Redesigned Differential Cover

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1,460
Location
Las Vegas
Nice, but for that price, I'd expect at least a drain hole. As to the doubling of fluid, that won't amount to twice the heat dissipating capacity. That would be dependent upon the surface area of the cover, and the heat transfer properties of the material. I've put a lot of miles on Chevy C/Ks and never has a problem with the rear end. Personally, I'd put a good fluid in it like Amsoil Severe Gear and be done with it.
 
Messages
530
Location
NC
I have the mag hytec for my ten bolt rear on my 06. Cant say enough good things about it. But this GM one looks cooler (and is one hundred dollars cheaper) in my opinion. And yes a drain plug should be on it.
 
Messages
674
Location
Gilbert, AZ
I don't care for ANY coated covers not even mag hytech. The paint actually hinders cooling ability. We blast off any paint and keep them natural. The PML and Genuine gear units are the way to go IMO. Another thing many people dont consider is how hard it is to cool a much larger capacity of fluid. Fluids heat up much faster then they cool. My trans builder for my truck really enlightened my thinking and he is the very best money can buy. My trans has a Unlimited HP warranty and lifetime warranty with a factory 4R100 pan on it and a 6.0 trans cooler. This same thinking goes for diffs also This is a nice unit for the money and has a drain plug http://www.summitracing.com/parts/SUM-730508/
 
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Messages
6,388
Location
Washington St.
Quote:
is how hard it is to cool a much larger capacity of fluid. Fluids heat up much faster then they cool.
It is exactly as hard to heat more fluid as it is to cool more fluid. You are transferring the same number of BTUs. If the heat source is greater than the cooling source, yes, it takes longer to cool. If the cooling source is greater than the heat source (Montana in winter), it takes longer to heat than to cool. I'd put my money into better gear oil (if not already used) vs. a different cover. An aluminum cover will transfer more heat from the oil than a steel cover. A finned cover will transfer more heat than a smooth cover. More gear oil will take longer to heat and take a longer time to oxidize.
 
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4,942
Location
Billings, MT
Originally Posted By: Smokefan1977
I don't care for ANY coated covers not even mag hytech. The paint actually hinders cooling ability. We blast off any paint and keep them natural. The PML and Genuine gear units are the way to go IMO. Another thing many people dont consider is how hard it is to cool a much larger capacity of fluid. Fluids heat up much faster then they cool. My trans builder for my truck really enlightened my thinking and he is the very best money can buy. My trans has a Unlimited HP warranty and lifetime warranty with a factory 4R100 pan on it and a 6.0 trans cooler. This same thinking goes for diffs also This is a nice unit for the money and has a drain plug http://www.summitracing.com/parts/SUM-730508/
Believe it or not, dark colored objects radiate heat better than light colored ones. Black paint also adds significant surface area (bumps, etc) which allows more air to contact it, giving more ability to dump that heat.
 

JHZR2

Staff member
Messages
46,303
Location
New Jersey
Yeah, cant say that Ive had any issues with heat given the larger fluid capacity and fins of my mag hytec. I do have an uncoated TCI deep finned pan on my AT.
 

Y_K

Messages
2,752
Location
WA (USA)
Originally Posted By: chevrofreak
Black paint also adds significant surface area (bumps, etc) which allows more air to contact it, giving more ability to dump that heat.
Paint of any color will add yet another thermal transfer layer, where the coefficient is a variable and always lower than 1. Simple Physics..
 

JHZR2

Staff member
Messages
46,303
Location
New Jersey
Originally Posted By: Y_K
Originally Posted By: chevrofreak
Black paint also adds significant surface area (bumps, etc) which allows more air to contact it, giving more ability to dump that heat.
Paint of any color will add yet another thermal transfer layer, where the coefficient is a variable and always lower than 1. Simple Physics..
it's very true, but then again, how much of an issue is differential thermal loading, what effect does the greater amount of fluid do on the steady state thermal conditions in the diff? Ive seen OEs use painted HXs on sensitive systems like AC condensers. And given that SA gained >> paint depth, it should be a very minor effect. Good point all the same!
 
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4,564
Location
NW Ohio
Originally Posted By: JHZR2
it's very true, but then again, how much of an issue is differential thermal loading, what effect does the greater amount of fluid do on the steady state thermal conditions in the diff?
Yeah, takes longer to get up to temp but ultimately it makes no (or little) difference in the ultimate temperature. Eventually, the fluid reaches the temp dictated by the operating situation. The larger capacity covers do have more surface area and often have fins, both of which helps bring down the steady state temps. After having two Mag-Hytec covers on two trucks and monitoring temp for nearly 10 years, I can say it's worth about 15 degrees (lower) on a Ford 10.25 axle. I had a similar setup on a GM 8.5 and the results were similar, though I ran that setup for a shorter period. The higher capacity does extend oil life some in terms of contaminant buildup. The Mag-Hytecs also have a magnetic dipstick, which you can pull and clean periodically, thus reducing the contaminant load a little.
 
Messages
530
Location
NC
Here is something Ive been wondering.. I replaced my stock cover with a MH. The stock one was very thin steel, the MH is much thicker aluminum. Which dissipates heat better, 1/16 inch steel or 1/2 inch aluminum? Discuss. (measurements are guesstimates)
 
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Y_K

Messages
2,752
Location
WA (USA)
It's like asking who wins if an elephant attacks a whale. Thermal conductivity is the quantity of heat transmitted through a unit thickness in a direction normal to a surface of unit area, due to a unit temperature gradient under steady state conditions. ('Normal to a surface' in scientific term). Aluminium is 250 1 W/(m.K) Chrome Nickel Steel (18% Cr, 8 % Ni) is 16.3 Stainless Steel is 16 Steel (1%C) is 43 Wool is 0.042 Platinum is 70 Magnesium is 156 Gold is 360 Copper is over 400 That's at 'normal conditions' in scientific terms, i.e temp ~68F for one. 1 W/(m.K) = 1 W/(m.Centigrade) = 0.85984 kcal/(hr.m.Centigrade) = 0.5779 Btu/(ft.hr.Fahrenheit) m=meter (unit of length) K=Kelvin (unit of temperature So, without thickness, hard to guess. Cover can be viewed as a heat conductor/insulator between ambient and internal environments, and we have quite a few variables for both besides the cover. Add to this bean counting and it is going to be your typical engineering assignment smile
 
Messages
3,742
Location
Northern California, USA
Nice cover, but I don't think it is worth $150. The only reason why someone would need a new cover is to beef-up or strengthen the rear end. My thought is that the increased size would create a space for the ring gear to push the oil so that there was less oil on the gears. The metal one, on a GM, is made to direct the flow of oil back to the bearings on the side of the gear housing (or whatever it is called). Oil doesn't transfer heat to itself very well; not like water or air. Oil only gets cooled where it touches a colder surface. To cool the gear oil, you would be better off having fins on the inside, rather than the outside: Increase the surface area on the inside to pull heat to the outside air.
 
Messages
4,564
Location
NW Ohio
Originally Posted By: Loobed
My thought is that the increased size would create a space for the ring gear to push the oil so that there was less oil on the gears. The metal one, on a GM, is made to direct the flow of oil back to the bearings on the side of the gear housing (or whatever it is called).
I have had discussions with axle engineers (Dana and AAM) about this and there is something to your comment. The proximity of the cover to the ring gear does direct the oil flow to an extent, both for cooling and lubrication. Certain GM covers (notably the 8.8 (12-bolt) and certain 8.25 10 bolts have a specially designed cover that directs oil flow to the carrier bearings for the reason you describe. All that said, the Mag-Hytec cover does reduce oil temp by 15 degrees and the man that designed it claims that he counters the possibility of any lack of lube by raising the oil level in the housing a little. Yes, I raised an eyebrow too but having run two covers on two trucks for about seven years, I can say that it's all worked pretty much as Mag-Hytec claimed.
 
Messages
476
Location
Virginia
Originally Posted By: Jim Allen
Originally Posted By: Loobed
My thought is that the increased size would create a space for the ring gear to push the oil so that there was less oil on the gears. The metal one, on a GM, is made to direct the flow of oil back to the bearings on the side of the gear housing (or whatever it is called).
I have had discussions with axle engineers (Dana and AAM) about this and there is something to your comment. The proximity of the cover to the ring gear does direct the oil flow to an extent, both for cooling and lubrication. Certain GM covers (notably the 8.8 (12-bolt) and certain 8.25 10 bolts have a specially designed cover that directs oil flow to the carrier bearings for the reason you describe. All that said, the Mag-Hytec cover does reduce oil temp by 15 degrees and the man that designed it claims that he counters the possibility of any lack of lube by raising the oil level in the housing a little. Yes, I raised an eyebrow too but having run two covers on two trucks for about seven years, I can say that it's all worked pretty much as Mag-Hytec claimed.
Jim & Loobed: This is a great point lost in most discussions. Years ago we tried out the completely clear diff covers when they became available. With the vehicle up on stands we ran the vehicles up to road speeeds so we could see what happened. As the speed increases, there was less and less liquid in the bottom of the diff. At very high speed, there was little to no fluid in the bottom of the diff (cool diff temps, hotter would yield different results). It is all in suspension. I believe a high capacity cover is going to possibly keep the mesh point (which is pretty high) of the ring & pinion in fluid better than a stock cover. Whether this is good or bad probably depends on your application. For durability, good. For performance at high speed, I dont know, I would think there is more drag. When using a Mag-Hytec, I would consider using 75W90 instead of 75W140 since the cooling and capacity is better and to reduce drag and pick up some more power at the wheels.
 
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