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-   -   How to determine gear ratio in Ford 9" (http://www.hotrodders.com/forum/how-determine-gear-ratio-ford-9-a-26211.html)

Kaylah 10-21-2003 01:56 PM

How to determine gear ratio in Ford 9"
 
Hi folks,

I thought this might be a "greenie" question, but I need to know anyway. How can I figure out the rear end gear ratio in my truck that has a 9" Ford?

I think it has an LSD of some sort, but I haven't checked that yet. I'm just guessing because whenever I goose it, I feel both sides engage. Yesterday I goosed it out of a corner, and it spun straight, did a little "S" then moved out real nice (everyone in the cab just kinda got momentarily pasted to the rear window).

I don't do this often (yeah right!), but anytime I do I get a good response from the rear end. My miliage is also pretty good on the open road anyhow. In the city I get about 13MPG and I have 225R 70 15's. Help in figuring out the ratio would be appreciated. THX...K

Centerline 10-21-2003 02:36 PM

Stick a floor jack under the rear end, put it in neutral and rotate the passenger's rear wheel one complete revolution. While you do this count the number of revolutions on the drive shaft. If it goes about 3 1/2 times then you probably have about a 3.50, if it goes almost 4 times around then you have a 3.90 etc.

This method will give you a pretty good idea of what you have and is the best method I know of without actually counting the teeth on the ring and pinion.

Centerline
http://www.hotrodsandhemis.com

willys36@aol.com 10-21-2003 02:57 PM

Ditto. And for a more precise ratio, turn the wheel 10 times which will give you the ratio to a couple decimal places accuracy.

roys63 10-21-2003 03:28 PM

Have you checked to see if there is a tag one of the bolts holding the pumpkin in to the housing,, i think the first #s are the gear ratio.

Kaylah 10-21-2003 04:37 PM

Thanks...will do.

I just jack it up under the pumpkin, right? Both wheels off the ground, and spin the passenger side wheel.

tm454 10-21-2003 04:45 PM

traction issue
 
First CK out your gear ratio and then get back to us. I tried to explain to the Troll with the imaginary Boss Stang he needed to CK his gear ratio and post back but I don't expect to hear from him. YOU WERE RIGHT ON GIRL, called it in the first post didn't you? Boss Troll is pissing around with the crew and cussing his little head off. Some people don't understand its not good to be caught in a LIE?? He's probably running bald tires, or did he say slicks???




Todd




Rat Rods Rule!

willys36@aol.com 10-21-2003 05:12 PM

Re: traction issue
 
Quote:

Originally posted by tm454
First CK out your gear ratio and then get back to us. I tried to explain to the Troll with the imaginary Boss Stang he needed to CK his gear ratio and post back but I don't expect to hear from him. YOU WERE RIGHT ON GIRL, called it in the first post didn't you? Boss Troll is pissing around with the crew and cussing his little head off. Some people don't understand its not good to be caught in a LIE?? He's probably running bald tires, or did he say slicks???




Todd




Rat Rods Rule!


Todd, what are you talking about?

Kaylah; Yes jack up the rear end so both wheels are off the ground. You wan to turn the passenger side wheel because it is attached to the ring gear. The driver's side wheel goes thru the differential and, unless both wheels turn (the passenger side may stay still or even go backward), you will get bogus results.

HemmiGremmie 10-21-2003 08:18 PM

Hi Kaylah.
Your real close to me in Ohio. Id hate to, but I could stop over and see ya, I mean help ya!:mwink: HG LOL


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