All I use my 87 f250 truck for is to haul the toys to the mountains about 10 times a year. I have a hard time staying in 5th <zf5> just going up and down small hills while towing with out having to shift.

I have 3:55 now and was wondering if 4:10s would keep me in a better rpm range 2400-2500 and let the turbo do its job. If so what years will fit? The junk yards have a bunch of mid 80s-mid 90s so I will just swap out axles for $100 and sell my old one rather than swap out gears. Thanks

6.9 093 turbo zf5 2 wheel drive

 

87-97. but why not just down shift, it is free

 

^^ Just don't use OD when towing, nothing wrong with that, many manuals tell you just that.

 

The junk yards should know what years fit.

 

Its wierd,this thing is super weak in reverse since the 5 speed transplant and I was hoping it would help there also. I know it will help in the taking off department.

I can down shift but it would be nice to use cruise and be at 2300 rpm rather than 2800.

 

I've been getting ready for that transplant myself, from what I've read the diesel ZF5 is really high geared in reverse. The thread I found had people joking about trying to back a trailer up with it.

Now, you're trying to cruise at lower RPMS, putting lower gears in your rear isn't any different than just keeping it in 4th when you're towing, either way you're going to get the higher RPMs.

Maybe someone can do the math to show the exact difference.

 

did you swap the od trans in?
you understand that OD isn't a performance gear? it's for economy when there isn't a strong load.did you expect to able to tow uphill with an idi engine while in OD?
if you only use the truck for 10 trips per yr,why did you bother to swap in an od trans anyway?
it's surprising the vast difference of what some people think this engine is and isn't/is and should be.

 

If you used a 87-95 trans YES, 1st and REVERSE SUCK. They are geared entirely to high. 4.10s are not going to really help with that though

 

I need a trans for my 92 IDI. My ZF pops out of reverse and grinds into 2nd when cold. What years should I look for to get a lower 1st and reverse?

 

swapping out the 3.55 rear diff for a 4.10 will make a difference.
you may still have to downshift on hills, but it will be easier on the drivetrain with the 4.10 gears.
as Brad said, 87-97 F-250 or F-350 will be a direct bolt in.

 

Swapping in some 4.10's will do almost nothing for you. In 5th gear you would have a final drive ratio of 3.16, which is just a tiny shade taller than what you currently have in 4th (3.55). What you loose is your overdrive gearing. If you hate to downshift out of 5th now, you will really hate it when 5th is similar to the 4th you have now. Take it from someone who owns a Gear Vendor overdrive gear splitter, 3.16 vs 3.55 is a very small difference, and not one wirth loosing your highway gear over. you "gain" at the low end, but in my experience 1st is annoyingly low with 4.10's unless you are pulling monster load. 4.10's still won't let you start out in 2nd though. I can also tell you from experience that 4.10's and a T19 plus GV overdrive (almost identical to ZF's 5th gear) leaves me wanting one more gear on the highway. Engine still revs more than i like and feels "strained" at modern freeway speeds. I own a 4x4, so a gear swap would be really pricey. My solution was to get a ZF ~and keep my gear vendor for "double overdrive". have not swapped it in yet, but that's what i chose *Here are a couple of spreadsheets i worked up to visualize the diffetence in axle ratios and engine rpms. Note you will not have 5th plus overdrive, as you are not running a GV unit. I actually crossed it out on the 3.55 sheet because i felt it would be over geared, and not really practical to use. Engine rpms are assiming stock 235/85/16 "31 inch" tires:

 

Thanks for the replies guys. I guess I will just leave the 3:55s in and go back to trying to get a little more power out of the motor.

 

Going to be no difference hardly between 4.10 and OD or 3.55 and 4th, so just down shift when you have to, and use OD when ya can.

 

95 + and iirc the ones from a gasser have better gear spacing.

 

The other guys are right you shouldn't pull in high gear. The diffrence between 4.10 and 3.55 on my truck was 500 rpm at 75mph.
if you are set on your axle swap you sould know that there are diffrent u-join sizes from 87-97. Im not sure but if you find another rear end out of a 250 of the same body style you should be good.
Also if you a doing a swap you might want to find a limited slip rear axle. Check the axle codes on the door sticker. A 35 is open 4.10 a c5 is the most comman limited slip 4.10.
I put a 3 speed aux transmission in my truck so I had the pulling range of 4.10s and the fuel ecom. of 3.55s.