1997 Mountaineer speedometer correction???

bronchole · September 9, 2012

So on my 1200 mile drive home from picking up my Mountaineer I noticed that the Speedometer was about 17% off. I also noticed that the transmission likes to hold a gear at partial throttle allot longer than I wish it would. It also kicks down allot easier than I think it should. I am basing this in comparison to my bone stock 1996 Explorer 5.0 AWD. I am hoping this is also related to the computer thinking its at a diffent speed than what it is. At full throttle The shifting seems to be correct.

Is this just a matter of replacing the gear on the sensor plugged in to the tailhousing? From what I have read on the 1998 and newer it’s a completely different animal that requires ABS computer reprogramming. Just wondering if this is like the gear on my Early Bronco.

If all I gotta do is replace the gear is it possible to do with the gas tank in place? Man it’s pretty tight up in there!

Rig specs:
- 35” tires
- 4.56:1 gears
- BW4406 transfer case with some sort of sensor on the top drivers side of the tailhousing (I can feel it up there).
- Mostly stock motor/trans (cold air intake)

Whatta ya guys think?

Dan

rickybobby · September 9, 2012

You need to replace the speedo gear. Im trying to find a formula to figure out what the ration correction needs to be for 35's and 4.56 gears, but not having much luck with google

Turdle · September 9, 2012

I thought Jim's truck had the later speed sensor in the rear diff. If so, it Sounds like the PCM needs to be programmed for the gear change. I think you need to enter gear ratio and tire revolutions per mile into a breakout box, which uploads this info into the pcm.

You'll need to go to the tire manufacturer's website to find revolutions per mile for your tire. All 35" tires will not be the same. If you do this your speedo should be spot on.

Check to see if the t case sensor is actually pluuged in. If it is, then yes you need to replace the gear. I think 410 fortune has this covered in his 99 build thread. ( making one from 2)

rickybobby · September 9, 2012

I see to the left it says 97 mounty, so im assuming that is the rig he is talking about, and if so the 97 explorer i have has a VSS in the t-case. At one point i had seen a calculator that if you input your current tire and gear info, along with stock tire size it would tell you what the equivelent stock gearing would be. Im sure im explaining it wrong, but long story short i used that calculator to determine that with 4.56 gears and 33's it is the equivelent to stock tires and 4.09 gears so i need a speedo gear for 4.10 gears. Im trying to find it again, but after nearly an hour on google i just cant find it again

deweyville65 · September 9, 2012

Pull the existing gear to determine the number of teeth on it. You will probably need a gear with two fewer teeth on it. For 17%, I dont think one tooth coarser will do. You can only go so far with the driven gear before you have to change the drive gear. Remember, fewer teeth on the driven gear will make the speedo faster, more teeth will make the speedo slower. I used to have one tooth different gear for 30-9.50-15 vs 31-10.50-15 tires. I know this really doesn't answer your question, but hope it will help anyway.

2TimingTom · September 9, 2012

I'm just going to throw this out there- you need the yellow speedo gear. Just a guess but a fairly educated one based on my experience going to 4.56 gears on 30" tires and switching to 33" tires.

bronchole · September 10, 2012

This is the 97 Mountaineer. All of the research I have seen says that the 97 does not use the sensor that is in the rear axle (which I also have) for correcting/calculating the vehicle speed. That said I will attempt to see if the sensor on the transfer case is plugged in to the harness (It's pretty friggin tight up there though).

IF all I need to do is replace the gear at the T-case than I am fine. I just did this correction on my Elarly Bronco. Calculation was pretty simple, but you have to know the tooth count on the current gear in order to know what gear to order to replace it. That means getting in there twice.

Does anyone know if I can get in there to remove that gear without droping the gas tank? Again, it's pretty friggin tight in there.

2TimingTom · September 10, 2012

Do you know what the original gear ratio was?

And yes, you can get to the speedo gear easily. It's on top of the rear output shaft of the transfer case- just ahead of the fuel tank.

BUT- this is based on my XLT with the "auto 4wd" and not the AWD that the Mountaineer probably has. Did Mountaineers come with selectable transfer cases or just 2wd or AWD options?

bronchole · September 10, 2012

This was a V8 AWD befor the PO installed a 4406. Now it is selectable. As I understand it there is considerably less room between the T-case and the gas tank with the V8/4406 conversion on a 4-door than on a 4.0 and/or 2-door.

I seem to remember the PO (Jim, nssj2) mentioning in his SAS build thread that the old axles were 4.10:1, but not sure. It doesn't really matter because in order for me to know exactly what gear to get I must know what gear I have and I have no idea weather the gear that is in there now was the factory original gear or was it a corrected gear for the 33" tire the Jim had in it prior to the SAS/re-gear of the axles and 35" tires.

I gatta say, there are all sorts of little things that are left to do on this thing, but I feel like I got one hell of a steal when I bought this rig.

Turdle · September 10, 2012

I referred you to this thread earlier--it's all in there starting with post 351

http://www.explorerforum.com/forums/showthread.php?p=1511175&highlight=4406#post1511175

edit--ooops
it is in this thread. Sorry, I was mistaken.

http://www.explorerforum.com/forums/showthread.php?t=166605&highlight=4406

bronchole · September 10, 2012

Hmm, I don't have the 2" body lift that he has. Still, I should be able to get an extension between the body and the frame. I'll give it a try tonight.

Turdle · September 10, 2012

He also had to change the tailshaft housing to accept the drive gear, As I understand it the 4406 has a hall sensor. I think you need to check to see if your transfer case has a drive gear inside first. The thread I linked is a good read for you I think.

bronchole · September 10, 2012

I can't directly see the sensor, but I can feel it pretty well. The connector definatly feels like it is this one:

NOT this one:

Also the centerline of it definatly feels as if it is going above the T-case output shaft and I can feel the stud that is used to hold the sensor in to the housing.

With that bit out of the way I feel confident that it is a gear driven sensor and that someone has not gone thru the trouble of converting the entire rig to a 98 wire harness and computer for it to use the other type of sensor.

Now back to the bad news. As I was feeling around up there I finally got a look at the plastic gas tank cover that everyone is talking about. There is a piece of it still sandwiched inbetween the sensor connector and the gas tank. I take that to mean that I must drop the tank in order to remove this sensor and see what gear is installed on the sensor assembly. While I am there I will remove the remaining piece of the plastic, do a bit more hammer work to the tank so it will stop rubbing on the side of the tank and maybe a bit more hammer work to assure good clearance to the speedometer sensor since it is pretty close.

For thoes that do not usnderstand the clearance issue to the speedometer sensor all I can think of is maybe it is a V6 vs V8 thing. Perhapse the V6 versions sit the T-case a bit furtherforward than the V8 so this is not an issue. I can tell you for this one I know I won't leave this the way it is, especially since I am going to have to drop the tank anyways.

Now I just gotta hope that I get enough gas out of the tank befor this weekend so I can drop the tank.

Tbars4 · September 10, 2012

..Get the gear out already.. :popcorn:

..If you by chance need a 21 tooth gear let me know..

bronchole · September 14, 2012

My early recordings of speeds and odometer readings show that the seedometer and odometer are not the same ammount off from each other. The readings I got would lead me to one size gear for the odometer and a different size gear (by 1 tooth) for the other. Can the speedometer be calibrated seperate from the odometer?

Is there any chance that the odometer is using one sensor and the speedometer is using another?

If not I will probably default to making the odometer as correct as possible and re-index the speedometer needle so that it is correct at highway speed.

bronchole · September 14, 2012

This assumes that I currently have an 18 tooth gear. It's on a spreadsheet so all I have to do is update the tooth count number and I will know from there what I need.

It's pretty interesting how non-linear the speedometer is also. I will be targeting the 50-75 MPH area and live with the little bit of error left at lower speeds.

MercuryMullet · September 14, 2012

I have a np208 in a mountaineer, 4:56 and 33s. My numbers are about with yours. Little more off with 33s vs 35s. Don't have a fix yet, either

bronchole · September 15, 2012

Have you compaired the odometer percentages to the speedometer percentages? I am wondering if this is common or if this is something weird on my setup. Actually, I am going to investigate the idea that the PO that installed the flaming gauge faces might have not put the speedometer needle back on in exactly the same spot. That would give me an offset all the way across the speeds. When I get my gear count I will play with that and see what is up.

Nominally your numbers should be about 6% worse than mine (35/33).

MercuryMullet · September 15, 2012

No I haven't checked that. I don't really drive it that much. I do know mine was stock as a rock until I got it. I'll drive it to work next week and check the miles. I had 3.73s factory so I should be around 2% fast but am more like 25-30%. I''l keep you posted with what I find.

bronchole · September 16, 2012

Well, the verdict is in. The current gear is 20 teeth (black). I actually counted the teeth because I have learned tha the color is not always right.

That means that ideally to correct the odometer almost perfrectly I need a 22 tooth gear. I seem to remember reading around on here that Ford has not produced larger than a 21 in several decades. I also remember reading on here that there is a near drop in equivelant Jeep speedometer gear. I'll look in to this next.

For now, here is that same spreadseet with the 20 tooth gear in it. I also played around a bit with adding an offset and I was able to get the speedometer to match the odometer pretty well. I inted to do this by pulling the needle off and indexing it a bit and putting it back on.

1997 Mountaineer speedometer correction???

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