Torque wrenches and adapters

[koolio]

Everything was going swimmingly on my CB500t engine rebuild until....

I was using a 3/8 torque wrench with several adapters to get to the M10 socket size I have, I set the torque to what the manual said, I was putting in one of the bolts in the lower crankcase and it snapped, I also noticed that despite setting the torque setting very low it seemed to be very very tight on everything I tried to bolt up. It's a Norbar torque wrench not a cheapie and luckily I was able to get the remains of the bolt out of the upper crankcase.

That said I have two questions for everyone.

1) Other than the bolts for the cylinders, head etc. Do you use a torque wrench at all on an engine rebuild or do you just go hand tight? What do you do?

2) I now first hand know using adapters and such is a no no for torque wrenches, if you do use one everywhere what are you doing and what torque wrench are you using to get at the hard to get smaller bolts such as the M10s on crankcases and things?

 

[Nookie]

i use a small 3/8ths torque wrench,minimum setting is 4 ft/lb for the engine bolts on rebuilds.

 

[VonYinzer]

I only use a torque wrench on head studs/bolts/nuts and case bolts if need be. The rest get a dab of LocTite and a "that'll do" tightening.

 

[koolio]

i use a small 3/8ths torque wrench,minimum setting is 4 ft/lb for the engine bolts on rebuilds.

Thats what I have, and according to the manual 21.7 - 29.0 lbs-ft is the setting for an M10 bolt.

I'd snap them all if I tried that. I had it set to 20 and it snapped an M10 bolt in the lower crankcase.

 

[SONICJK]

I'm with Von
Head bolts and can sprocket bolts get the torque wrench, everything else gets the ole calibrated elbow.

 

[VonYinzer]

Are you sure its ft-lbs and not in-lbs?

 

[koolio]

It's lbs-ft for sure. I can only think that I am using so many extenders for length and adapters from 3/8 to 1/4 that it is really throwing the readings out of sync and being much too powerful.

 

[VonYinzer]

It's lbs-ft for sure. I can only think that I am using so many extenders and adapters that it is really throwing the readings out of sync and being much too powerful.

That's entirely possible.

 

[lingo]

Gutentite with a box end wrench or ratchet on everything but head bolts. I have broken off my share of small fasteners with a torque wrench too.

 

[Tim]

Same as every one here - fancy tool on the head bolts and gut check on the rest.

If you have a good torque wrench you should also have a full metric set of 3/8 sockets so you don't have to mess with adapters.

 

[hursty]

It might be worth having the wrench calibrated or check it against another wrench - just a thought

 

[koolio]

If you have a good torque wrench you should also have a full metric set of 3/8 sockets so you don't have to mess with adapters.

You are right I really should.

It might be worth having the wrench calibrated or check it against another wrench - just a thought

You are right of course! But in this case it has been checked and has a certificate.

 

[notlob]

The torque for M10 is right, so your either reading the wrong scale or it needs calibrating. Using the adapter wont increase the applied torque if anything it should reduce it. You should always wind of the tension on the spring before storing your torque wrench or it will effect the calibration over time.

 

[koolio]

The torque for M10 is right, so your either reading the wrong scale or it needs calibrating. Using the adapter wont increase the applied torque if anything it should reduce it. You should always wind of the tension on the spring before storing your torque wrench or it will effect the calibration over time.

Not reading the wrong scale, I always do wind down the tension to the minimum, it has a calibration certificate from last year and has not been used much since I bought it. I did however make one error to all my posts, it is in fact a 1/2 socket, so I am adapting down to 3/8 then 1/4 then using an extender to get to difficult crank bolts.

I can only think it is the long extender and all those adapters some people believe they are a no no either that or the old bolts simply can't take the tension anymore.

Going to be buying a 3/8 torque and sockets before I go on.

 

[notlob]

when you get the sockets try it out buy bolting a couple of plates together and tighten them by feel not with torque wrench. Then try to tighten them with the torque wrench, if it clicks without moving or just tightens a bit then its probably there or thereabouts. Could be that the bolts have been over tightened and distorted beforehand.
Stacking up adapters could cause a false reading but usually not tight enough, the adapters or extensions need to be parallel with the bolt and the torque wrench 90 deg to it otherwise you get a false reading.

 

[Tim]

Bottom line is an M6 bolt (which has an M10 head) can be tightened by hand and should never be more than around 6-7 foot pounds.

 

[koolio]

Bottom line is an M6 bolt (which has an M10 head) can be tightened by hand and should never be more than around 6-7 foot pounds.

This is it thank you, I feel like banging my head with the wrench, indeed they are M6 bolts with M10 heads and so forth I had taken the values in the manual to mean the head size, really elementary mistake. Therefore they are a M6 bolts and 4 M8 bolts at 18.0 lbs-ft max.

 

[notlob]

Bottom line is an M6 bolt (which has an M10 head) can be tightened by hand and should never be more than around 6-7 foot pounds.

If I understand you correctly Tim and that is what the OP is doing no wonder it snapped. The torque setting is for the thread diameter of the bolt not the head/spanner size.

Settings vary dependent on tensile strength, thread pitch and whether hexagon or cap head.
An standard M6 can be between 7.8 an 13.1Nm and a M10 between 38 and 64Nm