HEMTT M984E1 Wrecker on the mend

[12vctd]

6680-01-412-3180 Tachometer, Mechanical, Fixed Mounting this is a website that shows the part since i cannot get the tm to post on here

 

[paradeduty]

Gee 12vctd - YOU DA MAN!

I didn't know that they used these chassis in mining as well. I have seen the fire equipment trucks. Cool to know. So far the only drive train part that I knew I needed was that transfer yoke and #3 axle driveshaft (propeller shaft) u-joint, which I was able to locate commercially.

Yes, the "engine gizmo" of which I spoke is the "little" mechanical tach drive assembly which "clamps" to the rear of the driver's side (on a foreward facing engine!) blower drive lobe assembly. It literally is just clamped in place on the back of the blower with a glorified U-clamp and bolt for a pressure fit with a gasket. Onto this mechanical tach drive is attached an "electronic pulse generator" or such (which I have already found) which drives the electric/electronic tach. The mechanical portion is the part that I am looking for. Thought I had found a source, but there was a discrepancy on the "input drive shaft" length as it protrudes into the blower and engages the end of the blower lobe main shaft, so it never went further and fell to the back burner.

Got to tell you - just locating that pulse generator in the parts manual is a chore in itself. Even Oshkosh Truck themselves wasn't sure at first if it was a part they had made special or not! For some reason I think that these Detroits were put in enough unconventional locations on trucks that the electric tachs may have been more common than I thought, though.

As far as the Tach Drive goes, all of the parts are as follows (per TM 9-2320-279-24P):

33 PAFZZ 72582 B1821BH025C125N SCREW,CAP,HEX HD ......................... 1
34 PAFZZ 24617 120375 NUT,PLAIN,HEX ............................. 1
35 PFFZZ 72582 5146410 STRAP,RETAINING ........................... 1
36 PAFZZ 72582 5106771 ADAPTER,TACHOMETER ....................... 1
37 PAFZZ 72582 5136678 GASKET ...................................... 1​

38 PAFZZ 72582 5146490 FLANGE,END,LOWER ......................... 1

If your manuals are anything like mine, it should be figure 35 "blower assembly".

I know that Detroit Diesel shows (2) different versions of the drive with different ratios. If I remember correctly, the HEMTT's use the drastically higher ratio.

Take Care, Dave

 

[paradeduty]

Hey R Racing!

Yes - A beast she is!

But she looks decievingly small - I think my 5-ton on 16/20's is actually taller. But I guess that was one of the intents of the design - low profile.

Consider it something like looking at a brick - small but everything is compact and dense.

Everything just seems to add up on this rig as far as weight. the fact that the rear drag winch including hyd motor and brakes is about 7 feet wide and carries 1" cable. All of the Towing and Recovery rigging is heavy pieces in their own right. And the list goes on.

Yes, I did get this one off of GL.

Dave

 

[12vctd]

I have your tach drive in hand, pm me your addy I will send it too you. The frames themselves were not used but the axles and trans and motor were. also pm me your email addy and I will give you any TM's you might need I can email them. you can call me also anytime you need help 502-542-0534 is my cell doesnt matter the time, I have a ton of experience with these trucks. Just pulled a crane off one today so I could rebuild the turn table.

 

[12vctd]

also tachs fall under STE/ICE in the tm's as well

 

[Ord22]

where did you get the hemmt wrecker? nice looking truck! i had several hemmt wreckers while i was in the army. they are a beast and fun to drive. they will tow there own weight, only. i think they can tow more. the engine use 40w, not 10w40. the truck seems to be good shape. check all your cables, make sure they're not kinked or shrayed, if so, replace them. best to be safe than sorry. i see that your tow cylinder is sitting low, thats because of your relief valves are not holding the pressure when in stowed. change you fuel filters before running the engine. if you need any help, don't hesitate to ask. good luck.

 

[paradeduty]

Hey 12vctd!

yup - found out the long way where the tach drive pulse generator is shown in the TM's!

Not to get greedy, but is there an "installation kit" of sorts for the mechanical tach drive to the back of the blower? I still have the old "C" clamp frame that was still on top of the block, but all of the other trinkets in the list I posted are AWOL.

I will PM to you my e-mail address so I can get a price from you - Thanks!

Dave.

 

[12vctd]

it all comes with the new one

 

[paradeduty]

Hi Ord22 -

Yes, I got a little lucky (my wife might say brain dead - amazing the different points of view folks can have!) and was able to get this one that somehow made it to auction. Trust me - there is probably not one thing on this old girl that is in "excellent" condition. But then again, each piece is not beyond the "TLC" realm of possible resurection. The 1" main recovery winch cable looks in good enough shape. I really doubt that it will ever again be put to its full extent with my uses. The winch is supposed to be rated at 60K lbs. The self-recovery side-mounted winch could be another story. I think it looks like they did some serious "unapproved" winching methods with it as some of the guides are a bit out of alignment and the cable on it is snapped. If the hyd motor is still OK, it may end up gravitating to replace the one on the side of the Baby Prototype HMTT that is its little brother. I already have a replacement for the 20k side winch when I get to that point. I have been getting a lot of heads up on the engine oil for the 2-stroke Detroits, so thanks for the info - it is important stuff. The Towing Jig cylinders may need some attention, again when I get to that point. First thing is getting her to huff and puff! Thanks, I'll try to keep you updated. I may need to get ahold of you for some tactical driving/operating tips when she is worthy! Take Care, Dave.

 

[hatteras4164]

A lot of boats came with the Detroit's ,as well as over the road buses. Good luck with the LARGE project.

 

[paradeduty]

Thanks hatteras,

You're right - I have heard of a lot of boats with twin Detroits and such. I think they were even put in the buses on an angle or sideways or something in the rear. Maybe it was the trans that was on an angle - I don't know - deffinitely something I have never played with.

Take Care, Dave.

 

[hummer4x4guy]

Dave,
Since I dont consider you to be to far out (driveing distance that is) I would be happy to help when my and your days coincide. The only issue is my days off being Monday and Tuesday. Tho there are days I have a weekend day off also. The Hemmtt is very nice and I wouldn't mind learning a lil more about them or just turning wrenches. Since my humvee is pretty much done with any major issues I have free time and I know how to work. Ill pm ya my cell/email and when ya need help I will do what I can.
Joel

 

[paradeduty]

Thanks Joel,

Never hurts to have a few extra hands or an extra noggin getting scratched!

I see the radiators are going to good use (very cool) but I havn't had time to do any tests on the tow lights. To be honest, they are in great condition so I'm not worried at all.

Take Care, Dave.

 

[Danger Ranger]

Consider it something like looking at a brick - small but everything is compact and dense.

It's not a flying brick is it??? (Space Cowboys)

I know many older construction/excavating equipment ran the old Detroits, like excavators, loaders, and I think many cranes. Certainly off road dumps too.
But they are reliable, simple, and popular, so the engine should be the least of your worries, I would think.

Good luck, but remember to have fun with it.

 

[paradeduty]

Thanks Ranger.

It's going to be a while, but we are looking foreward to having some fun with it for sure!

With it's towing capacity, we are hoping that it won't be too much of a PITA to towbar my deuce M45A2C (cab & chassis) w/w and 17' camper body (was water purification unit (erdilator?)) to some events. The "camper" sure makes a great home base/crash pad. She still has the original low miles (<5k) non-turbo multi that I can't bring myself to put a turbo on. So she is a very slow girl that definitely leaves a line of smoke and cars behind her! It might actually go down the road faster being towed behind the HEMTT than on her own power! But it would be kind of nice to run the pair out to an overnight trail ride and be able to park the "camper" in a good spot under her own power. Just have to make sure the trails can handle the HEMTT. Don't want that tow bill - getting it home was enough for me.

Take Care, Dave.

 

[Stalwart]

Hi Dave,

Glad you got the old girl at home now. I get my Dello 100 40 at a local supplier that caters to the local fishing fleet, there are a lot of boats still using the old oil leakers (Detroits don't burn oil, they mark their territory).

You have a spare side recovery winch? I want one if you find another, it would go great with my HUGE ground anchor.

Stuart

 

[paradeduty]

Hey Stuart !

Cool - you did end up finally finding one of those anchors - excellent.

I remember some pictures on here of one - hard to get an idea of size, but if it was for the HEMTT it had to be huge!

Thanks for the info on the oil. I still have some tinkering to do before I can get to putting in some fresh ink (for marking territory!).

I thought your truck had the side-mounted self-recovery winch. My memory is going I guess.

There are a few of these trucks around now - sure would be cool to get a HEMTT/LVS gathering together some year (trust me - mine will not be ready for anything for a while).

Talk to you soon, Dave.

 

[Stalwart]

Dave,

I wasn't the one looking for the ground anchor, mine came with the purchase of the truck and was created by someone who would like to remain nameless. It was a difficult thing to make and involved a LOT of effort to become such a refined piece of engineering and construction. It could have been much more easily made, but it wouldn't have had such an OEM quality that it has.

Because I mostly use my truck during the summer, I'm thinking about switching to 50 weight, the idle oil pressure when hot is a bit low for my tastes, I know it is a common thing with Detroits though.

S.

 

[paradeduty]

Sorry Stuart,

Guess I am getting my memories of past ads and such mixed up (But I am NOT going to let this be a sign of getting old - I have much better signs of that).

Dave.

 

[Stalwart]

No need to be sorry, I can hardly remember my name sometimes. Welcome to the "geezer club"!