Jer309GTi 3 Posted October 15, 2006 I've stripped my Mi engine down at last, and have measured the journals on the crank to check if they are oval and what bearing size to use. They are not oval, and the main bearing journals are 60.00mm and the big ends are 50.00mm (+/- 0.04mm). Will I nedd to buy standard size bearings or will I need oversize ones? Thanks Share this post Link to post Share on other sites
rescue dude 0 Posted October 16, 2006 On the back of your old bearings it will tell you whether they are standard or undersize or oversize. If you havent had the crank reground use the old bearings as a size guide. Share this post Link to post Share on other sites
Jer309GTi 3 Posted October 16, 2006 Ok thanks, I've had a look and what I found was: All big end shells are stamped with SK1 E539658 The top main shells have SK 87 E04938 The bottom main shells have SK 78 E04937 So if I give these numbers when I order my engine parts then they will know which sizes to send me? Cheers Share this post Link to post Share on other sites
Grahamrally 0 Posted October 17, 2006 50 and 60 mm are correct measurements for the standard bearings sizes. You need to be sure that the main and big ends journals are not ovalled and are really within tolerance. I can't remember what acceptable tolerance is for them. I would recommend you take the crank to a machine shop and get them to thoroughly measure it. You can't take risks in this area. You would only need 0.3 oversize bearings if they have to skim it anyway. Share this post Link to post Share on other sites
petert 601 Posted October 17, 2006 As I said on the 405 site, that much is oval. If you're unsure how to measure it correctly get some professional help. It's not worth stuffing up a crank/rebuild for the price of a regrind. The bearings will cost the same. It's unlikely the mains will be oval, so you should be able to put std. bearings back in. Most of the time the original mains bearings can go back in. Share this post Link to post Share on other sites
Jer309GTi 3 Posted October 17, 2006 I've checked again and theyre not oval, but I'm going to get it reground anyway for piece of mind. Was just hoping I could get it done a bit quicker by not getting it reground but as said its not worth risking it. Share this post Link to post Share on other sites
Jer309GTi 3 Posted October 20, 2006 (edited) I took the crank to my local machine shop (Padfields in Bristol if anyone knows it) and they've declared it perfectly within tolerances. They gave the journals a polish and supplied new std bearings and said the crank was actually in pretty good nick. Edited October 20, 2006 by Jer309GTi Share this post Link to post Share on other sites
