Gear ratio?

[914x4sport]

I dont have the owners manual for my Explorer, and was wondering if anyone knew what my gear ratio is. Its a stock 91 sport 4x4 Automatic O/D no EB or XLT or anything ,I figure there should only be one gear ratio for that year and model, right? If anyone knows,please enlighten me..Thanks.

 

[Stephen S]

ntrpriz has a page where you can check that. Just look at your the codes on your driver's door and go to this page.
http://www.users.qwest.net/~ntrpriz/main.htm

 

[sink]

Here's the deal-

Take the vehicle, a friend and a piece of chalk to a clear level area. Put it in neutral (engine off) with the wheels pointed straight. Mark one of your rear tires directly at the ground with a chalk line. Mark your driveshaft directly on the bottom. Hang onto the underbelly and have your friend push the vehicle slowly forward for about 4 or 5 full tire rotations while you count the driveshaft revs carefully. At the end you may want to take the tire another FULL rev or two to get the driveshaft at a position you can estimate well (like 1/4 or 1/8 or 3/8, etc). Then divide the shaft revs by the tire revs. More revs=better accuracy. This really works! It can't be done with the wheels jacked up or on a curve because the differential will throw it off. Its even easier if you do it running, in dri ve with someone you TRUST working the brakeor on a slight hill in neutral with someone who doesn't hate you.
At the least, its a great and easy way to verify the info you get from Stephen's good advice.

 

[Stephen S]

That's the first time I've heard that way to check a gear ratio. Seems an idea like that would work to give a number approximately equal to the ratio. Sort of unsual way, but hey, whatever works.

 

[914x4sport]

Originally posted by sink
Here's the deal-

Hang onto the underbelly and have your friend push the vehicle

Hee Hee! You know I've always wanted to do something like that...You know Indiana Jones style!!!LOL Thats a great idea i think Im gonna try it. Thanks for all the info you guys. I Love this site.

Piece Owt

 

[edogwv]

easier way

The easiest way is to look at the tag that should be on your rear axle. A small little aluminum piece that you should find under one of the bolts holding the cover on.

-Evan

 

[sink]

I love this site too!

The tag thing is good. Hope the 91 still has the tag. I became an expert at the count thing because the 1981 F250 4by I used to have seemed to take 6 grand RPM to keep highway speed on a good solid C6 trans. I knew they did tags, but my old truck had no tag. Since I knew all the gear ratios those vintage Fords could have- I rolled the truck by myself on my driveway and was absolutely positive I had 3.55's, not 3.25's or 3.72's. Finally though, I broke down and pulled the differential cover (I needed to chage fluid anyhow). When I counted ring and pinion teeth- I found I was dead nuts on- 3.56. I have also seen tags with a bunch of coded crap only on them. Reading tags IS quicker than the roll thing (tags are very precise but also only as good as the dude who hangs them, hardcore physics doesn't lie- have fun- yeeeeehah). By the way... Its pretty tame. I actually spun my driveshaft turn by turn with my hand, which caused the truck to slowly roll forward as I counted.