Getting behind or under the dashboard M35A2

[Redleg130]

searched but really didn't find much.

I have an M35A2 and I need to do a couple things behind/under the dash. I got replacement heater hose sections to replace the rotten hose thats in it now. The 4in sections are easy to reach, but the 3in sections going to defroster vents are not. Also the low air pressure buzzer is intermittent and likely needs the connectors replaced. Both of these tasks would be straightforward, except for the part where no matter how I stuff my body in the cab, I cannot reach these things well enough to actually work on them. I have the parts, just cannot reach the places no matter which direction I come from, cushion and laying on floorboard from passenger or driver side isn't cutting it, and upside down isn't, so I am not sure how to tackle this.

Tips or getting pointed in a direction would be appreciated.

 

[MG2936]

searched but really didn't find much.

I have an M35A2 and I need to do a couple things behind/under the dash. I got replacement heater hose sections to replace the rotten hose thats in it now. The 4in sections are easy to reach, but the 3in sections going to defroster vents are not. Also the low air pressure buzzer is intermittent and likely needs the connectors replaced. Both of these tasks would be straightforward, except for the part where no matter how I stuff my body in the cab, I cannot reach these things well enough to actually work on them. I have the parts, just cannot reach the places no matter which direction I come from, cushion and laying on floorboard from passenger or driver side isn't cutting it, and upside down isn't, so I am not sure how to tackle this.

Tips or getting pointed in a direction would be appreciated.

get a small person to help you, friend of mine had the same problem, he is a big man and he had large hands. He asked me to help him because I had done it on my truck. I weigh 130 lbs and my hands were about half the size of his. Even for me I struggled a littlle. Not a fun job.

 

[Guyfang]

Every Motor Pool has at least one small guy. Guess who gets these jobs. Got any young kids?

 

[Adrok]

Can relate, not a comfortable spot. Put in there a few times as a kid. lol

 

[Valley Rock]

I inadvertently discovered that you can see that unbelievably annoying buzzer from the passenger floor, it has one wire, it goes straight up to the bottom of the buzzer .

It's pretty much in the center of the firewall, wire came off pretty easy, absolutely by far the best mod I ever made to my deuce .

 

[HDN]

I feel your pain. I had to get under the dashboard of my truck to remove the tunnel to replace the engine's magnetic speed sensor on the bell housing. I could've removed the seat to make it easier but that seemed to be more trouble than it was worth at the time. So I sucked it up and did the job very uncomfortably, switching from the driver side and passenger side floor. I was also able to somewhat reach it from the engine bay, but it was a very tight fit as well, not to mention at the very limit of my arm's reach!

 

[Redleg130]

While messing with my M37, and watching some tactical repair videos, it occurred to me that the instrument cluster can come off, perhaps giving me access to the vent tubing and buzzer.

I looked around regarding the speedometer cable and saw where some folks have removed the speedometer cable from the cluster, which would give a bit more room to work.

there isn't much info on speedometers specifically, but it appears the cable interior spins with the drivetrain and is read magnetically inside the dash speedometer. The interior spinning cable is flexible and can spin even when curved.

If I were to disconnect the dash speedometer to gain some room, is there any trick to putting it back in? Having never done this before, I don't want to mess it up since the speedometer works.

 

[G744]

Speedo cables are easy to deal with. Unscrew the nut, and just pull it off.

You won't hurt anything. It is a good time to squirt a bit of oil down the cable, it likes to be lubed a little.

Putting it back on is easy as well, just wiggle it in and run the nut up snug.

 

[G744]

I've seen the entire dash panel removed to do those jobs, there aren't too many bolts to deal with.

 

[HDN]

I've seen the entire dash panel removed to do those jobs, there aren't too many bolts to deal with.

Maybe I should look into that next time I need to get under there. Even just lifting the panel up a bit to get under there and not disconnect everything would be great!

 

[G744]

This is a dash I pulled some time ago. I wasn't trying to repair anything, rather salvage everything before it was scrapped.

Not hard to do for firewall repairs, if one disconnects everything, pops out the instrument cluster and pulls the Bowden cables from wherever.



Sorry 'bout the chainfall in the way.

 

[kendelrio]

This was how I accessed behind my M715 when I didn't feel like pulling the dash... seat came out and I got dizzy...

 

[Redleg130]

After getting confirmation that tach is safe to disconnect, I removed the instrument cluster. It isn't straightforward really, but its easier than spelunking. The 4 flat tip anchors that hold the cluster on are easy enough, and you get just barely enough clearance to reach the speedometer and tach. I am told that if the vehicle does not move the tach will reconnect without issue. After disconnecting those the air hose going to the air pressure gauge is easier to reach. The wire is brittle on my truck so being very gentle and slow for disconnecting gauge wires worked.

Reconnect (assuming tags are in tact) using https://jatonkam35s.com/DeuceTechnicalManuals/7070301_circuit_numbers_dolph.pdf or mark them before removing. Silicone grease and a little paint brush to apply a thin coat of grease on connectors to make service easier later.

Once the cluster is clear it is much easier to reach the defrost tubes for replacement and the air warning buzzer to fix that connection.

Photo of behind cluster and halfway though disconnecting.


In any case, if anyone is considering replacing defrost tubes, this appears to be a way that isn't impossible (vs reaching up from below). My original defrost tubes were turning to dust.

Big Mikes found tubing that appears to be good thick material and black so it matches what my truck came with, I am happy with it. Big Mike was very helpful with info on his recommendations for getting to this stuff.

 

[Jeepsinker]

The Tactical Repair guy is me, just FYI. I was going to mention removing the whole cluster but you beat me to it. I replaced my defrost tubing with the entire dash out and it was still a pain just to get the tubing onto the inlet and outlet nipples.
When removing the cluster in the future, sit behind the shifter and reach straight up behind the cluster from underneath with a 3/4" wrench and either break the cable nuts loose or tighten them. I find a stubby wrench works best and you don't need much torque on them anyway. Anymore, I actually leave mine finger tight ( on the VERY finger tight side) and I've never had them loosen themselves up. If your wires are brittle you can get a new cluster spider harness from Big Mike's for pretty cheap.

 

[Redleg130]

I really appreciate your documentation of repairs, just fiddled with steering box while watching that video this weekend too. I have watched several of these videos to give me an understanding of what to expect when doing maintenance. I am not a mechanic, but I am able to do some of these projects with the knowledge you have recorded, thank you.

Driver side defrost tube was the most difficult, my spouse was able to assist with this one. Several things in the way that make it very difficult to get on.

Big Mike gave me an idea that seems workable too, verify that brittle wire stops being brittle where it is protected in tape, cut back to there, use adhesive butt splices to extend new wire to gauges from that. I still have the AF8 crimp tool from M37 rewire project, so probably now would be a good time to do this. Spider probably should be replaced as well.