Speedometer too slow by 3-4mph

[peer oliver schmidt]

As you may notice, I have some spare time at Camp Walmart

I noticed that the speedometer shows 50mph when the GPS shows 54mph.

I was always under the impression, the speedometer from the factories
should show faster than you actually go.

What could be the reason for this?
--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II, CA
'73 Sequoia, VA

 

[emerystora]

Tire size.

Emery Stora
77 Kingsley
Frederick, CO

>
> As you may notice, I have some spare time at Camp Walmart
>
> I noticed that the speedometer shows 50mph when the GPS shows 54mph.
>
> I was always under the impression, the speedometer from the factories
> should show faster than you actually go.
>
> What could be the reason for this?
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II, CA
> '73 Sequoia, VA
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[peer oliver schmidt]

Emery
> Tire size.

I have 16.5 tires atm. Is there an easy fix to calibrate the speedo, or
is the easiest fix to use the brain to just add some 5mph to whatever I see?

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II, CA
'73 Sequoia, VA

 

[Ron Clark]

or final drive ratio

On Sun, 30 Jul 2017 22:28:12 -0600 Peer Oliver Schmidt GMC

> Emery
> > Tire size.
>
> I have 16.5 tires atm. Is there an easy fix to calibrate the speedo,
> or
> is the easiest fix to use the brain to just add some 5mph to
> whatever I see?
>
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II, CA
> '73 Sequoia, VA
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

Ron & Linda Clark
North Plains, ORYGUN
78 Eleganza II

 

[hal stclair]

Or if the speedo cable doesn't have the correct gear installed.
Hal
--
1977 Royale 101348,

1977 Royale 101586, Diesel powered,

1975 Eleganza II, 101230

1974 Eagle Bus 45',w/slideout

 

[emerystora]

Often it's caused by the use of radial tires instead of the original 8.75 x 16 originals. Or as Rallymaster says possibly the final drive ratio. Whatever is causing it, record your odometer reading over a distance (such as 50 or 100 miles) and at the same time record your gps distance reading.
This will give you an accurate amount of correction. Then you either change the speedometer gear in the governor box or install a small speedometer speed correction box between the governor and the end of the speedometer cable. Jim Kanomata has heard or the speed correction boxes. Bring him the odometer/gps distance reading and he can get your speedometer reading correctly.

Emery Stora
77 Kingsley
Frederick, CO

>
> Emery
>> Tire size.
>
> I have 16.5 tires atm. Is there an easy fix to calibrate the speedo, or
> is the easiest fix to use the brain to just add some 5mph to whatever I see?
>
> --
> Best regards
>
> Peer Oliver Schmidt
> PGP Key ID: 0x83E1C2EA
>
> '76a Eleganza II, CA
> '73 Sequoia, VA
>
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org

 

[robert mueller]

KISS principle; add 5 mph!

Regards,
Rob M.
Sydney, Australia
AUS '75 Avion - The Blue Streak TZE365V100428
USA '75 Avion - Double Trouble TZE365V100426
USA '77 Kingsley - TZE 267V100808


-----Original Message-----
From: Gmclist [mailto:gmclist-bounces] On Behalf Of Peer Oliver Schmidt GMC
Sent: Monday, July 31, 2017 2:28 PM
To: gmclist
Subject: Re: [GMCnet] Speedometer too slow by 3-4mph

I have 16.5 tires atm. Is there an easy fix to calibrate the speedo, or is the easiest fix to use the brain to just add some 5mph to
whatever I see?

Best regards
Peer Oliver Schmidt

 

[johnny]

Every one I'vs enn including mine reads slightly slow. A couple of guys at the recent show at Redwine with 70s GMC prodeucts fitting what looks like
the same cluster say the same. I suspect 40 years of aging and wear are what's responsible. The Mac Dash one in my current coach is dead nuts on
speed according to my GPS. It's mechanical, running 16" tires, a 3.70 differential and a Manny supplied reduction gear on the transmission.

--johnny
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased

 

[d c *mac* macdonald]

If you are expecting the speedometer to indicate FASTER than true speed, you must have been driving BMWs in the past! Typically, 120 mph indicated was more like 110 or less true speed. This experienced in my 1971 BMW 2800 sedan. The same is generally reported by BMW motorcycle owners.

Believe your GPS!

D C "Mac" Macdonald
Amateur Radio K2GKK
Since 30 November '53
USAF and FAA, Retired
Member GMCMI & Classics
Oklahoma City, OK
"The Money Pit"
TZE166V101966
'76 ex-Palm Beach
k2gkk + hotmail dot com

________________________________
From: Gmclist on behalf of Peer Oliver Schmidt GMC
Sent: Sunday, July 30, 2017 22:47
To: gmclist
Subject: [GMCnet] Speedometer too slow by 3-4mph

As you may notice, I have some spare time at Camp Walmart

I noticed that the speedometer shows 50mph when the GPS shows 54mph.

I was always under the impression, the speedometer from the factories
should show faster than you actually go.

What could be the reason for this?
--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

 

[peer oliver schmidt]

Mac,
> If you are expecting the speedometer to indicate FASTER than true speed, you must have been driving BMWs in the past!

I rarely drove BMW. One BMW 1800 for a year or so until I gave it away,
a 320 as a company car, that I totalled driving too fast on a snowed in
Autobahn, and a 325. I like the comfort of the 1800, but didn't like the
3-series with the 6-cylinders at all.

In Germany *all* cars read too high. This makes it easier for you to
stay within the speed limit.

--
Best regards

Peer Oliver Schmidt
PGP Key ID: 0x83E1C2EA

'76a Eleganza II, CA
'73 Sequoia, VA