Differential heater

[Dion Hildebrandt]

The discussion that prompted this thread was around gear and transmission oils. The JG qualifier, and the ATI (also JG) and the properties were the focus and the pro's and con's of heat put to them. I guess the qualifier rear lube doesn't really like too much heat put to it ,somewhere around 160 degrees or so, and some of these heating pads and elements go way above that. The synthetic trans oil apparently works the same cold or hot so that is a push.

As I was working on my diff ,I was curious just how a measureable amount of heat could be applied and if it was worth it. I have heard about the ATF in the diff before but no evidence of any good qualities of using it, I assumed the gears would be sacrificed, as rear drive diffs weren't designed for that type of lube.

PS thanx for the pm's some really great ideas out there, I love the outside of the box thinking

[Bill Edgeworth]

Dion,

There are a few issues with this conversation. First off you really cannot take anyone’s advice on what to use in your combo unless they have the exact same combo right down to surface treatment on the gears. Where ATF may be the best choice for lets say a 4 cyl FWD 200 horsepower stocker its certainly not a good choice for some blown 900 horsepower new stocker. Its all about the pressure and surface speed on the gear faces. Best thing you can do is just try a few different oils and figure out whats best for your circumstances. You do not even have to rely on a time slip to do this. Just measure the differential temperature before and after a run. You can use a heat gun or a more accurate measurement can be taken but using an eye type thermocouple under one of your cover bolts. The fluid that causes the lowest temperature rise in a run is what’s best.
For those that want to use a heater it can easily be temperature controlled with the thermocouple under one of the cover bolts and a digital control. For me this is what I used to do when I ran 75 weight oil. The last couple years I have been running the Red Line super light and have no need to heat it

[art leong]

Originally Posted by Bill Edgeworth

Dion,

There are a few issues with this conversation. First off you really cannot take anyone’s advice on what to use in your combo unless they have the exact same combo right down to surface treatment on the gears. Where ATF may be the best choice for lets say a 4 cyl FWD 200 horsepower stocker its certainly not a good choice for some blown 900 horsepower new stocker. Its all about the pressure and surface speed on the gear faces. Best thing you can do is just try a few different oils and figure out whats best for your circumstances. You do not even have to rely on a time slip to do this. Just measure the differential temperature before and after a run. You can use a heat gun or a more accurate measurement can be taken but using an eye type thermocouple under one of your cover bolts. The fluid that causes the lowest temperature rise in a run is what’s best.
For those that want to use a heater it can easily be temperature controlled with the thermocouple under one of the cover bolts and a digital control. For me this is what I used to do when I ran 75 weight oil. The last couple years I have been running the Red Line super light and have no need to heat it

Bill I know of some 1400 HP FWD cars that use ATF in their differentials They have a 170 plus trap speed.
Could be the gears are cut differently (Not Hypoid?). But they use it I know.

[Ed Wright]

Originally Posted by art leong

Bill I know of some 1400 HP FWD cars that use ATF in their differentials They have a 170 plus trap speed.
Could be the gears are cut differently (Not Hypoid?). But they use it I know.

Think load from car weight could be part of it too?

[Bill Edgeworth]

Originally Posted by Ed Wright

Think load from car weight could be part of it too?

Yes, just equates back to pressure on the gear face. And what Art mentioned how the gears are cut can affect both how much the gears must actually slide against each other and the actual amount of contact area they have. As for a 1400 hp FWD car using ATF could it be due to necessity as the transmission and differential share the same oil?

[art leong]

Originally Posted by Bill Edgeworth

Yes, just equates back to pressure on the gear face. And what Art mentioned how the gears are cut can affect both how much the gears must actually slide against each other and the actual amount of contact area they have. As for a 1400 hp FWD car using ATF could it be due to necessity as the transmission and differential share the same oil?

Yes they share the same oil.

[tommy d]

I have a bunch of free Valvoline 75/140 synthetic gear lube that I would like to try. We have a Dana 60 and have had 0 problems in 9 years of hard racing so I'm afraid to change anything. What do you guys think? Just looking for consistency. We now use 80/90 conventional.

[art leong]

Originally Posted by Ed Wright

Think load from car weight could be part of it too?

Ed I'm pretty sure the way the gears are cut for a RWD application is the difference. Our ring and pinions make contact in a completely different area.