New (to me) Speedhut Speedometer Trouble


Joe Dozzo

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
May 22, 2006
777
Canon City, CO
Taking the first extended road trip in the GT with SpeedHut gauges (they were already in the car when I bought it).

The car's odometer / trip odometer matched several 10, 50 and 100 miles segments along the highways in eastern CO, WY and MT.

The needle on the SpeedHut speedometer was off... Way off... Between 10 and 30 miles an hour when traveling about 80 - that is to say the speedo wiould read anywhere between 50 and 70. Operation was smooth, not erratic and jumping around, just reading constantly wrong.

Most frustrating thing is it "seems" read ok the first few miles after starting but then just drifts off reading anywhere between 50 and 70 when all my other information suggests I was doing about 80 (including timed measured segment using highway mile markers to calculate avg speeds).

Anyone else have similar issues with their SpeedHut speedos? Rest of the gauges seem to be working just fine.

Any calibration available on these things?

I guess I'm driving off the tach the rest of the 3300 mile trip. Now... Off to find a speed vs RPM table for our cars... I know I've seen them here somewhere...

(Found it, thanks Black Ice!)
 
Last edited:

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
If you have an OBDII monitor device, I would scan the speed with it during a drive. If it is OK then the speedo is bad. If the OBDII speed is also wrong I would suspect the speed sensor in the transaxle.

Minor variations due to tire size can be expected and adjusted via a custom tune.
 

Joe Dozzo

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
May 22, 2006
777
Canon City, CO
Doesn't the fact the odometers are spot on suggest the speed sensor is ok?

Great tip on the OBDII device, thanks. I'll see if i can't pick up a cheapo unit somewhere on the road.
 

BlackICE

GT Owner
Nov 2, 2005
1,416
SF Bay Area in California
Doesn't the fact the odometers are spot on suggest the speed sensor is ok?

Great tip on the OBDII device, thanks. I'll see if i can't pick up a cheapo unit somewhere on the road.

If you have an SCT tuner that works too. If your odometer is ok then the sensor is probably OK too.
 

Joe Dozzo

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
May 22, 2006
777
Canon City, CO
Unfortunately, SCT is back in Denver...

Many thanks
 

MTV8

GT Owner
Mark II Lifetime
Jul 24, 2010
1,021
Houston Texas
You can also use your phone as a speedometer for comparison. I just checked my Speedhut speedometer this past weekend and it was pretty much spot on.
 

Joe Dozzo

Well-known member
Mark IV Lifetime
Le Mans 2010 Supporter
May 22, 2006
777
Canon City, CO
Thanks MTV8. I may be one of the last guys on the planet who does not own and does not want to own a cell phone.

Glad to hear your speedometer works correctly. My Speedhut speedometer is complete and utter junk.