[Fot] Final drive (differential) oil

[Enquiries Road & Track]

Agreed!

thats a common "fault" on rear drive cars. we typically get the exh pipe
thermal coated or wrap it in that region



On Fri, Aug 12, 2022 at 7:12 AM Philip Gott <vfracing at aol.com> wrote:

> Thanks, Terry:
> Good advice.
> The situation is not made any easier in my car as the exhaust is only a
> few inches from the differential!  Makes a good case for having the exhaust
> exit out the side!
> Phil
>
> Sent from my iPhone
>
> On Aug 11, 2022, at 5:03 PM, Enquiries Road & Track <
> enquiries at roadandtrack.net.au> wrote:
>
> 
> i offer some comments based on decades of dealing with this issue in lots
> of different race cars
>
> to select the correct viscosity, you really need to know the operating
> temperature
>
> Adhesive temp indicating labels on the outside of the main diff case are
> usually the easiest method. they will give you a good idea of
> whats happening inside
>
> typically, the outer case is a few degrees cooler that the circulating
> oil, so be cautious here as it is most likely a lot "cooler" then the oil
> film between the ring and the pinion at the point of their contact
>
> if you are seeing temps much over 100C on the outer, then the old 90
> weight diff oils are highly unlikely to acceptable
>
> once most 'off-the-shelf" oils get to about 100C, they are starting to
> degrade ,  some irrevocably (ie they are stuffed!!)
>
> once you have an idea of temps , start looking at kinematic viscosity of
> the oil being suggested. simplistically, its this value that allow the oil
> to function as a metal to metal separator and the hotter things get, the
> lower the viscosity becomes, and the lower the chance of it keeping metals
> apart. the various brands of "race oils" can differ widely in this regard
>
> in most modern rear-drive race cars we are using 140 grade purpose-made
> race gear oils, and these have all sorts of fancy additives
>
> microfinishing the ring and pinion gears prior to a diff build, can drop
> working temperatures considerably
>
> hope this helps in some way
>
> Terry
> Australia
>
>
>
> On Fri, Aug 12, 2022 at 12:35 AM Phil Gott via Fot <fot at autox.team.net>
> wrote:
>
>> 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 Gott
>> Red '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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