JimmieD

Hi,

I'm using a '97 2WD NV4500 for a '67 Dodge truck Cummins engine conversion. The tranny I got didn't come with anything but a hole where speedo stuff goes. Haven't been able to find out for sure: Electric or Mechanical Speedo!?? Was this a transition year? Was told it was the last year for mechanical on 2WD's, others say electric [and yes, I posted a similar question on this forum before] THANKS!
JimmieD

schaef_12

Should still be mechanical, Dodge didn't switch to electric until 98. I believe that the electronic pickup is in the rearend anyway's.

gmctd

It's an electronic module, gear-driven off the output shaft - takes 5v power from the ECM, sends 5v signal to the speedo

Should be able to locate a suitable mechanical-drive unit for your speedo, tho

JimmieD

Hmmm, I think I'm still confused...

There's a hole in the side of the tailshaft housing where some kind of speedo stuff goes. I would prefer a mechanical speedo but have no idea what I would need to do that. I guess Dodge could provide the necessary parts for electronic if it's originally electronic but no idea if they'd have conversion parts for electric to mechanical. Problem is this is being used in an engine conversion so no ECM and no 5VDC source! Thanks for the help anyway guys!

gmctd

It is a gear-driven mechanical unit which drives a generator for the electronic speedo

See if you can find an earlier cable-drive unit that fits the NV4500 - possibly out of the Getrag or the 727 trans, or maybe one of the transfer cases.

Maybe even from the GM T400, as used in American Motors Jeep and others.

The Hollander manual may have some info - most boneyards have one - or some of the trans\transfer case rebuilders.

JimmieD

So an earlier speedo assembly will fit in the same place and a cable will drive the speedo? If it's a bolt in I'm ready! Just haven't been able to find out if they match up, as early cable driven to '97 possibly electronic....

gmctd

First - what "they" mean by '97 was the last year for mechanical is this = an electrical generator was mechanically driven off the output shaft up thru the '97 model year, the speedo was electronic.

In '98 the ABS "generator" on the differential was used, except on some 47RE drivetrains - the '98-up speedo is driven by the ECM.

What you will need is a purely mechanical cable-drive unit - you'll need to do some R&D to see if one from some of the earlier '80s-'90's transmissions I mentioned will fit.

Possibly one is available aftermarket - lot of folks are putting the NV3500 and 4500 in early trucks with mechanical speedo's

JimmieD

Okay, NOW I get it

So, I wouldn't mind an electronic speedo. AutoMeter has a nice one that matches other gauges so that would be fine with me. Maybe [?] the last question: do the electronic speedos all require a computer/ECM or could an earlier one work with a straight up aftermarket electronic speedo? Auto Meter didn't want to give away the secret and vendors didn't have a clue and the local Dodge dealer didn't know squat from siccum about what sender my tranny used or what I needed for aftermarket.....Thanks!

gmctd

The 'generator' signal is 5 volt square wave - some aftermarket speedos are adjustable for signal and frequency - X-number of pulses per mile.

Ask the vendor if their speedo is suitable for the '94-'97 Dodge truck - will the indicated speed be correct.

JimmieD

Thanks JD, that may be the answer! It's almost pathetic humor that local parts stores and even Dodge dealers don't have many Dodge/Cummins answers: 'cause so few have needed parts & repairs over the years ha ha! These forums here are the major source of info that's reliable from what I've seen!!!!!! Thanks again.....

JimmieD

JimmieD

Well, something [don't know what] that somebody said here [don't know who] jogged that slimy soup I affectianately call 'Grey Matter'. Walked outside and pulled the plastic covering on the spare take-out A518 from another project. You guessed it!! right there in front of my eyes and stuffed in the tailshaft of the juice box was the complete speedo gear generator right down to the electrical connector! All I gotta do is chase the P/N and find out what vehicle it's from etc. It fit into the NV4500 same way it was clocked and matched the gear. Don't know what y'all said, but thanks for the boost

BTW it even seems to be the correct one for my 4.1 rear axle ratio and 30" tires: Red 36 tooth gear! Still laughing and shaking my head.....

JimmieD

Hauled the A-518 speedo part down to the Dodge dealer and talked to an old timer parts guy. This speedo part is actually 2 piece, a gear drive assembly and the signal generator, attached together with something like an EMT electrical conduit compression fitting nut. Gear drive assy. Mopar P/N is 253608, signal generator assy. Mopar P/N is 56027014. Here's the deal:

The gear drive is a stock '72-'01 Torqueflite part, which obviously means it accepts a cable drive mechanical speedo. This connects at that same EMT-style fitting in the normal manner.

The Signal Generator is a '93-'01 compatible part so any electronic speedo of that vintage, or aftermarket electronic meant to replace that vintage, will work!

So the answer is it's a mechanical sender, and an electronic sender, and will use any speedo from '72 to '01 So for my 4BT to '67 Dodge Town Wagon conversion it just couldn't get any better!

Thanks for the help, guys!

JimmieD

gmctd

Toldja.................

JimmieD

If there's one thing I hate ....

Problem was I couldn't figure out what you were telling me, thinking the answer to the question, "Mechanical or electrical speedo...?" MUST be either/or and not just "Yes." Live and learn.

Another wowser was the astonishing NV4500 slip yoke! Let's talk mass and motion!! Yipes

Thanks again, and yea, you did......

gmctd

Gotta six-year-old grandson - I get into the mode for playing with him, and don't bother to turn it off.

It is to laff.................