R model electronic speedometer

[Geoff Weeks]

PM sent to Stutz

[Joey Mack]

Here is the Service Bulletine for speedo calibration.  I am trying to post the link, but, im not that good. you can go to macktrucks dealer portal and type the number in the search bar. 

[mechohaulic]

at first thought I remembered that service bulletin , after enlarging and seeing 2005;; heck that' a  new bulletin.!!!LOL  it's another "hey I was there when these electronic things first appeared. big question then was " how do they make a speedo work with only wires and not a cable. I was the dipwit moving the dip switches 

[Geoff Weeks]

I think that one is too new, you need to go back to the 80's early 90's for the Treckstar.

Speedo is on the way to Stutz.

Edited February 8 by Geoff Weeks

[Joey Mack]

The bulletin is a reprint done in 2005.  However, it may be too new.  But the info is Free... The last truck i calibrated, i used modern tech... I downloaded a speedometer to my phone, then drove the truck, and pulled iver to change the setting and retest.. so Mech,,,, there are some advantages.  I was able to do ut alone, without a chase car to check my speed.

[Geoff Weeks]

For what it is worth:

My 1983 had a mechanical speedo, but the plugs were in the wiring harness for the Motorola electronic. My 1984 had the Motorola, with the tone ring in the hub and were not recalibratable , you had to order the head for the hub revs/mile.

My 1989 had the Prestolite trekstar and was settable by dip switches.

By the time of electronic engines, most speedo's were part of the whole CanBus and not stand alone. So looking at mid to late 90's

That leaves a ~10 year period where stand alone speedo (and tach) were used.

At some point I think Mack switched to Amteck (or something like that) Speedo. So Mack may have used the Prestolite for less time than IHC.

I can find little info on the Trekstar on on the .net.

[Joey Mack]

Im hoping that the charts in the booklet i posted will be correct.  We'll see..  i think his speedo is electric. 

[Geoff Weeks]

It will be when mine arrives at his address!

[Geoff Weeks]

Worse case, I've got a NIB one of these that I used when I put the '84's speedo in the '83 and used a 16 tooth gear on the transmission. It will allow for re-cal to just about anything.

https://www.summitracing.com/parts/DAK-SGI-5?srsltid=AfmBOorVpbEa8dgVMpyBjapdwrI3Uur-C6qqCadyeRYodCjpqVlt4EZr

[Geoff Weeks]

I also found I have ISSPRO's speedo calibration chart, but don't know if it is the same as Prestolite.

[Joseph Cummings]

We had some late 70's R models that had electric tachs and speedos in them. 3 wire senders. I assumed they were little permeant magnet 3 phase generators. When they broke I just put regular mechanicals in them. I had all the parts already in stock.

I know these are different, but I just didn't see the advantage over mechanical, and I always tried to keep them whole fleet the same as much as possible

[Geoff Weeks]

Electronics were a huge step forward. Very few mechanicals  can make it over 1m miles, and that is with several cable changes. Some of my electronics have over 2 million miles. No ratio adaptor or tailshaft gear to wear. esp good for long runs with and aux trans.  Most can handle an Eaton 2 spd axle internally with no changes. pick-up is non contact so non wearing.

Mechanicals needed adaptors to make the drive 1000 rpm@ 60 mph. so any driveline change need a speedo drive change also.

Only the 1st Motorola's  were fixed, everything after that were re-settable.

My Marmon had/has mechanical speedo and tach, I changed out the speedo when it died at almost 1million miles. Easy change and never a problem. It was nice when I fitted 2 spd rears, no gear box and cable change needed, just a wire to tell it when it is low.

Since my '83 already had the wiring and plugs for the Motorola, I installed that, but because of the ratio and tires being different I used the Dakota Digital box, rather than a tone ring in the hub.

My antiques will keep the OEM gauges, but anything I was running commercially, I would want electronic.

[Joseph Cummings]

34 minutes ago, Geoff Weeks said:

Electronics were a huge step forward. Very few mechanicals  can make it over 1m miles, and that is with several cable changes. Some of my electronics have over 2 million miles. No ratio adaptor or tailshaft gear to wear. esp good for long runs with and aux trans.  Most can handle an Eaton 2 spd axle internally with no changes. pick-up is non contact so non wearing.

Mechanicals needed adaptors to make the drive 1000 rpm@ 60 mph. so any driveline change need a speedo drive change also.

Only the 1st Motorola's  were fixed, everything after that were re-settable.

My Marmon had/has mechanical speedo and tach, I changed out the speedo when it died at almost 1million miles. Easy change and never a problem. It was nice when I fitted 2 spd rears, no gear box and cable change needed, just a wire to tell it when it is low.

Since my '83 already had the wiring and plugs for the Motorola, I installed that, but because of the ratio and tires being different I used the Dakota Digital box, rather than a tone ring in the hub.

My antiques will keep the OEM gauges, but anything I was running commercially, I would want electronic.

We never put a million miles on a truck. Based out of Philly, I think the farthest we ran was Bethlehem's Sparrows Point Mill. Mostly Philly area, NJ and NYC.

There were like 3 trucks out of 25 that had the electrics in them. Everything was 4.17 ratios and 2 different reduction boxes, one for the 20 inch rubber, and another for the 22. It was like a lot of stuff like wedge brakes, trailer lights and all. I didn't mess with it if it was working, but when it broke, it got changed over to our standard stuff to match the rest of the fleet

[mechohaulic]

7 hours ago, Geoff Weeks said:

I also found I have ISSPRO's speedo calibration chart, but don't know if it is the same as Prestolite.

ISSPRO is a name from the past waking the memory cells. just don't ask why. did a fleet change over to tachograph speedos/charts; don't recall them isspro. the isspro had regular speedo head with the flip switches.

[Geoff Weeks]

ISSPRO made the speedo I put in the Marmon, as well as the 270 deg sweep ammeters I put in the trucks. Also made the air suspension gauge in my IHC.

Used to be in Portland Or.