So I just swapped my rear end on my 87 f250 6.9 because the outer seals and bearings were shot, probably the inner as well, not sure. My new problem (do to lack of research) is that I went from 3.55 to 4.10 gear ratio. The axles are the same thing with different ratios. Would I be able to use the gears out of my old axle? If so, would they have to be re set? Could it be as easy as just swapping the pinion gear? Thanks in advance for any advice.

 

Welcome to FTE.

So you swapped the whole thing, drum to drum? Seals and axle bearings are, imo, a much smaller job.

You can swap your old gears over, but that is way more work than seals and axle bearings.

You will probably never get them back in the same pattern and will soon have a howler out back.

You can not change just one gear, pinion or ring. They are a set. Change one and you will have a howler right out of the gate.

Take your old axle and have the seals and bearings replaced. Reinstall it. Drive on. Serving suggestion.

 

Looks like I have a new lawn ornament, good thing it's at my brother in law's house. How much would a shop charge to swap em?

 

Since the old axle is out, take it to a shop you trust and get a quote. Swapping the old gears to your "new" axle is a non-starter. Just get your old one fixed and reinstall it. Serving suggestion.

 

Thanks for the advice. Should have done that in the first place. What if I took the five speed transmission from the truck that I got the new axle from? I don't know which would be easier but swapping transmission will be a lot cheaper. I just wonder if I would have a more reasonable final drive ratio.

 

going from 3.55 to 4.10 gears will give you a little more power, but less top speed. and a little less fuel mileage. as long as hte truck is a 2 wheel drive it is no that big of a deal.
but swapping the 4 speed manual trans for a ZF 5 speed is a popular upgrade because it gives you overdrive.
and it is not that big of a deal, as long as the trans is off a diesel engine. gas trans will not bolt to a diesel.

 

You said the zf has overdrive which would help immensely. Would it have higher or lower gears than my current four speed? Or about the same? If I had another gear I would be more than happy the axle gearing I now have. If the five speed is lower geared than my current transmission then it wouldn't help too much. Also I will have to use my current transfer case. Thanks for all the help

 

ooofff. four wheel drive..
you are going to have to either change the front axle to 4.10 gears, or swap the rear back to 3.55.
yes, the ZF is a 5 speed with overdrive. it is basically the same as your current 4 speed plus an overdrive gear. first is not as bad as the granny creeper gear you currently have.
if it is a 4X4 trans, your transfer case will bolt on.
i personally would leave the 4.10 gears in it with the 5 speed, it will make it better powered with the 6.9 than with 3.55's

 

Thanks for the input. I think that is exactly what I will do. I have easy access to the transmission and front axle, and can get them for cheaper than my local wrecking yard would sell them for. Kinda seems like a blessing in disguise now. Thanks again everyone.

 

what is the parts truck? if it is a F350 you will get the better front axle too.
if a 350, grab the front springs, steering parts, trac bar, and bracket while you are under there, the 250 springs are way too stiff for a solid axle and will give a rough ride.

 

Parts truck is an 88 f250. I guess that's when they switched over to the 7.3. Had to get a u joint to go from 87 to 87 as they are different sizes and I didn't have the drive shaft from the 88. I don't have the transfer case either so I hope mine doesn't reduce the gears any further. A solid axle would be nice but I like the old Ford ifs over anything else I've worked on and is a comfy ride. I wish I could use coil springs but I'm not aware of any that will hold the weight of the engine.