Gear ratio

[destroked]

Alright, I'm looking at buying a 96 psd and noticed when I test drove it, the truck was slower then usual getting out of first and into second gear, then its fine. I noticed today in the description that it has 4:10 gears, which are meant for tow/hauling if i remember correctly. Or may its slowness be due to its still in tow/haul mode and hasn't been turned off?

My questions are:

1. is it supposed to be slow with 4:10 gears? everyone has them
2. what should its mpg be with those gears?
3. how much would stock gearing cost?

[Red '97]

The 4:10 gears if anything will make the truck faster than the same truck with 3:55s or 3:73s because its lower gearing if that makes sense.

As a result of this lower gearing, rpms are going to be higher than a truck with the 3.73s or 3.55s, at 65 my truck is turning 2100 rpm, compared to my moms 3.73 truck that does 1850 at 65. this will result in lower mileage, but increased acceleration accross the board. youll also feel the difference from a truck with higher gearing when towing.

Now the truck most likely came from the factory with 4:10 gearing, this was a popular option in obs trucks. im not sure how much regearing the truck with higher gearing such as 3:55s or 3:73s would cost, but honestly unless you mainly commute in the truck id leave the 4:10s in.
as for the tranny shifting slow, i couldnt tell you much about that, sounds like it may be slipping. im sure other members will chime in, hopefully a little bit of what i just told you is correct...

[destroked]

I know for sure the transmission is in good shape since that dealer is pretty much #1 to buy a diesel from, so thats not an issue.

I think the truck may still be in tow/haul mode since they have been using it around the shop. Because one time at work I had to use a 350 gasser, and it was slow as crap the first day. The next day it took off like normal. I think it was in tow mode.

[351fifty]

my truck is slow as crap getting to about 15 mph, but once i hit it i can take off real quick from there, and hell sometimes if im getting to 15 slowly and then romp on it i can shirp the tires too, but just about anything before that its real slow and dont get no where

[superduty4x4]

There is no tow/haul mode in an OBS.
4.10's will give you more acceleration but limit top speed. Expect to get around 15mpg with that truck in a combo of city/highway driving on average. Both my OBS with 4.10's were a dog off the line too, I think its just a function of little injectors and a large turbine on the turbo. My 96 wasn't as bad, but this stinkin' federal emissions 97 I have now is the turd of turds. I'm hoping to fix that real soon...

[351fifty]

federal emissions? i live in cali and emissions is no longer required on 97 and older diesels, georgia doesnt have emisssions period on f-250 and larger or any size diesel period

[superduty4x4]

Originally Posted by 351fifty

federal emissions? i live in cali and emissions is no longer required on 97 and older diesels, georgia doesnt have emisssions period on f-250 and larger or any size diesel period

Late build 96 and 97 build trucks with the CA emissions package got AB split shot injectors, which are 120cc instead of the 90cc AA injectors in the 49 state trucks.

[destroked]

Well I dont have enough income to afford a new set of gears in the rear so I'm looking at an Edge Evolution color screen tuner.

So city mpg would be like 14-15 mpg and highway around 18-20 stock?

[08spartan250]

i was looking at doing the same thing. its going to be way more money than its worth. i got quoted 2400 bucks for the gears and installation today. i know that guy is a little high, but i've got somewhere close to that from everyone i've talked to. i'm just going to do stage 1's and a 17* hpop to help with mpg instead.

[superduty4x4]

Originally Posted by 08spartan250

i was looking at doing the same thing. its going to be way more money than its worth. i got quoted 2400 bucks for the gears and installation today. i know that guy is a little high, but i've got somewhere close to that from everyone i've talked to. i'm just going to do stage 1's and a 17* hpop to help with mpg instead.

I was quoted $650 for install/setup if I supplied all the parts needed to put 3.73's in mine. I'd say $2400 is WAY high.

Originally Posted by destroked

Well I dont have enough income to afford a new set of gears in the rear so I'm looking at an Edge Evolution color screen tuner.

So city mpg would be like 14-15 mpg and highway around 18-20 stock?

My 96 was an auto, my 97 is a 5 speed. I also used to have a 99 F250SD that was an auto. I NEVER saw over 18mpg with any of them, and that's skewed because I somehow managed to pull down 17+mpg last fill up with my 97. Expect more like 12-13 in town and 15-16 highway, IMO unless you are really conservative with your driving or have a 2wd.
Don't waste money on the Edge, there are far better options out there for tuning. I don't know what the Edge costs these days but you should be able to get a custom burned chip and 2-3 gauges for $700 or so.