[Fot] Final drive (differential) oil

Thu Aug 11 08:11:32 MDT 2022

Thank you, everyone!
It would seem that lubes designed for the everyday street-driven car aren't up to the challenge of racing our hyping diffs.  I thought the folks at Mobil would have done better, but apparently not enough.  I've taken all your inputs into consideration and going with the Redline Shockproof (lightweight) oil.  I'm also thinking of bolting on the aluminum cover of the 4A IRS diff to get a little extra capacity and perhaps some better cooling, although the added thickness may offset the higher rate of heat transfer through the metal.  Will do the math.
Your insights are much appreciated.
Regards,
Phil GottRed '65 4A, #114

-----Original Message-----
From: Alexandre Camoletti via Fot <fot at autox.team.net>
To: fot at autox.team.net
Sent: Thu, Aug 11, 2022 4:38 am
Subject: Re: [Fot] Final drive (differential) oil

Gents, when heats becomes a problem then you should definitely try the Lucas oils. Measure temperatures before and after the change, the difference is usually quite big !

De : Fot [mailto:fot-bounces at autox.team.net] De la part de fubog1 via Fot
Envoyé : mercredi 10 août 2022 19:25
À : fot at autox.team.net
Cc : fot at autox.team.net
Objet : Re: [Fot] Final drive (differential) oil

Bob you bring up another good point as well, there's a big difference between a 20 minute sprint race & an enduro, the heat is a much bigger consideration...

Glen Efinger

-----Original Message-----
From: Bob Kramer Gmail via Fot <fot at autox.team.net>
To: fubog1 <fubog1 at aol.com>
Cc: fot at autox.team.net
Sent: Wed, Aug 10, 2022 11:51 am
Subject: Re: [Fot] Final drive (differential) oil

Good point Glen. Welding up the center section makes the soft yellow metal cone washers moot.  

I’ve found EP90 GL4 from Car Quest (available from Advance) as a good substitute for StaLube GL4, but it overheats and failed us in endurance racing.  It has always worked in the shorter vintage race, and is cheap enough the drain and refill often. 

Sent from my iPhone

On Aug 10, 2022, at 10:03 AM, fubog1 via Fot <fot at autox.team.net> wrote:

Welded rear gears aren't that fussy about lube, any good hypoid gear oil should be OK;

I usually use 80-90 Valvo in them.

The metal in the sample is a different story, they normally don't "make" any metal in operation.

You'll have to remove the cover & get a visual on things, check the lash, mesh pattern & preloads best possible in situ.

Glen Efinger

-----Original Message-----
From: Philip Gott via Fot <fot at autox.team.net>
To: Friends Of Triumph <fot at autox.team.net>
Sent: Tue, Aug 9, 2022 9:53 pm
Subject: [Fot] Final drive (differential) oil

Amici:

At the risk of opening Pandora’s box, May I ask what gear oil you would recommend for the rear end in my TR4A (solid axle)? I am running Mobil 1 75-140 and found some metal flakes on my magnetic filler plug after Pitt Race. Usually there are some whiskers, but the metal flakes are concerning. The rear end is a welded diff carrying a relatively new (3 seasons) 4.1 gear set.  I have yet to pull the cover. Backlash seems “normal.” The rear end was set up by Quantum Mechanics whom I trust.

What do you all run for oil (brand and viscosity) and what is your experience?

Thanks and regards,

Phil

Sent from my iPhone

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