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MG TD TF 1500 - Differential Temperature

After installing 4.3:1 differential gears in my TD & taking initial drives, the temperature seemed too warm, 120 to 135 degrees. Anyone know what is typical temperature for these differentials? I did check the archives & one individual did ask this same question but, no answers.

Pete Ferrari

Pete, are you talking about the temperature of the differential gear lube? Celsius or Fahrenheit?
Bud Krueger

Hi Bud Yes, I measured the gear oil with an old candy thermometer reading in Fahrenheit. By the way I enjoy your website. Looking forward to future additions.
Pete Ferrari

Did you take the temp with the normal gearing? (Never thought to check the temp of my dif oil?)

I also have a 4.3 in my TF. I will check the temp next time I make a run, today I hope. I think that as long as you can hold your hand on the differential case, the temperature is probably not too hot. Did you have a chance to drive your car with the stock diff gears and how do you like the change? Have a good day!

John Progess

At one time I was involved with motorcycle reliability tests. As part of the data collected we measured air temperature about 4 inches above the pavement. 120 - 140 degrees F was not unusual on a sunny day. Your differental temperature seems moderate for well lubricated steel gearing in an underchassis environment. With a proper fill of good quality lubricant I would think the differential would last almost for ever. Just my guess based on related experience.

Jim Haskins

1953 MG-TD
J. M. Haskins

Reply to: G.B., John, & Jim
No, I didn’t check the temp prior to changing to 4.3 gears. The only reason I checked after was out of habit when installing new bearings. I'm still driving short trips & checking. Changed gear oil to a synthetic high temp,high pressure oil but, no significant change.

Thanks to all of you for responding, Pete
Pete Ferrari

Somebody had to say it.....haven't had my temperature taken at my rear end since I was a "wee-lad"....sorry, could not resist the "temp"tation!
David 55 TF1500 #7427
David Sheward

My first thought in checking the temp of a diff was "isn't that being a bit "anal"?"

Gotcha David....

If it is of any interest, I went for a drive yesterday evening in my TD (4.3 diff); it was a warm sunny evening, with the air temperature 24/25 C (75/77 F). I drove long enough, and with speeds over 80mph, to get everything up to temperature. Immediately I returned I measured the following temperatures with a digital thermometer (with a hand held probe).
Engine water 78 C (172 F) (bottom of header tank)
Engine oil 75 C (167 F) (lower side of sump)
Gearbox 54 C (129 F)
Rear axle 46 C (115 F)

(My engine doesn't usually run hot).
Roger Wilson

I am scratching my head as to why anyone would either think of or actually bother to measure the temp of the rear axle oil. What's the point? What temperature is too warm or too cool? If we drive the car in winter conditions should we have to wrap the diff. in a kind of electrical nappy to help keep it warm? If too hot, (whatever that is), must we now consider installing aftermaket oil coolers on the diff?

The thought of having to scrabble about under the car trying to undo the filler nut, hoping oil doesn't slop over me, just to shove a candy thermometer into it to take its temperature seems somewhat esoteric to me.

I have never given it a thought, and I changed my rear ratios to 4.3:1 and shoved a blower on the engine.

Far as I am concerned, as long as the diff. doesn't catch fire, I couldn't care less.
G.E. Love

Thanks for you input I appreciate it. Mr. Love I’m impressed, but I couldn’t understand your comment about “having to scrabble about under the car” when most owners would access the fill plug from the panel door directly above the dif.

Thanks Again Roger, Pete
Pete Ferrari

Pete, interesting check to make -- and good to have some baseline. Hotspot scanning has become fairly common for diagnostic work in industrial environments, both for electrical and mechanical -- seems similar.
D F Sexton

Pete, many thanks for your reply. My car doesn't have an access panel above the diff, so I did have to go under the car, but lying on a piece of carpet with the probe on the end of a lead wasn't that much of a problem. I only measured temperatures on the outside of casings. but I did check in several places. In addition, doing the exercise once for another T type owner did not make it a hardship.
Happy driving, Roger.
Roger Wilson

This thread was discussed between 18/06/2005 and 23/06/2005

MG TD TF 1500 index

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