So I'm refitting the preasure plate to the flywheel, the book says 2.5kg/m or 18 ft/lb
My tension wrench dosn't have kg/m it has newton meters (same thing ?) or ft/lbs so I'm using that but it only has markings down to 22.1 ft/lbs, so I set it a little below that however I need to put a hell of a lot of preasure on it and it still dosn't register, I'm thinking that the t/wrench is stuffed but to check it I set it back at 88.5 ft/lb and it "clicks" it easy. Am I reading the scale wrong? can I just do the preasure plate bolts up tight (do they realy need to be tensioned acuratly?)
Please answer AFTER the laughing is finished.
Thanks
Don

there are 10 newtons of force in a kg.

If you wanna be really specific, 9.81 newtons per kg of mass given Earth's gravity at sea level lol.

so 2.5kg/m is approx 25 newtons/metre (25 N/m)

Ok, as usual some good advise there, and I now know why it takes less force to "click" the t/wrench at the 22 mark than the 88 mark, on this t/wrench once the tension is set lower than the last mark then it no longer operates as a t/wrench, so that bit is solved. The book says to set the bolts at 2.5 kg/m, so close enough to 25 Newton-metres as noted by bajachris88, my t/wrench only goes down to 30 Newton-metres (3.06 kg/m) would that be close enough.
Yours in paranoia
Don
Oh. and my apologies to Mr. Newton, in my bewilderment I had forgotten that "Newton" was a persons name, high school was a long time ago , rest assured that I will not forget again, and the point about cleaning and lubricating the thread and the lbs/ft are also noted.
Thanks
Don

So at 30 Newton-metres I reckon I could tighten them tighter by finger, just dosn't seem tight enough, maybe I should stick to being a chipie

Theoretically, all bolts should be tightened with a tension wrench, but how tedious is that?
Most people simply use the tension wrench for critical stuff like head studs etc.
On VW's, however, a lot of tensions are much less than other makes.
So I use a tension wrench a lot more when working on them.

One day, when fitting an aircon to a new mitsubishi, I checked all bolts with a tension wrench after tightening by feel out of curiosity.
The destructions had all the bolt tensions in it and all but one (the 4 compressor bolts) were within spec.

Also be aware that tension wrenches can go out of whack and should be checked periodically.
The ones that go click have an internal spring and should be completely set to zero when you finish with them.
Store them with pressure on the spring and it will change the reading.

Thanks Phil, I'm doing a few other things B4 I put the motor back in so it's still hanging in mid air, I'm thinking I might bump the tension up a bit as it just dosn't seem tight enough, surely a bit tighter can't hurt,(I hope)

Hi Donn

first , there are NO dumbo questions...

We all had to learn sometime... and most of Us are still learning.

I probably would have just used a socket and breaker bar Donn
and done it nice and tight...

which isn't as tight as using a big long tension wrench..

another way is to cut a spanner in half.. and use your left hand

only joking.. as I do have a couple of half spanners but they are used where the longer one wouldn't fit..

I've only got a big long torque wrench too.. lol

LEE

Hi Lee.
Unless it is a ratcheting torque wrench do not use it in the reverse direction at all. Even the ratcheting wrenches are designed to tighten left hand threads. I calibrate torque wrenches as part of my job and have seen some wrenches in a bad way after being used the wrong way.

Cheers

You should buy a small torque wrench. I recently ordered a 3/8 inch from amazon.com and had it delivered for less than $30.

Cool, thanks modulus, so I think I'll get a new (smaller) tension wrench and do a double check, I havn't gone any further with it, maybe it would be a good idea to get new bolts, whatcha reckon / advise.

I've had to do a bit of research into bolt design, and it was fascinating. Short answer is torque is a very poor way to measure bolt force. We tested the bolts on a DN750 flange, and to get identical bolt force, the torque varied from 170 Nm to 540 Nm. IIRC about 80% of the torque goes into overcoming friction, the rest into bolt stretch.
The Ajax Fastener handbook puts the accuracy of torque wrenches at ±30%, which is a big improvement over operator feel at ±50% but still nowhere near accurate.
I would aim to get reasonably accurate, but don't bust a foof foof valve aiming for perfection.

just knew I should have stayed with being a chippie, drive a couple more nails if it dosn't seem good enough.

Excellent info waveman1500 and volumex

all makes sense too...

and what about a dry bolt and a lubricated bolt??

We all know why they don't make 10mm spanners 500mm long don't We??
as You would be snapping some bolts off..lol

I usually use new 8.8 or 10.9 hi tensile bolts on My beetle..

I used zinc plated hi tensile bolts for all My mud guard bolts,,
lol with never size...

LEE

The difference between a dry and lubricated bolt is reasonably significant as well. It's listed in engineering manuals and such. Just for example, I quickly looked up a table of calculations on a bolt supplier's webpage. For a 3/4" bolt to be at optimum tension, they calculated a torque value of 409ft.lb dry, 450ft.lb zinc-plated and 205ft.lbs waxed/lubricated.

http://www.zerofast.com/torque.htm 

As volumex said, applied torque is such a rough estimate of bolt tension that it's really only good enough to be used for non-critical applications. For a joint where the bolt is tensioned to near it's yield point, you would use a torque+angle spec at a minimum, or ideally you would measure the actual bolt stretch as you would on a con-rod bolt.

At a gasket makers seminar in the 90's, we were told and shown, the clampforce is changed by a factor of 7 between a dry bolt and a properly lubricated bolt at the same torque !!!!! Lube, lube, lube.......

Having said that though, most bolt torques in car manuals are quoted dry, so they should be tensioned dry.