How Do You Torque Inaccessible Nuts And Bolts ?

[rd84]

Hi,

How do I set an accurate torque on inaccessible nuts and bolts ? ie where I can only get a spanner rather than a socket on my torque wrench.

( It's an RD500 crankcase and cylinders - so I'm nervous of getting this wrong )

Thanks.

Cheers

Paul

[Damnthistinleg]

A simple spring balance on the end of the spanner works for me but you need to factor in the length of the lever and adjust the force as necessary.

[marcaztls]

You use a crow's foot socket attached to a torque wrench if there's enough room for one of those.

[Mahatma]

Gefuhlen

Edit:Find a nut which exceed the torque setting ,and tighten that a fair few times until you recognize the force needed,and aply that to said bolt.

[Simbo]

Tighten till it strips. Then back it off half a turn :-)

[Timbo S2]

Isn't there a torque wrench in the mag this month that incorporates a spanner type end for this kinda thing?

[Evilchicken0]

Isn't there a torque wrench in the mag this month that incorporates a spanner type end for this kinda thing?

Its from Venhill but it looks like a touque wrench with a set of crows feet

[rd84]

Hi,

Thanks for your tips and suggestions above - I'll look into them - except for "tighten till it strips, then back it off half a turn" which I've tried several times with great success in the past

In this case I'm really most nervous about distorting the crankcases.

Cheers

Paul

[Mark/Foggy]

Use caution when adding crows feet to a torque wrench. The additional length means that you'll end up setting a slightly higher torque.

You could visit some where like http://www.stahlwille.co.uk/online-catalogue/

and enjoy torque wrenches where the ratchet head pops out and you can fit individual crows foot inserts that will end up with you blinding yourself with the shere level of tool porn that can be investigated on the interweb.

Ask me how I know.

I now own a matching set of 3 Norbar torque wrenches, purchased this year. !/4, 3/8, 1/2, total cost on ebay getting lucky with auctions and being patient - about £250.

I have contacts inside of Stahlwille's UK distributor. If that lot fell out of the back door I'd be looking at 1k. Go digital I'd be looking at 3k.

Gulp.

[rd84]

Hi Mark,

I'm spending a fortune on the RD500 project at the moment - I don't want to spend too much on the tools but equally I know buying too cheap is not a good idea - I know the danger signs though when the tools start looking more sexy than the bike parts !! - I think I'll buy some Sealey crows feet sockets that I saw on Ebay - hopefully good enough for occasional use - I'll try and figure out a torque correction allowing for the leverage arm of the crows foot - presumably..........

Revised_Torque_Setting = Torque_Setting - [ Torque_Setting x ( Torque_Wrench_Centre to Crows_Foot_Centre ) ]

Keeping to either Feet or Metres as required when measuring the extra arm of the crows foot ? - I suspect we're talking a very small change ?? - Perhaps 5% or so ??

Cheers

Paul

[Mark/Foggy]

Gold star, you're awake then.

Probably inconceivable that you'd need to do this sort of calc. for a clutch hub centre nut or a front sprocket nut. 'Cause you're on large figures and the typical torque range accuracy of a decent calibrated torque wrench is +/-2%, plus the ability of the manufacturer to predict the quality of supplied components could be variable. In truth he comment about be ware of crows feet is probably being over cautious.

Likely you're down to 6-25 Nm on an m6/M8 fastener.

I'd actually stop getting too pedantic about it in this range. There's a lot to be said for feel and bear in mind that spanners and hex keys are usually a length that allows you to develop a feel for what is 'right'. Same hand position on tool. same force applied, correct result. Always be aware though that these tools were designed to bolt steel together, soft touch for aluminium.

Correction factor is probably slightly more complicated and may require you taking the torque wrench to pieces to get it perfect. I'm assuming that you'll not go this mad.

Roughly though

X = ratchet head centre to Wrench pivot / crowfoot centre (variable on fastener AF) to Wrench pivot

Where

X = correction factor

then

Torque wrench setting is

= X * suggested torque figure.

I've done it this way around so that you run around with the torque wrench in it's lower range as they're more usually accurate if the springs are less tight.

Hope this manages to persuade you that 2% accuracy is more that good enough for every application.

[rd84]

Hi Mark,

I'm convinced ! - although it is a very rare day when I'm accused of being awake ! - thanks so much for an excellent explanation. I know I'm being too pedantic - but its the first engine re-build I've ever done and I suppose I'm being over cautious - I just don't want to get it wrong on a rare, old and very expensive engine.( Its also a two-stroke which means it will probably self destruct if I look at it wrong anyway ! )

I saw a couple of useful tips for those who don't want to do the calculations or as you point out when the calculations aren't really necessary - put the crows foot at 90 degrees or if in line with the torque wrench move your normal grip position on the handle forward by the same amount as the length of the crows foot extension.

Anyway I'm going to get on with this job without correction when the crows foot sockets arrive.

One additional question - if I replace a steel fastener with aluminium - for example the engine side cover screws what torque settings do I use compared to those stated for steel fasteners ? - is there an accepted correction factor ?

Cheers

Paul

[Mark/Foggy]

^ Which is a good warning to people, try using a torque wrench at least once in your lives. 6 Nm is truly not a lot though I've got to confess to preferring 8Nm if I'm wanting things to stay put. Good ballpark for M8 is 15Nm on something like a fork stanchion (Though please don't use Aly Fasteners here), engine cases I'd go more like 12.

Beware you can quite happily push 20Nm down a Ball End hex key using the ball as the driver. Not good for fasteners, you'll wreck the heads quick smart if they're Ti let alone Aly.

For me though, if you've got a lot of money invested in an engine build, I'd never fit Aluminium fasteners. They're light for sure and come in pretty colours, but have the life expectancy of lemmings pressed against the edge of a cliff by Jim Davidson with a hard on.

[rd84]

MM and Mark - Thanks for the Advice - I was rather hoping the engine covers wouldn't have to ever come off again since it's going to be a low mileage engine - however since it is a two-stroke ........ I'll keep those steel fasteners handy.

PS:- Never mind torqueing things down I've spent the last several days cleaning up what feels like an hundred threads - every time I look around the engine I find more ! - I'm doing my best to avoid any disasters during the re-build - I just want the final build to go smoothly after a lot of aggro.

Cheers

Paul

[Mark/Foggy]

Standard style cordless drill, cheapo will do, set on minimum torque setting. fit a tap, Fluted, if you can borrow one, Greased. Hand start it then run it down the thread until it bottoms and then reverse it out. Clean and repeat.

If you really want to go to the next level, run a stone over the case faces, the original thread seats may have pulled up a little.

http://www.ebay.co.uk/itm/SHARPENING-STONE-BOX-Oil-Stone-to-sharpen-Wood-working-Chisels-Tools-/171065421995?pt=UK_Crafts_Other_Crafts_EH&hash=item27d44b30ab

Any dodgy threads, fit helicoil, before you assemble. It's tempting to think you'll do it later, the hole you'll drill with the cases assembled will mean that it will never go out of your mind.

[rd84]

Hi Mark,

I've bought one of those stones to run over the faces - next job after cleaning the threads. I'd read about using a cordless drill - I've got some fluted taps - however I have to say I'm really nervous about using this technique - some of the threads are taking a lot of care towards the end of the thread where I'm using quite a lot of force ( I've used oil rather than grease - is that OK ?) - but just a little twist at a time before reversing then advancing the tap again.

Cheers

Paul

[Mark/Foggy]

I suggested the grease to collect any debris/corrosion which should wind out particularly with a flute.. I'd stop being so nervous, sounds like you're going to the n'th degree.

Paul, stop being too nervous, Monkey Tractor Spanner Fuckwits have built these lumps successfully. You, however, have obviously thought this through.

Now get on with it.

[rd84]

Hi Mark

Good point about using grease to collect the debris - I'll adopt that technique from now on - I'm definitely being a bit of a mother hen with this engine - promise to get on with it

Just waiting for 4 crankcase bolts to be delivered then it can all go together except for the stator which West Country Windings are fixing for me. (Damn - forgot about the powervalves which SEP are fixing ) - I'll hopefully finish off all the threads today and I think the donkey work is then out of the way.

Must say there is something pleasing about doing this engine to a fussy / unnecessary standard - I'll try and post a few progress shots for those who like that sort of thing.

Cheers

Paul