[Fot] Fwd: Crown and pinion gear break in

Thu Sep 13 00:23:13 MDT 2018

Sometimes, I find that it is not possible to get the backlash and mesh pattern right at the same time (on a diff that has not been welded). I go for the correct mesh pattern then, with a backlash that is greater than recommended. Is that only a sign of wear ? 
Marcel 

Van: "fot" <fot at autox.team.net> 
Aan: "Bob Kramer" <rkramer56 at gmail.com>, mdporter at dfn.com, "fot" <fot at autox.team.net> 
Verzonden: Woensdag 12 september 2018 19:22:39 
Onderwerp: Re: [Fot] Fwd: Crown and pinion gear break in 

The pattern is everything when setting gears up, if they don't mesh properly, they're gonna run hot, make noise, and fail. 
There are plenty of photos and illustrations of different patterns on the internet. 
I mix a little injuneers blue in with lubriplate white grease, paint a half dozen teeth or so, and wrench the ring back and forth a few times, while holding the pinion flange for extra preload; repeat 3 or 4 times around the ring. 
I use set-up bearings but it's not unusual to have to make fine adjustments once the good bearings are fitted. 
Preload is equally important, I don't use the pinion crush collar either, I fab a solid collar and fit shims; a case spreader is easier to set the carrier in but I've done many without. 
Once you have everything set, you can put a box-end wrench on one of the ring gear bolts and work it back and forth hard and you can feel when the mesh is nice and smooth in both directions. 
A couple things to watch for, sometimes the carrier will have runout from warpage when it was welded, you'll never get a correct backlash setting or a good pattern all the way around, and I often find the carrier bearing inner races turning on the journal, if not too worn a little loctite is your friend but if that race turns on the carrier it won't live long... 
Glen 

-----Original Message----- 
From: Bob Kramer via Fot <fot at autox.team.net> 
To: Michael Porter <mdporter at dfn.com> 
Cc: Triumph 'Friends of Triumph <fot at autox.team.net> 
Sent: Wed, Sep 12, 2018 8:57 am 
Subject: Re: [Fot] Fwd: Crown and pinion gear break in 

I would add that if you buy the same brand bearing you can grind out the ID of the old races to make it easier to remove them for test assemblies. 

Bob Kramer 

On Tue, Sep 11, 2018 at 2:08 PM, Michael Porter < [ mailto:mdporter at dfn.com | mdporter at dfn.com ] > wrote: 

On 9/10/2018 3:41 PM, Bob Kramer via Fot wrote: 

BQ_BEGIN

I can't answer that but one could measure the dimension of the pinion head and subtract it from the total shown to get the depth you would want. 

Bob Kramer 

I suspect that there are variations in parts due to manufacturing errors, tolerances stacking up, etc. Most of the parts made at the time were not subject to the sort of scrutiny and computer-controlled measurements that are common today (although even that isn't a guarantee of uniformity--I had to redo a bunch of Toyota Supra IRS diffs in the early `80s because the computer that assembled them was misprogrammed and it swapped the shim stacks for the carrier bearings left to right). 

That said, the safest way to get the diff repaired properly is attention to the shims when disassembling, and then putting the shims back in the same thicknesses and checking for the proper engagement pattern. It does require some educated guesswork, and, often, disassembling and assembling a couple of times, but, if the pattern is right, the diff will be reliable. I'd also recommend using hard shims in place of crush spacers on the pinion whenever possible if the pinion originally used those. It also is a bit easier if one uses the case spreader judiciously on those housings requiring same, and doesn't crank it up too much. Spread the case just enough to get the carrier and bearings out. Figuring out the shim packs will be easier. 

Cheers. 
-- 

Michael Porter
Roswell, NM

Never let anyone drive you crazy when you know it's within walking distance.... 

BQ_END

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