Yeah for road use -.060", if you can still get the bearings.
My S crank was at -.020" when it almost spun the centre main- it cleaned up at -.030" with .001" to spare..
| ausmini https://www.ausmini.com/forums/ |
|
| how far undersized can a 1275 crank go ? https://www.ausmini.com/forums/viewtopic.php?f=2&t=33063 |
Page 1 of 1 |
| Author: | sports850 [ Tue Jun 19, 2007 7:04 pm ] |
| Post subject: | how far undersized can a 1275 crank go ? |
I pulled the main cap (knew it had a problem) off one of my spare 1275 motors tonight and it's spun the center main , I'm wondering how far under sized it can be ground before it becomes a doorstop , it's a 12G1288 I think (hard to read stamps) and is already at 20 thou . |
|
| Author: | doogie [ Tue Jun 19, 2007 7:13 pm ] |
| Post subject: | |
I know of a crank that went to 060 under Doogie |
|
| Author: | drmini in aust [ Tue Jun 19, 2007 7:28 pm ] |
| Post subject: | |
Yeah for road use -.060", if you can still get the bearings. My S crank was at -.020" when it almost spun the centre main- it cleaned up at -.030" with .001" to spare..
|
|
| Author: | Morris 1100 [ Tue Jun 19, 2007 7:39 pm ] |
| Post subject: | |
I have a -.060" crank. |
|
| Author: | Matt68 [ Wed Jun 20, 2007 9:05 am ] |
| Post subject: | |
Do you need to get the cranks re-heat treated after going more than .020" under? |
|
| Author: | drmini in aust [ Wed Jun 20, 2007 7:26 pm ] |
| Post subject: | |
Matt68 wrote: Do you need to get the cranks re-heat treated after going more than .020" under?
Depends on the crank. When Spiro reground my S crank's mains to .030" under he said it was still hard as, so no need. An Oz big journal 1275 crank, or an 850, 998 or 1098 one, are all EN16 material and non- heat treated so are soft anyway. Mk1 S cranks are EN40B, nitrided. If you re-nitride it there is a real good chance it will bend, as an ausmini member found out a year or so ago.. Most Mk2 S cranks and small journal 1100S cranks were tuftrided EN16. Good luck finding anybody who will do this process in Oz now, the EPA pretty much closed down the process due to environmental and health concerns. GR says there is 1 place, in Melbourne- they do mainly stuff for the aircraft industry. |
|
| Page 1 of 1 | All times are UTC + 10 hours |
| Powered by phpBB® Forum Software © phpBB Group http://www.phpbb.com/ |
|