please help with some speedo questions

[Alec]

Hey all, some speedo calibration questions for y'all. And yes, I've read through most of the threads about it and am fairly informed.

My friend has a 98 X that came from the factory with strange equipment. First, it has the "old" drivetrain: 4.0 OHV and 4R55E. It also came stock with 225/70/15 tires, and we recently went to 235/75/15s. So, her speedo is off. One Ford dealer said they can't recalibrate it (morons!), and the other said they need at least 2 days and they can't give me any answers. So, here it goes:

1) Is her speedo mechanically or computer calibrated?
2) If it's mechanical, what speedo gear does it have now? (3.73 gears)
3) What speedo gear do I have to get? When her speedo says 65, she's going 70.
4) Where is that bolt that I have to undo to get at the speedo gear?

If I get the new gear and know where that bolt is, I'm confident I can change it. Thanks for the help!

BTW, I have a 96 OHV 4R55E with 3.27s and 235/75/15s. I'm going to 31x10.5s.

What new gear do I need to get for mine?

Thanks Much!

 

[espnfreak]

when i upgraded to 31" tires from 29" stock tire, travis (95XLT) told me to get this part from ford "CODD-172171-B" and its about $10 and it will recorrect the speedometer on my 96 ohv. Lemme ask travis to check this post out, he knows a lot more, he said it would take about 20-30 min o install the new part for the speedo

 

[RytM1]

Alec, have you checked out the speedo calibration page in the "Explorer tips" section http://www.explorer4x4.com/speedo.html ? Check it out, it has some pretty decent instructions, and pics. Good luck.

 

[Alec]

Thanks, I had seen that page before (actually, I have a printout of it).

I guess I need to have a look at our old speedo gears to see which they are so I can see which new ones to get. If I understand those instructions correctly, do I need to slide the tailshaft out of the tranny? Is that the driveshaft? I need someone to actually point me to the correct bolts. I guess Kris will help me when we meet soon to do my lift.

I didn't want to mess with her truck until I actually had to change the gear, but it seems like I'll have to get in there to count the teeth on her current gear. I hope hers is still mechanical and not computerized!

 

[Ray Lobato]

Alec,
I have a 97 and my speedo gear is on the Transfercase.
It looks like this. Don't know it your friends set up is the same

 

[Robert]

Alec, Ray's pictures are what you should look for. However, I think yours is a 2WD, don't know what your friend's is. On the 2WD, the speedometer assembly is mounted to the end of the tranny. No you don't need to remove the driveshaft or anything else to remove it. It only has one bolt and one electrical connector. Remove them and pull the assembly straight out. The gear will be on the end of it. Ray's is the yellow gear. You would stand a much better chance of getting the correct gear the first time if you remove and look at yours first.

I would start with yours rather than your friends so you know what you are looking for. The jury is still out as to whether or not a '98 has the gear or if the speedometer uses the RABS sensor like the '99 and ups use. Your '96 uses the gear. Let us know what you find out on the '98. If it doesn't use a gear, then Ford can reprogram the computer to account for the larger tires. Gerald Jarret had his '99 done.

Here is a message I posted on the tire board a while back. the whole thread can be read at Dead Link Removed

The part number I needed for my '97 5-speed auto that originally came with 4.10 axle and 255 70R16 tires was C0DZ-B. It is the 19 tooth pink one. My original gear was the 20 tooth black one. One less tooth was all I needed. I used this formula: New Teeth = (Current Teeth x Speedo Reading)/Actual Speed. Be aware though that the table came from a Ford Ranger site. Unfortunately I don't have the link anymore so I don't know whom to give credit. The gear I used says that it goes on a manual transmission. When the parts lady first brought out the 19 tooth gear for the automatic, it was too big. Fortunately I took the gear out and brought it with me to compare (boy did it shift funny without the gear!). Here is the table that I used:

Manual Transmission:

16 tooth wine(C0DZ-A)
17 tooth white(C3DZ-C)
18 tooth yellow(C0DD-B)
19 tooth pink(C0DZ-B)
20 tooth black(C1DZ-A)
21 tooth red(C4OZ-A)

Automatic Transmission:

16 tooth blue(D0AZ-A)
17 tooth green(C7SZ-A)
18 tooth gray(C7SZ-B)
19 tooth tan(C7VY-A)
20 tooth orange(C8SZ-B)
21 tooth purple(D0OZ-B)

 

[Alec]

Thanks guys!

Is there any harm in running without the gear for a few miles?

That color code will make things very easy. Thanks! Wow! Yay!

 

[Robert]

It will shift funny, but that is how I did it. Within a couple of miles of home, my Check Engine light came on. I drove about 6 or 7 miles each way to the Dealership. Once I put the new one in everything was back to normal. The RPMs will be a lot higher and it will shift pretty hard into gear. If yours is a manual, then it won't affect it at all other than having no speed indication.

 

[Alec]

Well, I've got a problem guys. Seems my X already has a 16 tooth gear, and that's the smallest Ford makes. Guess I have a few options:

1) Deal with the speedo/odo being off
2) Get a little computer module pulse-thingy to change the pulse from the speedo sensor to the computer. Price quote for calibration and installation: $300.
3) Change my ring and pinion and then the speedo gear: $500.

Guess I'll deal with it for now, and maybe just go ahead and change my gearing later. I didn't notice a power change with the larger tires. Guess due to my supercharger. Hmmm, it'd be a chance to add that T/A diff cover...

 

[Robert]

Did Ford tell you that the smallest gear they make is a 16 tooth or are you just going by the list? I got the list off of a Ranger site so it's possible that Ford might have a smaller gear for a different vehicle.

 

[Alec]

The dealer said they didn't have any smaller ones than 16 that fit.

 

[go off road]

Alec call the Ford parts back and check on a gear from Ford Motor Sport I think they have some that will work.

 

[Tekeman]

I don't know that I would trust the color chart above. I went from the pink 19 tooth to the green 17 tooth, unless I got the wrong gear. Would a manual fit in an auto? vice-versa Once you do the change once, it is a 3 min. job.

 

[Robert]

I would say you might have gotten the wrong gear. Mine is a 5-speed automatic. My original gear was a 20 tooth black one. I went to a 19 tooth pink one even though the colors came from the manual. The first one I asked for was the 19 tooth tan since I had an automatic. When the parts guy brought it out it was slightly different than the black one I was holding in my hand. One of them was slightly shorter than the other. I asked him to bring me the 19 tooth pink one and the lengths matched up perfectly. I don't know if they can be interchanged or not since I took the pink one. If I remember correctly the only difference was the little protrusion from the end. I think on one it was about 1/8" longer. Maybe one will work in both types of transmission, but not the other? It is also possible that the colors on the chart are mixed up. Did you compare both gears side-by-side? There was a very slight difference between my original black gear and the tan gear (besides number of teeth). If you looked at one and then the other you wouldn't notice it.

I would recommend anyone using the chart, start with the group that includes the same color of the gear pulled out and take the original one along to compare. I got the chart from a Ford Ranger link a couple of years ago.

 

[Tekeman]

I will probably take my orig (pink) one back in. Also, I was hoping 2 less teeth woulg get me closer to stock. I put my #'s into 4lo.com and still seem to be reading slower than actual. 33's @2000 (OD)is about 70mph w/3.73
4lo says my actual is like 75. Even when I drop down to 32's which may be closer to actual size I'm still off at higher ( most exponential) speeds. 2000 in D is about 52 mph which is real close, 3000 in D claims 79n on 4lo but I read 70,71.
Pain in the a$$. Going stock tires to 33 BFG calculates 19 teeth to 17.1 on the conversion formula. 33 inches is probably generous too. Need to go to 16 teeth?

 

[Alec]

Well I finally got it calibrated. I went from my 3.27 gears to 3.73s. Then I established that I was 5 mph fast. So I went from my stock 16 tooth to 17 tooth gear and now I'm accurate!

THANK YOU to everyone for your help, especially the pics.

BTW, I advise to everyone not to try to do this after the truck has been running. It only took 10 minutes, but it was about 150 degrees under there!