[Fot] FW: Fwd: Crown and pinion gear break in

Tue Sep 11 13:12:12 MDT 2018

FOT:  forwarding the email below from Houston Club member Mike Rouse who is not on the list.

Mike Hado

From: Mike Rouse [mailto:mtrtrain at aol.com] 
Sent: Tuesday, September 11, 2018 10:23 AM
To: mhado at att.net
Subject: Re: [Fot] Fwd: Crown and pinion gear break in

Thanks, this write up is interesting. I have read the same notes about the reference to the measurement from the carrier/bearing center line to the back of the pinion head.

The manual does indicate how to interpret the stamping on the top of the head. ‘N’ means normal, +/- number indicates what to adjust the pinion set too.

The factory installed a shim between the pinion and the head bearing to adjust the center line to top of pinion measurement based on ‘N’ or the +/- #.

Of the diffs I’ve rebuilt I’ve found the +/- # and one with ‘N’. I’ve also measured the head shim thickness and pinion head thickness.

The measurement I make using a pinion setting tool from Jegs is critical, so far when I’ve installed new bearings and the original head shim, I’ve been able to set the pinion height as I found it.

The follow up check is to blue the gear mesh after first making sure the back lash is within spec (.004 to .006).

None of the normal parts houses sell this shim, the shim they sell goes behind the bearing race. The head shims I’ve measured has varied in thickness from .037 to .042.

Head thickness also has varied from 1.286 to 1.311.

The other variable, which I haven’t measured, would be the dimension to the race seat from a reference point which also could be a variable (cover gasket surfaced at the mounting surface or from the front support bar).

When these were built 40 plus years ago the factory had method that’s not described in the manuals. Not having bought a ring and pinion set yet, I’m wondering what instruction one would get. What I’ve read on line about current methods, instructions would be provided on how to set the pinion in relation to the carrier line as that’s how the gears were ground together to make a matching set. This would apply to Ford, GM etc.

Pass this on to those in the email thread if they’d like to pick my brain.

Mike Rouse

mtrtrain at aol.com

Sent from my iPad

On Sep 11, 2018, at 8:50 AM, M&M Hado <mhado at att.net> wrote:

Mike, you might find this thread interesting.

Mike

From: Fot [mailto:fot-bounces at autox.team.net] On Behalf Of John Styduhar via Fot
Sent: Monday, September 10, 2018 2:10 PM
To: Bob Kramer
Cc: Triumph 'Friends of Triumph
Subject: Re: [Fot] Fwd: Crown and pinion gear break in

I looked at my TR3, TR4/4A, and TR250/6 shop manuals, and all of them show the same factory tools to set the pinion depth measuring to the TOP of the pinion head.  So why do the TR3 and 4 manuals have a rear axle illustration that shows the critical measurement to the BACKSIDE of the pinion head??  Is the length of the gear on the pinion the same length regardless of ratio?  

<image001.png><image002.png>

On Mon, Sep 10, 2018 at 9:43 AM Bob Kramer <rkramer56 at gmail.com> wrote:

Len Renkenberger wrote an article a long time ago for the 6-Pack newsletter showing how to do this without the factory tools, using polished bar stock to set up to measure pinion depth. I've used his techniques for years with great success.

Bob Kramer

On Sun, Sep 9, 2018 at 7:06 PM, John Styduhar via Fot <fot at autox.team.net> wrote:

Barry, when you are measuring TR pinion depth, where are you measuring from and to?  The TR3 manual only has the dimension from the front face of the pinion to the center of the ring gear which would be impossible to measure directly with the pinion gear installed.   

On Sun, Sep 9, 2018 at 5:28 PM barry rosenberg <britcars at bellsouth.net> wrote:

There is a factory set of tools that one uses to measure pinion depth before taking a diff apart. Then you set the new pinion at the same depth plus or minus the number on the gear.

Barry

  _____  

From: John Styduhar via Fot <fot at autox.team.net>
To: Greg Blake <gblake58tr3 at icloud.com> 
Cc: Triumph 'Friends of Triumph <fot at autox.team.net>
Sent: Sunday, September 9, 2018 5:12 PM
Subject: Re: [Fot] Fwd: Crown and pinion gear break in

The "92" is the "matched set" number and should correspond with the set number on the ring gear  The other number is the difference in pinion shimming from the "normal".    Haha, what is normal?

On Sat, Sep 8, 2018 at 12:33 AM Greg Blake via Fot <fot at autox.team.net> wrote:

Ok guys and gals. 

Here is a pic of the new pinion head What do I do with the number on the pinion head? 

Error! Filename not specified.

Thanks. 

Sent from my iPhone

On Sep 7, 2018, at 1:07 PM, Bob Kramer <rkramer56 at gmail.com> wrote:

I have a 4.88 ring and pinion in a box. My Triumph club is running the VTR National near Austin next year and I've been volunteered to head up the autocross. I think I'll build a diff with it and put it in the Beandito, and sell tickets! 

Bob Kramer

On Fri, Sep 7, 2018 at 8:37 AM, barry rosenberg via Fot <fot at autox.team.net> wrote:

Wasn't this the new set of gears? If so, they were new old stock from England. They once belonged to Jim Ealy, who owned a black, 1966 TR4A race car. I bought his junk yard to get his race car and the gears were new in the box. I knew him since 1973 and he had the gears then. I had them until recently. I would not think that back then there were cheap reproduction gears available. He had 4:11, the 4:55 and 4:88 (great fun but useless). The 4:11 went in the car when I sold it, the 4:88 were put in a locked diff and played with on the street; the 4:55 sat on a shelf for all those years. If the diff still had fluid in it, then it has to be improper set up, unfortunately.

Barry

  _____  

From: Greg Blake via Fot <fot at autox.team.net>
To: Fot <fot at autox.team.net> 
Cc: fot <fot at autox.team.net>
Sent: Friday, September 7, 2018 6:14 AM
Subject: Re: [Fot] Fwd: Crown and pinion gear break in

Thanks guys for all the feedback. 

So far I have only put the car in the air and pulled the cover. There is ample evidence of excessive heat so something went wrong with my setup. 

I might get the chance to pull it all out of the car and take some measurements on Sunday. Once I do, I’ll share my original setup notes and what I measure upon disassembly.

On a related note. I ordered a new gear set from Rimmer on Monday and it arrived in Austin today, standard shipping. Amazing. Way faster than some of our domestic suppliers. 

This new gear set was supplied by Bastuck. Hopefully lasts a little longer.  

Sent from my iPhone

On Sep 6, 2018, at 7:41 AM, Rick Parent via Fot <fot at autox.team.net> wrote:

Looks like the pinion was way to deep.

On Thursday, September 6, 2018 6:38 AM, Bill via Fot <fot at autox.team.net> wrote:

I doubt if a break-in procedure could have prevented failure, but as Marcel says, checking the temperature of the diff could have stopped the damage. The likely culprits are incorrect engagement or bad parts, but anything that heats the gears enough to cook the oil off the parts will kill the gears. I had a close call with one of the gear sets I use. Apparently I screwed up somewhere in checking fit—when I pulled the rear end to assess the problem there was no backlash. I have a huge finned differential cover so checking temperature doesn’t help, but I could feel the car slowing quickly between shifts. Fortunately I wasn’t doing my usual clutchless shifts and noticed the sudden deceleration every time I disengaged the clutch. The gear teeth were slightly blued and the oil smelled like a cesspool, but the gears were still usable once I did the setup properly. 

Bill

> On Sep 5, 2018, at 1:48 AM, van.mulders.marcel--- via Fot <fot at autox.team.net> wrote:
> 
> 
> 
> ----- Doorgestuurd bericht -----
> Van: "van mulders marcel" <van.mulders.marcel at telenet.be>
> Aan: "Greg Blake" <gblake58tr3 at icloud.com>
> Verzonden: Woensdag 5 september 2018 10:47:59
> Onderwerp: Re: [Fot] Crown and pinion gear break in
> 
> I think it is good measure to check the heat of the differential casing after a few laps when the pinion and crownwheel are freshly mounted : when the casing gets very hot, something is wrong : or the parts are bad or they are mounted not correctly
> There are at least 2 manufactures of the TR parts, I forgot about the names. As far as I know, used original parts are running cooler than some of the aftermarked parts. How was the noise of the diff? Did you notice the smell during the first laps?
> Marcel
> 
> ----- Oorspronkelijk bericht -----
> Van: "fot" <fot at autox.team.net>
> Aan: "fot" <fot at autox.team.net>
> Verzonden: Woensdag 5 september 2018 03:25:39
> Onderwerp: [Fot] Crown and pinion gear break in
> 
> I would love to here the FOT experience in breaking in new differential gears. What has worked well for you in the past?  
> 
> Last weekend, I was running the TR3 at Hallett with a brand new 4.55 gear set and it failed. I probably got 30 laps total in 4 sessions on track. I did not think to follow any set break in procedure with the gears and I am wondering if that is why they failed. 
> 
> I am interested in the lists experience with brand new or new old stock ring and pinion break in. 
> 
> Here is a pic of the failed set. 
> 
> 
> 
> [image/jpeg:image1.jpeg]
> 
> 
> 
> Sent from my iPhone
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