Changing Rear axle gear ratio
 

:( Hi
I have a 1995 ford F150 supercab with a 4.9 liter 6 cylinder 300 cid engine, it has a 3.31 rear axle.
I recently bought a 24 foot travel trailer that weights 4150 lbs dry and a gvwr of 6440 Lbs.
I find that it is lacking on the low end and Iam thinking that changing the axle ratio to a 3.55 rear rratio will increase the low end. But I don't know if it is feasable to do this. thank you for your help.

Changing Rear axle gear ratio
 

I would think the difference between 3.31 and 3.55's would barely be noticable. If you're going to spend the money, I'd look to going to something like a 3.73. I wouldn't consider 4.10's unless you have much bigger tires than stock.

Changing Rear axle gear ratio
 

Hello again
can I just change the Gears to 3.73 or should I get a whole new axle?
will that increase my tow capacity? the tires are stock size.
Thanks again.:-X12

Changing Rear axle gear ratio
 

Nothing will increase your towing capacity that is all factored off of things like brakes, suspension and tires.

However lower your axle ratio to a 3.73, or a 4.10 will make the motor work less while towing.

Since you have 95 I assume that either trans you have (auto or manual) has an overdrive. I would go for the 4.10.

Changing Rear axle gear ratio
 

What tranny do you have? Definitely go to a 3.73 or higher. The tow rating goes up with higher axle ratio number. Also don't run overdrive when towing. OD is the weak link, expecially on a light duty Mazda manual tranny. As for changing the axle ratio, my pinion went out on me and my mechanic said it would be cheaper and easier just to get a whole unit from the wrecking yard. I did and now about 15,000 mile later it is still performing flawlessly. I paid $250 for an open differential unit with 3.08 gears. I have a '95 F150 brochure I will try to look up the ratings tonight for you and post tomorrow (if I can remember).

INLINE SIX POWER!Oo. '95 F150 XL
300 Cubic Inches of Low RPM Truck Torque! And twin-I-beams too!
"Drive a stick young man! There'll be time for automatics when you're old and unable."

Changing Rear axle gear ratio
 

From the 1995 Ford Pickup Truck sales brochure:

2WD Supercab 300 cid F150 4x2

For Auto Tranny:
Axel, Max GCWR, Max Trailer Wt.
3.08, 9000 lb, 4300 lb
3.31, 9500 lb, 4800 lb
3.55, 10000 lb, 5300 lb

Manual Tranny:
Axel, Max GCWR, Max Trailer Wt.
3.08, 6450, 1900
3.31, 7125, 2600
3.55, 7800, 3200

They don't list the 3.73 axle for any '95 pickup, but do list a 4.10 ratio on F250s: with auto tranny the 4.10 is rated 11000 GCWR and 6000 Trailer Wt., with manual (and it is listed for standard cab) the 4.10 is 10000 GCWR and 5200 Trailer Wt.

Seems to me the low numbers on the F150 manual tranny are due to the Mazda tranny, whereas on the F250 the manual is much closer the autos rating and likely is due to the beefier ZF tranny, but probably still comes up short because Ford probably figures trailer towing will be hard on clutches. Don't know, just guessing.

Changing Rear axle gear ratio
 

i know when i needed to replace the diffs in my bronco II ( i hit a storm drain and cracked front case) i bought both front and rear (stock gears w c-5 was 3.45) with a 3.73 ratio i payed 250 for both gear sets for one axle are close to twice that in most cases. i would go with 3.73 if you could find it. good luck the swap is easy if the bolts come off easy

Changing Rear axle gear ratio
 

How do you acutally change the gears? i've never done it before and have no clue, i have a 1996 f50 xl with the 3 speed transmission. TTB up front. not sure what my gear ratio would even be

I'm putting 4.10's in the rear on my 1994 f150 300 i6, i haven't done it before either so i'm in the same boat. Could use any Help

It's true that just swapping rearend is easiest.
and how heavy do you think the trailer will be typically when you tow it?

Setting up gears is not for the faint of heart. Its time consuming and requires quite a few specialized tools. You'll need to have 12 ton press (minimum) & a dial indicator with magnetic base. A set of setup bearings are usually quite handy to have, too. You can make your own out of cheap china bearings & a carbide grinding bit.

Patterning is tricky, and if you get things just a little bit off, you'll eat up your brand new gear set.



As has been previously stated, it is far cheaper to purchase an axle out of the local bone yard. It's will limit your available ratios to the factory offerings, but most of you are talking 3.55 or 4.10 anyway, so no worries

what stock axles come with 4.10 gears?

also, if i have 4.10 in the back what should i be running up front? say i got a dana 60 off a old F350 and put on it, would i need to get the gears changed? sorry if these are stupid questions.

Some good reading here for the basics of installing gears: Randy's Ring & Pinion - Installation Instructions

Both the front and rear gears need to match each other as close as possible. Example: 3.55 rear gear/3.54 front gear. Quite common in the older trucks.