Economical aluminum 8.8 rear cover,

[GT350HR]

I have test fit the T Bird "IRS" aluminum cover , Mustang "IRS" cover and found they will work in unmodified condition. They do not interfere with factory sway bars as they are on the front side of the housing , and the spare tire is far enough away to not be an issue. I went with the latest offering from Ford which is a finned aluminum piece. Ford states it will not work with the internal ABS ring but I found I could remove the offending internal rib with a die grinder. I know i posted that elsewhere on another post. I had the opportunity to test the other two covers this weekend. I pulled both from a local wrecking yard for $20 a piece just to see. As a bonus the T Bird and Mustang have tabs on the casting that could allow hooks or lights to be bolted on plus both have drain plugs that the stamped steel cover doesn't. Maybe this information has already been "out there" , I just wanted to share.
Randy

 

[Dirtman]

Do the aluminum covers have the same internal contours as the steel covers? I.e, does the oil still flow correctly?

 

[Curious Hound]

Do the aluminum covers have the same internal contours as the steel covers? I.e, does the oil still flow correctly?

Is there really a FLOW issue? I believe the oil level is high enough that the ring gear and the bottom of the bearings are all sitting in the pool of oil. Or am I really all screwed up on this?

 

[Dirtman]

When you start moving there is no more pool of oil. The oil is being sucked up and slung around the housing by the ring gear acting like a pump, the oil spray is then directed out to the axle tubes and to the pinion bearings by the shape of the diff cover and channels in the housing. There is very much a flow to diff oil.

Soome of those "high capacity" aluminum covers actually starve the bearings for oil because they don't direct the oil spray properly.

 

[Bird76Mojo]

Aftermarket differential covers often make oil heat up faster, due to the oil not having a smooth flow path as they did with the stock cover. You're essentially working the oil harder. Banks did a study on this. It depends on the internal shape of the cover though.

Also, some of the Ford oem aluminum covers have fins on the inside, and depending on how thick your ring gear is (4.10, 4.56 etc) the covers may need some internal trimming to fit right. A forum member ran in to this issue a while back. He had to grind a fin down on the inside for his to fit.

 

[86merc5.0]

I was one of the guys that had to grind off one internal rib, that was about 180,000 miles ago, still no issues.

 

[85_Ranger4x4]

I have one of the new Shelby ones but I need to grind down the one fin yet for my ABS ring.

I doubt factory Ford aluminum covers have much issue with flow.

 

[GT350HR]

I ended up using the "Shelby" cover that has internal fins and ground one fin as 86merc5.0 did. neither of the other two had internal ribs as they were both designed for use with the ABS ring. The internal ribs are for additional heat sink reasons and have no effect on oiling. That would be a BAD thing as the front pinion bearing relies on oil being "slung" forward off of the ring gear.
I will probably sell the Tbird and IRS covers at my local swap meet.
Randy