FT: Frame (Twin) cylinder head brackets

greg brillus

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VOC Member
Well just to answer the question........The nuts are actually a thin nut, so the torque figure technically should be lower than a standard sized nut.........I would say 25 Ft lb's at most.........The lack of torque figures quoted from the factory was probably because the amount of leverage was dictated by the length of commonly used spanners from that era and a reasonable amount of pull exerted on this spanner with normal human strength.......... I suspect most of you are laughing at this comment........i think you will find it to be correct of normal engineering practice..........The main issue now, is so few people have this so called "Feel" from a lack of experience.........No need to feel bad about it......It is just how things have become........torque wrenches are cheap enough to buy these days, so if in doubt, use one.
 

Martyn Goodwin

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Non-VOC Member
I think we all have to learn by our mistakes, I have made a few !,
Or we would do nothing,
The information on the computers now is Huge, Making almost anything possible ,
Just some of it is wrong !!, Been watching cutting down trees etc,
" Or how to get Killed " doing it !!,
So we have to chose who to trust, Maybe if 2 or 3 tell us the same , Should be OK ??.
check my signature... loosely translates to "experience is an accumulation of mistakes"
 

Monkeypants

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Non-VOC Member
From Know Thy Beast-
"All head nuts require careful tightening , especially with the early hollow bolts (cf, chapter 7) which, according to the Instruction Sheets, require 30 lb. ft. and a torque wrench. Even with the later solid bolts, overtightening must be avoided, because owing to the difference in expansion rate of the steel bolt and the aluminium jackets, it can lead to distorted and damaged crankcase bosses. If a torque wrench is available tighten to about 40 lb.ft., otherwise use a short spanner and not too heavy a hand"

Given the difference in strength and feel in humans, the last bit about " not too heavy a hand" doesn't mean much to me, especially in a world where torque wrenches are readily available. Many if not most people working on Vincents are enthusiasts, not professional mechanics. Even there, torque wrenches are required on critical parts such as head bolts, wheel studs and a great many other things, if following textbook procedure.
If everyone had identical strength and sensitivity, hand feel might get you in the ballpark, but that isn't the case.
If not tightened adequately, the head joint will leak. If overtightened, then damage occurs, and it's not an easy fix.


So if in doubt, it would be safe and precise to use a torque wrench to the figures above.

Glen
 
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vibrac

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VOC Member
The search engine at the top is your friend have a search. I am certain years ago the consensus was 32lbs ft. Thats what I use and have for years, light oil on the nuts run them down and back before fitting head. tighten to 30 leave overnight final tighten next day
 

Monkeypants

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Non-VOC Member
Glen. First you suggest 30 lb. ft. then you suggest 40 lb. ft. Big difference.
Two different bolt types, early and late, hollow and solid.
30 for the early hollow, 40 for the later solid, as in the KTB quote .

Glen
 
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