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Measuring pinion preload M86 differential


XEESPT

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  • Member For: 12y 8m 1d

Hi All,

I'm in the middle of installing new bearings and a truetrack torsion center into my spare M86 IRS diff housing.

I was wondering if someone can give me the nod as to wether the method I'm using to measure the required drag force on the pinion is correct.

The FWM calls for 1.4-2.4 nm

 (12.4-21lbs) pull on the pinion with new bearings and new seal.

(It doesn't state where I'm pulling from)

I've threaded a cord through the output flange bolt holes and have coiled it around the flange shaft.

I've got a digital spring scale to measure the required force, I'm just unsure as to wether I can take my measurements directly wrapped around the flange and pulling through or wether I should be pulling from a pre measured length of bar?

I had planned on taking 3 readings pulling clockwise and 3 anti clockwise with this method and just working an average out from there?

I've tried to attach  a few images to show how I have it setup for the measurement but my photo images appears to be to large?..

Will I get a correct/accurate reading using the above method?

Cheers

XEESPT...

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  • Puff
  • Gold Donating Members
  • Member For: 9y 10m 12d
  • Gender: Male
  • Location: South Australia

Dial style torque wrench is what you want.

 

If you wanted to use string and a spring gauge, measure the old one first, just the pinion with no diff, then set up your new one to that or a bees dick tighter. That way you can place the string in the same location to have an apples to apples comparison.

 

Only measure the force to keep it moving, not how much to get it started.

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  • Member For: 12y 8m 1d

Hi Mate,

Yeah it's all been stripped down and I only have the pinion installed at the moment with the new bearings and seal.

The initial measurement before pull down was only around 4lbs  as the pinion bearings where worn and it had "air bearings".

The pinion was marked in relation to the flange and also to the crown wheel so it goes back to original orientation.

As it has new bearings in it the FWM calls for around 12.4-21 lbs I'm just wondering where I should be pulling from?

I've seen some take it directly from the flange itself and some from a pre measured length of flat bar bolted to the flange. 

Thanks for your time Mate 

XEESPT

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