Speedometer error

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Jun 13, 2022 | 12:04 PM

tabijan

Thread Starter

Cargo Master

Joined: Sep 2012

Posts: 2,112

Likes: 286

From: Eastern TN

Speedometer error

I compared the speedometer with a GPS app. The app says 72mph steady for miles while the speedo indicates 75mph. This is with spec LT245/75-16 highway tires. The odometer tracks with highway markers to a tenth of a mile (+/- 0.05 miles?) over 50 miles. Is there a way to calibrate the speedo without putting off the odometer? Is it a matter of pulling the pointer off the post then pressing it on a pointer’s width CCW? As in not practical.

Sixto
07 E350 5.4 182K miles

Jun 13, 2022 | 02:37 PM

EARL91

Cross-Country

Joined: Jun 2022

Posts: 58

Likes: 6

That's within the margin of error, honestly. Why worry about 3mph difference?

My speedo reads 55mph when I'm actually doing 65mph.

Jun 13, 2022 | 04:39 PM

tabijan

Thread Starter

Cargo Master

Joined: Sep 2012

Posts: 2,112

Likes: 286

From: Eastern TN

I hear you. I won’t tear the cluster apart just for that. Maybe there’s a way to tweak it using an OBD tool.

Sixto
07 E350 5.4 182K miles

Jun 14, 2022 | 04:05 AM

JWA

Fleet Owner

Joined: Aug 2010

Posts: 21,254

Likes: 1,656

From: Reynoldsburg, Ohio

Quote:

Originally Posted by tabijan

Is it a matter of pulling the pointer off the post then pressing it on a pointer’s width CCW? As in not practical.

Doing that tends to damage the delicate movement of the driving motor and in effect ruining the entire cluster. I've tried "rebuilding" a failed gauge inside analog clusters and have never mastered how to do this without problems. I do have a thread entitled "cluster anatomy" or something similar with quite a few images of the fully analog instrument clusters that are common right up until the 2009's E-Series or so.

As already said its smarter to simply live with the minor discrepancy in MPH, perhaps rely solely on the GPS or the cluster read out?

Jun 14, 2022 | 12:27 PM

tabijan

Thread Starter

Cargo Master

Joined: Sep 2012

Posts: 2,112

Likes: 286

From: Eastern TN

I hear that too. I’m already too lazy to pull the cluster to put some darkening film over the cruise indicator. I’m not going to risk damage by repositioning the speedo pointer. Maybe someday there’ll be a Forscan trick to calibrate the speedo.

Sixto
07 E350 5.3 182K miles