Anyone know if 644MT or HT740

[Dave5Cs]

Thought and was told that this is a HT 740 on the back of my MC 5C Saudi bus 6V-71, but after talking to and reading the board RJ's bus with same motor has the 644MT which I original thought mine was but was told later that it probably was the other. In looking at the 2 different tranny's it does not look like the HT 740. Have looked all over it and can not find a info plate, and yes looked on the drivers side 1/2 way down and not there.

Can anyone tell me which it is by the pictures of mine?
TIA

Dave5Cs

[sparkplug188]

That looks like a MT to me



Here is a link to the operators manual for the following transmissions:

AT 540
AT 542(N)(R)(NFE)
AT 543
AT 545(N)(R)
AT 1542P
AT 1545P(N)
MT 640, MT(B) 643, MT 643R, 644 647
MT 650, MT(B) 653, 654CR
HT 740(D)(RS)(FS)
HT 747
HT 750CRD, HT 750DR (DB)(RS)
HT750DRI, HT 750DRD (DB)
HT 754CRD, HT 754CR (RS)

Allison Operators Manual PDF
https://dl.dropboxusercontent.com/u/13580112/Allison%20Transmission%20Manual.pdf

[luvrbus]

Looks like a 600 series to me by the rear bolt spacing a 740 has no space the bolts are in a uniform pattern all around the back cover ,  have you ever changed the oil ? even with the 7inch oil pan the 600 series just holds 17 or 18 qts the 740 will take over 8 gals fwiw ,the 600 series will also free wheel in 1st and 2nd no lockup  

[bevans6]

The Saudi buses came stock with the MT, not the HT, or so I have always believed.  Cannot recall where I learned that, though.  FWIW.

Brian

[Dave5Cs]

Thanks guys that's what I always thought and then a fellow Busnut ( no name to protect the innocent) came to visit me and see the coach and told me he thought it was the 740HT without looking at it that a 644 would probably not fit. Me being a relative newbie at the time I believed him   until I was reading RJ's   thread last night and I went out to take pictures and thought I'd ask the experts.
Yes Clifford it does have spaces around it and thats what I noticed on the ones I looked at on ebay. Thank you for confirming.

[Stormcloud]

Looks just like my MT 654.

[Dave5Cs]

Clifford, No haven't changed it yet thats why I was asking also. It has a 5 inch pan? ATF in it now. Will use transyn or dextron III. That saves about 4 gallons from the 740.
cool Dave

[luvrbus]

Dave,those transmissions run cooler and and shift smoother with 15/40 unless you just want the red color I would go with the 15/40 the 15/40 is the recommend oil for the 600 series with retarders   

[Purplewillie]

My V730 is running 15/40. ....
Just saying...
Mark

[Dave5Cs]

Doesn't have the retarder or does it. The manual I was just looking at said transyn or Dextron III was recomended by Allison. Your saying 15/40 regular oil? It wouldn't have to be hydrolic type? Interesting

Edit: found another section. i stand corrected. 15/40 down to 5 degrees F. That saved some doe!...

[luvrbus]

You will like the 15/40 it can even be Delo 400

[Fredward]

I am running 15/40 in my 654/8V71. The Allison shop I worked with when I was setting up this transmission on my 871 said to use synthetic oil. He said it will run about 15-20 degrees cooler!
Fred

[Lin]

Fred, I thought you had a 647.

[luvrbus]

No need for Transynd in the older Allison you just benefit from longer mileage change intervals but the 24 months catches up with long before mileage on the RV buses.

I do think the Transynd will drop the temp a few degrees on the World Transmission but no 25 degrees that would below the normal operating temperatures I can't see the difference with Transynd and 15/40 on the older Allison's myself     

[B_K]

If any of you guys remember "Sammy" our onetime east coast guru (who unfortunately passed away way too soon) that was very knowledgeable in the ECM's and transmissions.

He told me once that if it was any other Allison than a "World Series" (aka B400 or B500) he'd always use 15/40 in it.
But he also warned me unless I wanted to replace my B500's early (like around 100,000 miles) not to use ANYTHING BUT Transynd in them!

This was after I'd called him to ask his opinion after someone else told me to switch over the 740's we had at that time to 15/40. I'd also called and asked our local Allison dealer and asked them their opinion and was told "Yeah we do use the 15/40, but only on the extreme heavy duty units"

I mentioned that to Sammy an his reply was "what could be more extreme than a bus driver? They either have their foot flat on the floor on the gas pedal or the brake but either way it's all or nothing! And they also think the tire sidewalls are part of the braking system too!"
  BK