Just bought a m813a1 have a few questions

[5tonman1971]

So I am a new happy and proud owner of my first 1971 m813a1 with the 855 big cam non turbo.

i love this monster.

the questions I have are :
1. The tach does not work but the hours work so does this mean the gauge is shot and the drive cable is still good? 70$ gauge so I hope it's just a gauge.

2. The fuel gauge Dosent work, surprised? I unplugged the wire from the sending unit and the gauge still stays buried on E. I know on the m35s there are 2 grounds one on the frame by the tank and one on the gauge I do not see a ground wire on the gauge I'm not sure if it's the same or not but I'm assuming I will have to also replace this gauge as well.

3. The truck had 1600 series tires on it to make it a 6x6 but to make it cheaper I had the tires switched back to the 1100 ndts, huge mistake I know. But my issue is that the truck tracks like a brand new pickup but for some reason the front tires are disappearing. I have put 50 miles on it and the driver side front is bald as a baby now and the passenger front is cupped like no other I can't drive it on the pavement anymore until I figure this out. Is it possible it was aligned for the 54" tires? I'm thinking I may just have to nut up and get the 1600s


any any input would be greatly appreciated!! Thanks guys

 

[supermechanic]

I have seen old tires go away like what you are describing.
The rubber degrades from 30 years exposure, it looks good,but it's cohesiveness goes away, it just peals off , leaving little particles like what you see from a pencil eraser. You can tell where the truck has been by following the black marks.
I don't know if an alignment change is needed when going to larger tires.
I put 12-22.5 on the front of mine due to steering problems- the truck would push through the steering on wet roads, you will have this with no inter-axle differential.

Good idea to get the tach fixed.
Wiring can be a somewhat ongoing battle, rubber insulation gets brittle,just as the tires.

 

[fuzzytoaster]

Pull the tach and get a replacement, opening them is a nightmare. Used ones can be had for about $25 +/-. The fuel gauge is going to be a long battle, so as supermechanic said and hunt for bad sections of wire first. Now for the passenger front tire wear I can shine on as I'm having the same issue. Nearly new production 11's and after 400 miles the front passenger is cupping. SS research shows a number of potential issues:
-improper inflation
-poor alignment
-bad shock(s)
-Murphy

Please note #4 is always included in any answer but NDT/NDCCs dont last long on the front generally. Combine that with age, the forces put upon the tire for hard surface turning, and any of the potential issues mentioned and you have bald tires. I'm looking to step up to the 16's for cruising speed but those who have done it express that if you live in a hilly area it will take a bite out of your acceleration. I can't comment on how much but I live in a flat area so it won't bother me as much. In all it's the price of playing the game.

 

[Scrounger]

On the tire issue i would check the alignment first. It doesn't take much error to eat the NDCC tires up. I have an 818 that would go thru front tires in a couple of hundred miles. When i did the alignment the front was off by about a quarter of an inch. It would seem like that little amount wouldn't make a difference, but now they will probably last a few thousand miles. That truck by the way only gets about six to eight thousand miles on the rear tires. There is some info on this topic from an earlier post that you may find helpful.
http://www.steelsoldiers.com/showthread.php?20617-abnormal-tire-wear&p=211737&highlight=#post211737

 

[73m819]

I would put 1100rx20s on, (g177s) the difference is like night and day, then have the toe set, the best fuel gauge is a marked STICK

 

[Squirt-Truck]

Check if the MWO for front axle disengagement has been done, PROPERLY. Sounds like you have a front axle lock issue. (Ask 73m819, he had the truck for years before that issue shows its ugly head.)
But that being said, alignment is major, but NDCC's should go 3000 to 4000 on the front.