Tachometer not working!!

[Funbobby]

Hey guy's im new the forum and like what is see I just bought my first duce last month up here in canada "1967 m35a2 Kaiser jeep" and I've been working on it none stop with the help of all you guys and your posts, but now i need to post a Q.. before i start braking brittle wires behind the cluster can anyone point me in the right path to find out why my tack's not working right?
at start up it sits at 500-700 rmp and running at 40-50 mpa it's at 1300-1500 rpm.. 1500 is it's peek.

thanks

 

[R Racing]

There is a flex shaft that drives the tach from the engine , Its not electrical.

 

[Wildchild467]

so are you saying at 50 mph it does not read over 1500rpm?

 

[televisionman007]

my tach was bouncing and now nothing

 

[Flyingvan911]

I'd guess the problem is the tach gauge itself. Try letting it idle and tap the gas pedal with your foot enough so you can hear the rpm rise a little bit. See if the tach responds according to the sound of the engine. Your gauge might not be able to show the upper rpms.

 

[hklvette]

There is a flex shaft that drives the tach from the engine , Its not electrical.

Is there a source for NOS cables? I know that mine is broken.

 

[Funbobby]

when I start it up it will bounce on the 500-600 rpm like it should, then I give it a snap and it will go up to 1000-1200 rpm's, get it out on the hwy at 50 mpa and it won't go higher then 1500 rpm

 

[Wildchild467]

sounds like a tach issue. if it does not read above 1500rpm. If the tach is bouncy, i would lean to a dry tach cable that needs lube. also make sure to put a drop of oil on the part that sticks out of the tach that turns. cant hurt to put a little lube on that also. seems like i have seen a civy tach/speedo that had a hole where a drop of oil could be applied to the shaft on the tach/speedo itself. not sure if deuces are like that or not.

 

[R Racing]

ERIKs military supply has new cables in stock.

 

[Funbobby]

Thanks for the info guys, I'll let you know how i make out.

 

[Capt.Marion]

If it doesn't bounce, you need a new (or working used) Tach. Mine never bounced, but it read in the neighborhood of 300 RPM to high. I put in a good working used tach, and now everything reads where it should. I didn't do anything to the cable.

Also, a tip on removing the tachometer from the gauge panel (only works if you have feeling in your fingers):
Go from the passenger side, and stand on the step looking up under the dash. Use a wrench to loosen the tachometer cable. While you're in there, loosen the two nuts on the mounting bracket. Now you can sit in the passenger seat, and reach under the dash and unscrew those nuts with your fingers. Slide the bracket backwards onto the tach cable. Pull the tach about 1/2" out of the dash, and turn it counter-clockwise while holding the tach cable under the dash with your other hand. This will unscrew it from the tach cable, and you'll be good to go.

Reinstalling is exact opposite.

 

[big1096]

I had a non-working tach in mine when I got it. It just bounced a bit when the truck was running. I took the cable off and it wasn't turning, so I got a new cable. When I tried to get it off the truck, it would not come out of the angle drive on the front of the engine. I took the whole drive off the motor and found that the mechanism had gotten some water in it some time around the end of the Vietnam War, and was rusted solid. The shaft inside the block had sheared off.

Luckily, the guy I got the truck from has some parts trucks as well and I was able to get a new angle drive and shaft. Now everything works like new!!!

Hopefully your fix is easier than mine!

 

[Wildchild467]

I had a non-working tach in mine when I got it. It just bounced a bit when the truck was running. I took the cable off and it wasn't turning, so I got a new cable. When I tried to get it off the truck, it would not come out of the angle drive on the front of the engine. I took the whole drive off the motor and found that the mechanism had gotten some water in it some time around the end of the Vietnam War, and was rusted solid. The shaft inside the block had sheared off.

Luckily, the guy I got the truck from has some parts trucks as well and I was able to get a new angle drive and shaft. Now everything works like new!!!

Hopefully your fix is easier than mine!

Do any of the right angle drives on the engine have grease fittings? where do they get their lubrication from? example is the drive on the transfercase has a grease fitting, why not the one on the engine?

 

[big1096]

There aren't any grease fittings on the drive. From looking at the design of the mechanism when I took it apart, it appeared that the drive gears get oil from the engine. I think the problem occurred when the seal at the tach cable connection failed. Apparently it had gotten some moisture in it (through some previous owner's adventure I would guess) which filled the top half of the angle drive. Rust and corrosion quickly set in leading to the issue I ended up with.