How hot is your differential?

[Beeger]

My restoration, or should I say refurbishing, of 1970 Minnesota GT has progressed to the point that I'm actually spending time behind the wheel getting to know the car. The front end (engine, tranny, suspension) is rebuilt and functioning wonderfully. I have done nothing to the rear end mechanicals other than fill the differential with oil and rebuild the rear brakes. After a mild drive (no more than 45 MPH for no more than 30 minutes) through some hilly terrain I noticed that the differential seemed warmer than I would have thought it would be. Not hot to the point that it would burn skin, but significantly warm to the touch. Is this normal? I have notice a mild "clunk" noise when I take off from a stop at times, especially when turning from a stop sign. I recall reading somewhere that this is "normal". I haven't noticed any other noises from the rear end, but the inside of the car is gutted and it's pretty noisy in there anyway. I suppose an exhaust leak would make it heat up, but I haven't noticed any.

[vikesman101]

Hello Wisconsin (Farve should retire)

I'm in Minnesota (eastern) probably not to far from you.
Truthfully, I have never checked how hot the differential gets on my Opels but if you are sure that the noise you here is from the differential then I would look into it soon. I would think warm to mild hot would be acceptable but hopefully someone on here will shed more light on the subject. I would like to see your car someday and maybe we can hit a few car shows when our cars are done.

Good Luck

Tom (go Vikes!)

[jordan]

Your clunking problem is most likely caused by a worn torque tube donut. Try a search for "torque tube donut" and you should obtain all the information you need. There are 4 rubber components in this area that are replaceable and with all new you will never have the problem again.

Differentials will heat up, This is caused by kinetic energy (parts moving) being resisted by friction and the energy is then transferred into heat energy, The only way this could be a problem is if there are excessively worn components, Too tight of a differential set up, or trashed bearings and bushings. But some heat is normal. Ask your passenger sometime if the tunnel by the transmission feels hot, this is notorious to becoming very warm.