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| SNAP! https://ausmini.com/forums/viewtopic.php?f=5&t=32648 |
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| Author: | jbeenz [ Sat Jun 09, 2007 8:19 am ] |
| Post subject: | SNAP! |
Um, i was putting a 998 engine together last night, and i snapped a rod bolt 
Through overtightening due to torque wrench issues, anyway, its got me thinking, if i can snap one, whats the enging going to do to the rest? these were not stock bolts, stamped with 10 lines and "FX". so do i try find another, or revert to stock rod bolts.? 998 lightened rods wade cam. going for nice revvy smallbore. |
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| Author: | drmini in aust [ Sat Jun 09, 2007 9:02 am ] |
| Post subject: | |
Best rod bolts for a quick smallbore are `Unbrako' brand socket head capscrews, that's what GR uses. Lube em with oil or a smear of molygrease, do up to 40lb/ft, with no lockwasher. Alternative is go buy ARP race ones from Minispares etc. I don't trust the standard rodbolts, particularly if S/H. They make an awful mess of the motor and box if they let go. I bought a ventilated one last year. 
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| Author: | jbeenz [ Sat Jun 09, 2007 9:07 am ] |
| Post subject: | |
Yea, i have a ventilated 998 block at home also, thats why im woried! worst thing is it was smeered with loktight so i had to get the broken half out fairly quickly! its been a while since bolt grade school, what does 10 dashes mean? what are a set of "unbrako" 's worth? |
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| Author: | PetenSoaf [ Sat Jun 09, 2007 9:46 am ] |
| Post subject: | |
jbeenz wrote: Yea, i have a ventilated 998 block at home also, thats why im woried! worst thing is it was smeered with loktight so i had to get the broken half out fairly quickly!
its been a while since bolt grade school, what does 10 dashes mean? what are a set of "unbrako" 's worth? And I guess, just as importantly, where do you get them? |
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| Author: | drmini in aust [ Sat Jun 09, 2007 9:50 am ] |
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See http://www.americanfastener.com/technic ... _steel.asp can't see any bolts there with 10 marking. Unbrakos are grade 12 I think. But don't buy Chinese made... see http://www.unbrako.com/ download the catalog <edit> I'd avoid ANY fasteners that are plated.. I once peeled the threads off some plated Grade 8 (7/16 UNF) diff bolts before they got up to the torque setting..... 
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| Author: | mason [ Sat Jun 09, 2007 3:16 pm ] |
| Post subject: | |
Is there two rod bolt sizes from factory |
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| Author: | drmini in aust [ Sat Jun 09, 2007 9:02 pm ] |
| Post subject: | |
mason wrote: Is there two rod bolt sizes from factory
The smallbores all run a 3/8" UNF hex bolt. Don't have one handy right now but I think were all the same. The 1275s with S rods (ie small journal crank) use a 3/8" UNF `shaped head' bolt, and nut. The 1275s with big journal crank (both A series and A+) use 11/32" UNF `shaped head' bolts and nuts. |
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| Author: | slinkey inc [ Sat Jun 09, 2007 11:12 pm ] |
| Post subject: | |
Interesting. S has bigger diametre rod bolts than big journal ones. mmmmmmm yummm 
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| Author: | brickworx [ Sat Jun 09, 2007 11:19 pm ] |
| Post subject: | |
That also means they have less meat in the conrod... 6 of one 1/2 dozen of another |
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| Author: | slinkey inc [ Sat Jun 09, 2007 11:28 pm ] |
| Post subject: | |
Bugger!! Less meat = lighter. Less meat also = more chance of break! To quote the Blues Brothers, or close enough Quote: Oh no, the motor's thrown a rod!
Ah that's ok. My motors not a race motor. |
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| Author: | drmini in aust [ Sun Jun 10, 2007 12:18 pm ] |
| Post subject: | |
slinkey inc wrote: Bugger!!
Less meat = lighter. Less meat also = more chance of break! To quote the Blues Brothers, or close enough Quote: Oh no, the motor's thrown a rod! Ah that's ok. My motors not a race motor. All Cooper S rods are made of EN24V, the good stuff. Big journal rods for the 1275 A series were 50g heavier than S rods and made from EN19 and later EN16. A+ rods are nice and light, made of EN15. In spite of this Vizard says they are fine for a 7500 rev limit. Weakest point on all these 1275 rods is the bolts- if S/H you don't know how old they are or how used. Buy new ones, preferably ARPs. 
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