3.08 questions

[L1011tristar17]

On this forum I've noticed that a lot of people have swapped out the stock rear ends and replaced them with different gears. Will swapping out the standard 3.08 gears (what my car most likely has) increase performance or fuel mileage? It'd be an interesting project to work on, provided it's not too expensive or difficult to do. How hard is it to make the swap? And what rear end gears should I be on the lookout for?

[marquisman]

Yes and no, depends on where and how you drive. But, these cars really dont drive great with anything less than 3.27, from my experience anyway. My brothers '88 town car with 3.27 gears, runs great in town and hiway. Best of both worlds. If you do lots of in town driving, haul weight(i dont mean drugs lol) or have engine mods, you might find 3.55 work best for these heavy boats. I put 3.73s in my lincoln and is very good in town on hills and such but, my lincoln sucks on the hiway. The smogger 351W is prolly some to blame for that.

[jaywish]

Check your door tag for the gear code, it may say axle? But it is a short code. This will tell you where you are starting. Look up a goodsamaritan post he has the code table in his signature. You may have a posi.

[Glen]

3.27 is a very good overall gear. I went from a 2.73 to the 3.27 and it runs a lot better. Mileage didn't change. I changed the axle, but I wanted disk brakes in the rear.

[mcninetyone]

I went from an open 2:73 gear in my box CV to a 3L55 rear, and so far so good. I love it.
I should have done this swap long ago.
My first highway trip I got 25MPG, which I was very happy with. But I plan to check that again.
I swapped the whole rear end not just the gears, it was not that hard at all.
I highly recommend this swap.

[marquisman]

I forgot to mention, my lincoln had 2.73s before going to 3.73s. In the wagon, I went 3.27 from 2.73. Noticed a huge difference.

[pantera77]

3.55 or 3.73
Otherwise don't waste your time.

[marquisman]

Well, on a LOPO 3.27s or 3.55s are ideal. But I agree, 3.55s or more are a must on HO or anything more modified.

[SVT98t]

Check your door tag for the gear code, it may say axle? But it is a short code. This will tell you where you are starting. Look up a goodsamaritan post he has the code table in his signature. You may have a posi.

Eh, you would be better off crawling under the car and checking out what the axle tag says. I've found that the door sticker/axle code (and build sheet) aren't always correct.
It would read 3 27 for 3.27 open or 3L27 for locking 3.27.


-ryan s.

[1990LTD]

I can't wait to get rid of my 3.08 open rear end for a 3.55 locking

[87gtVIC]

This is not a beginners job.

[gadget73]

proper gear setup does take some tooling and experience. On the surface its pretty easy, but the touchy part is getting the gear alignment correct. if its not right, it will whine or could self-destruct if its too badly off.

[sick88tbird]

Set up is critical, but with ford gears and carrier you almost never need to change or re-shim anything...unless something is critically out to begin with. Countless times, I changed gears and carriers from one car to another(all ford parts) and used any original shims (on the pinion) and reused the original carrier spacers with no problems...however I always replace bearings and the crush sleeve...you can get pinion depth dead on by counting the number of exposed threads and making a punch mark on the pinion and the pinion nut for proper orientation...now if you're putting any other brand gear and/or carrier in, then absolutely you need the break out the marking compound and dial indicator.

I went from 3.08 to 3.73's and love it...however with my 17" wheels and tires it effectively makes those gears more like 3.55's.

Good luck,
Don

[miamibob]

Always forget - which ratios provide better City MPG's - lower numbers or higher??

[phayzer5]

Numerically lower is generally better mileage. But with these cars, a higher gear does good in the city to get and keep the weight moving. 3.55s didn't reduce mileage much (if any) for me