[Fot] IRS Diff Cover

Sat Aug 13 19:41:42 MDT 2016

I just had to tear this diff down due to a broken output axle flange. It broke at the typical stress point at the keyway when the clutch started acting up (grabbing) and that put too much instant torque thru everything...yeah the hip bone connected to the ... The diff gears and bearings were all in great shape,  the pattern looked good and the clearances were spot on. Even the Detroit locker looked good. So, who has installed a cooler on their diff, and how did you route it? The pickup part should be pretty simple, but I don't know whether to just reintroduce the oil back into the diff at some recess, or should it be aimed on the ring or pinion gears directly? I can see plus and minus aspects to each style of setup.
Anyone have good empirical evidence for either?
What sort of pump did you use?
What sort of cooler did you use...radiator style matrix or just  a tube with fins attached (like a power steering cooler)?

Never considered cool myself...
Nick in Nor Cal

-----Original Message-----
From: Marcel Van Mulders <van.mulders.marcel at telenet.be>
To: malaboge <malaboge at aol.com>
Cc: fot <fot at autox.team.net>
Sent: Fri, Aug 12, 2016 12:41 am
Subject: RE: [Fot] IRS Diff Cover

Some years ago, I tried a new 4.33 pinion and crownwheel : after a road test, the differential housing was already very very hot. No way to race with that. It was installed correctly and running quiet.Returning to the original 4.1 pinion and crownwheel in the same casing and the same LSD solved this problem. The temperature of the diff is a result of how much heat is generated and how much heat is transferred to the air. Probably an overheating diff can also be caused by too much heat that is generated? LSD of course, but also the heat generated by the pinion and crownwheel because of some fault of the parts or the installation.
Marcel

Van: Fot [mailto:fot-bounces at autox.team.net] Namens malaboge at aol.com
Verzonden: woensdag 10 augustus 2016 05:37
Aan: pvucinic at netspace.net.au; fot at autox.team.net
Onderwerp: Re: [Fot] IRS Diff Cover

Nope, no chance of the exhaust...or anything else that might be hot back there. The heat looked like it came from the diff cover out to the poly bush. The bush was melted the most on the back edge where the cover had the biggest mass next to the bushing.
And this is with a Detroit locker, no heat building clutches inside!

-----Original Message-----
From: Peter Vucinic <pvucinic at netspace.net.au>
To: malaboge <malaboge at aol.com>
Sent: Tue, Aug 9, 2016 5:45 am
Subject: Re: [Fot] IRS Diff Cover

Wow! Melted poly mounts! Never seen that before! Sure it's not the exhaust systems proximity to the differential casing that's adding to the equation?

Regards
Peter Vucinic

On 9 Aug 2016, at 11:55 AM, malaboge at aol.com wrote:

Oh I'm so jealous of that finned alum diff cover!
BUT, a more practical question...do you think the most oil capacity, or directed internal oil dispersion is more important. (Already using RedLine heavy shock proof oil).
Some history...
The Duke of Oil, our 4A has melted a set of the poly mounts (see a previous pic someone else submitted...same deal here) in  a normal sprint race. So, diggin thru the pile-o-parts I find I have an early one piece TR6(?) diff cover that is pretty much a square reservoir in the back (the oil reservoir area looks about like the reservoir on the 2 piece 4A diff cover), and another later (?) one piece cover that directs the oil flingin around in the diff toward the ring gear and has more fins on it. However, the later more heavily finned unit holds about 8 ounces less fluid, but it directs the oil directly onto the gear and has those additional fins.

I would really like to skip the oil pump and cooler setup in the back of the car, but may have to go that way anyhow.

BUT,
Has anyone had any experience with running the later, smaller oil capacity but more finned and directed oil units? And how would it compare to the larger open chamber cover?

If not, who has installed a pump and cooler back there? What did you use for a cooler and where did you put the outlet and inlet on the diff...and why?

Usually in hot water myself...this time oil!

Nick in Nor Cal

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