1970 M35a2 Tach problem

[MilitaryRestoration]

I have a 1970 m35a2 and the tach is running backwards does anyone have any suggestions...

 

[mangus580]

Shut off the engine, start it in the forward direction!!

 

[ARMYMAN30YearsPlus]

Welcome to the site and I am not sure on the tach but my speedometer is acting strange and goes on strike for long periods I am quite sure this is a worn sending end on the cable. running backward sounds strange since I do not have a negative on my 1970 M35A2 tach can you post a picture of what it is doing? That will help and there are tons of guys here that know so much you will want to come back often.

 

[MilitaryRestoration]

ArmyMan~ The actual needle isn't going backwards but the hour meter is. I.e.- I put a brand new tach on because I figured the old tach was the problem so the hours showed '00000.0' (however many digits there are i forget) and after driving it for a lil while I noticed the needle not working but the hours showing '99994.5' Therefore some how it is running it backwards. This weekend I'm going to put the old one back in and check to see if it doing the same, I'll try to take video then. Thanks for the help though.

 

[clinto]

Hmmm..................You don't happen to have 5 reverse gears and one forward gear, do you?



Sorry, couldn't resist

 

[gimpyrobb]

I guess this means some tachs are for counter clockwise rotation?

 

[CCATLETT1984]

wrong forum
Jeeze Mike, your slipping

 

[mangus580]

yeah, I guess so...

moving now

 

[Recovry4x4]

I would venture to say you have a problem or wrong drive unit at the front of the timing housing. Looks like a speedo cable unit.

 

[JDToumanian]

I believe that the tach drive unit, like the speedo drive unit, can be assembled to run in either direction required... Someone probably serviced the drive unit on your truck sometime in the past and reassembled it backwards. Should be an easy enough fix.

 

[m38inmaine]

The speedo drive unit on my deuce was assembled backwards, it took me a while to figure out why it wasn't working untill I noticed the speedo working when backing up.

 

[personsmg]

I have a 1970 AMGen M35A2 WW. The Tach don't work. I tried another Tach that I know works, the cable spins, but when I attach the cable, neither Tach works. How long should the driver on the cable be?