Allison 1545 Automatic Transmission Specs

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Alredneck

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good one, I have the regular Allison AT545 in my International. Its a pretty good trans for a for speed and no overdrive. I think it would be pretty easy to put these in A2 Deuces for folks wanting a simple auto.
 

Bear9127

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Okay, guys, if anybody is still checking this thread, I found some info (maybe outdated) on these 1545 trannies.

Gear ratios: 3.45, 2.25, 1.41, 1.00 to 1.00 and R 5.02

It shifts 1c, 2c, 3c, 3L, 4L . C = converter, L = locked clutch

L 27.2", W 20.7", H 18.9" and weighs 302 lbs Mounts to a #3 bellhousing
 

tobyS

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I bought two A3's, one to hold and one to sell, and want to follow up on this (Allison 1545) subject. One of the A3's was purchased with a known tranny problem and I'll share what I have learned.

The truck that I purchased had a used tranny put into it and it does the same thing, fourth and reverse. The former owner's gamble with used did not pay off. I purchased the truck with a non working tranny in it and the original transmission was in a tote box in the bed, entirely disassembled. I ran across this thread and wish the link to the specifications was active...it's not...but I'll add what I have learned.

The military M35A3 was the only one to use the locking torque converter on the 545 series transmission. They added a 1 in front of it but that is not the same as an Allison 1000 series, an entirely different animal. Unlike the 545, there were only 5,600 A3's made so the availability of the 1545 transmission is extremely limited. It causes fear of this series...and rightly so.

I had not received the torque converter with the rest of the tranny in the box, I contacted the former owner. He located what he thought was the original torque converter. Because of the very good condition of all the gears and bearings on the original 1545 (in the box), I decided to rebuild (using an Allison factory trained technician for the tranny rebuild).

The Allison AT 1545 and the 545 share most components except the locking torque converter and valve body. The hub on the locking converter is larger however, so the non-locking and locking torque converter are NOT interchangeable. You cannot simply put a locking torque converter on a 545 and likewise, cannot put a 545 non-locking converter on a 1545 tranny. But a (very common) 545 with a non-locking converter will bolt right into place of the 1545. Unless one is on the highway all the time, this would be my choice if the 1545 is not rebuild-able.

The parts, clutches, steels, pistons in the 545 are the same as the 1545. You can get a gasket or rebuild kit for the 1545 or order the parts for the 545 and get the two larger seals for the 1545 separately. I had purchased the rebuild parts before I got the torque converter and had the entire rebuild completed when the torque converter arrived. Unlike the original tranny...this torque converter showed wear like one with higher miles. A torque converter rebuild shop said no problem until they say the input hub wear.

Looking at the Allison book of replacement hubs for the converter we discovered they were not available. My heart sank and I was considering a sleeve if the interior locking clutch was in good condition. There was no way to tell without splitting it, cutting the weld off.

Because of diesel popularity there has become an aftermarket industry where significant upgrades to torque converters can be had with billet hubs and additional upgraded clutches (going from one to three). That is the weakness of the original 1545 and probably why they were not more widely used. Of course at low speed, a locking torque converter would be entirely un-necessary.

I found two re-builders that were willing to take on the upgrades to my 1545 converter and I have just today sent it to Dacco in Tennessee (a Transtar company). I'll provide more information and cost when mine is returned. I was extremely happy with the quoted cost.

So to conclude, there are valid reasons to fear the automatics put into the A3, with the locking torque converter since there were only about 5600 of them made, but there are reasonable alternatives. For example: the original seals on the fourth piston hydraulic supply wear and won't put good pressure on the clutch pack but new PTFE seals allow about 20% higher locking pressures and don't degrade near as quickly. Likewise the rebuild on the torque converter hub is important because a seal leak can reduce the fourth clutch pressure. It has to be tight. If you rebuild the entire tranny and not the torque converter, you are only doing half the job.

While this is not about specifications of the 1545, I hope my information may help the next guy that is trying to decide if the A3 is a dog or a plum.
 
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bj1104

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I have recently had issues with my A3. When I bought my truck it still had motor oil instead of normal ATF. I had a problem with it going into reverse. So the first thing I did as drained the fluid and the spin on filter. After that it started shifting so much smoother. But about 2 weeks later 4th gear was acting up and reverse was no longer working. While hoping the fluid needed changed to remove more of the motor oil from it I got a pan gasket(bought the wrong pan filter), screw on filter and fluid. I dropped the pan, cleaned the residue out of the pan and pan filter(has a brass screen in it) and the screw on filter. I put it together and shifted through the gears but reverse barely works. By barely I mean on flat ground.
 

tobyS

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I have recently had issues with my A3. When I bought my truck it still had motor oil instead of normal ATF. I had a problem with it going into reverse. So the first thing I did as drained the fluid and the spin on filter. After that it started shifting so much smoother. But about 2 weeks later 4th gear was acting up and reverse was no longer working. While hoping the fluid needed changed to remove more of the motor oil from it I got a pan gasket(bought the wrong pan filter), screw on filter and fluid. I dropped the pan, cleaned the residue out of the pan and pan filter(has a brass screen in it) and the screw on filter. I put it together and shifted through the gears but reverse barely works. By barely I mean on flat ground.

Don't keep going. The more you use it the worse off the piston in the 4th and rev. clutch pack will get. Mine had gotten so hot, the aluminum piston melted, sending aluminum debris, mixed with clutch fiction materials into the pan. Note that the filter (pan) has probably kept it from going into the pump, but continued use could take it into the pump and valve body. Sorry for your luck.
 

tobyS

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bj1104, If you have not ran it too long with this condition, you may not have destroyed the aluminum piston in that clutch pack (it's not the end if you have). In that case, seals, new friction plates and steel plates will be required but not necessarily the piston replaced. The cause is probably leaking seals on the clutch pack or torque converter. There is no way of knowing until it's entirely disassembled.

Here is a suggestion...consider using a rebuilt 545 and forget the locking torque converter.

I still don't have mine back in, but have about $2k in the rebuild.

Here is the problem with new old stock tranny replacement. The new seals are PTFE and can hold 20% more pressure and have considerably longer life than the OEM. Also, if like me, the torque converter needs upgraded with new input hub and the single locking ring replaced with a three clutch setup. They do this on a lot of racing diesels.

So while NOS is available to replace the entire tranny, you won't have the upgrades that are known to make this a better tranny.
 

bj1104

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tobyS, did you end getting your torque convertor updated? Who did you find out to do the work? I am more than likely taking my truck to the local Allison shop to have them look at it. I don't have the space to keep a inoperable truck nor any easy way to remove it.
 

tobyS

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Dacco in Tennessee did the TC. Had shipping 2 ways but they only charged me $150.

http://www.daccoinc.com/products/torque-converters

Yea, Allison will know what to do. the Torque converter issue may throw them a curve ball, as their books say TC components are not available. The tranny guts (frictions and steels...parts you have to replace) other than 2 seals are the same as the 545.

I'd almost bet they have a 545 with a std (non locking) TC setting around. Unless a highway truck, why have the locking torque converter?
 

bj1104

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Well I got word my transmission is shot and needs rebuilt. They were able to get a replacement torque convertor but I decided to send it to Dacco instead. The replacement was $2100, but Lee at Dacco said I could get the triple clutch upgrade for about $1000. I will be shipping it to him Monday. It is going to take about a week for Penn Diesel to get the parts to repair the rest of the transmission. Will hopefully get it back in a few weeks.
 

bj1104

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tobyS I got the total for the stock rebuild for my torque convertor. It was only$200 and with shipping to and from Dacco my total ended up being about $350. I was thinking of the billet center and better lockup clutch set ups but I really didn't want to have to wait till mid January to get my truck back. The guy that does the custom work was only there a few more days this year and was on vacation till the first week of the new year. One advantage is it kept the cost down.
Thanks again for the referral. Was totally worth it
 

tobyS

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tobyS I got the total for the stock rebuild for my torque convertor. It was only$200 and with shipping to and from Dacco my total ended up being about $350. I was thinking of the billet center and better lockup clutch set ups but I really didn't want to have to wait till mid January to get my truck back. The guy that does the custom work was only there a few more days this year and was on vacation till the first week of the new year. One advantage is it kept the cost down.
Thanks again for the referral. Was totally worth it
Glad it worked out. As far as I know, they are the only ones that can do it. And after having the tranny rebuilt, it makes no sense not to have it done, just to know there are no clutch particles inside. Best of luck.
 

tobyS

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I'm bringing this thread back to add the part number for the fourth and reverse aluminum piston, when I get it located. If anyone has that part number, when I went through the rebuilding process, I didn't record it. It's an important part since the OEM piston seals were inferior and result in burnt clutch's AND a melted aluminum piston for that clutch pack.

DO NOT GIVE YOUR ENGINE MORE FUEL WHEN YOU FEEL THE SLIPPAGE, MELTING THE ALUMINUM PISTON IS ONE THING... GETTING HOT ENOUGH TO TAKE THE TEMPER FROM THE STEEL HOUSING AND SHAFT IS MORE SERIOUS...entirely avoidable.

The piston is the same as the much more common Allison 545. Will add numbers when I find them.
 

tobyS

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The fourth/reverse piston is Allison 29505882 and they have an E on them across from the part number.

Here is what I posted on another thread also. 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.

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, as the TC is after the pump but before the other items in the hydraulic circuit.. Thus any debris made in the TC is after the filter....not good.
 
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Redneck of Enon

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I have a 545 and I have changed the transmission fluid and filters ... it seems to be doing fine except if I don't hold the peddle to the floor when speeding up the transmission jerks when going from 3rd to 4th ....any ideas about what could be going on ?
 
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