Changed Final Drive - Speedo Off?
Thread Starter
|
Tuned
Joined: Jun 2003
Posts: 465
Likes: 53
From: Connecticut
Changed Final Drive - Speedo Off?
I just picked up my '99 E-350 from the shop today; they changed my final drive from a 3.73 (LS) to a Yukon 4.30 (thanks Randy's!) The first thing I noticed as I merged into the highway is how fast the speedo was spinning up! I was like, man this thing rocks! Next thing I noticed was that I was indicating over 80mph!
However, as I slowed down to an indicated 70 (65 speed limit), I also noticed traffic passing me by; I was the slowest guy on the road. Never happened before; most of the time I was cruising along with traffic at that speed. So, I watched the mileage boards go by, and after 10 miles the odo had spun just over 11.4 miles. 4.30/3.73 equals - ta da! - 1.153
I could have SWORN that I read on this board that changing the final drive does not affect the speedo. This is obviously incorrect. Can anyone assist me in what I need to do to get my speedo corrected?
Thanks!
Greg
However, as I slowed down to an indicated 70 (65 speed limit), I also noticed traffic passing me by; I was the slowest guy on the road. Never happened before; most of the time I was cruising along with traffic at that speed. So, I watched the mileage boards go by, and after 10 miles the odo had spun just over 11.4 miles. 4.30/3.73 equals - ta da! - 1.153
I could have SWORN that I read on this board that changing the final drive does not affect the speedo. This is obviously incorrect. Can anyone assist me in what I need to do to get my speedo corrected?
Thanks!
Greg
Guest
Joined: Nov 2004
Posts: 7,988
Likes: 55
From: north west new jersey
stick or auto trans?
when i set up a sct tuner i have to set the tune with gear ratio and tire size so the auto trans shifts correctly and the speedo is correct.
my personal sug. is get a dealer or shop to reset your speedo calabration.
when i set up a sct tuner i have to set the tune with gear ratio and tire size so the auto trans shifts correctly and the speedo is correct.
my personal sug. is get a dealer or shop to reset your speedo calabration.
Thread Starter
|
Tuned
Joined: Jun 2003
Posts: 465
Likes: 53
From: Connecticut
Sorry: auto tranny (4R100?).
So it requires a tuner, eh? Maybe this is my excuse to buy one. How much you figure a dealer charges? If it's one hour labor (at $100 per) that money is better spent on buying one... Thanks!
So it requires a tuner, eh? Maybe this is my excuse to buy one. How much you figure a dealer charges? If it's one hour labor (at $100 per) that money is better spent on buying one... Thanks!
Guest
Joined: Nov 2004
Posts: 7,988
Likes: 55
From: north west new jersey
ussally about 1 hour labor. a good tuner will set you back 3 or 400. yes a 4r100 has 2 speed sensors in put out put or road speed and the rear axle senser goes to the speedo and pcm. so your shifts are also off. probily searching on the up of 3 to4 and lock up. /have it set then if you want more go for a tuner later just don't get a sct excal SF series they stink.
Logistics Pro
Joined: Jan 2002
Posts: 3,733
Likes: 38
GregA
Something is not right brother... if you E 350 has the speed sensor on the differential...go look.... it is the only plug and wires going into the front of the differential...then there is NO WAY a ring and pinion change can effect the speedo.
If there is no pick up and tone sensor n you differential then I have no clue where they get the signal from but sees to me Ford used to have a sensor in the trany tail shaft...if that is the case yes you need to re-calibrate for new rear end ratio.
Did you also change tire diameter?
Something is not right brother... if you E 350 has the speed sensor on the differential...go look.... it is the only plug and wires going into the front of the differential...then there is NO WAY a ring and pinion change can effect the speedo.
If there is no pick up and tone sensor n you differential then I have no clue where they get the signal from but sees to me Ford used to have a sensor in the trany tail shaft...if that is the case yes you need to re-calibrate for new rear end ratio.
Did you also change tire diameter?
Senior User
Joined: Apr 2004
Posts: 290
Likes: 1
From: South TX
Most of the vans DO use the trany output shaft for the speedo. They call it an output shaft speed (OSS) sensor on the gasoline engines (4R100 & 4R70W), but a VSS on the diesel (4R100). The signal goes straight to the PCM (no doubt for a number of functions), and a seperate PCM output feeds the speedo (via the instrument cluster microprocessor).
There is a speed sensor on the rear axle, but it is only for the ABS.
Hope you have better luck recalibrating yours than I have had with mine ('03 6.8L 4R100). Been to the dealership twice, and they said my PCM won't take this recalibration.
My speedo is off because of larger tires, but it goes way off in 4L (4X4).
Hopefully your PCM will adjust.
There is a speed sensor on the rear axle, but it is only for the ABS.
Hope you have better luck recalibrating yours than I have had with mine ('03 6.8L 4R100). Been to the dealership twice, and they said my PCM won't take this recalibration.
My speedo is off because of larger tires, but it goes way off in 4L (4X4).
Hopefully your PCM will adjust.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 422
From: Long Island USA
SO, we've FINALLY FOUND where we can get a 4R100 with a speedo-gear-type-sensor for shoving V10's into vintage cars and trucks and not jerry-rigging a VSS!
Hey, better park that E-series in the garage, I have plans for that tranny!
There are black boxes to take care of the speedo signal, but not sure what that will do to the rest of the PCM's calibrations.
Now, that output shaft sensor, is that really on the output shaft, or is there a speedo-gear w/sensor on it like the 4R70W in my '96 t-bird/'97 cougar ???
Hey, better park that E-series in the garage, I have plans for that tranny!
There are black boxes to take care of the speedo signal, but not sure what that will do to the rest of the PCM's calibrations.
Now, that output shaft sensor, is that really on the output shaft, or is there a speedo-gear w/sensor on it like the 4R70W in my '96 t-bird/'97 cougar ???
Trending Topics
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 422
From: Long Island USA
From my 2001 service manual, for the E-series:
Output Shaft Speed (OSS) Sensor — Gasoline Engines
The output shaft speed (OSS) sensor is a magnetic pickup that provides transmission output shaft rotation speed information to the powertrain control module.
The OSS sensor is mounted externally on the top of the transmission extension housing. The powertrain control module (PCM) uses the OSS sensor signal to help determine electronic pressure control (EPC) pressure, shift scheduling and torque converter clutch (TCC) operation.
Looks like a plain sensor, no speedo gear on it.
Output Shaft Speed (OSS) Sensor — Gasoline Engines
The output shaft speed (OSS) sensor is a magnetic pickup that provides transmission output shaft rotation speed information to the powertrain control module.
The OSS sensor is mounted externally on the top of the transmission extension housing. The powertrain control module (PCM) uses the OSS sensor signal to help determine electronic pressure control (EPC) pressure, shift scheduling and torque converter clutch (TCC) operation.
Looks like a plain sensor, no speedo gear on it.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Top 10 Ford Trucks Coming to Mecum Indy 2026
Brett Foote
5 Best / 5 Worst Ford Truck Wheels of All Time
Joe Kucinski
Senior User
Joined: Sep 2005
Posts: 159
Likes: 0
From: Rancho Cucamonga, CA
You don't need a tuner, it won't work. The vans use a speedo gear in the transmission. Just take the plastic gear out of the side of the transmission (10 minute job) and go to the dealer. You will need to calculate the number of teeth you need on the new gear and make sure it is the correct drive direction. I did this on a 99 E350 PSD. It took me about 3 hours to correct the speed and 2 1/2 of those hours were spent driving to the dealer and figuring out the correct speedo gear. If you want, you can take the truck to a speedo shop and they can take care of it easily.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 422
From: Long Island USA
Yeah, I would have posted the pic of the OSS sensor on the top of the 4R100 for the gas motors, but the pic came out split in half...
Either way, the OSS (gas models) does not use a gear.
Either way, the OSS (gas models) does not use a gear.
Senior User
Joined: Sep 2005
Posts: 159
Likes: 0
From: Rancho Cucamonga, CA
Originally Posted by Ultraute
The PSDs use a VSS on the 4R100, and it is a gear driven sensor. The V-10s (GregAs) on the 4R100 use an OSS sensor that is mag pulse pickup. No gears.
Thread Starter
|
Tuned
Joined: Jun 2003
Posts: 465
Likes: 53
From: Connecticut
Thanks for the info, guys. As requested: no tire diameter change.
Hey, I love a good mystery as much as anyone, but not today. I dug out the creeper and a flashlight just now and snuck under there. I found the sensor at the top front of the diff. I worked my way forward and saw the sensor on the trans extension housing.
I get to be the tie-breaker: I removed it and found that it did, indeed, have a gear.
As FastDEW noted, it was a 10-minute job (coulda been 7 but I picked the wrong socket). Pulled the gear off and counted the teeth: 18. So, to slow down the gear I need more teeth, right? 18*1.153 to be exact. Anyone know the Ford part number for a 20.75-tooth speedo gear?
Krewat, keep your grubby paws offa my E-350...
Hey, I love a good mystery as much as anyone, but not today. I dug out the creeper and a flashlight just now and snuck under there. I found the sensor at the top front of the diff. I worked my way forward and saw the sensor on the trans extension housing.
I get to be the tie-breaker: I removed it and found that it did, indeed, have a gear.
As FastDEW noted, it was a 10-minute job (coulda been 7 but I picked the wrong socket). Pulled the gear off and counted the teeth: 18. So, to slow down the gear I need more teeth, right? 18*1.153 to be exact. Anyone know the Ford part number for a 20.75-tooth speedo gear?
Krewat, keep your grubby paws offa my E-350...
Senior User
Joined: Sep 2005
Posts: 159
Likes: 0
From: Rancho Cucamonga, CA
Originally Posted by GregA
Thanks for the info, guys. As requested: no tire diameter change.
Hey, I love a good mystery as much as anyone, but not today. I dug out the creeper and a flashlight just now and snuck under there. I found the sensor at the top front of the diff. I worked my way forward and saw the sensor on the trans extension housing.
I get to be the tie-breaker: I removed it and found that it did, indeed, have a gear.
As FastDEW noted, it was a 10-minute job (coulda been 7 but I picked the wrong socket). Pulled the gear off and counted the teeth: 18. So, to slow down the gear I need more teeth, right? 18*1.153 to be exact. Anyone know the Ford part number for a 20.75-tooth speedo gear?
Krewat, keep your grubby paws offa my E-350...
Hey, I love a good mystery as much as anyone, but not today. I dug out the creeper and a flashlight just now and snuck under there. I found the sensor at the top front of the diff. I worked my way forward and saw the sensor on the trans extension housing.
I get to be the tie-breaker: I removed it and found that it did, indeed, have a gear.
As FastDEW noted, it was a 10-minute job (coulda been 7 but I picked the wrong socket). Pulled the gear off and counted the teeth: 18. So, to slow down the gear I need more teeth, right? 18*1.153 to be exact. Anyone know the Ford part number for a 20.75-tooth speedo gear?
Krewat, keep your grubby paws offa my E-350...
Good luck.
Oh, so does this mean that the E350 changed at some year. My PSD was a 99MY and this is a 99MY V10. Sounds like Ford made a change on the later models to a different type of speedo drive. Perhaps this is because Ford started using the IP from the SuperDuty when they finally put a tach in the vans?