Towing with a Finned Rear Aluminum Differential Cover ?

warp2diesel · **Posted:** Sat Dec 22, 2007 8:12 pm

I plan to haul my Antique Tractors behind my Liberty CRD on a tandem axle trailer with an equalizer hitch and electric brakes. Years ago when I had a 4X4 4cly IH Scout that did OK with the same tractors on the same trailer and the wheel base of the old IH ScoutII (100") is close to the Liberty(104.3"). I put in the 75W140 Synthetic oil already and I will be towing through Illinois, Indianan, and Michigan, some hills but no mountains. My estimated load will be just shy of 7000lbs. I installed the 7000lbs hitch instead of the 5000lbs hitch.

Would a finned aluminum differential cover help my rear end stay cooler or do my factory alloy wheel do the job?

Almost all of the Half ton Japanese full Size Pick Ups all use finned aluminum differential covers and tend to have smaller diameter pinions and bearings than the domestic Pick Ups do. I suspect they do this because they have to, not for show.

Does any one know of a brand of finned differential cover that is more function than show?

Does any one know what Dodge trucks use the same Chrysler 8. 25" rear end so I can find a used one?

Regards,

Steve

Joe Romas · **Posted:** Sat Dec 22, 2007 8:36 pm

That's a lot of weight for our CRD's :!:

I towed a 1938 JD model AR on a tandem axel trailer I made with a v8 f-150 and I didn't know it was there. Those old scouts were pretty rugged as I recall and even the 4 poper was a power house.
I would think any finned aluminum cover would help but what ever you do PAINT IT BLACK so it won't look pimped out :shock:

But first check for clearence, as I recall, could be wrong, that on the XJ's there was a clearence problem back there

Goglio704 · **Posted:** Sat Dec 22, 2007 9:13 pm

http://www.yourcovers.com/dc_9864.shtml

Not cheap though...

chrispitude · **Posted:** Sat Dec 22, 2007 9:20 pm

Goglio704 wrote:

http://www.yourcovers.com/dc_9864.shtml

Not cheap though...

Nice. Actually, that doesn't seem bad at all.

- Chris

Sir Sam · **Posted:** Sat Dec 22, 2007 9:26 pm

ya that $180 for the one aboove isnt bad.

I remember I saw one made out of lexan a while back, That would be neat if only to see the status of your fluid, metal chunks, water, etc.

warp2diesel · **Posted:** Sat Dec 22, 2007 10:45 pm

Thermodynamics 101 says that black radiates more heat than as cast and I am one who will not try to defy the laws of physics. Harbor Frieght has a Powder Coating kit for a reasonable price, $49, I hope my Wife does not make me sleep in my Jeep if I use her oven. I remember that some of the fins need to be trimmed if it is used with a fuel tank skid plate. I will worry about that when she wants to go on a serious rock hunting trip.
The most I ever Hauled with my Scout II was 11,000 lbs and that was for a short distance with an International TD-6 dozer. My tractor is a '46 Farmall BN that weighs about 4,000 and the trailer is about 1,900 empty. I will be throwing on a few attachments like the plow, a blade and some other stuff. I suspect that I will be limiting my speed to 65 MPH to keep Smoky going after the College kids who are going 85. I will not be trying this until spring.

Steve

warp2diesel · **Posted:** Sat Dec 22, 2007 11:14 pm

The link: http://www.airram.com/product.php?categ ... chquery=sa

Steve

Sir Sam · **Posted:** Sat Dec 22, 2007 11:32 pm

warp2diesel wrote:

Thermodynamics 101 says that black radiates more heat than as cast and I am one who will not try to defy the laws of physics. Harbor Frieght has a Powder Coating kit for a reasonable price, $49, I hope my Wife does not make me sleep in my Jeep if I use her oven. I remember that some of the fins need to be trimmed if it is used with a fuel tank skid plate. I will worry about that when she wants to go on a serious rock hunting trip.
The most I ever Hauled with my Scout II was 11,000 lbs and that was for a short distance with an International TD-6 dozer. My tractor is a '46 Farmall BN that weighs about 4,000 and the trailer is about 1,900 empty. I will be throwing on a few attachments like the plow, a blade and some other stuff. I suspect that I will be limiting my speed to 65 MPH to keep Smoky going after the College kids who are going 85. I will not be trying this until spring.

Steve

There are some black coatings like that that are made to improve heat transfer, however I have no idea on the standard oof the shelf powedercoatings.

That powder coat at harbor frieght could just mess up any heat transfer transfer properties, the cheap powder coat in fact could reduce heat loose by conduction, and only moderately increase heat loss by radiation.

IMO for my money I would leave it be, Im betting any cheap powder coat would only impair the heat transfer properties.

warp2diesel · **Posted:** Sat Dec 22, 2007 11:42 pm

Black paint is cheaper than powder coating and my Wife won't make me sleep in the Jeep for using her oven. Besides, with the scrap rats steeling Copper (Two Journeymen Electricians in NY City were electrocuted with 480Volts and died) and Stainless Steel from construction sites, Aluminum could be next. Gee I better get some wheel locks as well.
Even if the laws of Physics did not favor painting it black, chlorides from the salt they dump on the road will eat away at bare aluminum and black paint would offer some protection. And black paint draws less attention than polished aluminum.

Steve

danoid · **Posted:** Mon Jan 07, 2008 12:45 pm

While it's not finned and still doesn't have a drain plug, I've been curious about trying to fit the cast iron diff cover from a 4WD Durango on for armor purposes. In the Durango the rear diff cover is a suspension structural member (I didn't design it!) and is a nice 12 mm thick cast iron job with the same bolt pattern...

warp2diesel · **Posted:** Mon Jan 07, 2008 7:36 pm

The tensile strength of 356 aluminum alloy is greater than cast iron. I suspect the function of the cast cover is to dampen out an undesirable harmonic that may be characteristic of the Durango. :idea:

Steve

danoid · **Posted:** Tue Jan 08, 2008 7:03 am

My guess is the function of cast iron over aluminum is cost. Either, however, will be stronger than a 1.5 mm thick stamped steel pan. The reason the increased strength is required is a large (M10 or something) bolt boss in the middle of the cover that fastens to some funny looking bobbit linkage for the rear suspension.

And the aluminum is only stronger than cast iron if it's heat treated. That introduces a new set of problems regarding warpage during heat treat, green vs. hard machining, etc. Cast Iron is much simpler do deal with.

warp2diesel · **Posted:** Tue Jan 08, 2008 9:05 am

Cast Iron needs to be stress relieved or it will distort, some times we get lucky and the crate of castings will sit for a month or so and nature will start the process. This is why racers never use unseasoned engine blocks to blue print. Driving the engine for over 100,000 miles does the best job of stress relieving.
As far as tempering Aluminum to get the extra strength, even Detroit's finest bean counters think that is a no brainer.

Another thing to consider is the bracket mount pointed out for use on the Durango, it may be a wee bit too close to the Liberty fuel tank (better check). As much as we all want Jeep to survive as a viable devision and in the future become another independent like Harley Davidson, we don't need to buy needless spare parts like replacement fuel tanks.

Steve :wink:

DarbyWalters · **Posted:** Tue Jan 08, 2008 10:20 am

I would be more worried about Tranny Temps than rear end. Someone does make a deeper aluminum finned tranny pan...a member on here has one. The other thing would be to put an inline tranny fluid cooling unit.

As for black paint vs aluminum vs steel...whatever you use you can coat it with a thermo dispersing coating on the out side and a slick coating on the inside. Swain Coatings or most speed shops have coatings now.

I would definitely do the ORM...with the SEGR...to reduce intake temps. In Europe the CRD is rated for towing more than here...rules and stuff...7500#s there.

Towing with a Finned Rear Aluminum Differential Cover ?

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