3.31 to 3.73 question ?

[smokinzx14r]

I found a brand new 2015 complete IRS with a 3.73 AXLE ratio.
ALUMINUM CENTER SECTION HOUSING at a good price ...Do you think the aluminum housing would hold up behind a 6 speed manual trans with drag radials ?

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[Brent302]

What's a good price?

 

[ORANG50]

I'm pretty sure the IRS Cobras had an aluminum housing. A lot of aftermarket companies made diff cover braces to keep the cover from getting ripped apart under load, but other that that, they were fine.

What are the stock S550 housings made of?

 

[smokinzx14r]

I'm pretty sure the IRS Cobras had an aluminum housing. A lot of aftermarket companies made diff cover braces to keep the cover from getting ripped apart under load, but other that that, they were fine.

What are the stock S550 housings made of?

My 6 speed Base GT has a cast iron third member ..this one that is for sale is a new 2015 with 3.73 gears but it has a alum case ..I was just unsure if it would hold up with a 6 speed ..my guess is the alum case comes in auto cars ..?

 

[cbrtrx]

I dont think any aluminum carriers came factory with 3.73's something you might want to look into if it was claimed factory.

 

[EXP Jawa]

Right now, the 3.73 is only part of the performance pack, and the performance pack is manual transmission only. The aluminum carrier is used on automatic transmission applications. I'm quite certain that the 3.73:1 gears only come out of the Sterling Axle Plant in one configuration - iron carrier, 3.73 gear, Torsen diff. There aren't any factory-built assemblies that combine aluminum with 3.73:1.

For the record, there's a reason that Ford elected to accept the mass of the iron carrier for the manual transmission cars. They needed it for impact durability. In this vehicle application, the aluminum didn't withstand the more severe test cycle of manual transmissions well enough.

 

[DR_]

I think the OP is looking at this auction with what the seller describes as a 3.73 and aluminum carrier. I was surprised when I read aluminum carrier as well. The seller has many more in many different ratios so they seem to know what they have.

 

[EXP Jawa]

Well, it appears to be aluminum all right, and the tag indicates a 3.73:1 ratio. But it still doesn't fit with known information about the axle build combinations. I wonder if the tag is correct, or was switched. Its too bad that its torn, because the image of the bar code is probably clear enough to otherwise scan to see what info comes up. It should contain a record of assembly and what components were used.

 

[EXP Jawa]

I spoke with a colleague that works in the axle plant and is, um, familiar with the S550 axles. He told me that Sterling Axle has never built an aluminum/3.73 combination. He also said that the axle tag visible on the cover does not describe an aluminum carrier (though what is shown does appear to be), and there should also be a tag on the bottom of the assembly (not shown in the photos) that identifies the production information. The bottom line, though, is that I'd be leery about what is being sold here. Regardless of whatever it may actually turn out to be, it is not a take-out axle from a regular production S550.

 

[smokinzx14r]

I spoke with a colleague that works in the axle plant and is, um, familiar with the S550 axles. He told me that Sterling Axle has never built an aluminum/3.73 combination. He also said that the axle tag visible on the cover does not describe an aluminum carrier (though what is shown does appear to be), and there should also be a tag on the bottom of the assembly (not shown in the photos) that identifies the production information. The bottom line, though, is that I'd be leery about what is being sold here. Regardless of whatever it may actually turn out to be, it is not a take-out axle from a regular production S550.

I'm seeing the same thing in the ad ...I also didn't think they made a 3.73 with a alum case .. But the pictures show just that ... He has 3 complete IRS rears on Ebay .. 3.31 3.55 and that 3.73 rears all listed at the same time ..I wonder where they came from ? Wrecked cars ?

 

[EXP Jawa]

I'm seeing the same thing in the ad ...I also didn't think they made a 3.73 with a alum case .. But the pictures show just that ... He has 3 complete IRS rears on Ebay .. 3.31 3.55 and that 3.73 rears all listed at the same time ..I wonder where they came from ? Wrecked cars ?

My colleague wondered that too - he commented that from the pictures, it doesn't appear that they were ever installed in the first place. So, possibly not from wrecks. They appear to be in GA, so its not like they're diving through the dumpsters at FRAP either, so its odd.

Then there's the fact that 3.73/aluminum is not a combination that they build. What we see in the picture appears to be an aluminum carrier with a 3.73 sticker. But like I said before, he told me that the coding on that sticker is incorrect for aluminum, so my money is on the sticker being switched for some reason. Either way, this thing is not take-off from a normal production variation.

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