Installed some kind of temp sensor on the rear end and auto tranny?

I have rear end problems every couple of years. I now have a problem. When the rear heats up from some spirited driving and it doesn't take much. I get terrible snapping and popping once I get to my destination and start doing slow tight turns in forward or reverse. In the past it would start out just like this and the posi units always broke within a short period of time. I was told by a forum member that he thought that 4.11's produce lots of heat.

It's a Richmond Gear 4.11 super duty rearend with Toms Differnetial $685 posi unit and custom hardened yokes. Bigger U-joints and bigger half shafts.

I'm using 85-120 weight fully synthetic gear oil with two tubes of posi lube and a antifriction additive.




[Modified by gkull, 3:32 PM 6/14/2002]

 

I know this isn't the answer your looking for, semis that I've driven have had both front and rear differential temp guages on the dash. But I can't remember what the temp range was. Wouldn't an oil temp gauge work?, or doesn't it have enough temp range. If you've all ready modified your diff for a drain plug couldn't it go in there(the sensor). Also I was getting popping in the rear too, coming off of long freeway drives. Changed lube and posi additive with the GM stuff, didn't stop. Did it again with the Kendall posi additive and new lube, no popping coming off of long freeway drives now. For what its worth.

Scott

 

Scott I was thinking about JB weld a sensor to the pumpkin and have a switch for one temp gauge for both. I had to put on a HD rear cover because my original broke and I didn't install a drain plug.

Some of the C-5 road racers have rear end coolers. So I'm wondering if I'm just burning mine up. This one has lasted 17 thousand miles since last May.

 

At 4.11 it is spinning pretty good and may be building up heat and causing self-destruction. I've seen cooler- pump setups for the diff, and they're belt driven by a pulley off the driveshaft. Mostly in oval track racing , road racing or 4WD endurance racing. Could go the experimental way if you've got access to thermocouple and meter. Some of the higher end electrical hand meters have temperature capabilities and a thermocouple "glued" to the diff would give you an idea of what it's running for temp. I thought the oil temp senders had a probe that needed to be immersed for readings.

Scott

 

I have seen a rear diff breather similar to a valve cover breather in summit's catalog. I know absolutely nothing about them but thought I would throw it out there. It might help release some heat build up but again I am not sure how well they work or if they would cause any new problems. It says tap a threaded hole and screw it in.

You could always try waterwetter. :jester

 

BTW what does Tom's Differentials say about fluid and posi additive?

 

I'm not sure why you would want a breather. Some people have mentioned going back to normal gear oil. I have never ask Tom's what they recommend.

You would think that Valvoline full synthetic 85W-120 could take on lots of heat.

What has always failed on the posi units is the pin that goes throught the case starts to elongate the hole. Then at some point it actually induces cracks in the posi housing. Then I floor it through a turn and it sounds like all hell broke loose and you hope that it's just a busted U-joint or half shaft. When you open it up the pin is ripped out and wedged inside the housing.

The good thing about it is you can still drive in on home. It sounds terrible and people are staring at you, But You can't hurt it any worse!:)

 

Like you, I too have considered installing temp sending units in my transmission pan, diffrential housing and oil pan. Then just use the OE temp gauge to monitor each of the components independantly via a rotory switch.

Do the coolers used on road race car rear ends have an electric pump that circulates the gear oil or do they rely on circulation by convection?

Could a slightly thinner gear oil help reduce the temperature? I don't know much about lubrication properties.
There's an article written by a corvette race team that sings high praises for this companies lubrication products. Lubrication Engineers, Inc. http://www.le-inc.com/index2.cfm The article claimed that they trememdously reduced the number of gear related failures once they began using this companies products. I'm trying to find that article for you.

What is the average speed you drive while on those long open stretches of Nevada highway? . . . nevermind, don't answer that question in public forum :lol: I have a number in mind and that number tells me that you NEED to emulate the setups used by the competitive road race teams. Those guys can give you the right answers. :yesnod:

 

Heat builds pressure and vise versa. I am guessing you are not pushing any fluid out of your seals so you might have some pressure in there. Buy releasing the pressure, you reduce the heat. Of course this is speculation on my part regarding the pressure but depending on how hot it gets back there you are building some pressure, just not sure how much.

 

Fevre,
I think the differentials are vented already.

Gkull,
Slow down :D

 

I think there's only 8 or 9 teeth on the pinion gear for Corvette 4.11 gears so it's no surprise that things would get hot. There's alot of turning going on! Perhaps redvetracr could fill you in on a diff. cooler setup.

 

gkull
if i moved to your neck of the woods, i would change the fluids more often due to the severe duty of high speed.
i would suck out 1 qt. from the rear every 5,000 miles, and add a fresh qt of whatever works best. that would be like a full change every 10k or so. The fluid might be wearing out even faster, but that is where i would start. actually it's the additives that break down and wear out.
the temp gauge may provide valuable clues, over time. i would go to an auto store and get a reducer(bushing) for the fill plug so the sender could be screwed in, not glued on.
:cheers: