[Fot] Fwd: Crown and pinion gear break in
John H. Hasty
jhasty at mhc-law.com
Mon Sep 10 17:31:02 MDT 2018
John, as you so eloquently said once before, “class dismissed”
Sent from my iPhone
On Sep 10, 2018, at 7:20 PM, Robert Lang via Fot <fot at autox.team.net<mailto:fot at autox.team.net>> wrote:
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
On Monday, September 10, 2018, 7:08:31 AM EDT, John Styduhar via Fot <fot at autox.team.net<mailto: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<mailto: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<mailto:fot at autox.team.net>>
To: Greg Blake <gblake58tr3 at icloud.com<mailto:gblake58tr3 at icloud.com>>
Cc: Triumph 'Friends of Triumph <fot at autox.team.net<mailto: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<mailto: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?
[image1.jpeg]
Thanks.
Sent from my iPhone
On Sep 7, 2018, at 1:07 PM, Bob Kramer <rkramer56 at gmail.com<mailto: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<mailto: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<mailto:fot at autox.team.net>>
To: Fot <fot at autox.team.net<mailto:fot at autox.team.net>>
Cc: fot <fot at autox.team.net<mailto: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<mailto: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<mailto: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<mailto:fot at autox.team.net>> wrote:
>
>
>
> ----- Doorgestuurd bericht -----
> Van: "van mulders marcel" <van.mulders.marcel at telenet.be<mailto:van.mulders.marcel at telenet.be>>
> Aan: "Greg Blake" <gblake58tr3 at icloud.com<mailto: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<mailto:fot at autox.team.net>>
> Aan: "fot" <fot at autox.team.net<mailto: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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