I put 3.73 in the title just becuase I see that alot of people seem to like those. Maybe this answer is going to be more involved than I'm anticipating, but...


What all is involved in swapping out the stock gears and putting in something like 3.73s? Is this a challenging thing to accomplish?


Also, what kind of changes would you see over a stock 1986 MPFI bird's gears?
Like MPH compared to RPM?

 

the 3.73 is a posi rear end i'm pretty sure. but i'm not a mechanic so i'm not that sure. the only thing you gain is traction, and i'm pretty sure u don't gain a higher top speed if thats what your asking.

 

Specialized tools are required. The install might be best left to a pro.

You probably already have 3.42's, so you'll lose some top end with 3.73's and RPM's, of course, will increase (detrimental to gas mileage as you can imagine). All things considered, I'd stick with the 3.42's, if indeed that's the gear set you have.

JamesC
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Not all 3.73 rears have posi.

 

It won't be posi unless he switches in a posi carrier too.

If you're just swapping gears, then leave it to a pro, you have to have a pinion depth guage to get the pinnion shimming done right because if that's off, it screws everything else up. Most gear manufacturers recommend that you set [pinion depth to a +/-0.005", that's really close. Not something you want to eyeball.

Than you have to set the carrier bearing preload and backlash. All this has to be done as close to perfect as possible or you'll get a rear-end whine from the gears...ask me how I know...

Now, if you're swapping out the entire rear end and housing, then it's easier since they'll come already built and it's just a swap-out operation, unless of course, you put new gears in, then you're in the same boat as you are if you just swapped the gears in yours in the first place.

 

Eh. Nothing at all like what I pictured. I've learned to not expect anything easy when it comes to my car .

Thanks for the info guys. I was mostly curious.