Typical rear differential temperatures
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Originally Posted By: turtlevette
One of my theories is the larger the ratio the hotter it'll run. I have a 4.56/1 in my vette and it runs 210 at 60 mph. Measured with an it gun.
Yes. As the ratio increases, the pinion gets smaller, so the contact area with the ring decreases and this causes more friction.
Originally Posted By: mjoekingz28
meep,
A question about temps rising. Do you think it is the load they are under AND speed?
Because, an off-road dumptruck pulling max GVW going 25mph isnt getting (it seems) a whole lot of cooling because of limited airflow. Then add the dust coating the pumpkin and that probably holds a lot of heat in.
Then an OTR truck is pulling heavy AND fast, but is on clean(er) pavement and is getting alot of airflow. So, maybe heatsinks and someway to direct airflow, that coupled with cool synthetics and it seems there shouldn't be a problem!
If you use a 1 ton pickup to tow 40k lbs at 15mph the diff will get very hot, very quickly. This is due to the load on the gears and bearings.
If it goes 100mph unloaded it will also get very hot, as the speed increases the amount of heat input into the differential. Its the same thing. The load is much lower than the first scenario, but everything is moving so fast its still creating a lot of friction.
One of my theories is the larger the ratio the hotter it'll run. I have a 4.56/1 in my vette and it runs 210 at 60 mph. Measured with an it gun.
Yes. As the ratio increases, the pinion gets smaller, so the contact area with the ring decreases and this causes more friction.
Originally Posted By: mjoekingz28
meep,
A question about temps rising. Do you think it is the load they are under AND speed?
Because, an off-road dumptruck pulling max GVW going 25mph isnt getting (it seems) a whole lot of cooling because of limited airflow. Then add the dust coating the pumpkin and that probably holds a lot of heat in.
Then an OTR truck is pulling heavy AND fast, but is on clean(er) pavement and is getting alot of airflow. So, maybe heatsinks and someway to direct airflow, that coupled with cool synthetics and it seems there shouldn't be a problem!
If you use a 1 ton pickup to tow 40k lbs at 15mph the diff will get very hot, very quickly. This is due to the load on the gears and bearings.
If it goes 100mph unloaded it will also get very hot, as the speed increases the amount of heat input into the differential. Its the same thing. The load is much lower than the first scenario, but everything is moving so fast its still creating a lot of friction.
I heard NASCAR has some sort of cooling system for their differentials.
Originally Posted By: mjoekingz28
I heard NASCAR has some sort of cooling system for their differentials.
They are pushing 500HP though them pretty much continuously while doing 200MPH. They pretty much have to.
If you take that 4% loss number into 500HP thats 20HP, or almost 15Kw. They've probably got the R&D in these things to try to get every .1% of efficiency, so they're more likely better than that, but surely more than 10Kw.
We heat our whole house (2000 sqft) with 10Kw.
For funsies one day, I put together a parts list for if I wanted to setup diff cooling and filtering on one of my cars. There are electric pumps to handle hot fluid like this.
I heard NASCAR has some sort of cooling system for their differentials.
They are pushing 500HP though them pretty much continuously while doing 200MPH. They pretty much have to.
If you take that 4% loss number into 500HP thats 20HP, or almost 15Kw. They've probably got the R&D in these things to try to get every .1% of efficiency, so they're more likely better than that, but surely more than 10Kw.
We heat our whole house (2000 sqft) with 10Kw.
For funsies one day, I put together a parts list for if I wanted to setup diff cooling and filtering on one of my cars. There are electric pumps to handle hot fluid like this.
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Originally Posted By: dparm
Decided to stick with the FF Castrol Syntrax LS, but not the BMW version with extra FM. I'll see how it does and add more FM if it really is as noisy as some people complained.
+1
Typical operating viscosity of this FF Castrol Syntrax would've been about 79ish cSt offering highest MOFT film thickness and stronger wear protection over all others , never mind it's lowest KV@100*C of 24.47 cSt(but,highest KV@40*C) among the four!
The Gulf's op vis would be inferior at 71 ish cSt .
JMHO
Decided to stick with the FF Castrol Syntrax LS, but not the BMW version with extra FM. I'll see how it does and add more FM if it really is as noisy as some people complained.
+1
Typical operating viscosity of this FF Castrol Syntrax would've been about 79ish cSt offering highest MOFT film thickness and stronger wear protection over all others , never mind it's lowest KV@100*C of 24.47 cSt(but,highest KV@40*C) among the four!
The Gulf's op vis would be inferior at 71 ish cSt .
JMHO
Originally Posted By: mjoekingz28
I heard NASCAR has some sort of cooling system for their differentials.
They also aren't concerned with it lasting quite as long as mine.
I heard NASCAR has some sort of cooling system for their differentials.
They also aren't concerned with it lasting quite as long as mine.
Originally Posted By: mjoekingz28
I heard NASCAR has some sort of cooling system for their differentials.
There is a pulley on the driveshaft yoke yoke driving a pump to circulate the oil through a cooler. Newer setups have a pump inside the housing driven off of the pinion gear.
I heard NASCAR has some sort of cooling system for their differentials.
There is a pulley on the driveshaft yoke yoke driving a pump to circulate the oil through a cooler. Newer setups have a pump inside the housing driven off of the pinion gear.
you could use an electric pump triggered by a thermal switch?
Originally Posted By: turtlevette
I have a 4.56/1 in my vette and it runs 210 at 60 mph. Measured with an it gun.
It appears to me that temperature is rather high and not quite normal.
What's the viscosity grade in use ? Have you tried gear oil of a grade thicker and compare ?
I have a 4.56/1 in my vette and it runs 210 at 60 mph. Measured with an it gun.
It appears to me that temperature is rather high and not quite normal.
What's the viscosity grade in use ? Have you tried gear oil of a grade thicker and compare ?
My Mag-Hytec diff cover has a threaded port for screwing in a temp sensor. I don't have a sensor or gauge (yet), but I could.
Originally Posted By: zeng
Originally Posted By: turtlevette
I have a 4.56/1 in my vette and it runs 210 at 60 mph. Measured with an it gun.
It appears to me that temperature is rather high and not quite normal.
What's the viscosity grade in use ? Have you tried gear oil of a grade thicker and compare ?
Hes talking in Fahrenheit. So, about 100C is what was measured. I'd consider that a normal operating temperature.
Originally Posted By: turtlevette
I have a 4.56/1 in my vette and it runs 210 at 60 mph. Measured with an it gun.
It appears to me that temperature is rather high and not quite normal.
What's the viscosity grade in use ? Have you tried gear oil of a grade thicker and compare ?
Hes talking in Fahrenheit. So, about 100C is what was measured. I'd consider that a normal operating temperature.
Originally Posted By: zeng
You may be right ......
but still somehow I believe the temp could be brought down with a thicker grade gear oils , and would be glad to find out in this instant, actual visc grade in use.
I think its too high also. I bought a bunch of that GM grape oil but it's really thin. I don't know if it's appropriate for this application. Was going to use it in my manual trans.
You may be right ......
but still somehow I believe the temp could be brought down with a thicker grade gear oils , and would be glad to find out in this instant, actual visc grade in use.
I think its too high also. I bought a bunch of that GM grape oil but it's really thin. I don't know if it's appropriate for this application. Was going to use it in my manual trans.
Originally Posted By: turtlevette
Originally Posted By: zeng
You may be right ......
but still somehow I believe the temp could be brought down with a thicker grade gear oils , and would be glad to find out in this instant, actual visc grade in use.
I think its too high also. I bought a bunch of that GM grape oil but it's really thin. I don't know if it's appropriate for this application. Was going to use it in my manual trans.
I'm afraid this GM grape oil isn't appropriate for your application, despite it's factory recommended.
This 75W90 grape oil would've a typical KV@40*C of about 105 cSt, which isn't adequate for your use.
If it were me, I would've firstly evaluate a 80W140 , then compare against a 75W140 (and evaluate a 75W110 if need be).
JMHO
Edit:In my climate, I would've tried an 85W140.
Originally Posted By: zeng
You may be right ......
but still somehow I believe the temp could be brought down with a thicker grade gear oils , and would be glad to find out in this instant, actual visc grade in use.
I think its too high also. I bought a bunch of that GM grape oil but it's really thin. I don't know if it's appropriate for this application. Was going to use it in my manual trans.
I'm afraid this GM grape oil isn't appropriate for your application, despite it's factory recommended.
This 75W90 grape oil would've a typical KV@40*C of about 105 cSt, which isn't adequate for your use.
If it were me, I would've firstly evaluate a 80W140 , then compare against a 75W140 (and evaluate a 75W110 if need be).
JMHO
Edit:In my climate, I would've tried an 85W140.
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I don't think temperatures are abnormal until you get to about 225F. I realize this was taken at only 60mph though. Does this car see track usage? Seeing as you have 4.56s in this car, I suspect you are doing more than just running down the highway. I'd be interested to know what its at with more load/speed. If the temperature is signifactly higher, jumping to a 75W110/140 would probably be required.
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Track time won't get it that hot. Most don't have long straights to go that fast and it's limited to 20 minutes with an hour cooldown.
The worst scenario is hours on the highway somewhere where you could go 80 or better for hours at a time. I agree that a something_w 140 would be best.
The worst scenario is hours on the highway somewhere where you could go 80 or better for hours at a time. I agree that a something_w 140 would be best.
Originally Posted By: turtlevette
Track time won't get it that hot. Most don't have long straights to go that fast and it's limited to 20 minutes with an hour cooldown.
The worst scenario is hours on the highway somewhere where you could go 80 or better for hours at a time. I agree that a something_w 140 would be best.
You may have gotten yourself into a 'thermal runaway' with prolonged 80's ...
so says Amsoil over here,
http://www.amsoil.com/techservicesbulletin/Drivetrain/TSB DT-2008-03-25 Thermal Runaway.pdf
I'm confident a xxW140 would greatly help in your case.
Track time won't get it that hot. Most don't have long straights to go that fast and it's limited to 20 minutes with an hour cooldown.
The worst scenario is hours on the highway somewhere where you could go 80 or better for hours at a time. I agree that a something_w 140 would be best.
You may have gotten yourself into a 'thermal runaway' with prolonged 80's ...
so says Amsoil over here,
http://www.amsoil.com/techservicesbulletin/Drivetrain/TSB DT-2008-03-25 Thermal Runaway.pdf
I'm confident a xxW140 would greatly help in your case.
I don't know what normal is. When we got our first power stroke F350 (2000?) to pull our car trailer to the track and to tow horses around the state, the paint blistered off the diff cover in line with the ring gear. This was after a few months of use. Seemed like it might be too hot, Ford said it was OK.
Originally Posted By: zeng
Originally Posted By: turtlevette
Track time won't get it that hot. Most don't have long straights to go that fast and it's limited to 20 minutes with an hour cooldown.
The worst scenario is hours on the highway somewhere where you could go 80 or better for hours at a time. I agree that a something_w 140 would be best.
You may have gotten yourself into a 'thermal runaway' with prolonged 80's ...
so says Amsoil over here,
http://www.amsoil.com/techservicesbulletin/Drivetrain/TSB DT-2008-03-25 Thermal Runaway.pdf
I'm confident a xxW140 would greatly help in your case.
It's different. The pinion is spinning fast but there is not much load on the gears. I don't think it's thermal runaway.
Originally Posted By: turtlevette
Track time won't get it that hot. Most don't have long straights to go that fast and it's limited to 20 minutes with an hour cooldown.
The worst scenario is hours on the highway somewhere where you could go 80 or better for hours at a time. I agree that a something_w 140 would be best.
You may have gotten yourself into a 'thermal runaway' with prolonged 80's ...
so says Amsoil over here,
http://www.amsoil.com/techservicesbulletin/Drivetrain/TSB DT-2008-03-25 Thermal Runaway.pdf
I'm confident a xxW140 would greatly help in your case.
It's different. The pinion is spinning fast but there is not much load on the gears. I don't think it's thermal runaway.
Originally Posted By: dparm
What are the average operational temperatures for rear differentials?
Car in question is my stock 2011 BMW M3, which has a GKN Visco-Lok LSD in the rear diff. No cooler. Obviously it is street-driven, but I do take it to the track.
The operational temperatures have a very wide range depending upon ambient temperature, speed and load. Obviously driving 30 MPH in winter in your M3 vs. towing a 7,000# boat in summer heat with a pickup truck on the highway would yield a low and a high temperature value.
I would say the low end would be ambient temperature + 5F and the high end would be ambient temperature + 100F in a performance car. In trucks, the temperature can be much higher.
Vehicles with high numeric gear ratios (4.11, 4.56, 5.11 etc) are much harder on gear oil and run much hotter. Although the transmission overdrive ratio can reduce the engine RPM to a low level with these ratios, the driveshaft RPM is still very high. The driveshaft (and pinion) RPM on a performance vehicle can run 25 to 100% higher than a standard vehicle.
When truck ring and pinions fail, it's almost always overheating destroyed the oil. And it's usually during the break in period or very early in the life cycle.
For your lightweight, but high performance M3, I would choose a lighter cold oil with the reasonably high VI. Most driving for a daily driver favors oil for lower temp rises. Im not familiar with the oils you mention.
What are the average operational temperatures for rear differentials?
Car in question is my stock 2011 BMW M3, which has a GKN Visco-Lok LSD in the rear diff. No cooler. Obviously it is street-driven, but I do take it to the track.
The operational temperatures have a very wide range depending upon ambient temperature, speed and load. Obviously driving 30 MPH in winter in your M3 vs. towing a 7,000# boat in summer heat with a pickup truck on the highway would yield a low and a high temperature value.
I would say the low end would be ambient temperature + 5F and the high end would be ambient temperature + 100F in a performance car. In trucks, the temperature can be much higher.
Vehicles with high numeric gear ratios (4.11, 4.56, 5.11 etc) are much harder on gear oil and run much hotter. Although the transmission overdrive ratio can reduce the engine RPM to a low level with these ratios, the driveshaft RPM is still very high. The driveshaft (and pinion) RPM on a performance vehicle can run 25 to 100% higher than a standard vehicle.
When truck ring and pinions fail, it's almost always overheating destroyed the oil. And it's usually during the break in period or very early in the life cycle.
For your lightweight, but high performance M3, I would choose a lighter cold oil with the reasonably high VI. Most driving for a daily driver favors oil for lower temp rises. Im not familiar with the oils you mention.
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