serious discussion of 5-ton speed increase via gearing (transmission, differential)

[OPCOM]

The NHC250 will be short on power for that. It is pretty much 'all in' with the T-case. A Cummins big-cam would.. but I'd be scared to run that fast.

Pictures are here:
http://www.steelsoldiers.com/5-ton-...r-case-upgrade-t-138-t-1138-a.html#post696753

The hardest item was the shaft between the transmission and transfer.

 

[m816]

Just to step in here rather late, but On the Untouchable and Satans lil Angel, and on the Ace of Spades , We are all M54's with the Multifuel engine so it realy isn't much help to you. The multifuel engine redlines at 2600 or so and the cummins tach's out at 2100. We swapped out the transmisions from the 800 series trucks and hooked them up to the multifuel engines. the 500 rpm gain gives us the added top end. Ir really makes a difference. Now if you are going to run the truck hard, keep in mind that they are over forty years old and things go bad real fast. We just rebuilt the engine in mine and added a pyro to keep me honest. Slower,but safer. Listen to papabear and don't be no old fool like Vinny

 

[73m819]

I know the 819 wants to run from about 1800 to 2100, when it gets down to the high 1600s it says pleass, please down shift me

 

[Lurch]

So I just skimmed the thread so please don't burn me at the stake if it's already been mentioned but what about using some 4.10, 4.42, or 4.64 3rds from a Mack dumptruck? Not sure what they'd need to work? Possibly a few new holes drilled for the chunk to bolt in and possibly new spider gears made if they're a different spline count. Shafts are usually different lengths with the chunk more offset on them. I've seen people do this with the super low 9.34 and 10.26 ratios before. I'd assume it would be the same for the highway gear commercial truck chunks as well. I think that combined with a RTOO9513 (Roadranger double over 13 speed. .62 ratio) would make for a very highway friendly truck that's always in its power band. And possibly 11R24.5 semi tires as well (measure 44-45" and can be had in aggressive tread versions too). Seems like all of the above could be found at most any big truck junkyard. And they would pretty much let you go as fast as you wanted to.

 

[OPCOM]

There are some 4.10's around for the M818's axles, the price of the gears alone was >$3000 per axle. Other axles might be fine, what about the front drive? I do plan to go with OTR traction tires on the rear and OTR steer tires on the front to improve safety, just a question of time and $. First the body work needs done on the box.

 

[The PIG Smith]

I wish someone would start a new post and consolidate some the info contained here.
...like a 'Cliffs Notes' version of how to make your 5 ton run 70MPH! hehehe

Anyways....my thoughts are...from what I remember driving 5 tons when I served....they were a handful at 55MPH.
So, being older and hopeful wiser now, willing to take less risks, I would think a 5 ton at 65/70MPH would be down right scary.

 

[Lurch]

There are some 4.10's around for the M818's axles, the price of the gears alone was >$3000 per axle.

Yeah, that's a ridiculous price. With the high availability of high geared 5 ton rockwells in Macks, it seems like it would be much much cheaper to find some at a junkyard and adapt them. How much is 3 chunks at a junkyard going to run you? I'm just not sure if they're 16 spline or not, so they might need new side gears made to run them with stock shafts.

 

[OPCOM]

The goal is to get the truck off redline at 52MPH. Any means of doing it can be discussed here. Starting a new thread will only fragment this information.

I have no idea what center sections from junkyards cost. I changed the T-case, but that was not an easy job at all in an M818 due to the short wheelbase..

 

[m816]

I was thinking about putting an A3 duce Cat engine in a older M 54 but I went on the wrong thread. Any one here attempted that type of swap. We just rebuilt the multifuel engine and have the overdrive trans from an 800 seires in the truck but now that I have to drive by the limits of my pyro and keep the egt under 1200 it has me back at the 55mph range. It will do 55mph @ 2100 all day long on flat ground but the thing dogs on hills real fast. I also don't want to cook another engine. Looks like plenty of room for the swap in the five ton. I wonder if the cat has the power and if the auto trans would bolt up? We are at 33000 for the total weight for the truck but we won't be towing trailers anymore.

 

[R Racing]

Unless you tweek the Cat engine I think you would be unhappy with the swap. My M35A3 towing a 6000 lb trailer is a dog . So combined weight I'm at around 20000 . So 33000 would be more than a strech.

 

[OPCOM]

The performance is poor at 1600RPM, but it is not an issue going through the gears to get on the highway. Its slow but no worse than it was before. If the ramp is uphill, I just stay in the necessary gear until I can resume acceleration. My truck weighs only 23000 and that is an advantage over a heavier vehicle. I can also disengage the front axle due to the swapped T/C saving a few HP. All I can say is that this solution is perfect for me at 60MPH.

 

[quickfarms]

interesting

 

[Welder Sam]

hmmm

interesting

Indeed, very.

 

[OPCOM]

I got the truck weighed yesterday and did not find this in the search after a couple tries, so I ask: what is the usual weight rating of the 11.00x20 NDT military tire? I've been told there are a couple different ratings and do not know what to believe.

The weight cert. says I have 16380 on the steer axle and 7360 on the rears and it seems wrong somehow. I never worried about this because I had a deuce before which is a lot lighter in front. I want to remove any safety issues before they happen and may have to go to a semi tractor steer tire (likely 24.5" rims and a tubeless) on front sooner than anticipated if the safety margin is not great enough for my confidence.

Looking at that weight, it has to be wrong -no tire is rated for that, the 11.00x20 NDT's are rated 5920 each - from the Titan website - the T-hawk 373 12 ply, F-load range NDT. Maybe I pulled too far on the scale and only one rear was on the scale's drive section. It might be more like 9020 on front and 14720 rears.

 

[73m819]

that sound awful heavy for a 818 with a 109 box, the 819 data plate calls for 13900 on the front, 10020 on each of the rear axles. 16380 ????, I have a long wheel base, a crane, triple frame, ect. for the 13900

I would think 7360 on the front and 16380 on both rear axles combined would be closer

you edit, sounds better, also a J rated tire will get you that heavy load

I would sugest a reweigh

 

[m16ty]

The weight cert. says I have 16380 on the steer axle and 7360 on the rears and it seems wrong somehow.

Most states only allow 12K on the steering axle without permits. 16K on the steer axle sounds too high. Are you sure on those weights?

 

[OPCOM]

I don't know at all. The CAT scale is something I have only used twice.

All I can think of is I might have stopped in the wrong place, pulled up too far. I probably have to go back and get this straightened out at the scale. A PITA because I have insurance but it means driving the truck again with no title

There should be a mark on the scale where to stop or where the middle of the truck is supposed to be.

============================================

WEIGHT CORRECTION / UPDATE:
8660 front
14680 rear
23540 total

Previously, I stopped in the dark when the cab was across from the "push button". The rears were half on the front scale pad but I did not know it because I could not see the marking. I had to get out and use a stick to reach the button.

Most 18-wheeler tractors you see at a truck stop are much longer than an M818 so the pads are much longer than an 818 would need. Once I did this in the daylight I got the true numbers. Much happier now!

 

[mckeeranger]

I would find someone that will let you "borrow" their scale (I use the local landfill) and see if they will let you weigh just the front axle, then just the back. A rock quarry would have a scale as well.

 

[rwbrown72]

Go to your local grain elevator... I guarantee their scale is right!

 

[spicergear]

Yep, local feed mill if you have one. My place charges $2 to scale you. Pull just the front on and get your weight, then full truck, then if you really want to be sure you can just weigh the tandems. My crane truck was 7980lbs front and 10,020lbs rear. Was only off on the total 18,000lbs by 20lbs when the whole truck was weighed.

Oh, and I had already swapped out to A3 wheels and super single Conti's to up my front tire rating...