I bought an 8" rear end from a 65 Mustang to put in my 66. I drained all the gear oil after I bought it, and it has sat in my garage for about a year and a half. It appears to be in good shape, but I noticed the other night that the ring gear has some rust spots on some of the gear teeth. Here's a picture of what I'm talking about:

(Look at the 11:00 position of the gear)



I also believe this has a gear ratio of 2.80 or so (not sure if it's 2.79 or 2.80, or what, but I know it was less than 3 complete turns from the yoke/pinion). I don't think that's a good ratio to be running behind a T-5, so I'm contemplating upping to a 3.20 gear. How much on average would a shop charge me to swap to that gear into it, if I provided the part?

Thanks.

 

Well, I think with a T5 from a V8 car you would be happy with a more aggressive gear ratio than a 3:20, unless MPG is the end goal. I am planning on buying a rebuilt 3rd member from an Ebay seller for around $700 shipped.

If your T5 is from a 6 cylinder you may have a decent rear ratio already.

If you find a shop that is willing to rebuild yours let us know what he charged will ya?

My last FOX body with a 5.0 and a t5 had a 3:55 ratio and it was about perfect for fun and highway use, so thats close to what I am going for, a buddy had the same car with a 3:73 and it was a hoot and still decent on the highway.

All of this varies slightly with tire extremes of course, so YMMV.

 

Don't have the T-5 yet, but most likely it will be from a 4-cyl. Since I'm running an I-6, there's no reason to get the more powerful T-5, as there's no way I'm putting out that much HP/torque lol.

I think I can get the entire rear end cleaned up with a wire-cup and wire-wheel, then just have the shop do the R&P. Hopefully that will be less $$

 

I just sold a t5 from a 4/6 cylinder (for $150) and after doing the investigation on gear ratios it turns out that with it the 3:00 rear end figured to be about the same as a 3:55 with a v8 t5 gearset. The small engine T5 is still a great trans, it gets a bad wrap from some internet commandos that never really race there car. If I had an in-line 6 I would look for the small shaft T5 and keep the low rear end.

Here is a RPM calculator that may help you out.

 

Clean worst tooth off and inspect depth of pitting. If it passes finger nail test it is definitely good. If it does not pass fingernail test it will likely still be ok; judgement call.

If rebuild, clean all rust off or else rust will make its way into bearings and trash them.

I would buy a DVD or book and rebuild DIY. You will be more careful than shop.

Last rebuild kit I bought cost $100.

If you don't wanna buy a cheapo china shop press you can still do the rebuild and just outsource the press work for cheap.

It is pretty enjoyable and simple to rebuild.