-done by the machine shop. These guys are driveline specialists and they know what the work was for, so one would think they would know what they are doing. However, from my powers of observation this bearing seems much looser than any others I have dealt with in these gearboxes before. Thoughts much appreciated!! Tom. Quote Link to comment Share on other sites More sharing options...
dan5138 Posted May 4, 2009 Share Posted May 4, 2009 Just speaking in general here, most of time you want a good snug fit when putting any bearing in. With what you are describing I would definately take that bell housing back and ask some questions. What will end up happening is the counter shaft will load that bearing and spin the entire thing inside the bell housing, making the problem worse. If the machine shop refuses to do anything my suggestion is to basically glue that bearing in. A little bit of blue Loc-tite or a smidge of black silicone should do the trick. Anything to guarantee that the bearing wont spin around in the bell housing is what is important. Quote Link to comment Share on other sites More sharing options...
Whittie Posted May 4, 2009 Author Share Posted May 4, 2009 Cheers dan5138. I'm not too comfortable with glueing the bearing in to be honest. Certainly sounds like it's too loose though. Oh well, I will speak to them on wednesday and see what they have to say. Quote Link to comment Share on other sites More sharing options...
Trevor Posted May 4, 2009 Share Posted May 4, 2009 I would make a spacer between the bell casting and the outer race out of shim stock. You definately want a snug fit to prevent the outer race from spinning in the case. http://www.mcmaster.com/#metal-shim-stock/=1q732b Quote Link to comment Share on other sites More sharing options...
Whittie Posted May 5, 2009 Author Share Posted May 5, 2009 Ok, well before i go in tomorrow and make a fool of myself is there any other reasons why a bearing shouldn't be this loose? The gearbox guy was saying (and it makes sense) that the wobble would allow the shaft to bend and twist under load. The gears are essentially trying to push themselves apart with the force from the motor and this wobble will allow the shaft to twist. This would allow the gears to come out of mesh and they would literally eat themselves apart. Is this possible or rubbish? Sounds feasible to me... Tom. Quote Link to comment Share on other sites More sharing options...
Flexicoker Posted May 5, 2009 Share Posted May 5, 2009 You do not want the shaft to 'bend and twist' under load. Any misalignment is going to accelerate gear wear. I don't understand his reasoning for saying the gears coming out of mesh is a good thing? In a normal bearing application you want an interference fit, where you have to heat the housing to fit the bearing in, and press it onto the shaft. However, in this situation you need to be able to easily assemble the gearbox. You want more of a locational clearance fit, where you can push or tap the bearing into place. However, it should never 'wiggle' around. Thats bad. If you can't get them to find you a new bellhousing or somehow fix it, you might be able to find another bearing with 1 or 2mm larger OD, and have them re-bore the hole to match (this time without going over) or you can use some green loctite to hold it into place. Quote Link to comment Share on other sites More sharing options...
Whittie Posted May 6, 2009 Author Share Posted May 6, 2009 Cheers Flexicoker! The gearbox guy said the shaft would bend and twist, I figured that this would put the mesh out and would be bad. No good about it. Well armed with everyone's ammunition I went in and spoke to the machine shop. When I originally got them to do the work I supplied a photo of a completed bellhousing (http://home.comcast.net/~zheimsothtn/Transmission2.htm) that had measurements on it. I told them to ignore the measurement of the bearing and said that 'this one' (i supplied a bearing) should fit in this hole, but total work should look like the pic. They promptly forgot that I said ignore the gear measurements and went by the directions on the photo and put a 4 tho clearance on the bearing. My fault for not crossing it out I suppose. They are going to score the bore on the bellhousing to reduce the clearance and reccommended I use locktight to hold the bearing in. I also supplied a new bellhousing and they are doing the work again with proper bearing clearance (0) this time. Total cost for new bellhousing and scoring the bore $100 less than the original bellhousing. I'll use the good bellhousing and sell the patched one to someone who isn't racing their car. This is my first project on the car without outside assistance from my old man, so if it costs me $200 on a $1200 project to learn these leasons then I guess it coulda been a lot worse. Thanks again for the help guys! Tom. Quote Link to comment Share on other sites More sharing options...
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