what size speedo gear do I have?

[yob_yeknom]

Okay, I searched and searched, but did not come up with an exact answer.
How many teeth are on my speedometer gear? '95, automatic tranny, 4x4, 3.55 gears
How many should be on a new one if I calibrate it for 31" tires?

 

[jimbo74]

i think it is 19 and no you wont need a new one, but your guage will be a little off.

 

[Okrazie1]

The 31's are roughly 5% bigger in diameter than the 235's, so the speedo will be close enough to not worry about it. For example, if you switch to 31's, when your speedo reads 65, your actual speed will be around 68.

 

[GJarrett]

One tooth equals about 3 mph so you could go up one tooth and pretty much be right on again after going to 31's. Just remove your old one and count the teeth and go to your local Ford dealer and get another one. They're cheap and easy to replace.

 

[yob_yeknom]

I DO need to replace it to save my transmission! The speed limit is 55 most places I drive around here, so I'm going about 50 on my speedometer to get it close to 55. My transmission keeps going back and forth between 3rd and 4th all the time and in doing so it's wearing itself out faster than it should. I need to get it to realize it's going 55 again so it won't shift so much.

Shouldn't I have to go DOWN a tooth? With the speedometer gear being the driven gear, don't I need to make it smaller to have it turn more turns per one turn of the transmission gear? Please correct me if I'm wrong.

 

[01EB5.0]

I thought the 95+ was all electronic?! I thought i heard that the computer just needed adjustment by ford. i dunno. All I know is my speedo doesn't have a speedo cable. it is only wires running into the gauge cluster

 

[Okrazie1]

Is the gear selection of the automatic determined by speed, RPM of the engine, or a combination of these and/or other factors? I'm not too familiar with the functioning of the auto since I don't drive one, but it seems to me that gear selection would be more of a function of engine speed than road speed. If this is the case, changing the speedo gear will not make any difference, since the engine is now turning a lower RPM at any given actual speed due to the larger diameter of the tires.

 

[go off road]

YOB-YEKNOM
you need to git a gear with one less tooth and then rest your computer just pull off a battery cable for a few, this will help your problem.

Wade

 

[Robert]

Go to http://www.explorerforum.com/forums/showthread.php?postid=172106#post172106 for a thread already dealing with this. Go down to my post with the gear part numbers. You will need to get a gear with one less tooth. It only takes a couple of minutes to pull the gear and see what color it is, count the teeth or look at the number molded onto it. My 5-speed automatic shifts more as a result of engine RPM, not road speed. If your '95 is controlled like my '97 then changing the gear won't do anything for your shifting. It will only make your speedometer read correctly. Mine used to shift into OD around 45 MPH, now it is closer to 50 MPH when it shifts into OD.

 

[Robert]

Originally posted by yob_yeknom
I DO need to replace it to save my transmission! The speed limit is 55 most places I drive around here, so I'm going about 50 on my speedometer to get it close to 55. My transmission keeps going back and forth between 3rd and 4th all the time and in doing so it's wearing itself out faster than it should. I need to get it to realize it's going 55 again so it won't shift so much.

Shouldn't I have to go DOWN a tooth? With the speedometer gear being the driven gear, don't I need to make it smaller to have it turn more turns per one turn of the transmission gear? Please correct me if I'm wrong.

It is probably shifting back and forth more as a result of the increased rolling resistance from the larger tires. It takes more gas to get moving and accelerate so it is probably downshifting more. My '97 automatic shifting is more of a function of engine RPM than road speed.

 

[yob_yeknom]

Road speed is also taken into account when it decides to change gears. I'm hoping that having it read the right speed will be enough to get it to stop shifting so much.

 

[01EB5.0]

WOuld putting 16" wheels and P255/70 tires change my speedo at all if i am currentl;y using P235/75 R15?

 

[GJarrett]

Originally posted by yob_yeknom
Shouldn't I have to go DOWN a tooth? With the speedometer gear being the driven gear, don't I need to make it smaller to have it turn more turns per one turn of the transmission gear? Please correct me if I'm wrong.

Yep, sorry, my bad; my fingers weren't typing what I was thinking.

Travis, of course it will; it's a larger tire. Go to www.4lo.com to calculate the difference in sizes and how much error your speedo would have.

 

[01EB5.0]

Thx, Gerald