Speedometers revisited

[belfert]

My bus has a Series 60 engine so I know I can get the speed from the DDEC.  My Silverleaf VMSpc shows the current speed.  Anyhow, my bus appears to have had a new speedometer installed at some point, but it was the kind that used magnets on the front brake drum.  It was completely inaccurate so I actually bought a cheap GPS to show my speed for the 1,000 mile drive home from the dealer.  I installed a GPS speedometer when I got home, but I am on the second GPS speed unit and it is having problems.

Should I install a regular electronic speedometer with a signal from the DDEC, or go with another GPS speedometer?  I assume there is a wire under the dash that provides the signal for an electronic speedometer.  The wiring under the dash is such a mess that I have no idea which wire it would be.  Some are labeled with circuit numbers, but certainly not all.  Could I run a new wire from close to the engine and splice into that line, or is a bad idea to splice into the line?  I have the wiring diagrams for the bus.

[luvrbus]

Buy a good GPS you are going to get into the digital and analog wiring from the DDEC it has both,If yours read from the front wheel it probably a analog and there is no wiring from the DDEC , The DDEC has to get a signal from the Allison speed sensor it doesn't read the speed direct. Văn installs GPS speedometer around here I forget where he orders from but they are not cheap but they work call Van   

[Van]

Brian get the good gps units from Auto Meter. That is all I install, a little pricey but they come with a Warranty and are of good quality. They have a few styles and sizes to match what you have in you dash now. Simple install and hook em ups too!
https://www.autometer.com/catalogsearch/result?q=Gps%20speedometer

[Iceni John]

Another contender is the ISSPRO R8480M-SET that I recently used to replace my original Teleflex when its odometer went tits up.   I chose the ISSPRO because it has a resettable odometer, maybe unique among aftermarket speedos, so I didn't need to start over again at zero mileage.   It's 3-3/8", gets its signal from the front wheel (and can be programmed for complete accuracy), has 2 MPH increments on its 80 MPH dial face, is made in USA, and is way better than the miserable Teleflex ever was.   And it works in tunnels!

John

[plyonsMC9]

I put in a GPS speedometer in our DL3 - so far no issues, it's about 1 - 2 MPH different than our trucker's Garmin GPS. 

However I wonder - would this make getting a dyno readout impossible, as I have no functioning speedometer?  We have a DDEC 2, and the few mechanics I've talked w/ don't have that interface.

Just curious - thanks bus folk!,
Phil 

[luvrbus]

DDEC ll don't use the J1939 protocol very little out there in interfaces, to make a Allision World transmission work with one it has to be programed to standalone, the translocators they made for communication between the ll and J1939 have been gone for 25 years   a real PITA the DDEC lll is a J1939 protocol the standard of today 

[Van]

I put in a GPS speedometer in our DL3 - so far no issues, it's about 1 - 2 MPH different than our trucker's Garmin GPS. 

However I wonder - would this make getting a dyno readout impossible, as I have no functioning speedometer?  We have a DDEC 2, and the few mechanics I've talked w/ don't have that interface.

Just curious - thanks bus folk!,
Phil

  I thought dynoing was looking primarily for rpm, torque and horsepower not speed?
 I get the same 1mph differance in speed between my truck garmin and whatever gps speedo I use also.

[luvrbus]

A chassis dyno will look for speed ,rpm , torque and HP they show it all at different speeds WW Wiliams in Phoenix won't do a chassis dyno on older buses or a in frame engine rebuild,Bill told me the repairs on older buses the dyno cost won't cover the repairs.They do dynos on engines and transmissions out of the bus though.He did one on my Eagle years ago after hours and told me if the drop box came out in pieces it was on me     

[richard5933]

I've installed two GPS speedometers from Speed Hut. They were accurate and reliable. Best part is you can customize the dial to match your other gauges as well as pick the features you need on the speedo. Costs more, but to me it's worth it.

[belfert]

I had surgery on my hand this week so I haven't done much with this yet.  I pulled out the wiring diagrams for my bus.  Indeed, the original speedometer on the bus used the speed signal from the transmission.  I am certain the speedometer that used the front wheel was a replacement.  For starters, the gauge said MCI on it.  Second, the cable going to the wheel was poorly run like it was added later.

GPS speedometers are great when they work.  I bought a Dakota Digital GPS interface that also has an accelerometer too so the speed will still show in tunnels and other situations when the signal is lost.  The problem is the accelerometer is very sensitive and even braking hard will cause the accelerometer to go crazy and stop displaying the speed.  The only fix is to disconnect the battery voltage from the unit.  I am thinking I might be just as well served by a speedometer fed by the transmission.

If I buy another GPS speedometer I have no issue buying the Autometer one.

[Van]

My first dakota digital speedo was back in 90-91 IIRC. It was a replacement for my Electraglide Harley it did just what you describedn they replaced it 3 times with the same results. They looked cool when not in motion but went crazy under way. until I used the Autometer ones I never looked back. I have one left that will go in our Prevo stock one works but is in KPH though. I hope your hand job surgery went well😁

[belfert]

I don't even have a Dakota Digital speedometer head.  I just have their GPS module sending the signal to a Intellitronix speedometer.  I see that Autometer sells just the GPS module I could use with any electronic speedometer.

I don't think the Dakota Digital GPS module would be a bad option for a car or motorcycle.  It is just that the accelerometer in their GPS module doesn't like the motions of a big vehicle under heavy braking.

[RJ]

WW Wiliams in Phoenix won't do a chassis dyno on older buses or a in frame engine rebuild.

Cliff -

That's interesting. . . WW Williams in Phoenix was the outfit that did the inframe rebuild on my Prevost's 8V92 after the PO cooked the engine.

Will they do ANY work on the two-strokes anymore?

RJ

[luvrbus]

Cliff -

That's interesting. . . WW Williams in Phoenix was the outfit that did the inframe rebuild on my Prevost's 8V92 after the PO cooked the engine.

Will they do ANY work on the two-strokes anymore?

RJ

No , only on the sationary DD 2 cylce engines ,they have the 10 year old policy now also ,they work on very few series 60 now since they have been gone since 2010

[richard5933]

Cliff -

That's interesting. . . WW Williams in Phoenix was the outfit that did the inframe rebuild on my Prevost's 8V92 after the PO cooked the engine.

Will they do ANY work on the two-strokes anymore?

RJ

Interstate Power Systems has locations which still work on both buses and DD 2-stroke engines. The location in Milwaukee is where my bus was serviced - top notch work but not cheap.