A3 transmission replacement questions

[mactiredearg]

I'm looking for advice, suggestions, examples of similar work, etc. Your help is greatly appreciated.

So, I have an M109A4 with a frozen transmission. (yes I know A3s suck, I agree, moving on now...)

My issue: If the engine is running the transmission locks up, meaning the output shaft to the transfer case becomes stuck in place as if it were welded, even in neutral. The transmission actually went while I was driving and brought the truck to a complete stop faster then the brakes would have. Luckily I was on a side road at the time. Anyways, turn the engine off and the output spins freely like kid's toy top. I've checked all the usual suspects including fluids and everything is normal. But I have to admit I have not dropped the pan to see how many pieces are sitting there.

Since the transmission obviously has to come out anyways I'm looking for alternatives to spending the time, effort and money to just stick the same POS back in. Also, I know where I can lay my hands on a good A2 manual transmission.

I've searched here repeatedly and found lots of threads about how swapping out the A3's transmission is very do-able, but nothing showing it actually done. And while I can turn a wrench (keep comments to yourself SteelAndCanvas), I have no experience swapping transmissions. So I'd like to pick folks brains about the best ways to do this and if it is even possible. Help me out and if I pull it off I'll post the pictures!

First, I know any transmission can bolt to almost any engine if you use the right bell housing adaptor. The question here is once the A2 tranny is bolted to the Cat will the transmission line up with the cab correctly so that the shifter will not only be able to come through the floor, but will be usable (meaning the shifter can be moved into the various gears without running into the dash or the seats first). (kind of a deal breaker if I can't shift)

Second, from briefly talking with Cat and posts on here I believe I need an engine SAE 1 to transmission SAE 2 bell adapter. Can anyone confirm?

Third, the list of parts I can think of that I will need is: flywheel, clutch, clutch linkage, hanging pedal. I know I'm missing something, probably important, from the list. What else do I need?

Fourth, suggestions and advice. I'm reading up on the threads I can find about removing a Deuce tranny, but any and all suggestions would be greatly appreciated. I knew when I got these trucks that I was signing up for some heavy duty work eventually, just didn't expect it to be this soon.

Thank you in advance,
Brendan (aka mactiredearg)

Thread requests:
- I'm not trying to start an A2 vs A3 religious war, just trying to get my truck rolling again so my girls can enjoy it. If you have hate for the A3s please express it elsewhere (I may even join in).
- Purists, I realize I'm modifying. If the tranny hadn't broken I'd have left it. But I see no reason to rebuild a tranny that broke with less than 2k miles just so it can do it again later. Also, the motor pool guys have been known to throw whatever they had together to get something moving. So it's not out of the realm of possibility that this wouldn't be representative of their ingenuity if presented with the same issue and the same resources.

 

[steelandcanvas]

And while I can turn a wrench (keep comments to yourself SteelAndCanvas)

 

[doghead]

Are you interested in diagnosing your problem?

 

[steve6x6x6]

There is a lot of talk about a swap (some of it mine)but there is no room for the trans. you would like to use.

 

[gringeltaube]

M35A3 with M35A2 transmission...

I've searched here repeatedly and found lots of threads about how swapping out the A3's transmission is very do-able, but nothing showing it actually done. And while I can turn a wrench (keep comments to yourself SteelAndCanvas), I have no experience swapping transmissions. So I'd like to pick folks brains about the best ways to do this and if it is even possible.

That particular swap: I have not seen it done yet, but I'm certain that the A2's Spicer 3053 will fit- and work nicely- behind your engine. No problem at all with the position of the shift lever. In the worst case its material allows for it to be heated and bent, if it would hit the dash for example.

Pulling your transmission: do a search for Deuce transmission/ clutch removal and/or installation. (Too)many threads... that will give you a good idea of the procedure; tools needed and the grade of difficulty (if any...) to do such a job.

Bell-housing size: the A3's CAT-engine bell-housing size is a true SAE #2 and both Allison model options (AT-545 and AT-1545P) that came with it are SAE#3, so you have an adapter-ring already, which may be useful (?) when adapting the manual transmission.

Flywheel: the one that comes on the A3 with the AT-545 transmission has 6 large through-holes, to access the mounting bolts for the torque converter. (pics FW01& FW02)
I think that that FW could be used as is, despite the holes. Most of the contact area of a typical 13"-clutch disc (-> M35A2) seems to be there, untouched. All it needs is drilling/tapping the holes for a new pressure plate (of choice). (Let a certified shop do that job, as well as balancing all parts!).

If the truck had the AT-1545P then a new FW would be in order, anyway. (like shown in pic FW03)
Differences of both AT-options can be seen in TM 9-2320-386-24P, figures 83 and 83A.

All I would need for an exact drawing is some dimensions, like a) depth and diameter of the center cavity on the rear of the 3116's crankshaft, to fit a pilot-bushing or -bearing; b) distance from the 3116's flywheel surface to its bell-housing mounting flange; c) distance from FW-surface to T-case input companion flange. (see my diagram and fill out the ??)


G.

 

[mactiredearg]

Are you interested in diagnosing your problem?

Actually yes I would be. I'll be honest, I am more inclined to swap for something else. But the overriding goal is to get the truck operational without breaking the bank. If that means fixing the Allison then so be it...

 

[peashooter]

I don't have anything to add personally, but this might be of interest to you.... I was talking to another SS member and he mentioned he had put a Eaton 6406, 6-Speed manual transmission into his m35A3 truck. I asked for some pictures and here is what he sent me. (he hasn't had time to post them up and write about it, but he did say I could post them).

Here is a quick write up from him: "The trany is a Eaton fso 6406 6 speed. It started life as a fso 5406 and I had it rebuilt at west coast trucks in Anaheim ca. They also provided me with flywheel clutch and accessories to put it together. Works great I get about 60 mph. 2400 rpm before the new tires (mrap/395s). And 1st gear is really low so I still do good off pavement"

 

[steve6x6x6]

I love that setup, i hate this allison 1545P. If my truck had not broke down in Kansas i would have put the money in that 6 speed setup. Hey peashooter we need moore info. on the parts and this install.

 

[goodguyzy]

I plan on doing the same thing. I already have the parts just no time and skill. Hope you do it so you tell me how it works.

 

[Jeepsinker]

Sounds like the trans is having a valve body issue. Possibly a failed solenoid, and possibly a valve body gasket has failed allowing fluid pressure to bypass one fluid passage and apply pressure to another, causing a hydraulic lock of the internal components. Seen it happen on every other brand and nearly every type of transmission in the civilian industry.

 

[rustystud]

Sounds like the trans is having a valve body issue. Possibly a failed solenoid, and possibly a valve body gasket has failed allowing fluid pressure to bypass one fluid passage and apply pressure to another, causing a hydraulic lock of the internal components. Seen it happen on every other brand and nearly every type of transmission in the civilian industry.

I agree with "Jeepsinker" ,it is probably in your valve body. These trannys use manual valves, no solenoids so the fix could be very simple. More likely then not, you sucked up something from the sump and it got stuck in a valve not allowing it to fully open or close . You can drop a valve body with the tranny still in the vehicle. The worst case scenario is that you lost a sealing ring, then the whole tranny has to come out.

 

[peashooter]

Thread requests:
- I'm not trying to start an A2 vs A3 religious war, just trying to get my truck rolling again so my girls can enjoy it. If you have hate for the A3s please express it elsewhere (I may even join in).
- Purists, I realize I'm modifying. If the tranny hadn't broken I'd have left it. But I see no reason to rebuild a tranny that broke with less than 2k miles just so it can do it again later. Also, the motor pool guys have been known to throw whatever they had together to get something moving. So it's not out of the realm of possibility that this wouldn't be representative of their ingenuity if presented with the same issue and the same resources.

I Like your Thread requests idea! You probably should put it at the top and make it bold though with the way things go around here

 

[m-35tom]

it is a known fact that the 3053 will bolt right up to the cat motor as is, with no adapter at all, and that the inter shaft will fit, and that the shifter etc will clear. it has been done with no real problems. of course you will need some clutch pedal parts from an A2, and a flywheel and clutch, all readily available.

probably far cheaper to just fix yours.

tom

 

[BKubu]

I'm looking for advice, suggestions, examples of similar work, etc. Your help is greatly appreciated.

So, I have an M109A4 with a frozen transmission. (yes I know A3s suck, I agree, moving on now...)

My issue: If the engine is running the transmission locks up, meaning the output shaft to the transfer case becomes stuck in place as if it were welded, even in neutral. The transmission actually went while I was driving and brought the truck to a complete stop faster then the brakes would have. Luckily I was on a side road at the time. Anyways, turn the engine off and the output spins freely like kid's toy top. I've checked all the usual suspects including fluids and everything is normal. But I have to admit I have not dropped the pan to see how many pieces are sitting there.

Since the transmission obviously has to come out anyways I'm looking for alternatives to spending the time, effort and money to just stick the same POS back in. Also, I know where I can lay my hands on a good A2 manual transmission.

I've searched here repeatedly and found lots of threads about how swapping out the A3's transmission is very do-able, but nothing showing it actually done. And while I can turn a wrench (keep comments to yourself SteelAndCanvas), I have no experience swapping transmissions. So I'd like to pick folks brains about the best ways to do this and if it is even possible. Help me out and if I pull it off I'll post the pictures!

First, I know any transmission can bolt to almost any engine if you use the right bell housing adaptor. The question here is once the A2 tranny is bolted to the Cat will the transmission line up with the cab correctly so that the shifter will not only be able to come through the floor, but will be usable (meaning the shifter can be moved into the various gears without running into the dash or the seats first). (kind of a deal breaker if I can't shift)

Second, from briefly talking with Cat and posts on here I believe I need an engine SAE 1 to transmission SAE 2 bell adapter. Can anyone confirm?

Third, the list of parts I can think of that I will need is: flywheel, clutch, clutch linkage, hanging pedal. I know I'm missing something, probably important, from the list. What else do I need?

Fourth, suggestions and advice. I'm reading up on the threads I can find about removing a Deuce tranny, but any and all suggestions would be greatly appreciated. I knew when I got these trucks that I was signing up for some heavy duty work eventually, just didn't expect it to be this soon.

Thank you in advance,
Brendan (aka mactiredearg)

Thread requests:
- I'm not trying to start an A2 vs A3 religious war, just trying to get my truck rolling again so my girls can enjoy it. If you have hate for the A3s please express it elsewhere (I may even join in).
- Purists, I realize I'm modifying. If the tranny hadn't broken I'd have left it. But I see no reason to rebuild a tranny that broke with less than 2k miles just so it can do it again later. Also, the motor pool guys have been known to throw whatever they had together to get something moving. So it's not out of the realm of possibility that this wouldn't be representative of their ingenuity if presented with the same issue and the same resources.

It seems to me as if you are taking a more expensive truck and basically making it a less expensive truck, forgetting about preference for an automatic or manual transmission. The M109A4s bring GOOD money. There are few M109A3s out that that are going for $10K, regardless of what the sellers are asking. So, I'd try to find the same transmission to swap back in. From what little I know about the series...I have owned an M35A3, but it was a few years back...the transmission was a strong point, and guys who know CAT motors said bad things about the motor. I had good luck with both. So, I suggest trying to find another automatic. But, I wouldn't rush into a swap until you fully diagnose the current transmission. Good luck.

 

[steelandcanvas]

I'm sure the OP would be OK with fixing the tranny, provided it would give him some reliability. He had just got the brakes fixed when the tranny decided to go south on him. The OP can get a screamin' deal on a brand new 3053, and just needs to find the other parts. I know for a fact at this point with that A3, he just wants in running with the least possible outlay of cash. He loves that A4 and has the box all set up with bunk beds for his little girls, but I can understand his frustration at this point. If we can pull that valve body and replace or repair, and get that Allison turning again, that would make him a happy camper. It's a very nice truck, it's just been Lemon-Yellow since he's had it.

 

[porkysplace]

I'm sure the OP would be OK with fixing the tranny, provided it would give him some reliability. He had just got the brakes fixed when the tranny decided to go south on him. The OP can get a screamin' deal on a brand new 3053, and just needs to find the other parts. I know for a fact at this point with that A3, he just wants in running with the least possible outlay of cash. He loves that A4 and has the box all set up with bunk beds for his little girls, but I can understand his frustration at this point. If we can pull that valve body and replace or repair, and get that Allison turning again, that would make him a happy camper. It's a very nice truck, it's just been Lemon-Yellow since he's had it.

That's " Cat yellow"

 

[Jeepsinker]

First step is to drain and drop the pan. Let us know what, if anything you find in the pan. Then we'll go from there. Didn't think about the sealing rings, but most sealing ring failures cause slipping/ failure to drive at all.

 

[BKubu]

Unless you are sure the transmission is toast when you drop the pan, I'd take it to an Allison tech. Just my $.02. I wish you luck.

 

[mactiredearg]

The main goal is to not just fix the transmission but have it (and the truck) be reliable. I picked the vehicle up with the idea of making yet another RV109 to take my girls camping and to over night events with the club here.

I'll make a run at diagnosing the current tranny first, but I'm still exploring the swap idea. Because come **** or high water a working truck is my goal.

First I'll drop the pan and we'll see where to go from there depending on what I find. But that may be at awhile since I'm yard parked and its -5 outside right now.

I started the thread with the idea of getting things lined up when the weather warmed up. Guess I'll be doing some wrenching a little sooner than expected. Thanks for the suggestions on diagnosing and please bear with me and the weather.

 

[mactiredearg]

I Like your Thread requests idea! You probably should put it at the top and make it bold though with the way things go around here

Yea, I've learned that the quickest way to start a flame war around here is to put the letter A together with the number 3. *bleck*