Speedometer/Odometer Intermittent

2badazzstangs

New Member
Apr 21, 2004
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Jersey
My speedometer/odometer has begun acting up. Sometimes the car drives fine. Other times the speedometer will start to shake a little bit while I'm cruising at constant speed and eventually after several minutes the needle works its way to 0 mph and the odometer stops working. I took the gauge cluster out and the gears look fine. I put some grease on them to no avail. It's pretty annoying because when this happens the car wants to stall when coming to a stop. Any ideas?
 
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2badazzstangs,

Yes, 23 teeth is the one you need. Or, you can use the stock gear (fewer teeth but they are more robust) and a SpeedCal. I have been using a SpeedCal for many years and it has worked flawlessly. Dallas Mustangs is the 'maker' of SpeedCals but there are other retailers.

HTH,

Chris
 
Thanks Chris...

It looks to me like it is the VSS gear teeth missing. My car came from the factory with 3.73s. Of course I didn't count the teeth when I was under the car, but it appears that I need the one with 23 teeth. Can anyone confirm?

2badazzstangs,

Yes, 23 teeth is the one you need. Or, you can use the stock gear (fewer teeth but they are more robust) and a SpeedCal. I have been using a SpeedCal for many years and it has worked flawlessly. Dallas Mustangs is the 'maker' of SpeedCals but there are other retailers.

HTH,

Chris
Man, I haven't been on this site in forever or so it seems... nice to see a familiar nickname!

To the OP... your stock gears would either be 2.73 or 3.27, those were the only 2 choices from 96-98. The white gear that's all chewed up is actually made for a Chrysler application and does not mesh properly with the 96 - 98 GT T-45's. They will, however, work with the Cobra T-45's of the same years due to a different drive gear. As Chris mentioned your best bet is to go back to the stock VSS gear, then correct your speedo / odo with a SpeedCal. My SpeedCal is 10+ years old and still works flawlessly. Hope some of this info is useful to you!
 
Howdy BlueStangGT:

Talk about a blast from the past! You ain't been here for a while, Thomas. :D Glad to see you're alive and well and still in a Mustang. Headswapped now, too - nice!

Good info you posted about the gear. I did run one for about a month until my SpeedCal arrived. The error in the reading really bugged me and I worried about the teeth wearing out. With the SpeedCal, all is dead-on and there are no "ghost miles" adding up on the odometer.

Don't be such a stranger. Come on back and post up with what's going on in BlueStangGT World. :flag:

Chris
 
I gathered bits and pieces for a few years and finally got a big bore motor together. Still got a ways to go but granny shifting at 6500 netted a 12.71 @ about 109 on drag radials. A new trans and slicks ought to yield at least low 12's.
 
Man, I haven't been on this site in forever or so it seems... nice to see a familiar nickname!

To the OP... your stock gears would either be 2.73 or 3.27, those were the only 2 choices from 96-98. The white gear that's all chewed up is actually made for a Chrysler application and does not mesh properly with the 96 - 98 GT T-45's. They will, however, work with the Cobra T-45's of the same years due to a different drive gear. As Chris mentioned your best bet is to go back to the stock VSS gear, then correct your speedo / odo with a SpeedCal. My SpeedCal is 10+ years old and still works flawlessly. Hope some of this info is useful to you!


So i put the same white gear in again. It lasted a day and now this one is all chewed up like the last one. So here are my questions:

1. Is there anything else to worry about, or are these white gears really that brittle?

2. What color is the stock gear that I need to get? I will purchase a SpeedCal too.

Thanks Chris and BlueStangGT
 
2badazzstangs:

Sorry to hear about the new gear getting chewed up. Here's the poop: 23-teeth mean the blade of each tooth is thin (so, easy to damage). I recall that my stock VSS gear is orange but it is for an auto with 3.08's. I *think* it has 18 teeth. The teeth are thicker and stand up to wear much better thann the white gear. Only thing that I suggest is to ask your local Ford Parts guy for a stock VSS gear for an auto with 3.08's and you will get a stout little VSS gear.

edit
In fact, the orange gear has 20 teeth. There are other VSS gears that have 19, 18, ... gears but I don't have my ancient FRPP catalog handy to tell you what they are (sorry).
end of edit


Once you get the SpeedCal, you have to fish the SpeedCal harness up into the cabin. for me, I brought the harness up at 12 o'clock and the S/C sits between two plastic buttresses on the inside of the console - nice and snug and it doesn't rattle around. You can always use a strip of Velcro to hold the S/C box in place if your console is different than mine.

Calibrating the S/C is easy. Start with the settings that you get from Dallas Mustang (they give you a table in the instructions) and then you can use milemarkers, a stopwatch (operated by your co-pilot), and about 3.0 miles of steady speed at 60 or 65 mph on a flat stretch of highway. Then, calculate the true speed and compare it to the indicated speed on the speedo. Adjust DIP switches accorrdingly. It takes a little trial and error but you can eventually get the speedo/odo error down to less than 1%. Of course, if you have a GPS unit then you don't need the stopwatch & co-pilot. Just run for 3.0 miles at steady speed and see how things look.

Phew, that's a lot of typing. Keep us updated, please.

Chris
 
2badazzstangs:

Sorry to hear about the new gear getting chewed up. Here's the poop: 23-teeth mean the blade of each tooth is thin (so, easy to damage). I recall that my stock VSS gear is orange but it is for an auto with 3.08's. I *think* it has 18 teeth. The teeth are thicker and stand up to wear much better thann the white gear. Only thing that I suggest is to ask your local Ford Parts guy for a stock VSS gear for an auto with 3.08's and you will get a stout little VSS gear.

edit
In fact, the orange gear has 20 teeth. There are other VSS gears that have 19, 18, ... gears but I don't have my ancient FRPP catalog handy to tell you what they are (sorry).
end of edit


Once you get the SpeedCal, you have to fish the SpeedCal harness up into the cabin. for me, I brought the harness up at 12 o'clock and the S/C sits between two plastic buttresses on the inside of the console - nice and snug and it doesn't rattle around. You can always use a strip of Velcro to hold the S/C box in place if your console is different than mine.

Calibrating the S/C is easy. Start with the settings that you get from Dallas Mustang (they give you a table in the instructions) and then you can use milemarkers, a stopwatch (operated by your co-pilot), and about 3.0 miles of steady speed at 60 or 65 mph on a flat stretch of highway. Then, calculate the true speed and compare it to the indicated speed on the speedo. Adjust DIP switches accorrdingly. It takes a little trial and error but you can eventually get the speedo/odo error down to less than 1%. Of course, if you have a GPS unit then you don't need the stopwatch & co-pilot. Just run for 3.0 miles at steady speed and see how things look.

Phew, that's a lot of typing. Keep us updated, please.

Chris
I was operating under the assumption that he had a T45 5-speed. If so, start with the stock setup, then calibrating the SpeedCal can be done instantly with no trial and error, perhaps just a measure of your tire height and setting the switches according to the SpeedCal instructions.
 
Well the stock 3.08 black gear with the speedcal also failed. I think. The speedometer started acting up again today on the way home from work. I so aggravated with the whole issue I just parked the car. I'll probably just let it sit until the weekend. If the gear is chewed up I'm not sure what else to do.
 
3.08 isn't your stock setup, there's no such gear set for 96-98 T-45 cars. It's either 2.73 or 3.27. Find out which yours is, start with the stock setup, calibrate with the speedcal, then let us know what happens.
 
2badazzstangs:

Sorry to heat that the problem persists.

From my 2000 FRPP catalog, page 95: 1996 to 1998 GT with T-45 transmission has an 8-tooth drive gear (F0ZZ-17285-A, green) and the VSS (driven) gear is a 20-tooth black gear (C1DZ-17271-A) for 3.08:1 axle. However, the 3.08:1 axle was usually the stock gear for the automatic (I had these gears). I would be surprised if your car came with 3.08:1 gears and a manual transmission. I recall that the gear choices for the stick cars were 2.73 or 3.27 but I may be wrong. For the 3.27:1 axle that may have been in your car originally, the stock driven gear is a 21-tooth red gear (C4OZ-17271-A). The catalog only lists the black and red gear for the 8T driving gear setup. For 2.73:1 gears, it looks like the 18-tooth yellow gear (C0DD-17271-B) would be correct.

You might want to try the 18-tooth driven gear because the teeth will be thicker and more robust. With the SpeedCal, you can dial in whatever is needed to correct the speedo/odo (as you know).

HTH,

Chris

***edit: LOL! BlueStangGT already posted the correct available gear ratios. I should have looked before posting. Sorry about that.
***end of edit.
 
I put the 18 tooth 2.73 gear in and reset the Speed Cal. Same problem. The speedometer needle will start vibrating slowly and eventually work its way to 0 mph after a few minutes. The 18 tooth gear is fine. What else could this be?