Hello I would like to know how hard it is to change the gear ratio in a 1990 F-350 4x4 with 4.10 gearing right now?

 

If your asking how hard it is you can't set up a ring and pinion.

 

I agree with garthneddy.

 

As previously implied it's not rocket science but it does require a few special tools, a press and a good handle on what the specifications mean. There is plenty of room for expensive errors.

I have done several gear swaps over the years in my home garage without air tools, but I also had the advantage of learning from some very experienced mentors before hand.

 

welcome to FTE.
there are two way to change gear ratios.
the hard way and the easy way.
the hard way is to pay someone to swap out the gear sets front and rear.
the easy way is to swap out the front and rear axle housings with someone that has the gear ratio axles housings you want.

 

Why do you want to change? 4.10s are a good all around ratio for these trucks. I'm thinking about switching to that from 3.55s myself.

 

The tough part in my mind would be setting up the pinion depth properly. Shimming the carrier wouldn't be that hard, just need a dial indicator, that mesh pattern paint, and some patience. A little beam style torque wrench for pinion bearing preload checking, a good brass drift and a kitchen oven and it shouldn't be too bad.

I've had rear ends apart and successfully reassembled with new bearings but never replaced gear sets, so I just reused all the shims.
I too have a great mentor, he said tolerance for error is very slim for axles.

 

GoinBording and garthneddy are both right. Changing gears yourself is very doable, but it does take some specialized (although not that expensive) tools, some detailed information, and a lot of patience. If you are able to look up the info and collect the tools, or if you have someone working with you who knows what they are doing and are willing to show you, you can do it. If you need to ask whether you can, you probably can't.

Changing gear ratios can (of course) be done without changing the gears yourself. tjc transport gave you those options. A decent rule of thumb is that a shop will charge you about $1000 / axle to change gears. Swapping axles can be significantly cheaper if you can find good axles with the ratios you want and can sell your old axles for a reasonable amount.

If you are looking to take out 4.10 gears you must either be looking for better mileage and want to go higher (lower numerically) or else you've put big tires on and you want to go lower (higher numbers) to get better performance. The cost of swapping gears is probably too high to justify with better mileage, you'll never recover your investment (although I'd sure rather have 3.55s in the F-250 in my sig). If you're looking for performance with bigger tires, only you can decide if it's worth the cost. Personally I wouldn't bother if you're only looking to go up to 4.56. The benefits wouldn't be worth the cost to me. But if you need to go lower than that it might be worth it.