torquing Head bolts

kerinorton · Sep 21, 2014

hobot said:
Hm I worry if there's a possible issue of hydraulic lock in hole if applying thick film of thick oil?

Yes and don't.

Best advise is use a spanner no longer than 6 inches and do it up tight. Should not be able to ovetighten with this method, but I guess gorillas do exist.

Dereck

Hobot · Sep 21, 2014

hehe Dereck, as much and often as ALL engine fasteners need going over its way more practical to ignore torque wrench funny business and twist em good with a 6" rachet or end wrench. I've gotten the most fastidious t-wrench devotee's to admit in a pinch they just used good sense to get on. If so vital critical did they very soon re-troque wrench it to keep up their pure faith in t-wrench indicators. In my miserable meager engine experiences, beyond just cycles, its the horror of fasteners refusing to come out that I fear most rather than not staying tight, so mine get light ant-sieze or oil wipe. So I too twist to torque spec then a bit more. I quit the break free first proper routine and just try to torque on em, catching the ones that needed it but not moving the ones that didn't.

kerinorton · Sep 21, 2014

I'm getting slack. I haven't gone over my bike checking for loose nuts etc for a looooooooooong time, apart from the odd item that did need my attention. Haven't even checked the Iso's. Bugger. But I did replace the original ptfe [ or breakable rubber shit they used ] washers with a more solid white plastic type of stuff that I am sure wont disappear like the originals. the only thing a haven't done with the isos that I should have was figure a way of locking the shim plates solidly to the iso tubes. [ they flog and flog and flog f em ] .

Spring is coming but the is still a lot of rain in the air. Crap. Haven't been on the bike for over a week.

All the best. Dereck

Dean · Sep 22, 2014

As an aircraft mech I get a bit funny about torquing bolt and nuts. I always torque..... More because I love using my toys. Torquing is so satisfying....

I have been trying to find some adapters. They have a 3/8 square drive one end and a ring spanner on the other and about 2" long, but am having trouble getting whitworth sizes. I know we used to have them for doing rolls Royce dart engine assy. But not many around now. May have to make some up out of a whitworth ring spanner. Trouble is can't even get a spanner here. :? (UAE) they seem to think whitworth is a brand???? No sir we don't have Whitworth brand, how about these Chinese made spanners.

Anyway back to to torque settings using an extension. Just simple math.

R = T x L divided by L + A
Where:
R = corrected torque
T = actual torque from the manual
L = length of torque wrench. From middle of the handle to the centre of the drive.
A = length of extension (adapter) from the middle of the square drive to the middle of the ring.

So....
For a torque of 30 ft lbs with a 20" torque wrench and a 3" adapter it is...
30 x 20 divided by 20 + 3 = 600 divided by 23 = 26 ft lbs

Simple......

Nater_Potater · Sep 22, 2014

Dean said:
...they seem to think whitworth is a brand???? No sir we don't have Whitworth brand, how about these Chinese made spanners.

:mrgreen:

Thanks for posting the torque wrench math.

Nathan

Tin Man · Mar 4, 2017

Dean said:
As an aircraft mech I get a bit funny about torquing bolt and nuts. I always torque..... More because I love using my toys. Torquing is so satisfying....

I have been trying to find some adapters. They have a 3/8 square drive one end and a ring spanner on the other and about 2" long, but am having trouble getting whitworth sizes. I know we used to have them for doing rolls Royce dart engine assy. But not many around now. May have to make some up out of a whitworth ring spanner. Trouble is can't even get a spanner here. :? (UAE) they seem to think whitworth is a brand???? No sir we don't have Whitworth brand, how about these Chinese made spanners.

Anyway back to to torque settings using an extension. Just simple math.

R = T x L divided by L + A
Where:
R = corrected torque
T = actual torque from the manual
L = length of torque wrench. From middle of the handle to the centre of the drive.
A = length of extension (adapter) from the middle of the square drive to the middle of the ring.

So....
For a torque of 30 ft lbs with a 20" torque wrench and a 3" adapter it is...
30 x 20 divided by 20 + 3 = 600 divided by 23 = 26 ft lbs

Simple......

I was wondering how this was done. Thanks for posting. Ken

Danno · Mar 4, 2017

Yes, a very handy formula. Does this mean I have to stop using hammers and ring spanners now?

lcrken · Mar 4, 2017

Danno said:
Yes, a very handy formula. Does this mean I have to stop using hammers and ring spanners now?

Of course not! But equally of course, you must use precision hammers.

Ken

Deets55 · Mar 5, 2017

Tin Man said:
Dean said:

As an aircraft mech I get a bit funny about torquing bolt and nuts. I always torque..... More because I love using my toys. Torquing is so satisfying....

I have been trying to find some adapters. They have a 3/8 square drive one end and a ring spanner on the other and about 2" long, but am having trouble getting whitworth sizes. I know we used to have them for doing rolls Royce dart engine assy. But not many around now. May have to make some up out of a whitworth ring spanner. Trouble is can't even get a spanner here. :? (UAE) they seem to think whitworth is a brand???? No sir we don't have Whitworth brand, how about these Chinese made spanners.

Anyway back to to torque settings using an extension. Just simple math.

R = T x L divided by L + A
Where:
R = corrected torque
T = actual torque from the manual
L = length of torque wrench. From middle of the handle to the centre of the drive.
A = length of extension (adapter) from the middle of the square drive to the middle of the ring.

So....
For a torque of 30 ft lbs with a 20" torque wrench and a 3" adapter it is...
30 x 20 divided by 20 + 3 = 600 divided by 23 = 26 ft lbs

Simple......

Click to expand...

I was wondering how this was done. Thanks for posting. Ken

Good info Dean,

Just to add to this information. That applies if the extension and T W are in a straight line. The numbers will change as the angle changes. Once you get to 90 degrees there is no multiplyer (sp?)

Pete

torquing Head bolts

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