limited slip on M35A2?

[mudguppy]

... I am certain that the MF's problems with reliability stem from a couple of things. First, a turbocharged 22 to 1 compression ratio is a brutal thing to do to an engine. Virtually all turbocharged diesels are in the 17 to 19 to 1 range. Second, the MF piston is a heavy thing. Third, the oil filters should never have been mounted upside down, and above the oil pan. The MF engine runs 12+ seconds with air being puffed through its bearings before the oil filter canisters fill up and provide oil pressure, and Fourth, the Fuel Density Compensator's tendency to leak and dilute the oil kills bearings. ...

Chuck, i agree with everything you said here. people keep asking about reliability and what it will take to get more of it and more power output. those 4 things you mentioned are at the top of the [long] list of design obstacles that is keeping the multi (in its current form) limited in reliability and power output.



oh, and that weight was pulled off of Table 1-4 from TM 9-2815-210-34-2-1 page 1-11.

 

[flighht2k5]

I have a 68 GMC 1500 pick-up it has posi it drives completely different from limited slip like what was in my 98 Ford i had. It got stuck a the smallest chance. My GMC will plow past 4X4's

It is just a tighter LSD. Go and try to order a "posi" from an manufacture they will tell you it's just a LSD. They are the samething. One may be tighter than another but in the end it's just a LSD. My 1500 ram has a suregrip LSD, when I have one tire on dirt and the other on pavement I can getboth to spin.

 

[armytruckdriverddsso]

we lost the usefulness of this thread. we stopped talking like civil adults

 

[mudguppy]

... we stop talk like civil adult

i'm sorry........ what?

 

[armytruckdriverddsso]

Is there is someone that knows about commercial semi tractors and can explain what the dif lock is and dose please do

 

[Chief_919]

This is right for driving on solid surfaces. If you are looking for traction on loss ground sand, snow, and mud, It will work fine that is why in national guard the added selectable air lockers. So we could unlock the diff's for HWY driving.

Huh?

M35A2's never had any sort of selectable locker authorized or installed, nor was one really even available until just recently. Even now that one is made, it is not, nor has it ever been, an authorized modification.

I am interested in what state did this, what locker they used, and what type of setup it was.

 

[armytruckdriverddsso]

Oregon did it. And I will double check. She was my first deuce and I remember that she had two diff locks one marked front the other marked rear. Chief Morrison told me only to lock them in on soft ground, if I had to lock them in on paved surface then I had better have NOTHING in front of me because I wasn't going to get her to turn for (****)

 

[buggyman]

Locker vs Limited Slip

All right, I will try to explain.
Limited Slip = When one tire turns more/faster than the other a device/discs turn against each other inside the differential; the end result is, the tire which has more traction gets more torque applied to it and this REALLY helps move the vehicle. This system will not apply 100% of the torque to the tire/wheel which has the traction; this means that you can have one tire up in the air and one tire on solid ground, and still be stuck. The rig may move some, but not all the energy/torque will be delivered to the good traction side and you may or may not move.
Limited slips are the only thing available on new rigs because they are forgiving and drive like an open differential and don’t break things by themselves.

Lockers on the other hand are really useful but, do have their drawbacks. The first locker I ever seen really do it’s job was in a Road Grader, all 4 rear tires turned the same rpm even under very different traction conditions; this made the grader go sideways as well as go forward and the operator didn’t get stuck. So lockers allow up to 100% of the torque be delivered to the tire/wheel which has higher traction; the result is, if there is enough traction between the tire and earth then the rig will move, will it move forward? Well maybe, but it will move.
The down side of Lockers is that the vehicle will move, maybe it will move forward but it may move sideways even going down the road at 55 mph “this always seems to make the trip more exciting”.
There are a few different styles of lockers; the old style was when one tire turned faster than the other they would automatically lock in. Newer/better system is one which locks when activated by the operator, they can be operated by air pressure or electric or combination. The down side is, if they are locked in when both sides have traction and the driver continues, “Like a loaded truck in a parking and the locker gets locked in, if the driver makes sharp turns” then things can, and do break!

These are like any other tool, one is better in some places the other is better in others. Which is right for your rig?

Paul

 

[greenjeepster]

Thank you for digging up the correct weight on the MF engine. I will edit my post to reflect your number.


In the White tractor, the engine the MF was derived from lasts basically forever. Plowing is a tough job, the White engine is rated to put out 220HP at 2200 RPM continuously.

I am certain that the MF's problems with reliability stem from a couple of things. First, a turbocharged 22 to 1 compression ratio is a brutal thing to do to an engine. Virtually all turbocharged diesels are in the 17 to 19 to 1 range. Second, the MF piston is a heavy thing. Third, the oil filters should never have been mounted upside down, and above the oil pan. The MF engine runs 12+ seconds with air being puffed through its bearings before the oil filter canisters fill up and provide oil pressure, and Fourth, the Fuel Density Compensator's tendency to leak and dilute the oil kills bearings.

It would be interesting to modify an MF engine back to the tractor engine it once was. It would put out 80 more horsepower and should last 500,000 miles easily. I personally think fixing the oil filter drain back problem will do the most towards making the MF a 500,000 mile engine.

I think that 90% of the time just having the other three wheels contributing in a slippery situation would do the trick.

-Chuck

DOD put out this report in 1967 that is now housed in the Library of Congress. Interesting note that the multi-fuel in both the 5 ton and 2.5 ton was reported to have a life expectancy of 10 000 miles. Was the multifuel turbo charged in 67?

The cost and efforts involved in transporting, overhauling, and storing the components that should not have been worn out were significant and preventable. Though not a maintenance fault, failures of multifuel engines created the requirement for a major off-shore maintenance effort and a sizeable supply problem. In January 1967, more than 300 5-ton trucks were deadlined in Vietnam because of inoperative multifuel engines (a similar condition existed for 2½-ton trucks) due to cracked blocks, blown head gaskets, valve stems and connecting rods. A study indicated that many failures occurred between 9,000 and 10,000 miles and that the units hardest hit were the line haul transportation units whose engines were subjected to continuous use (2,000 miles per month in Vietnam). The prospect for improvement at this point was negligible because of the lack of repair parts and overhaul capacity. Multifuel engines powered both 2½- and 5-ton trucks. A similar condition also existed in Thailand. The annual engine replacement rate of 6 per 100 vehicles per year increased to a rate of one engine per vehicle per year. Simply put, despite years of testing effort, the multifuel engine did not possess the ruggedness and tolerance to withstand the abuses inherent in field operations.

 

[stumps]

DOD put out this report in 1967 that is now housed in the Library of Congress. Interesting note that the multi-fuel in both the 5 ton and 2.5 ton was reported to have a life expectancy of 10 000 miles. Was the multifuel turbo charged in 67?

Yes, I have seen the report, and the entire line of MF engines was modified by Continental/Hercules/White to correct some of the perceived problems. The engines in that report were almost certainly LD-427's. Virtually all of the deuces showing up from the guard units are LDT-465-1C's, or 1D's.

I have also heard stories from guys that were there that it was easier to get a blown engine replaced than it was to get a minor problem with an injector pump worked on... I have been told that many of the engines with minor problems were grenaded by stuffing a rag soaked in gasoline in the air horn, and running the engine at full throttle until a rod was thrown through the crankcase.

I have also heard stories from guys that were there that the fuel was turned up, and the governors were turned up, and the engines were run full throttle all the time they were in use.

Are these stories true? Maybe, I wasn't there. Nixon stopped the draft when I was 1A and my B.D. was 10 on the lottery. I missed out on the Vietnam experience by a matter of months.

-Chuck

 

[mudguppy]

look at it this way: the deuces and 809 5 tons lead a hard life to say the least. with a road network so bad that most would be considered trails at best, imagine putting 10,000 offroad miles on your truck.

compared to present day: i ran a DS maintenance company out of Ft. Stewart recently. i would agree that the engine service life for HMMWVs, HEMMTs, HETs, and PLSs are probably no better than 20k miles - and that's 99% on-road mileage. (in 2005 in Taji, i had 7 out of 233rd's 24 HETs in my bay for engines at the same time).

compared to the infrequency that we recieved FMTVs, 915s, 916, 920s for engines leads me to believe that a lot has to do w/ the vehicle design and power/weight ratio [also could be viewed as duty cycle]. now, lets call the group w/ high frequency engine replacement group 1 and the low freq group 2.

group 1: with examples of a 6.5T trying to push around 14k#+ (loaded up-armored HMMWV), it ain't going to last long. and a [now] 500hp DDEC V 8v92T trying to push 220k# (HET), well you're going to be going through engines faster than socks. [the duty cycle on these truck would be extremely high - say, something like 100% power 85%+ of the time.]

group 2: FMTVs, 915s, etc all had decent engine power for the task/load given. except for a small rash of 3116 blocks that split for no reason on the M1078s, we hardly had any of the FMTVs ever come in for an engine. [duty cycle's much lower - 100% power maybe only 25-30% of the time, maybe less.]

interesting point: oddly enough, though, we would rarely change transmissions on vehicles in group 1 but would frequently change trannys on those vehicles in group 2. go figure. well, except for HMMWVs - nothing on those things lasted...

 

[stumps]

I recall that the report either stated, or implied that the longevity for the gassers the MF's replaced was drastically better. Which, given the gasser's 6.73 to 1 compression ratio, vs the MF's 22.1 to 1 compression ratio, might not be all that surprising?

I would dearly like to see some longevity information for the deuces that were made several years after the '67 report. Those would be the deuces that most of us own, and have LDT-465-1C/1D engines in them. I would bet that they faired much better!

Common lore has it that the LD427 was a bad engine... maybe they were? For one thing, the LD427's started out life without a Fuel Density Compensator (FDC), and they lived when the service was truly in a multifuel mode, as they were in the process of eliminating gasoline. The documents for the LD427 show that the Injector Pumps (IP) were adjusted so they smoked on diesel, and still would run on gasoline. The tabulated data for the LD427 showed gross power levels of 140HP diesel, 128HP CI fuel, and 113HP gasoline... all at 2600RPM. And the documents showed that the gasser of the same vintage put out a gross 146HP at 3400RPM. As far as I can tell, into the same transmission/transfer case/differentials.

That compares to the LDT-465-1C/1D's tabulated 140HP @ 2600RPM all fuels.

Makes me wonder if the MF engine drivers might have been a bit pissed that they didn't get lucky and get a gasser?

-Chuck

 

[mudguppy]

... As far as I can tell, into the same transmission/ ...

gassers had the spicer 3052 5spd. starts at about the same 1st of ~6:1 but ends in direct 1:1 - no OD because it winds up higher.

because of this, supposedly the performance of the gasser/3052 is about the same as the MF/3053 on diesel. but, when it's not on diesel, you're right - the gasser will probably move out quicker.

 

[stumps]

gassers had the spicer 3052 5spd. starts at about the same 1st of ~6:1 but ends in direct 1:1 - no OD because it winds up higher.

because of this, supposedly the performance of the gasser/3052 is about the same as the MF/3053 on diesel. but, when it's not on diesel, you're right - the gasser will probably move out quicker.

I have seen a few M35A2's that had a 45MPH maximum sticker on the speedometer, and a 45MPH maximum plate screwed to the dash. I suspect that they were gassers that got an MF engine transplant.

I bet it was fun when the whole convoy was fueled up on gasoline, and there was a mix of ancient gassers and brand new shiny LD427 powered MF's that couldn't get out of their own way.

Surely there are some guys here that have driven both and could comment?

-Chuck