diff ring gear pattern

challenger · Post by **challenger** » Sun May 04, 14 9:55 pm

hey fellas, for those who have built there own diffs etc would you be fine with the pattern on these gears ? just fitted a new lsd unit with solid spacer instead of crush sleeve all new bearings, have tryed a few shims under the big pinion bearing and this seems to be the best i,m coming up with, cant seem to match them up level each side, the flash has made the pic look like theres not much tooth contact but i assure there is, back lash is at 8 thou

Guy · Post by **Guy** » Mon May 05, 14 9:18 am

to me it looks good and even Jim nice and central on ramp and slope

Dave-R · Post by **Dave-R** » Mon May 05, 14 11:26 am

Yeah I would live with that Jim.

challenger · Post by **challenger** » Mon May 05, 14 7:07 pm

thanks chaps, even with that pattern it still wines a tad on the over run from 40mph but i can live with that, MOTIVE gears for ya !! take my hat off to anyone that builds diffs on a regular basis seems to take forever to do, even using my 3.73 used gears due to new bearings fitted it throws the contact pattern out not that it was set up correct before !!! , thanks to mick 70rr for on the phone advice for setting preload on them huge side bearings

Dave-R · Post by **Dave-R** » Mon May 05, 14 7:18 pm

I have done it three times now and I found the key to getting it right first time is VERY careful and accurate measuring. That way you can work out the shim thickness needed to match the numbers stamped into the pinion.

The professionals use a special measuring tool but I found I could do it with a vernier and adding all the measurements together to find the pinion depth needed.

Dave-R · Post by **Dave-R** » Mon May 05, 14 7:19 pm

Always put a bit of resistance on the ring when turning the pinion to check the pattern too. That way you make sure you are taking up all the backlash.

challenger · Post by **challenger** » Mon May 05, 14 7:24 pm

Dave wrote:Always put a bit of resistance on the ring when turning the pinion to check the pattern too. That way you make sure you are taking up all the backlash.

yeh did that dave and showed the pattern up a lot more with a little more spread, for the bit of wine there is there aint no way i want to pull it apart again not just yet anyway

might of stood a better chance had i used richmond gears but these have only around 3000 miles on them, trip to dave b,s next for slicks i,m sure you miss all this expense !!

Roger · Post by **Roger** » Tue May 06, 14 9:30 pm

challenger wrote:thanks chaps, even with that pattern it still wines a tad on the over run from 40mph but i can live with that, MOTIVE gears for ya !! take my hat off to anyone that builds diffs on a regular basis seems to take forever to do, even using my 3.73 used gears due to new bearings fitted it throws the contact pattern out not that it was set up correct before !!! , thanks to mick 70rr for on the phone advice for setting preload on them huge side bearings

Ive had this whining issue with Motive gears. Something to do with the machining process, milled not hobbed maybe? Cant remember the details.

Stopped using motive and went back to OE and no more problems.

It might whine a little, but that pic will be fine.

Dave-R · Post by **Dave-R** » Tue May 06, 14 9:41 pm

challenger wrote: i,m sure you miss all this expense !!

Like a hole in the head.

Oh yeah. I had one of those too!

challenger · Post by **challenger** » Tue May 06, 14 9:59 pm

Roger wrote:
Ive had this whining issue with Motive gears. Something to do with the machining process, milled not hobbed maybe? Cant remember the details.

Stopped using motive and went back to OE and no more problems.

It might whine a little, but that pic will be fine.

yeh i read that somewhere too mate, most common gear sets for being a tad noisy, the coast side ended up with a slightly better pattern than in the pic yet still has a slight whine on the over run

challenger · Post by **challenger** » Tue May 06, 14 10:01 pm

Dave wrote:
challenger wrote: i,m sure you miss all this expense !!
Like a hole in the head.

Oh yeah. I had one of those too!

out of interest dave how did you set your preload on them big side bearings as per workshop manual ?? just interseted if theres any other ways it was quite a good learning curve building a diff from a bare casing

Dave-R · Post by **Dave-R** » Wed May 07, 14 8:45 am

Exactly as per manual. Not that I remember what it was now though.

I do remember something about having to torque just one of the bearing cap bolts up to do something? Was that the backlash?

I do remember having to think of ways to replicate the factory methods. Like a two pound bag of sugar on a set length along a bar to check the torque resistance when compressing the collapsable spacer.

I would have to read the manual again to remember what I did.

Philth · Post by **Philth** » Wed May 07, 14 1:19 pm

Hey Jim,

I have just rebuilt a diff too (well, the whole lot - diff, axle, shafts, bearings, seals, brakes, etc.) and I also needed to preload the carrier bearings.

The best method I found after extensive internet research was to position the ring and pinion gears into 'touch', ensuring both side bearings are snug, lock down the non gear facing adjuster ring, then tighten the adjuster on the gear side until the correct back-lash is achieved (regularly spinning the assembly before checking the back-lash with the DTI).

This may seem tight as you do it, but it is effective (and recommended) as the forces in the pinion gear will always try and 'push out' the ring gear, and if the bearings are not properly pre-loaded they will prematutely wear, as will the gear teeth.

For what it is worth my gears also display a small amount of whining but I am hoping this will settle down after a bit of bedding in (I used US GEARS & the contact pattern I have is much the same as yours).

Hope this helps!

Best,

Phil.

challenger · Post by **challenger** » Wed May 07, 14 9:03 pm

nice one phil, the one thing i learned was shut yourself off in the workshop with no one bothering you and you can keep ya head in it and hopefully get it right, gota say i,m glad i used a solid spacer instead of a crush sleeve as the new ones in the rebuild kits require 300-400ft llb torque to crush thats asking a lot from the pinion nut, set the pre load with the solid, loctite the nut and hit it to 150ft llbs, its great being able to do this as you cant with most of the modern sh!t i work on daily