rear end gearing

[flaminblack]

Hello all.... I have an '02 7.3L PSD lifted 8" w/37's... I was talking with a tech yesterday about changing out the stock 3.73 gears yesterday, but he could not tell me right away what gears should be installed. I have not done much to the truck. Have a TTS chip that I have removed for now and will probably go back in with a Hypertech programmer instead so I'll gain the flexibility of changing driving requirements. Does anyone know what gears should be installed to match up properly for best all-around performance?

[Tom]

To get back to stock (265/75 w/ 3.73 gears), you'll need about a 4.30 ratio. With the larger/heavier tires, you'll still lose some seat-o-da-pants accelleration.

If you don't tow much (if at all), use 4.10's.

If you tow often and heavy, use 4.56's.

Keep in mind that 4.10's will allow you to run a 35" tire (later) with an effective 3.73 ratio.

Bigfish is running 4.10's and 37" MTR's. He'll probably respond soon.

-T

[DrDenny]

Tom, I have 315's and tow quite often(12K 5th wheel). I'm thinkin the 4:30's sound good, I had 4:10's with 33's and thought I could use a little more... But think 4:56's might be a little much. I don't see ever going smaller than 315's...

Denis

[Tom]

Tom, I have 315's and tow quite often(12K 5th wheel). I'm thinkin the 4:30's sound good, I had 4:10's with 33's and thought I could use a little more... But think 4:56's might be a little much. I don't see ever going smaller than 315's...

Denis

Well, 315's are about 34.5" tall, so...if you didn't like the 4.10's with the 33's....lol

I'm doing 4.56's with 315's on my 2000. It's pretty much like stock tires and 4.10's. (not great for top speed, but it can pull like heck)
-T

[flaminblack]

Thanks for the info Tom... will consider the 4.30 option since I don't tow often and rarely if ever heavy. Not really too concerned with top speed (or would have bought sports car .. lol), but that little extra kick in a PSD is a nice bonus.

[Tom]

4:30 gearsets are usually inexpensive (used). They are an option on the gas trucks and guys that order that option often end up putting larger tires on and re-gearing.
-T

[beretzs]

I know I don't have a PSD, but my truck runs 4.56's with 37's and they are awesome for pulling. I run about 2500Rpm's at 75MPH. That is what my buddy says. I have been able to drive it since I had the OD installed, but the overall gearing is the same as a 1-1 direct with 3.55's. So overall in OD I am running the eqivalent of 3.55's.. The 4.56's are awesome for pulling, I pull my Jeep and a trailer alot when I am home, all through the mountains and there are not many hills that are big enough to pull it out of drive and my truck doesn't put out the torque your truck does. If you can steal 4.30's from a gasser, you will have about the same effective gearing.. Also, there is a shop in Pomona called Hicks 4x4 that set my truck up. They are way below what others quoted me and they did a great job. Just ask for Vince if you call.. Anyhow, hope this helps. Scotty

[DrDenny]

Tom,
When do you think you will put your 4:56's in? Don't you run a big tire? Anyway I'd like to go for a ride and see how it goes...Denis

[ragenford]

I have a question, my code # on the the door jamb, is saying I have 3:73. I crawled under my PSD tonight and the the tag says 409, and there is a sticker to the right that says 409c. Is this a discrepancy? I have no idea

[Tom]

No, i think that's just a code.
I remember mine said something like that too, on the tag.