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[Fot] Fwd: Crown and pinion gear break in

Subject: [Fot] Fwd: Crown and pinion gear break in
From: jhasty at mhc-law.com (John H. Hasty)
Date: Mon, 10 Sep 2018 23:31:02 +0000
References: <7FAC951C-9CE7-49E5-8DCA-37BDD2E7B8E6@icloud.com> <1425223651.1077147502.1536137279966.JavaMail.zimbra@telenet.be> <1518278895.1077153139.1536137336417.JavaMail.zimbra@telenet.be> <C32F1C79-7520-43DA-8280-01E2EAB5C50A@ponostyle.com> <2031959496.408884.1536237686897@mail.yahoo.com> <AE6D512D-2CF2-42AB-BA52-9B1F9F5065C3@icloud.com> <520565677.1085482.1536327452002@mail.yahoo.com> <CABFvdWsbXWYtGnNyspFni8QcX78LjRtr+iKcLy1Ypv7f0QaYkQ@mail.gmail.com> <102B5B39-2FE9-47F3-9924-9EEBC05F08EC@icloud.com> <CAMJWJcEPp_fRgonGoDVaS-BOBA_iXuuRuchyTum1eqBRjHBFeQ@mail.gmail.com> <1149127785.1972619.1536528479495@mail.yahoo.com> <CAMJWJcGpeLhzjpfYP1tUeKz4MBDSVZMRWCnbigB9SYy_WaTzgA@mail.gmail.com>, <1275752650.2214971.1536579990064@mail.yahoo.com>
John, as you so eloquently said once before, ?class dismissed?

Sent from my iPhone


The factory pinion installation uses a dummy carrier that sits in the saddles 
for the differential carrier. This tool holds a dial indicator that you use to 
measure the depth (which is referred to as "pinion head height") . The tools 
that you use for the common diffs have a fixed-length adapter for your dial 
indicator, but these are "too long" for big TRiumph diffs, so you have to 
improvise.

You can also use a home made tool to bolt onto the case using the saddles' 
bolts and a fixed size spacer and feeler gauges (ala Len Reckenberger). The key 
here is that you need to get repeatable measurements to within .001 which is 
tricky.

To your question, John,  you are measuring the distance from the center line of 
the axles to the face of the pinion. The number should be the radius of the 
inside curve of the ring gear (which is roughly 2.35 inches). You do this 
measurement using the dummy carrier or the improvised tool and then shim as 
needed.

I've done a few diffs and always find that adding or subtracting shims is 
needed to get the pattern exactly right after using the Reckenberger method. 
But at least you get in the ballpark!

I hope this helps.

Speaking gear sets, I used a 4.88 for a few seasons of autocross and found that 
first gear was useless and the top speed of just over 80 MPH was "limiting" for 
the autocrosses in my region. I have that set on the shelf and switched to 
4.33's which work awesome for hillclimbs, but still limit top speeds which 
really matters on some hills (like Reading, PA). I'm talking 4 speeds and 23 
inch slicks. For vintage road racing, I switched to taller tires and I had to 
re-do all my gear calculations. That led to my current gear selection which is 
"all gear sets available", 3.45, 3.70, 4.10 and 4.33. I then gear for the track 
based on best guesses. So far, I've been guessing pretty well!

Regards,
Bob Lang



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.



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


________________________________
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?


Ok guys and gals.

Here is a pic of the new pinion head. What do I do with the number on the 
pinion head?
[image1.jpeg]
Thanks.


Sent from my iPhone


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

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


________________________________
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


Looks like the pinion was way to deep.




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

>
>
>
> ----- Doorgestuurd bericht -----
> 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 -----
> 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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