Torque wrench advice?

thechangingman

So, last time I snapped a bolt (on my stem clamp) I promised to buy a torque wrench but was put off by the prices and so didn't bother. "I've learnt my lesson and won't be so heavy-handed next time..."

Hmmmm

Today, as I was prepping a Spesh Roubaix for a test ride (on loan from my LBS) I have just sheared off a bolt - d'oh!!!

Please advice me - which torque wrench should I get so that I don't snap number 3?

Thanks.

JRooke

Never ever snapped anything, why are you tightening things up so much? Things really don't need to be as tight as you seem to think they need to be

chrisw12

Follow this link and have a look at the third post down in particular. http://forum.slowtwitch.com/cgi-bin/gfo ... =ASC;mh=25

Make your own mind up about torque wrenches rather than just following advice for the sake of it.

mmacavity

thechangingman

its possible that you have more hands-on experience than most, ... on how tight is too tight.

brettjmcc

I got one recently from CRC that was reduced to £35. It cover 2-20NM. I also have heavier ones for working on cars.

In my experience, having rebuilt many cars and engines and only just starting on bikes.

DO: Use new bolts, use a torque wrench

DON'T: Use old pre-tensioned bolts, use dirty/rusty bolts, think your hand is calibrated to know how much torque you are putting through it (you can vary the load setting depending on the type/length of lever)


For the peole who think they know how tight is tight, I would point to people I know who have engines fail on them because fastners have come undone, because they did them up by hand and 'felt' OK... Sure the loads are higher, but I still see the same principle in operation.

Yossie

Do a search on this here forum and you'll see threads infinitum about tourque wrenches.

Buy one. Read the instructions use it on absolutely everything.

You need 2 -20 Nm for push bikes (apart fron the rear cassette that needs 40Nm) NOTE: That's Nm, not lbs/ft. Completley different. I think 40 lbs/ft will hold an oil rig to the sea bed.

Sealey Draper in the deals they do all the time. Teng. One from CRC as above. B & Q do one. Snap On/Facom (but vvvvvvvvvvvvvvvvv expensive but lovely)

+ 1 for Brett's advice as above - remember the copperslip.

As an aside, they did a test of the "you don't need one - my fingers are calibrated" brigade in a motorbike magazine a while ago: go some dudes who thought they knew best to do stuff up then compared the torques with a newly calibrated tourque wrench.

Out of the 10 dudes they tested, 1 came close - everyone else was miles out or in. No one was exact.

Make of that what you will.

Put it this way - I don't see John McGuiness' mechanic not using one, and he's quite good at bolting things together

chrisw12

Yossie wrote:

Do a search on this here forum and you'll see threads infinitum about tourque wrenches.

Buy one. Read the instructions use it on absolutely everything.

You need 2 -20 Nm for push bikes (apart fron the rear cassette that needs 40Nm) NOTE: That's Nm, not lbs/ft. Completley different. I think 40 lbs/ft will hold an oil rig to the sea bed.

Sealey Draper in the deals they do all the time. Teng. One from CRC as above. B & Q do one. Snap On/Facom (but vvvvvvvvvvvvvvvvv expensive but lovely)

+ 1 for Brett's advice as above - remember the copperslip.

As an aside, they did a test of the "you don't need one - my fingers are calibrated" brigade in a motorbike magazine a while ago: go some dudes who thought they knew best to do stuff up then compared the torques with a newly calibrated tourque wrench.

Out of the 10 dudes they tested, 1 came close - everyone else was miles out or in. No one was exact.

Make of that what you will.

Put it this way - I don't see John McGuiness' mechanic not using one, and he's quite good at bolting things together

As soon as you put copperslip or any other chemical on the bolt the recommended torque can be thrown out of the window. So please explain why you would now use a torque wrench?

brettjmcc

Read this here, ARP explain it pretty well in my opinion: http://arp-bolts.com/pages/technical_installation.shtml

Fundamentally, you should actually lubricate when you install bolts...but then again, some of the stuff I doon American V8s calls for 100ft lbs

chrisw12

brettjmcc wrote:

Read this here, ARP explain it pretty well in my opinion: http://arp-bolts.com/pages/technical_installation.shtml

Fundamentally, you should actually lubricate when you install bolts...but then again, some of the stuff I doon American V8s calls for 100ft lbs

Just taking a few points from my quick read of that article, doesn't the graph imply that unless you use 'apr ultratorque' using a torque wrench for bicycles is a pretty pointless exercise as the variability in preload is very high?

Throw in the fastener surface finish and condition of receiving threads bit as well and the variability goes even higher, it just becomes ridiculous to want to use an accurate device.

Then the bottom bit about torque wrench accuracy...

nferrar

Does anyone know the torque range of the one Aldi have on offer tomorrow? I already have a mid-priced one and £15 seems a bit too cheap if it it's anywhere near accurate but might be worth having it as a backup. I'm assuming it will probably be the higher torque range type designed for cars etc. though

rolf_f

chrisw12 wrote:

Throw in the fastener surface finish and condition of receiving threads bit as well and the variability goes even higher, it just becomes ridiculous to want to use an accurate device...

All true enough. However, even if a torque wrench doesn't deliver meaningful accuracy, it does deliver consistency. You might not know how much you torqued up, but you do know it was the same as what worked before.

Besides, however innaccurate a torque wrench might be at giving a specific torque, it is in a different league of accuracy to the sort of person who thinks they can get it right by feel - the torque wrench is probably wrong, the experienced hand is definitely wrong

rolf_f

nferrar wrote:

Does anyone know the torque range of the one Aldi have on offer tomorrow? I already have a mid-priced one and £15 seems a bit too cheap if it it's anywhere near accurate but might be worth having it as a backup. I'm assuming it will probably be the higher torque range type designed for cars etc. though

Useful for bottom brackets and cassettes only - but worth having for those I reckon. I got one from Lidl and it is very well made. Similar to my little BBB one that does cover the rest of the bike.

lef

the bbb one is great and I just bought a longer silverline one from toolstation for about £20. I only wanted a socket wrench for tightening BBs but saw the torque one cheaply and it seems to be good quality, 28-120nm I think.

Wirral_paul

chrisw12 wrote:

Yossie wrote:

Do a search on this here forum and you'll see threads infinitum about tourque wrenches.

Buy one. Read the instructions use it on absolutely everything.

You need 2 -20 Nm for push bikes (apart fron the rear cassette that needs 40Nm) NOTE: That's Nm, not lbs/ft. Completley different. I think 40 lbs/ft will hold an oil rig to the sea bed.

Sealey Draper in the deals they do all the time. Teng. One from CRC as above. B & Q do one. Snap On/Facom (but vvvvvvvvvvvvvvvvv expensive but lovely)

+ 1 for Brett's advice as above - remember the copperslip.

As an aside, they did a test of the "you don't need one - my fingers are calibrated" brigade in a motorbike magazine a while ago: go some dudes who thought they knew best to do stuff up then compared the torques with a newly calibrated tourque wrench.

Out of the 10 dudes they tested, 1 came close - everyone else was miles out or in. No one was exact.

Make of that what you will.

Put it this way - I don't see John McGuiness' mechanic not using one, and he's quite good at bolting things together

As soon as you put copperslip or any other chemical on the bolt the recommended torque can be thrown out of the window. So please explain why you would now use a torque wrench?

Actually, its generally assumed that lubrication will be used and the specified torque is correct. Dry torquing bolts is very inaccurate and not repetitive (as well as being bad practice). I should know - i spent the morning having to extract a bolt out of a Yamaha R1 bike engine that had seized due to being dry installed. New one installed using the correct threadlock WITH A TORQUE WRENCH.

Halfords are fine for torque wrenches too - especially with all the sales they seem to have. The online reservation system often gives extra discounts over store prices too.

I'll always use a torque wrench myself - especially with all the carbon parts on my bikes. Also ensure the correct lubricants are used as recommended. Copper grease is good for the often removed bolts.