Advice rebuilding Allison 1545 Tranny?

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Mark3395

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Silly me. Bought a 109A4 even though the description noted "no reverse".

I was happily prepping the truck when the thought hit me: If this pig doesn't have reverse, what else doesn't it have?

Well, the answer I feard was "fourth". I can tell you with great authority that it takes 9 hours to drive to my shop from Ft. McCoy in 3d gear at 30 MPH. Quite and adventure. Shifted and ran well in the remaining gears.

So the tranny is out and I'm told a remanufactured tranny will cost me $2200. I've gone over the manual and it seems that rebuild is quite straght forward. Guess I'll try it.

So my questions are these:

Have any of you rebuilt one of these trannys, and what would you advise?
What special tools are needed?
Where's the best place to buy a rebuild kit?
What secrets pertain to this project?

Of course, I guess somebody will have a spare tranny out there.

I look forward to the thrills of this thread.

Mark3395
 

motomacguyver

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My A3 developed the same problem, I took the truck to the local tech college to have them remove and replace the transmission. They don’t do tranny rebuild there so I sent the tranny to Inland Power group near Milwaukee. Inland Power replaced the fourth gear clutches and dyno tested the unit, and the bill was ~1100$. The tech school did the R&R for free.

If you do the rebuild yourself, pay close attention to the valve "O" rings, A torn o-ring will cause the loss of pressure on the clutch packs. This is probably what caused my problems.


Here is a link to the story.




http://www.steelsoldiers.com/deuce/66399-m35a3-transmision-question.html
 

Monkeyboyarmy

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I rebuilt mine for $120. Had the exact same problem as yours. The direct clutch pack was toast. Probably because of a lack of fluid do to the plugged vent issue. Some parts are interchangeable with TH400. Taking the trans out and putting back in was the real bear.PM me for any other details.
 

Mark3395

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Yes, getting the thing out was a pain, but it's on a pallet now. Have a small rotisserie that I'll use to hold and rotae the tranny during work.

The main issue remains finding the best rebuild kit and any tricks/tools to the job.

Mark
 

BKubu

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$2,200 to have an Allison rebuilt? That is cheap. Get it done. If it will be a true re-man, the parts alone are near, if not more than, that.
 

tobyS

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I'm going to post this on a couple of old threads that are likely to get hits when researching the Allison 1545 that is in our M35A3's.

They are prone to having the fourth/reverse clutch pack go out, probably at least in part to the locking torque converter but also inferior OEM seals on that piston. New seals are better.

If you find non-magnetic aluminum in your pan, that is probably the piston for the fourth clutch pack....and a full rebuild, including steels and frictions should be your next step. If you find small magnetic metal, it is probably the vanes in the torque converter that are coming in contact. Those are the conditions on 2 that I have encountered and I'm soon to start a third.

When a full rebuild is necessary, the Allison 545 is the mother of the 1545 and except for the seal that is on the locking torque converter, the master rebuild kits for the 545 will be what you need to rebuild the 1545. Those kits are readily available. I prefer the Raybestos frictions myself.

The seal on the locking torque converter (input seal) which mounts on the pump input that is NOT included in that kit is National Seal #29506179. EDIT....the fourth piston is Allison 29505882

I was told on my first one of these that there were 2 seals and they were proprietary, so I had to order the basic seal kit that included them. They must have wanted to sell the extra kit....because this seal can be bought individually.

Don't look at the outside of your torque converter and think all is okay within...have Dacco rebuild it or you risk dumping metal into the fresh rebuilt 1545, straight into the bearings, gears, governor and valve body....not good.
 
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rustystud

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I'm going to post this on a couple of old threads that are likely to get hits when researching the Allison 1545 that is in our M35A3's.

They are prone to having the fourth/reverse clutch pack go out, probably at least in part to the locking torque converter but also inferior OEM seals on that piston. New seals are better.

If you find non-magnetic aluminum in your pan, that is probably the piston for the fourth clutch pack....and a full rebuild, including steels and frictions should be your next step. If you find small magnetic metal, it is probably the vanes in the torque converter that are coming in contact. Those are the conditions on 2 that I have encountered and I'm soon to start a third.

When a full rebuild is necessary, the Allison 545 is the mother of the 1545 and except for the seal that is on the locking torque converter, the master rebuild kits for the 545 will be what you need to rebuild the 1545. Those kits are readily available. I prefer the Raybestos frictions myself.

The seal on the locking torque converter (input seal) which mounts on the pump input that is NOT included in that kit is National Seal #29506179. EDIT....the fourth piston is Allison 29505882

I was told on my first one of these that there were 2 seals and they were proprietary, so I had to order the basic seal kit that included them. They must have wanted to sell the extra kit....because this seal can be bought individually.

Don't look at the outside of your torque converter and think all is okay within...have Dacco rebuild it or you risk dumping metal into the fresh rebuilt 1545, straight into the bearings, gears, governor and valve body....not good.
One nice thing you can use is TH400 plates in the Allison Forward and Direct clutches. This way you can benefit from all the racing clutch plates out there including the heavy duty "Kolene" steels. The early trick for racing TH400's was to use the Allison AT540 clutches since they where very heavy duty. Now the reverse is true ! Also since the newer TH400 clutch plates are thinner, you can have a 6 or even 7 clutch pack instead of the factory 5 clutch pack. These newer plates are able to handle up to 1000 HP easily, so they will work just fine in our A3 deuces.
Just something to consider when rebuilding one of these units.
Also if you want to get "crazy" and put a high performance engine in instead of the CAT you can use TH400 torque converters with high stall speeds ! Of course you will no longer have a lock-up unit anymore, but with a high performance engine say a 454 HiPo unit who cares ! Just think about it, a "racing" deuce !
Yes I'm still taking my meds, and yes I'm sure they are effecting my mind severely !
 

rustystud

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One other thing to think about is, can a TH4L80E torque converter be used on the Allison 1540 ? The torque converters are identical between the TH400 and Allison 540 except that Allison uses 6 mounting bolts instead of 3. In fact a lot of rebuilders (myself included) used to use Allison 540 converters in heavy truck TH400 applications. Now the newer Th4L80E uses a lock-up converter and is physically deeper in width (due to the lock-up clutch) then the TH400. Can it be adapted to fit the Allison 1540 ? Interesting question.
 

tobyS

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Really Rusty, hope you are feeling better.

You brought up a couple of things that I would like to follow up on about the clutch pack and torque converter interchange with the Chevy tranny. I'm wondering about pump sections too.

Since the 4th and rev pack goes out most, that would seem to be the best place to strengthen the weak link. I'll look into that pack first.

I'm helping Joe to get his rebuild but I have one in the truck to use to experiment on....And maybe my want ad will find a core.

Frank...not sure what the link links to...give me a bigger hint.
 

tobyS

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Okay Rustystud, talked to Matt that is rebuilding the 1545 and the entire fourth clutch pack may be substituted, he thinks. He has mentioned several times before that there is a steel piston with vulcanized rubber seal that is superior to the aluminum piston. He said when the new style is operated with air, there is a noticeable better seal on the new one. He thinks that purchasing the unit complete may come with that piston in it plus more and advanced frictions and plates. He's going to be checking on an L480E that he has.

If you have a reasonable priced supplier for the L480E clutch components that are considered superior to OEM, let me know who.
 

frank8003

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Really Rusty, ~

"Frank...not sure what the link links to...give me a bigger hint"

This is what is at that link......................................

AT-1545 piston and seal numbers
Here are two important numbers for the M35A3 Allison AT-1545 (I posted earlier of Joe's on this thread) when it comes to a rebuild time.

The fourth/reverse piston is Allison 29505882 and the seal for the locking torque converter input is National Seal #29506179.

With these 2 parts plus the master rebuild kit for an AT-545 (readily available) (and Dacco rebuild of the torque converter), a mechanic will have the parts he needs and you will save a lot.
 

rustystud

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Really Rusty, hope you are feeling better.

You brought up a couple of things that I would like to follow up on about the clutch pack and torque converter interchange with the Chevy tranny. I'm wondering about pump sections too.

Since the 4th and rev pack goes out most, that would seem to be the best place to strengthen the weak link. I'll look into that pack first.

I'm helping Joe to get his rebuild but I have one in the truck to use to experiment on....And maybe my want ad will find a core.

Frank...not sure what the link links to...give me a bigger hint.
Thanks Toby. I'm still feeling pretty sick from the anti-biotic treatment, but I'm getting better. I hope !
Since I retired I no longer have access to my wholesale suppliers. There are several "performance" venders I still use. I'll send you the information.
This is fun ! When I rebuilt the Allison's I wasn't allowed to deviate from stock. The transmission rebuild company I worked for frowned on that kind of thing, as did the transit department I worked at. I almost got fired once for "modifying" a fuel system on several bus's to make them perform better ! After the "engineers" from Gillig came out (the buses where still under warranty) and saw what I did they said it was better, but I was never to modify a bus again without Gillig approval.
I always wanted to "play" with the 540 Allison to see what kind of performance I could get out of it. But without a vehicle having one in it, and the cost of a "core" alone I never did. At this time I'm still collecting parts for my major Hydro-Matic rebuild for the M135/M211 trucks. I might just have to have several bushings made from a machine shop. Along with several parts I want to add "Torrington" bearings to. I have the gear to gear front pump assembly from the Pontiac (used in only two years) to replace the "vane" pump. That along with several other mods will make this transmission last a good long time I hope. I'm sorry, totally of topic here. Must be the meds !
 

rustystud

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Okay Rustystud, talked to Matt that is rebuilding the 1545 and the entire fourth clutch pack may be substituted, he thinks. He has mentioned several times before that there is a steel piston with vulcanized rubber seal that is superior to the aluminum piston. He said when the new style is operated with air, there is a noticeable better seal on the new one. He thinks that purchasing the unit complete may come with that piston in it plus more and advanced frictions and plates. He's going to be checking on an L480E that he has.

If you have a reasonable priced supplier for the L480E clutch components that are considered superior to OEM, let me know who.
OK Toby. Here are several places I have bought parts from. All sell good quality parts

www.transmissioncenter.com Good quality race parts
www.transpartsonline.com General good quality kits and parts
www.transmissionpartsusa.com General good quality kits and parts
www.coanracing.com Really good quality racing parts
 

tobyS

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Good news. Between Rusty, Matt and Transmissioncenter, I think we have found an improvement to the fourth/reverse clutch pack problem on our Allison 1545 (or 545). Many parts are the same with the GM 4L80E. In the 4L80E this clutch pack is the "direct" clutch pack.

Thus a performance set of frictions, steels, (caged) spring and steel/vulcanized piston can be used to increase our clutch area 40% in this weak point and the steel piston will provide better clamping force...at a much lower cost than an OEM piston. Darn Joe, I wish I had known this 5 days ago.

https://www.transmissioncenter.com/shop/powerpack-th4004l80e-direct-hp-64-95/

https://www.transmissioncenter.com/shop/4l80e-1997-on-direct-clutch-piston-bonded-piston/
 

rustystud

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Good news. Between Rusty, Matt and Transmissioncenter, I think we have found an improvement to the fourth/reverse clutch pack problem on our Allison 1545 (or 545). Many parts are the same with the GM 4L80E. In the 4L80E this clutch pack is the "direct" clutch pack.

Thus a performance set of frictions, steels, (caged) spring and steel/vulcanized piston can be used to increase our clutch area 40% in this weak point and the steel piston will provide better clamping force...at a much lower cost than an OEM piston. Darn Joe, I wish I had known this 5 days ago.

https://www.transmissioncenter.com/shop/powerpack-th4004l80e-direct-hp-64-95/

https://www.transmissioncenter.com/shop/4l80e-1997-on-direct-clutch-piston-bonded-piston/
There's lots of little "secrets" transmission rebuilders find out through the years. Since I worked on the larger trucks I had more opportunity's to find out these little gems about the early Allison's and the connections between "GMC" and "Detroit Diesel Allison". Glad this knowledge is finally helping someone.
 

tobyS

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There's lots of little "secrets" transmission rebuilders find out through the years. Since I worked on the larger trucks I had more opportunity's to find out these little gems about the early Allison's and the connections between "GMC" and "Detroit Diesel Allison". Glad this knowledge is finally helping someone.
Thanks Rusty. We have Joe's 1545 apart and just got the master rebuild kit. We will have the OEM aluminum piston in a day or two.

I called Joe and explained. Since we have new OEM steels, frictions, seals and piston, I gave him the option of being the first or just continuing to have new OEM....either will probably last the life of the truck. Cost is under $200 for the parts at this point but he could sell the new (Raybestos) steels, frictions, springs and OEM piston with new style seal to someone on an SS ad, I bet.

Since the Allison about to come out of my truck needs rebuild, I am planning on doing it to my spare to see how it works.
 

rustystud

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Thanks Rusty. We have Joe's 1545 apart and just got the master rebuild kit. We will have the OEM aluminum piston in a day or two.

I called Joe and explained. Since we have new OEM steels, frictions, seals and piston, I gave him the option of being the first or just continuing to have new OEM....either will probably last the life of the truck. Cost is under $200 for the parts at this point but he could sell the new (Raybestos) steels, frictions, springs and OEM piston with new style seal to someone on an SS ad, I bet.

Since the Allison about to come out of my truck needs rebuild, I am planning on doing it to my spare to see how it works.
You need to do a "project" rebuild posted here for all to see !
This series of Allison's was my favorite. The "AT" "MT" and "HT" transmissions are a blast to rebuild. The newer series of Allison's called "World Transmissions" are a pain to rebuild. All the new electronics to test and worry about.
When I first started rebuilding Allison's at Neil's Detroit Diesel, it was on the old style "MT30" - "MT42" cast-iron six speeds. They can be a bit tricky to rebuild too. Also extremely heavy !
Before I left the transit department I had a week of classes put on by Allison, on all the new stuff coming out. That included the new 1000/2000 series. These transmissions really impressed me ! I might just have to buy some specialty tools to work on them ! Of course my wife thinks I'm nut to buy any new tool anymore. I tell her it gives me personal satisfaction to work on vehicles, and that might keep me living a bit longer. With nothing important to do I think you just wither and die.
 
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