"Speedometer Driven Gear" vs "New Drive Gear"

searcherrr · 07-09-2009, 03:22 PM

I just sent this to a Ford parts department. Up for comments:

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Please bare with me in my explanation. My problem is, I am wondering if the wrong speed sensor gear was installed on my VSS.

What is the difference in a "speedometer driven gear" and a "new drive gear" mentioned in the same remove/install instructions in the manual?

Is there more than one "new drive gear" for my year 3.8L?

In my Ford Service manual for my 1995 3.8L Ford Windstar (2FMDA5149SBB05565), removal of the VSS (Vehicle Speed Sensor) talks about "a speedometer driven gear" and a "new drive gear".

The manual lists EOTZ-17271-A as "speedometer driven gear". This is apparently the same as "C2DZ17271H" that you gave me back in April 08.

The manual lists F58Z-17285-A as "new drive gear". Is "new drive gear" the gear that goes on the end of the VSS?

Assuming "new drive gear F58Z-17285-A" goes on the end of the VSS & C2DZ17271H is a "speedometer driven gear" the question is: Which of the 2 gears affects MPG if the wrong gear is installed?

Can F58Z-17285-A & C2DZ17271H be erroneously swapped? Say I only provided C2DZ17271H to the shop to install and the tech mistook where to install it, putting it where F58Z-17285-A should go instead... is that possible?

I had the shop install "C2DZ17271H" along with a new VSS some time ago and after nearly rebuilding the entire engine bay I am still getting 9 mpg and no codes.

I am trying to conclude if the tech put "C2DZ17271H" "speedometer driven gear" where the F58Z-17285-A "new drive gear" (assuming thats on the end of the VSS) was supposed to go.

Using your parts web site I see the following:
EOTZ17271A GR-SPEEDO DRVN
C2DZ17271H GR-SPEEDO DRVN (same as above, but new number)

F58Z17285A GEAR-TRANS SPEEDOMET

I hope I haven't been too confusing.

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Service manual procedures for installation:

1. Change speedometer driven gear (EOTZ-17271-A); note position of retaining clip and return to same orientation, (flange towards speedometer cable).

2. Reinstall VSS into speedometer cover and tighten retaining bolt 4 N-m (3 lb-ft).

3. Inspect O-ring seal on speedometer cover for any damage.

4. Install new drive gear (F58Z-17285-A) and reinstall bearing (black side up), into transaxle. Take care not to drop bearing into case.

5. Insert speedometer cover, VSS, and speedometer cable assembly through opening above power steering rack. Take care not to damage O-ring seal on the speedometer cover. The speedometer cable must be routed between filler tube and transaxle case.

6. Bolt speedometer cover to transmission case. Hand snug bolts to insure cover is evenly mated to case. Torque retaining bolts to 10.5+/-1.5 N-m (8 +/- 1 lb-ft) evenly.

7. Reconnect VSS wire.

8. Reinstall VSS heat shield.

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- Wiswind!! I looked on RockAuto.com and our VSS are the same for 95 and 96. Have you or anyone else ever replaced this and could chime in?

I was thinking about this and had the tech install C2DZ17271H. I also gave him at the same time a new VSS to install. I think I goofed in thinking that C2DZ17271H was for the VSS, but if I'm understanding the documentation right now in the manual it looks like if "new drive gear" is for the VSS mounted on the tranny that the part number would be F58Z17285A.

I would think the two gear would look a lot different, but the tech that installed my engine made so many mistakes that I wouldn't be surprised if he didn't pay attention to the teeth and shape of the old gear (which I never got to see).

Anyone have pictures of these animals?

wiswind · 07-09-2009, 09:42 PM

Well....mine was just replaced on June 19 of this year.
It went out while on my mission trip with my church youth group.
I had a shop do the job.
They bought a aftermarket part through a local auto part store (by chance the same one that I had stopped at for directions).......and used the same gear on the new sensor.
I have no idea of what the part number of the part was...I just checked the receipt and it is not listed.

He DID tell me that he gets the wrong part all the time.....and actually has to physically check them out......to make sure that they match up.
One of the reasons that I was more than happy to have someone else do it as they know what they are looking at...and can spot a wrong part.
The other....it is not easy for someone who knows what they are doing to do this job.....much less me doing it for the first time.....so far from home.

Of course, I was MANY miles from home....with a return trip with my youth group......with a trailer....the very next day....so it was fix it.....or rent a van to get the group home and then return to get mine.
Reason being.....even though there was nothing wrong with the transmission......the eratic shifting was likely to overheat it on the long hills that we had on the way home.

It is NOT a easy job......right above a catalytic converter......cannot see it.....have to do the job by "feel"

He transfered the gear and bracket and cable over to the new sensor....and installed the unit.

I had the repair done at Layne Transmission Service near Tracy City, TN and am VERY happy with the service that I got.....so they get a 2 thumbs up from me!

onit · 07-09-2009, 10:13 PM

wiswind what do they charge for a job like that. Also how long does it take for them to do it?

searcherrr · 07-09-2009, 10:22 PM

Where you broke down kinda seems like a msg from a higher power doesn't it?

I read the instructions for its removal & installation and yeah.... its not in the best of places to reach. I was wondering if it could be reached from the top of the engine if the cowl was removed and maybe a pad was put down to lay on while you reach down "SOMEWHERE".

Anyway, I'm trying to understand what other symptoms I would be seeing if the wrong VSS gear was installed or the wrong Speedo Driven Gear.

Are there wheel speed sensors besides the VSS?

Is it possible to have one of the wrong speedometer driven gear or the other drive gear and still get the right vehicle speed reported?

Which of the two gears involved with the speedo and VSS would be responsible for bad MPG if the wrong gear was installed?

wiswind · 07-09-2009, 10:27 PM

Well.....they charged me $35 for the part and $75 labor.
He had to let the vehicle cool down as he was hugging a catalytic converter.
He also had to go get the part......I did not keep track of the time.....maybe a couple hours?.

Another note for Searcherr......if they used the wrong gear on on your speed sensor, your speedometer will be wrong....as that gear drives the speedometer and the electrical sensor for the computer.
You can get a close idea of your speedometer by timing the time from mile marker to mile marker...... 1 mile is 60 seconds at 60mph.
If you wonder if somehow the electrical portion is off, your monitoring software should give you that value from the OBDII port......as I have monitored this with my scangauge from the OBDII port.

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