wheezy
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| posted on 24/4/07 at 03:10 PM |
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Diff bolt TQ ?
I am about to change my sierra diff and I have lost the TQ loading figures for the drive shaft and prop shaft bolts . Can any one remember? Cheers
Dave
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Mr Whippy
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| posted on 24/4/07 at 03:13 PM |
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man your all so professional, I just tighten stuff till it feels like it’s just about to snap 
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balidey
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| posted on 24/4/07 at 03:26 PM |
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quote:
Originally posted by Mr Whippy
man your all so professional, I just tighten stuff till it feels like it’s just about to snap
I was told to tighten them until they snap, then back it off half a turn
Sorry, we're not helping are we. But can you get to it with a torque wrench?
[Edited on 24/4/07 by balidey]
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flak monkey
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| posted on 24/4/07 at 03:30 PM |
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Prop to diff bolts are 45lbft from memory.
Sera
http://www.motosera.com
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BenB
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| posted on 24/4/07 at 03:43 PM |
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FT every time
(F'ing tight)
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goodall
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| posted on 24/4/07 at 03:51 PM |
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80 Nm for side shaft cv (from haynes manual for audi 80,90 and Coupe{has the same joints})
and
60 Nm for the propshaft uj (from haynes cortina manual for the propshaft, might be the same since its a ford)
putting them so tight they are about to snap is wrong thing to do as you lose all the elasticity, thats the idea of backing them of 90 degrees so that
there still is some i believe
but personally i eould just put them nice and tight as they are very strong bolts normally but not so tight that your swinging on them
[Edited on 24/4/07 by goodall]
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NS Dev
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| posted on 24/4/07 at 04:13 PM |
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OK, if you want to get technical............................
If you tighten them till they just start to give then that is the highest clamping force it is possible to exert with that bolt, but it is then scrap
if removed or backed off, as you have tightened it past its yield point, into its plastic strain region.
if you look at a stress strain curve for steels, (youngs modulus chart) you will see that it extends upwards at a gradient, then flattens off, before
a further upwards brief stint, then the steel fails.
The highest point on the graph is the highest stress, i.e. the maximum load it will take, and is beyond the elastic limit (the first flat bit of
graph) and into the plastic deformation region.
"Torque to yield" bolts commonly and incorrectly called "stretch bolts", are torqued until they are in their yielded
condition, hence the need to replace them if they are ever undone. (i.e. commonly applicable with cylinder head bolts)
IN ANSWER TO THE ORIGINAL QUESTION.............for the driveshafts:
The manual suggests 45NM, but I usually go to 50NM (ok if you are using decent quality 12.9 class capheads like Unbrako ones) as they tend to work
loose not far below the book torque figure.
I have never had one come loose that has been washed in solvent, (holes washed with solvent too) then lightly dabbed with gear oil under the head and
on the thread, then torqued up, and that is in 4 years of racing with a locked diff and pretty fierce car.
[Edited on 24/4/07 by NS Dev]
[Edited on 24/4/07 by NS Dev]
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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wheezy
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| posted on 24/4/07 at 04:46 PM |
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Thanks guys. We got there in the end
The drive shaft bolts are 12.9 cap heads which were torqued to the right value when I first fitted the diff. They have been on for a year and were
still F*** stiff to remove.
My wrench would probably snap before the bolts
Dave
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goodall
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| posted on 24/4/07 at 06:49 PM |
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yea hah, thats exactly pretty much what my dad told me the other night when i asked about the head bolts on a k-series
i did read 45Nm in the manual for the audi but that was for the 4 cylinder models so i qouted the one i believe to be safer
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NS Dev
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| posted on 25/4/07 at 11:48 AM |
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The higher value would be for the 108mm cv's (the smaller ones most use on here are the 100mm ones like the 4 cyl audi ones)
The 108mm ones use an m10 x 1.25 bolt, not an M8 x 1.25, hence the different torque
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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