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.
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.
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! '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."
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
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.
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
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