M936A2 wrecker tranny needed - Can I use MT654 instead of MT654CR

[Mario]

Guys, we believe that the tranny on new to me '91 wrecker is shot. I have a lead on a fresh takeout out of a 250 truck but since I don't know crap about our trucks, I don't know if I can easily mate it to my 8.3
The donor tranny is a non-close-ratio.
I read this post but didn't seem to answer the question: https://www.steelsoldiers.com/threads/allison-mt654-vs-mt654cr.116491/

Donor trany comes complete with flywheel so, unless there are differences in connection, bell housing, etc., I'm hoping for a bolt-on.
I know that I'll have to move the PTO from mine to the new one.

 

[simp5782]

You need to know which ratio torque converter it has in it.

And the front the pump number.

 

[98G]

You need to know which ratio torque converter it has in it.

And the front the pump number.

What kind of badness ensues in case of a mismatch?

 

[simp5782]

What kind of badness ensues in case of a mismatch?

power multiplied could be more or could be less, Depending on the ratio.

 

[Mario]

You need to know which ratio torque converter it has in it.

And the front the pump number.

How can I get that info? Is there a decoder ring on the serial number or data plate?

 

[simp5782]

How can I get that info? Is there a decoder ring on the serial number or data plate?

Part number on the TC you intend to use.

What motor was that transmission hooked to? With the gear ring it was some type of Detroit.

Like a M939A1 transmission won't bolt up to an A2 8.3 as the torque converter and front pump are different. And torque converter has a different bolt pattern for the flexplate

 

[Mario]

Part number on the TC you intend to use.

What motor was that transmission hooked to? With the gear ring it was some type of Detroit.

Like a M939A1 transmission won't bolt up to an A2 8.3 as the torque converter and front pump are different. And torque converter has a different bolt pattern for the flexplate

She came out of M923 mated to a NHC250

 

[simp5782]

She came out of M923 mated to a NHC250


View attachment 841318

Then it won't work.

Weird usually the flexplate has the starter teeth and is attached to the engine

 

[Mario]

Part number on the TC you intend to use.

What motor was that transmission hooked to? With the gear ring it was some type of Detroit.

Like a M939A1 transmission won't bolt up to an A2 8.3 as the torque converter and front pump are different. And torque converter has a different bolt pattern for the flexplate

You're asking what transfer case I'm going to use it with?
I don't have the part number on hand (away from my truck), but it's a standard '91 M936A2 wrecker. I believe my transmission is bad and a guy in Iowa is selling his because he's upgrading to a 13 speed.
I'm just looking to get my wrecker going, and I'll just be using it as a hobby, so if it fits, the non-close ratio shouldn't bother me too much.

 

[simp5782]

You're asking what transfer case I'm going to use it with?
I don't have the part number on hand (away from my truck), but it's a standard '91 M936A2 wrecker. I believe my transmission is bad and a guy in Iowa is selling his because he's upgrading to a 13 speed.
I'm just looking to get my wrecker going, and I'll just be using it as a hobby, so if it fits, the non-close ratio shouldn't bother me too much.

TC is torque converter

That transmission won't fit without using your Torque converter and Front pump @Coffey1 had to do this swap.

 

[Mario]

Another question.
I know a lot of transmissions will start in 2nd, sometimes 3rd gear.
Do you know what gear the regular MT654 (non CR) starts in?
I'm reading the manual for the MT654CR and it states that it starts in 1st gear, which makes sense since the wrecker is almost 40,000lbs.
It would also make sense for the standard transmissions to start in 2nd gear since the 923, 925 trucks are roughly half the weight of the wrecker.

 

[BKubu]

Another question.
I know a lot of transmissions will start in 2nd, sometimes 3rd gear.
Do you know what gear the regular MT654 (non CR) starts in?
I'm reading the manual for the MT654CR and it states that it starts in 1st gear, which makes sense since the wrecker is almost 40,000lbs.
It would also make sense for the standard transmissions to start in 2nd gear since the 923, 925 trucks are roughly half the weight of the wrecker.

All of the M939 series trucks start in first gear. FMTVs start out in second gear unless you manually move the transmission into first before starting out.

 

[Mario]

TC is torque converter

That transmission won't fit without using your Torque converter and Front pump @Coffey1 had to do this swap.

Forgive my ignorance. Why won't this work?
Is the 250 bolt pattern different from my 8.3l?
The seller is getting his engine modded and will be using a different transmission (13 speed) so my guess is that's why he's letting me have the flexplate as shown in the picture.
The plate does have the starter teeth on it.

You also said that I would have to use my own TC and front pump. Is that a problem? I do have my tranny still in the truck. While I don't know what's wrong with the transmission if the TC and pumps were good, could I simply transfer them from my MT654CR transmission to the 'new' MT654 one?

 

[simp5782]

Forgive my ignorance. Why won't this work?
Is the 250 bolt pattern different from my 8.3l?
The seller is getting his engine modded and will be using a different transmission (13 speed) so my guess is that's why he's letting me have the flexplate as shown in the picture.
The plate does have the starter teeth on it.

You also said that I would have to use my own TC and front pump. Is that a problem? I do have my tranny still in the truck. While I don't know what's wrong with the transmission if the TC and pumps were good, could I simply transfer them from my MT654CR transmission to the 'new' MT654 one?

You have to swap the torque converter and front pump from your A2 truck to that transmission that is made for the nhc250. You would want to have your converter tested and or flushed out atleast.

His flexplate won't help you. The torque converter bolt pattern is different and the torque converter ratio is different for a motor with a different power band than the other. The bellhousing on the A2 is a different depth than the nhc250 trucks.

 

[Mario]

You have to swap the torque converter and front pump from your A2 truck to that transmission that is made for the nhc250. You would want to have your converter tested and or flushed out atleast.

His flexplate won't help you. The torque converter bolt pattern is different and the torque converter ratio is different for a motor with a different power band than the other. The bellhousing on the A2 is a different depth than the nhc250 trucks.

Thank you! That helps a lot.
Can any automotive shop test the TC or do I have to take it to a truck shop? Any rough idea on the cost of the flush/test of TC?

 

[Mario]

Anyone know the torque specs for the front pump housing on the MT654?