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| Main and Big End Bolts... https://www.ausmini.com/forums/viewtopic.php?f=2&t=51295 |
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| Author: | spraycanmansam [ Tue Mar 17, 2009 2:47 pm ] |
| Post subject: | Main and Big End Bolts... |
I need some new main and big end bolts for my 1100 rebuild... I've found what I need for the big ends --- drmini in aust wrote: Unbrako brand socket head cap screws, 3/8 UNF.
Grade is 12.4 I think. ..but I'm not sure what I need for the mains? |
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| Author: | drmini in aust [ Tue Mar 17, 2009 2:59 pm ] |
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Thread on mains bolts is 7/16" UNF. Standard main bolts are fine if they are Grade 8. These have 6 slots cut in then, like a castellated nut. Just check with a magnifying glass that the threads are not stretched or damaged. If they are damaged I buy new ones, or buy Grade 8 bolts (6 marks on head) and cut to length. |
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| Author: | spraycanmansam [ Tue Mar 17, 2009 3:07 pm ] |
| Post subject: | |
Thanks Doc. Yeah, a few of the main and big end bolts are buggered so I'm just going to replace the lot. So I need --- Big Ends: Unbrako 3/8" UNF Socket Head Cap Screws Mains: 7/16" UNF Grade 8 Bolts |
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| Author: | drmini in aust [ Tue Mar 17, 2009 3:11 pm ] |
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Take one of the mains bolts with you if buying bolts from a fastener place. They are an odd length, you have to buy longer ones and cut them off. And they MUST be Grade 8. Or get Unbrakos, (they are higher grade) if you can find them. Easier to buy new mains bolts from Karcraft, if they have them. 
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| Author: | spraycanmansam [ Tue Mar 17, 2009 3:20 pm ] |
| Post subject: | |
I was just about to this silly question... 
Karcraft have the main bolts listed as: BOLT - MAIN BRG CAP - MINI 1275 (NOT S) These are fine for a 1098 right? They're all the same apart from the 'S' that had 2" mains(?) |
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| Author: | drmini in aust [ Tue Mar 17, 2009 3:22 pm ] |
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Cooper S all had 6 main studs & nuts, not bolts (except early 1071S in UK). I'm pretty sure the 1275 bolts fit a smallbore OK, ask em or check length. |
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| Author: | spraycanmansam [ Tue Mar 17, 2009 3:25 pm ] |
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Thanks for the help Doc, much appreciated 
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| Author: | justminis [ Tue Mar 17, 2009 8:30 pm ] |
| Post subject: | |
drmini in aust wrote: Cooper S all had 6 main studs & nuts, not bolts (except early 1071S in UK).
And those bolts in the early 1071S can not be replaced with the later S studs as the holes in the caps and block are a different (smaller) diameter. Just a bit of trivia for a Tuesday night
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| Author: | drmini in aust [ Tue Mar 17, 2009 9:34 pm ] |
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spraycanmansam wrote: Thanks Doc. Yeah, a few of the main and big end bolts and are buggered so I'm just going to replace the lot.
You should run a 7/16" UNF bottoming tap into the block, to ensure there is no crud and the threads are AOK.
Before bolting the caps on, run the bolts in by hand, check that the heads are 1mm or so below the cap height. ie not bottoming out. Shorten a little if needed. Oil the threads and bolt head face when assembling. |
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