Allison AT1545 failures

Has your 1545 failed (any reason, not just R/4)?


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rustystud

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Just to be clear I would never say engine oil peforms better than ATF on road in the Allison. My only fear is I will be the one that with the switch has a problem. I think I will just stay with the engine oil for now in the 915A2. If it has a problem in my life time then since my motor is computer controlled switch out from the governor controlled Allison four speed to a computer controlled newer one. Sold the Deuce A3 so that takes care of that truck. As always your truck so do what you think is best. Was interesting reading that for off road Allison has engine oil listed thanks URSATDX. https://www.allisontransmission.com/parts-service/approved-fluids/off-highway-fluids
Having worked on off-road Allison transmission's I can tell you they have large Helical gears in there just like manual transmissions do which need extra "shear stability" . Your over the road transmission doesn't have large gears in them. They use Planetary gearsets only. Also that oil must meet SAE standard J300, that's what the "TES439" means. Your comparing apples to oranges here Floridianson .
The AT1545 needs Dexron to run properly and draining it and refilling it properly will not harm anything.
 
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rustystud

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I decided to post a picture of the "innards" of an Off-Road Allison so people can see what I'm talking about.

View attachment Scan0172.pdfSorry it came out at a funny angle, but you can clearly see the gears are helical gears just like a manual transmission uses. Also these transmissions do "not" go over 20 MPH on average. Usually they never go past 10 MPH in daily use. Ever seen a Bulldozer flying down the freeway ? I haven't. Military "Hi-Speed" tractors don't count either.
 
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Floridianson

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Thanks for the clarification. Yea I like to research and do not like to go by one person opinion as said "anyone" can "claim" anything on the web even lie. As I said some of the bigger transmission trucks like the HEMTT had problems with the switch. Do not know all the facts and if heat was the problem or ATF cleaning out the crud. Found this one doing just a search here and will take it as opinion.
https://www.steelsoldiers.com/showthread.php?77746-Allison-Transmission-Fluid-Research


Was just looking and found this C4 rating SAE 15w40. Would think that is a engine oil and not military.

http://manuals.chudov.com/M939-Seri...on-AT-MT-HT-Transmission-Operators-Manual.pdf

Guess there were some Allison's that could use engine oil from the manufacture and not use in the military.
http://manuals.chudov.com/M939-Seri...654CR-Transmission/MTB-600-Mechanics-Tips.pdf
 
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rustystud

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Was just looking and found this C4 rating SAE 15w40. Would think that is a engine oil and not military.

http://manuals.chudov.com/M939-Seri...on-AT-MT-HT-Transmission-Operators-Manual.pdf

Guess there were some Allison's that could use engine oil from the manufacture and not use in the military.
http://manuals.chudov.com/M939-Seri...654CR-Transmission/MTB-600-Mechanics-Tips.pdf

Floridianson look where they allow this use though. Here's the page from the MT600 series you posted about.

View attachment Scan0173.pdf
You see their use in "drop boxes" which have helical gear to gear contact.(special C-4 rated SAE 30W weight only) . You see them in "slow speed" "off road" applications, (again special C-4 rated SAE 10W or C-4 SAE 30W only) .
But you see they recommend "Dexron" transmission oil for "ALL" use.
Really Floridianson I don't know why you persist in trying to prove engine oil is desirable in an Allison transmission. No where is engine oil recommended for over the road use transmissions by Allison .
The reason I am so adamant about this is that some newbee will see this or other posts where someone who has been here for a while says it is OK to use engine oil in their AT1545 transmission (or any Allison transmission) and they end up hurting their transmission or greatly reduce it's life. The reason for this whole forum is to spread "knowledgeable" information about our military vehicles, not hearsay or old outdated information.
I would never tell someone that they "must" use original "Whale fat" based gear oil for their car or truck. Yet that was the standard back in the 1950's and 1960's. Now we have far superior oils and no longer need to kill whales either.
Dexron transmission oil is "far" superior to any engine oil in a Allison or any over the road automatic transmission. So why say otherwise ?
 
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glcaines

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One of the first things I did was switch to Dexron III. I talked with an Allison Engineer at their factory. He suggested getting rid of the motor oil and switching to either Dexron III or Castrol TranSynd. TranSynd is too rich for my blood. He told me to make absolutely all of the motor oil was gone as it isn't compatible with Dexron III. I drained, filled with Dexron III, drove several miles shifting up and down and then repeated several times. I used NAPA Dexron III which is made by Ashland and is the same as Valvoline. My transmission now shifts much smoother than with the motor oil. I have had absolutely zero problems with my 1545 transmission. I attached a document from Allison showing the proper alternatives.
 

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rustystud

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One of the first things I did was switch to Dexron III. I talked with an Allison Engineer at their factory. He suggested getting rid of the motor oil and switching to either Dexron III or Castrol TranSynd. TranSynd is too rich for my blood. He told me to make absolutely all of the motor oil was gone as it isn't compatible with Dexron III. I drained, filled with Dexron III, drove several miles shifting up and down and then repeated several times. I used NAPA Dexron III which is made by Ashland and is the same as Valvoline. My transmission now shifts much smoother than with the motor oil. I have had absolutely zero problems with my 1545 transmission. I attached a document from Allison showing the proper alternatives.
Thank you "glcaines" for this excellent information. We as a community need to spread accurate information about our vehicles if we are to continue as the "main" source of military vehicle knowledge.
Also your practical information about converting your AT1545 back to the proper fluid and how it has improved your performance will help motivate others to do the same.
 

Floridianson

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To be clear I am "not" persist about using engine oil. As I said I worry the switch out will cause mine to fail. As glcaines Allison tec tip said must be done correct and to get all the old engine oil out. As I said my friend that runs the Allison shop that reprogramed my computer said for "me" just keep the engine oil for now. Do not over heat it and warm the oil up when cold. Then switch when / if the transmission failed. Yes of course the Allison will perform better with ATF "on road". From what I read it was not only the military as you make out but there were some Allison's in trucks we given the ok to run engine oil in "off road" or "extreme conditions". Sure would have been bad for Allison to ok engine oil in a combat truck and have it fail. As far a accurate information I agree but since my transmission was born on engine oil it might be the only thing holding it together.

Older thread some had problems with the switch. Post #48 another opinion from a said Allison mechanic but the whole thread is a good read. Not saying it is right or wrong. Anyone before doing anything with google there are plenty of people to talk / search too or search threads here if MV related. I am sure you read all the back threads on this Allison and if anyone had a problem after switch. Also thought there were some HEMTT's that had a problem. Just for smitts and giggles I will pull an oil sample from my 915A2 and send it to Blackstone. Thanks

https://www.steelsoldiers.com/showt...stion/page5&highlight=A3+allison+fluid+change
 
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rustystud

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To be clear I am "not" persist about using engine oil. As I said I worry the switch out will cause mine to fail. As glcaines Allison tec tip said must be done correct and to get all the old engine oil out. As I said my friend that runs the Allison shop that reprogramed my computer said for "me" just keep the engine oil for now. Do not over heat it and warm the oil up when cold. Then switch when / if the transmission failed. Yes of course the Allison will perform better with ATF "on road". From what I read it was not only the military as you make out but there were some Allison's in trucks we given the ok to run engine oil in "off road" or "extreme conditions". Sure would have been bad for Allison to ok engine oil in a combat truck and have it fail. As far a accurate information I agree but since my transmission was born on engine oil it might be the only thing holding it together.

Older thread some had problems with the switch. Post #48 another opinion from a said Allison mechanic but the whole thread is a good read. Not saying it is right or wrong. Anyone before doing anything with google there are plenty of people to talk / search too or search threads here if MV related. I am sure you read all the back threads on this Allison and if anyone had a problem after switch. Also thought there were some HEMTT's that had a problem. Just for smitts and giggles I will pull an oil sample from my 915A2 and send it to Blackstone. Thanks

https://www.steelsoldiers.com/showt...stion/page5&highlight=A3+allison+fluid+change

I never said the military was the only ones who could use engine oil.
I know Allison OK'ed the use of "Special" C-4 rated oils in "off-road" transmissions, those that used Helical gear to gear drives in them. The also allowed the use of C-4 oils in "Desert" conditions under extreme circumstances. As long as the temperatures consistently stay above 95 degrees F.
I also know the military never expected their trucks to last long in a military engagement. So who cared if the transmissions only lasted a few miles.
What I have said from the beginning and still say today is ATF should only be used in automatic transmissions. Engine oils belong in engines.
So when someone comes along saying it's OK to use engine oil in your truck on this site, they need to be corrected. We don't need to be giving out false information or we will have no credibility in the military vehicle community.
I do know what your saying about "your" transmission. That is your right to do with it as you please. This is still a free country (at least for now) .
Also about me reading all the back threads on this topic. I never wasted my time. I already know what Allison's should be using for oil. Remember I was "factory" trained on them. I worked on them for years at Detroit Diesel, at the truck shops I worked at, and in the transit department. When you talk about going to the Allison mechanic, I would have been that guy.
 
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Floridianson

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I know Allison OK'ed the use of "Special" C-4 rated oils in "off-road" transmissions, those that used Helical gear to gear drives in them. The also allowed the use of C-4 oils in "Desert" conditions under extreme circumstances. As long as the temperatures consistently stay above 95 degrees F.
So when someone comes along saying it's OK to use engine oil in your truck on this site, they need to be corrected. We don't need to be giving out false information or we will have no credibility in the military vehicle community.
Also about me reading all the back threads on this topic. I never wasted my time.
Just trying to learn myself but I do not under stand. Does the Allison HT740 and the MT654cr have Helical cut gears?
They seem to be running engine oil or a sae10 weight. Mine on the HT740 is 10 weight.
Thought there was also something about the oils to be used in 95* and above and also if used in below 50* to let the oil heat up for 20 mins. before driving. Think I found a member that had problems taking off in very cold weather with oil and no warm up then the problems showed up.
Maybe you should be reading the other post's on the other forums you might learn something about others having problems with the switch or there thoughts.
I never said to use engine oil only that I talked to the Allison fluid engineer at the time is was they put the ok on it.
As far as anyone thinking I gave out false info I think our members are smart enough to see the only thing I was saying was I am afraid to make the switch.
Yea you posted it twice about the false info and credibility so I think we get it thanks OM.
I am not a fluid engineer and if I had a question about it I think I will go to a fluid engineer that worked for Allison. Here is a thread in the 5 ton forum that was interesting where they run the MT654cr. and the oils they talk about, the problems plus oil and also switch out.


https://www.steelsoldiers.com/showt...ange-for-HEMTT&highlight=Allison+fluid+change
 
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Sgt Jiggins

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You know something Floridason: I'm right there with you on changing the fluids. And it's just time to bite the bullet and get all that motor oil out of there.

Put in Dexron III (or the more expensive full syn stuff), run it for several miles, change oil and filter out, run it for 25-50 more, same thing, do it again at 100 if you feel like it. But it's pretty much normal maintenance.

Good luck,
SJ
 

Floridianson

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Yea I called the friend at Allison and asked him when I could bring mine in for the swap. He said he would hook it up to there blowy sucky machine and no problem. I failed to follow through as other things always pop up when your old, grumpy and tired.
 

Floridianson

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One of the first things I did was switch to Dexron III. I talked with an Allison Engineer at their factory. He suggested getting rid of the motor oil and switching to either Dexron III or Castrol TranSynd. TranSynd is too rich for my blood. He told me to make absolutely all of the motor oil was gone as it isn't compatible with Dexron III. I drained, filled with Dexron III, drove several miles shifting up and down and then repeated several times. I used NAPA Dexron III which is made by Ashland and is the same as Valvoline. My transmission now shifts much smoother than with the motor oil. I have had absolutely zero problems with my 1545 transmission. I attached a document from Allison showing the proper alternatives.
Thanks for you input. In the thread I posted about the M35 transmission fluid question post #83. You said after it looks like there might have been some transmission having trouble after a swap. "Although my transmission is working fine. I am starting to get nervous". When you guys say that I get nervous about a swap. Hope your truck is still working ok and no worries.

You know something Floridason: I'm right there with you on changing the fluids. And it's just time to bite the bullet and get all that motor oil out of there.

Put in Dexron III (or the more expensive full syn stuff), run it for several miles, change oil and filter out, run it for 25-50 more, same thing, do it again at 100 if you feel like it. But it's pretty much normal maintenance.
Good luck,
SJ
From the looks if it just get a good change out as there has been more ok with the switch than had problems. That is why I figured if I do decide to do it I would take it to my friend. He said 200 bucks and price of fluid. Don't know if that is a good deal but for when your already old and tired 200 bucks does not sound like all that bad. Plus I can sit in the waiting room watch TV, eat popcorn and drink my Geritol infused energy drink.
 
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rustystud

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Just trying to learn myself but I do not under stand. Does the Allison HT740 and the MT654cr have Helical cut gears?
They seem to be running engine oil or a sae10 weight. Mine on the HT740 is 10 weight.
There are several combinations of transmissions you can order from Allison. Many ordered a "drop box" which is a reduction unit with front and rear outputs optional. Basically a built in transfer case. They use Helical gear to gears in them so they need the "heavier" weight oils in them. They are "not" to be used on "over the road" use though. Slow speeds only.
Then there's the units with a "divorced" torque converter or "Fluid Coupling" used in Bulldozers. Again slow speed only.
Also you need to think about the 10W oil itself. That is basically "Hydraulic" oil. ATF just a little thicker. In high heat situations Allison has recommended it's use, but again not for over the road use.
 
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Floridianson

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Floridianson - I'm curious, did the fluid engineer give any reasoning to why the transmission would run cooler with a thicker oil? I've always assumed that a thicker oil would allow components to heat up more, but that was always my assumption, I don't have any basis behind that.
I did not talk about different oils to him. I should not have said that as it will run cooler with ATF. From what I have been reading with oil it takes just a little longer to thin out and over heat. So much reading but also looks like with oil and outside temps. lower than 50* it needs at least 20 mins. minimum warmed up to get it thinned out to where you can take off.
 
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Sgt Jiggins

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Not exactly the thread for this, but I'm trying to (discretely) spam this info I just found about AT 1545s:

For those 1545s with serial #s GREATER than 321-101-6535 (or retrans GREATER than 9108-0912-20), there is a newer option for the front pump. This newer option involves replacing the front pump and stator. It retains the lockup. Darpco in Dallas (likely among others) can assist with this.

Good luck!
SJ
 

Eliteweapons

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Could an admin add this to the parts sticky??

Not exactly the thread for this, but I'm trying to (discretely) spam this info I just found about AT 1545s:

For those 1545s with serial #s GREATER than 321-101-6535 (or retrans GREATER than 9108-0912-20), there is a newer option for the front pump. This newer option involves replacing the front pump and stator. It retains the lockup. Darpco in Dallas (likely among others) can assist with this.

Good luck!
SJ
 

HDN

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SJ, I'm glad you found a replacement pump for your tranny! That failure point is one of the reasons why I think I'm going to like my A3's 545 on the account of parts availability.

I'm still running the military 15W oil in my tranny, though I plan on switching to Dexron III next spring when the salt is washed off the roads. I haven't decided if I'm going to flush it myself or take it to the local Allison shop.

I've read plenty of concerns about these trannies failing after a fluid conversion, or even just replacing the fluid with the same stuff. Google tells me that these failures happen because the tranny was dying anyway, and not because the fluid was changed.
 

rustystud

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SJ,


I've read plenty of concerns about these trannies failing after a fluid conversion, or even just replacing the fluid with the same stuff. Google tells me that these failures happen because the tranny was dying anyway, and not because the fluid was changed.
Exactly right ! Sometimes it's just the sludge holding things together. Then along comes clean fresh fluid and washes all the gooey sludge away.
 
For those of you that are performing the switch from 15W-40 to ATF, please keep us posted on your results. I have a perfectly functioning 1545 right now with 15W-40 and plan on making the switch this summer to Dex III using the drain, refill, run, drain, refill, run method. I too had reservations about performing the switch based on past posts here. Ultimately I will be doing the switch because of better warm up time(Maine), easier shifting, and hopefully just making the tranny last longer.
 

mann650

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I'm 6 months and about 500 miles (I know I don't drive it that much) into my fluid change. So far I have noticed much better warm up times in cold weather ( It will shift smoothly about 5 minutes sooner) . I have also noticed softer shifts, not sure if that is good or bad. The old shifts were enough to lock up the rear tires on downshifts and it up-shifted with a bang and lurch. As for any issues caused by the fluid change, I don't think I have enough time to really report on it. My oil didn't come out looking bad or burnt so perhaps it was just fine to begin with.
 
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