I ordered an MT644 and I received an MT647

Fredward · May 27, 2014, 07:17:50 AM

What is the difference between transmissions? I have some information but can't figure out the difference. Obviously they are in the same family and have similar torque and horsepower input limitations.

Thanks, Fred

luvrbus · May 27, 2014, 07:28:18 AM

Houston you may have a problem the 647 is almost 6 inches longer and some are electronic controlled unless Bobby changed the valve body or is that the 653 that is longer I will check on it for you but measure it anything over 31 inches won't work for you

good luck

Lin · May 27, 2014, 09:18:37 AM

We have the 647 in our 5a. It is definitely not electronic. I have not checked anything, but I do not think it is longer than the 644. As I remember it, the 647 had some internal durability upgrades from the 644.

TomC · May 27, 2014, 09:23:13 AM

Lin is correct-the MT647 is a MT643, MT644, etc with the most upgrades. Still a 4spd and the shorter transmission compared to the 5spd. As long as it is a mechanical trans, you'll be fine. Good Luck, TomC

Fredward · May 27, 2014, 11:27:38 AM

OK Thanks guys. They say the only way to install the bolts that go through the flexplate into the torque converter is to remove a plug in the rear case and reach through that opening with the extension socket. Haven't had a chance to look but I wonder if I could reach those bolt locations through the starter opening.

Should I loctite those bolts? If so, which color should I use? What is the torque specification for those bolts?

Fred

bevans6 · May 27, 2014, 11:35:11 AM

Dang, that looks nice! Would you care to PM me the ballpark cost for the package? It looks very complete. Do you need an adaptor ring or different rear housing on the 8V-71?

Brian

luvrbus · May 27, 2014, 12:52:42 PM

Torque the flywheel to the engine @ 180 to 190 ft lbs look above the starter there is a plug to remove to get to the plate to bolt up the transmission.

I don't see any ATEC crap on the transmission and I checked it is 30-1/2 long. I got into a 647 that had a electronic park before man was that a night mare it was a off road 647 it was a strange duck indeed

Fredward · May 27, 2014, 02:32:30 PM

Brian,
THere is an SAE1 to SAE2 Bell Housing Adapter on there. Here is another view where you can see the silver ring. There is also an adapter from the 8V71 crankshaft to the torque converter but I don't have it yet. THere aren't many of them in existence anymore and mine got lost in the mail apparently. Yes it is a very complete kit, even came with a dipstick and tube and an air to oil cooler. A manual modulator and cooling line fittings. Transmission is a running take out that was dyno'd and has a new filter installed.

I did not have a core so the total bill came to around $5,900.00. It would have been about $10,000.00 installed. A lot of money but the bus is worthless with the manual transmission and I really needed another project to go with the hole in my head............

Fred

bevans6 · May 27, 2014, 02:48:37 PM

Thank you! I am amazed at how much smaller it looks than the 8844. Tighter and tidier. Good deal, it should be wonderful.

Brian

lvmci · May 27, 2014, 05:26:29 PM

Hi Fred, my MT643 is set for a max of 250 horsepower I think, were the updated MTs higher horse capable? Lvmci...

Ed Hackenbruch · May 27, 2014, 06:24:34 PM

My 644 is rated for 300 hp.

luvrbus · May 27, 2014, 07:12:26 PM

The 647 is rated for 300 hp also but the torque rating is 950 # it will standup behind the 6V92 325hp the 644 has torque rating of 780 # with 300 hp,the 643 is only rated at 640# of torque with 250 hp but can be used on a 4000 rpm engine where the others cannot be used over 3000 rpm

TomC · May 28, 2014, 08:44:27 AM

Since you have both the engine and transmission out, this would be the perfect time to add a turbocharger. By keeping the N65 injectors, you'll boost the engine from 300hp and 800lb/ft torque to 325hp and 975lb/ft torque. It is a bit over the transmissions advertised capability, but, like me, you're typically not driving the bus with your foot on the floor like a commercial bus driver would be. The most noticeable change will be no performance loss at higher altitude. And with just keeping the same injectors, you can keep the turbo boost under 10psi so not to create a lot of heat.

The V730 is rated at 275hp and 780lb/ft torque. Yet I'm pushing 375hp at 1125lb/ft torque through mine with no problem. Course, I had the trans rebuilt and they also increased the oil pressure. Good Luck, TomC

Fredward · June 04, 2014, 07:30:22 PM

Oh Boy having a heck of a time getting the correct adaptions for this combination. Need to put a crankshaft hub adapter on to mount the flexplate. The flexplate has the starter gear on it with an MT647. So I got that right, but now am having problems finding a SAE 1 bell housing adapter that is the right length. Looks like I need 1.500" and a step down from SAE 1 to SAE 2 because the tranny is SAE2. Might be able to find a step down adapter that is 1.500" here in town hopefully.

Then I'll need to shorten the driveshaft. And I'm being told I may need to shim the engine up an inch to help line up the new shorter drive shaft. The project seems simple enough, but it's not.

Does anyone know if I'm going to need to shim that engine after I get the driveshaft shortened? The engine is so tight in the MC-5 that I can't imagine shimming the transmission end. Maybe the fuel pump end?

luvrbus · June 04, 2014, 08:19:05 PM

Unbelievable Fred they knew you needed the spacer Kim sent me a blank and I had to have the holes drilled been a long time ago but I was thinking it was 15/16 If I had a SAE 2 bell housing I would ship it to you and you would be done I lowered the front of my engine with different mounts not by much isn't the drive shaft 13 inches ?