FJ40 Diff settings

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Xr246
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FJ40 Diff settings

Postby Xr246 » Thu Oct 23, 2014 8:53 pm

Hi

Im looking for some diff settings for a 1974 FJ40 rear diff. Semifloating axles and no crush tube just shims

Need torque for pinion nut
Pinion bearing preload
Backlash setting
Crownwheel carrier bearing preload

Any help would be appreciated. Hoping to reassemble this weekend

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tgaguy1
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Re: FJ40 Diff settings

Postby tgaguy1 » Fri Oct 24, 2014 6:57 am

Men do not quit playing because they get old.
They grow old because they quit playing.

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SMOKEY
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Re: FJ40 Diff settings

Postby SMOKEY » Fri Oct 24, 2014 9:15 am

Hi taken from Max Ellerys work shop manual, this is for a #70 semi floating 1972--- 1990. Torque for Pinion Nut 181-- 325 ft lb, ** torque nut to the values above and the preload indicated below---- Preload at starting 8--12 in lb. Crown wheel to pinion backlash .006 -- .008in Bearing Cap bolts 58 ft lb. Now this is my way of setting side bearing preload ----- turn side cap adjusters till there is no play in the side bearings then tighten till there is a slight drag on the bearings if you are running big tyres and hard 4WDing you want to stop you crown wheel and pinion from moving out of mesh in other words a preload that is tighter than you would use on a road vehicle . Mind you I have done a diff or two and you get the feel for it.

OLD MECHANIC,

FITZY.

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Xr246
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Re: FJ40 Diff settings

Postby Xr246 » Wed Oct 29, 2014 8:06 pm

Ive put new pinion bearings in and set the up the preload to 10 in pounds no problems at all
Set up my carrier bearing preload to the correct spec with the new bearings no problem
Went to set up my back lash by turning each carrier cap the same way to keep my preload correct but move the crown wheel closer to the pinion.
Got my back lash correct on one tooth, Moved into another tooth about a third of the way round and it was different first tooth was 0.17mm second tooth way 0.25

I went abit over the top and checked every single tooth (took for ever) and I'm getting a range from the tightest being 0.11 to the biggest of 0.27
Most of the backlash is in the 0.15 to 0.23 range with only the odd one being out

The spec is 0.15 to 0.20

Never had this before (but I've never checked every tooth)

Does anyone have any ideas as to why this may be happening?
Warped crown wheel maybe it is 40 years old?

Anyone else ran into this?

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churchill
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Re: FJ40 Diff settings

Postby churchill » Wed Oct 29, 2014 10:23 pm

Yeah had this, you could have a bent carrier, side bearings not seated properly or just need to give the side bearings more preload. Make sure the bearings are all the way home on the carrier. Toyota 8" diffs run 180ftlb torque on the side bearings so a 9.5" should be able to take heaps as well. If this doesnt work check the run out on the ring gear and the carrier with the dti to determine where the issue is.

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