ausmini https://www.ausmini.com/forums/
Crankshaft tail wear https://www.ausmini.com/forums/viewtopic.php?f=2&t=100509	Page 1 of 1

---

Author:	JEA [ Tue Nov 03, 2020 7:57 am ]
Post subject:	Crankshaft tail wear
Hi everyone, Yesterday I pulled down a 1275 engine that I had sitting under the bench. One thing I came across was some wear on the end of the crankshaft. The taper feels okay, but there is definite wear where the primary rums. Hopefully it clear enough in the picture, but the scores are deep enough that a quick polish probably won’t fix. Is this an issue? If it’s ground down, are oversized bushes available for the primary gear? Cheers, James.

---

Author:	drmini in aust [ Tue Nov 03, 2020 1:55 pm ]
Post subject:	Re: Crankshaft tail wear
I replaced the outer flanged bush in a 1275 primary gear recently. It was undersized, I bored it out after fitting. I think it was about 0.010" undersize before boring. These are sintered bronze and pretty fragile. At the other end, a floating silicon bronze bush is available but is standard size. If the original 1275 bush is still available it would be undersize too. 1275 cranks can wear badly there. One solution is to grind the 1.625" journal down to 1.500" and fit a 998 primary gear. Use with 1275 thrust washer. Some racers have done this mod.

---

Author:	Mick [ Tue Nov 03, 2020 11:11 pm ]
Post subject:	Re: Crankshaft tail wear
I had to choose to machine a 1275 crank to suit a 998 primary gear some time ago, to date I have 12 years and about 25000 kilometers without an issue from this modification.

---

Author:	JEA [ Wed Nov 04, 2020 7:02 am ]
Post subject:	Re: Crankshaft tail wear
Thanks for the info guys. It looks like all is not lost. James

---

Author:	drmini in aust [ Wed Nov 04, 2020 12:21 pm ]
Post subject:	Re: Crankshaft tail wear
Polish the burrs off and measure it with a micrometer if it's only a thou or 2 under 1.500", stop worrying.

---

Page 1 of 1	All times are UTC + 10 hours
Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/