5.9 to MT643 Questions..

[Scooter141]

My Bus has a 545, I am cooking the thing so I bought a MT643. I have scoured the interweb for HOURS and cannot find a definitive answer.

Without pulling the 545, I have to assume its SAE#2 bellhoushing....

So are the Flywheel and adapter (not bellhousing) different between the 545 and 643?

Is the Flywheel and adapter (for MT643) the same between the 5.9 and 8.3 Cummins?

I have the part #'s for 5.9 to MT643, but i can not find the part numbers fro 5.9 to AT545....

23045240 is the 643 to 5.9 Flywheel
23045241 is the 643 to 5.9 "adapter"

Anyone know anything else for sure??
I can't be the only person to do this...!!!

THANKS, Todd S.

[Tango]

If I remember correctly, all 543's are SAE #3 (I know for a fact my last two were). And, once again, if I remember correctly, all Cummins 3.9 & 5.9's are also SAE #3 (my current 3.9 is for certain). Ergo...all 543's should bolt up directly to any 3.9 or 5.9 and the 643 should be the same.

Also...the new 5th gen Allison 6 speeds are also SAE #3. That is what I have bolted up to my 3.9.

NOTE: Allisons typically set at about a 3 degree angle off vertical which forces the engine to be tilted to the passenger side a bit in order for the tranny to be flat & parallel to the ground. All of the P-30 vans, taco trucks & such had the famous "Cummins Tilt" as seen below on my '46 Shorty.

[Scooter141]

Says SAE#3 on here....
AT545 and "B" and "ISB" Cummins.

[Scooter141]

But says SAE#2 on here...................
MT643 and "B" series Cummins.

[/URL][/IMG]

[Scooter141]

Originally Posted by Tango

If I remember correctly, all 543's are SAE #3 (I know for a fact my last two were). And, once again, if I remember correctly, all Cummins 3.9 & 5.9's are also SAE #3 (my current 3.9 is for certain). Ergo...all 543's should bolt up directly to any 3.9 or 5.9 and the 643 should be the same.

Is the Hub adapter and flywheel the same from 5.9 to 8.3?

[Booyah45828]

B series cummins came with both sae #2 and #3 flywheel housings. I wouldn't assume anything. Measure what you have and go from there so you're not ordering useless parts. I can probably find the numbers if you desperately need them but you should be able to find them on the net, try the 4bt forums for example.

The B and C series flywheel housings should be interchangeable(save for a few odd tractor applications)

Tango, I've seen a slight tilt, but nothing like what you have. Is the camera tilted too? I can't tell.

[Scooter141]

Originally Posted by Booyah45828

B series cummins came with both sae #2 and #3 flywheel housings. I wouldn't assume anything.

According to the picture above and the Allison tech I talked to just now, all 5.9's with 545's were SAE#3, and all 5.9's with 643's were SAE#2. I gave him my Trans serial # and VIN. He called back and said 100% mine is SAE#3.

Originally Posted by Booyah45828

The B and C series flywheel housings should be interchangeable (save for a few odd tractor applications)

He confirmed that the B and C series adapter hub and flywheel should be the same bolt pattern.
THANKS for all the help.
Anyone have a 5.9L to SAE#2 housing they wanna part with ? ?

[nat_ster]

SAE 2 adaptors for the 5.9 are worth big money due to the guys putting 13 speeds in dodge trucks.

The Cummins engine is no SAE pattern. It has a adapter bolted to it. There are many different adapters. Dodge had their own to mate to the Getrag 360 ( 5 spped first gen, and the NV4500 (5 speed second gen) and the NV5600 (6 speed second gen).

Medium duty stuff like buses use SAE 3 and SAE 2. Unlike in the light duty trucks where there is only the adapter and the transmission, the Medium duty trucks use three pieces for more versatility.
You have the engine adapter, the bell housing, and the transmission.
On auto transmissions, the bell housing contains the torque converter.
On standard transmissions, the bell housing contains the clutch and flywheel.

I'm sure I have seen MT643's with SAE 3 torque converter housings.

I have also seen combo's like a DT 466 with a SAE 2, a slim ring to adapt it down to a SAE 3 to connect a AT545 to it.

Industrial application's like generators are a completely new set of adapters.

Here is a chart to help you figure out what your new MT643 is.



Hope this helps.

Nat

[Scooter141]

Originally Posted by nat_ster

SAE 2 adaptors for the 5.9 are worth big money due to the guys putting 13 speeds in dodge trucks.

Well, I gotta have one......

Originally Posted by nat_ster

The Cummins engine is no SAE pattern. It has a adapter bolted to it.

I understand that. The engine adapter is one bolt pattern on the engine end and SAE on the other (trans end).
The B series engines and the C series are different patterns. (so says the allison dealer i talked to )

Originally Posted by nat_ster

Medium duty stuff like buses use SAE 3 and SAE 2. Unlike in the light duty trucks where there is only the adapter and the transmission, the Medium duty trucks use three pieces for more versatility.
You have the engine adapter, the bell housing, and the transmission.
On auto transmissions, the bell housing contains the torque converter.
On standard transmissions, the bell housing contains the clutch and flywheel.

I understand that too. Not my first rodeo.

Originally Posted by nat_ster

I'm sure I have seen MT643's with SAE 3 torque converter housings.

I have also seen combo's like a DT 466 with a SAE 2, a slim ring to adapt it down to a SAE 3 to connect a AT545 to it.

If you saw a MT643 with a #3, it wasnt from a B series Cummins.

The trans I have is from a Cummins, it HAS to be..... Otherwise the torque converter will be the wrong ratio, and the and shfit points wont be at the right RPM's.

Originally Posted by nat_ster

Here is a chart to help you figure out what your new MT643 is.
Hope this helps.

Nat

Yes, I have this chart.

The problem is, I cannot pull the 545 to see if its #3 for sure. I cant have it sit in my buddies shop that long.

[Scooter141]

Here is my bus...








I built it into a camper. 6500W Onan, Roof A/C, TV, DVD, Carpet, bla,bla,bla.

[nat_ster]

All AT545's are SAE 3. They don't make a SAE 2 AT545.

That's why DT466's with a SAE 2 use a ring to adapt down to SAE 3 when they have a AT545.

You don't need to pull the trans to find out. Measure and count the bolts on the SAE pattern.

If I was you, I would do a Google search to find out if the 8.3 uses the same adapter as the 5.9.

I looked once, but don't remember off hand.

Nat

[Scooter141]

Originally Posted by Scooter141

My Bus has a 545, I am cooking the thing so I bought a MT643. I have scoured the interweb for HOURS and cannot find a definitive answer.

Without pulling the 545, I have to assume its SAE#2 bellhoushing....


23045240 is the 643 to 5.9 Flywheel
23045241 is the 643 to 5.9 "adapter"

Anyone know anything else for sure??
I can't be the only person to do this...!!!

THANKS, Todd S.

oops TYPO,.... I meant to say my 545 is SAE #3.

Originally Posted by nat_ster

All AT545's are SAE 3. They don't make a SAE 2 AT545.

That's why DT466's with a SAE 2 use a ring to adapt down to SAE 3 when they have a AT545.

I have never heard of an adapter ring...

Originally Posted by nat_ster

If I was you, I would do a Google search to find out if the 8.3 uses the same adapter as the 5.9.

Nat

I was told by a Allison tech, the Engine adapter is different, but the flywheel and hub adapter should be the same.

And when I say adapter, I mean the hub adapter not the flywheel housing.

[bluebird90]

Ok, this is the easiest way to tell what flywheel housing you have. Look at where your 545 joins the engines housing. if it bolts directly to the housing you have a sae#3, if there is a reducing adapter between the trans and engine flywheel housing you have a #2

[nat_ster]

Originally Posted by Scooter141

I have never heard of an adapter ring...

Nothing more than a ring of steel about half inch thick with the bigger SAE2 bolt pattern on one side, and the smaller SAE3 bolt pattern on the other.

They use them both ways. Some engines never had a SAE 3 adapter but bus manufactures still wanted to use SAE 3 transmissions so they made a spacer / adapter ring.

Bluebird 90 knows what I'm talking about.

Nat

[bluebird90]

Yeah, I forgot to mention that you would see 2 different bolt circles. I have seen some adapters that were nothing more than a spacer for the same bolt patturn

[nat_ster]

Originally Posted by bluebird90

Yeah, I forgot to mention that you would see 2 different bolt circles. I have seen some adapters that were nothing more than a spacer for the same bolt patturn

Sometimes that is a solution for a input shaft that was to long with that combo.

Nat

[Scooter141]

My Engine and trans are SAE #3........

[reddog]

I know this is an older thread, but this thread seems to have the most info on this subject I have found thus far. I recently picked up a Thomas MVP flatnose shorty and want to replace the 545 with a 643 for obvious reasons. (And repaint it for obvious reasons...)

I can't find a part number for the flywheel housing on the diagrams shown on this thread. Does anyone have the Cummins part # for a 5.9 ISB SAE #2 flywheel housing?
Thanks in advance!

[2kool4skool]

Cummins Flywheel Housing - Cast Iron - 4B, 6B, ISB

http://www.vanderhaags.com/detailview.php?part=24200840

[reddog]

Perfect, exactly what I was looking for!
Thanks!