rmurad38

Hello all,

This weekend I'm getting 3.73's installed in my Mustang.

When I spoke to the shop, asking general questions, the topic of breaking them in came up. The shop said that for the first couple hundred miles, trips should be kept short (just a few miles at a time) to allow the gears to heat and cool, more or less hardening them. Going on a multiple hour road trip could be detrimental due to possibility of overheating them. After about 500 miles he also suggested the fluid be changed as the mating of the new gears will produce some metal shavings in the fluid, i'd believe that.

Now i'm sure he was just staying on the side of caution but it seems a bit extreme. (the very short trips part.) However, after the lengthy break in, drive it like you stole it.

For those of you who may of changed gears, what do you recommend?

rmurad38

Cusp

My installer did the first heat cycles on the lift for me. Said to just drive it easy for the first 500 miles. I drive it home on the highway 35 miles. Refrained from doing WOT for a bit but I did enter the freeway fairly spirited a few times. No oil change recommended though. That was 8K miles ago. All is still fine with the 3.73s.

Grabber2012

If you look on a magnetic drain plug after 6 months on all-new gears, bearings, and spacers, you normally see a very minimal amount of magnetic shavings/particles. By "minimal" I mean about the volume of an aspirin pill. There may be a tiny amount of migration down the axle tubes, but I have always been surprised by how little there has been on my own gear/bearing/Trac-Lock builds. I would guess some of the visible metallic stuff comes from the Traction-Lock steel disks.

I think we all worry too much about this stuff (including me). Considering the degree of violence inflicted on the rear axle in several axes at once, I don't think voodoo methods of heat cycles, however well-intentioned, determine how your stuff will wear as much as the original manufacture and heat treating!

Get in and abuse it, er, enjoy!

Cusp

So how did the gear install go? Do you like them?

rmurad38

Very much so, I haven't really pushed the car all that hard, I want to run them in a little first, but the car seems far more aggressive with them, I have noticed however that the transmission seems to shift far faster (as would be expected) but also is a bit "lurchy" when coming to a stop (moreso than with the 273's) perhaps BAMA can tweak my tune a bit. I also seem to have gained 1-2mpg city, but im sure ive lost that much hwy. Overall, seems to be one of the better bang for your buck upgrades

rmurad38

Cusp

2.73s to 3.73 is a big jump. 37% increase in torque at the rear wheels. But also a 37% increase in RPM in the highway. Must feel a little like my old Jeep did (auto) in low range. When in low the shifts felt abrupt and harsh is what I mean. Not that you wind out 1st at 5 MPH. lol.

AMChrisRose

Did you get your tune updated for the 3.73s? If not, the MPH will be off, so will the shifting.

rmurad38

Yes, I got the tune adjusted, the problem I have now is a very hard 1-2 shift and a nasty "bump" (I assume the 2-1 shift?) when decelerating..The car is quite zippy though. I'm working with BAMA, they have sent a few tunes to me wanting to report my findings.. Hopefully they get it sorted soon because as much as i like the increased performance, the harsh shifting and moreso, the jolt when coming to a stop, is getting tiring. But I do have faith in them, we shall see.

rmurad38

AMChrisRose

I know exactly what the 2-1 shift issue is. Call Bama, but this time ask for Mike Wilson (call Tuesday, we're filming Monday). He'll get you taken care of in one try. I'll make him aware of the situation.

rmurad38

Awesome, will do. I have been dealing with Ryan McDonald who has sent me a few tunes to experiment with. Perhaps get him involved with this too so we dont duplicate efforts?

rmurad38

Just want to express again, how much I appreciate the level of customer service presented by AM/BAMA, everyone seems to be doing their part to make me a satisfied customer!