Bellhousing questions: Ht740 onto 8v71

Tenor · June 19, 2019, 04:10:26 PM

I have the option to put an HT740 behind my 8v71 and be rid of my 4 speed spicer in my MCI7 I have been told that I need to change the bell housing to make the starter engage with the flex plate. I have also heard that there were 2 different bell housing on the 8v71. Is any of this true, and is there a way to tell the difference? Thanks!

chessie4905 · June 19, 2019, 04:19:19 PM

Here is a dimension chart of different sizes. You are probably talking only #1 or #2

https://www.powerlinecomponents.com/literature/detroit_diesel/flywheel_chart.htm

luvrbus · June 19, 2019, 04:59:33 PM

Quote from: Tenor on June 19, 2019, 04:10:26 PM
I have the option to put an HT740 behind my 8v71 and be rid of my 4 speed spicer in my MCI7 I have been told that I need to change the bell housing to make the starter engage with the flex plate. I have also heard that there were 2 different bell housing on the 8v71. Is any of this true, and is there a way to tell the difference? Thanks!

If you have the SAE 1 4-1/4in inside to outside it will work for a 740 but if the 3-1/2in it has to be changed,you have a photo of the starter location on the bus now ?

Tenor · June 19, 2019, 05:22:48 PM

Chessie, thank you for the diagram. I have many more than 12 bolts! I can see 6 in about 1/4 of the bell housing. Luvrbus, is there a location available (with the engine still installed) that I can get that "inside to outside" measurement? Here are three photos of the starter and bell housing. Thanks guys!!

chessie4905 · June 19, 2019, 07:45:46 PM

If you pull the starter you could count flywheel teeth. Mark one tooth with some white out or white paint or chalk and turn slowly with large screw driver or prybar. #1 is 118 teeth, #2 is 102 teeth, and #1 1/2 is 112 teeth.

luvrbus · June 19, 2019, 09:04:50 PM

The MCI 7 has a SAE 1 bellhouing fwiw lol just noticed I posted SAE 2 all MCI's were SAE 1 odd ball bellhousing I have a few SAE 1 from MCI's laying around

bevans6 · June 20, 2019, 05:35:32 AM

My MC-5C has a SAE 1 sized bellhousing with a SAE 2 sized flywheel and ring gear (hence starter motor location). This caused me much grief when I installed a MT 647. Finding a flex plate was impossible. I used a 15/16" thick SAE 1 to SAE 2 adaptor ring to mount the transmission. Are the other MCI's different? On my bus the engine mounts bolt to the bellhousing, and I thought that was MCI specific.

chessie4905 · June 20, 2019, 06:26:03 AM

I think the easiest would be to buy a takeout 740 or find a parted out one and get hsg, flywheel, converter and or everything you need. Out of an MC8, unless MC7 had 740 from factory with 8v-71. Will eliminate the headaches that Bevans6 had to deal with. Those types of issues can double the cost of a changeover.

lostagain · June 20, 2019, 06:30:26 AM

All the MC7 cars we had were 4 speed manual. I don't remember seeing an automatic until the MC8s.

JC

buswarrior · June 20, 2019, 06:52:28 AM

The 740 was available right at the end of the MC7.

Not very many of them around stock.

I second grabbing a whole take-out or parts coach to get the bits.

happy coaching!
buswarrior

luvrbus · June 20, 2019, 09:02:19 AM

The MCI 7 had both the 740 and the Allison 70 a 6 speed with the wet torque converter transmission,there is a guy back east here on the board that has a original HT 70 in his MCI 7 but I forget his name,he is installing a 740 parts won't be hard to find he is not looking for the drop ring.the starter ring is on the transmission the starter location is his problem some times they are ok then some times the bellhousing needs changing plus his is a belt driven alternator which makes life easier,a bellhousing from a MCI 9 is not going to be value for him,I almost will make a bet his bellhousing will work

chessie4905 · June 20, 2019, 11:43:17 AM

Hope so. How big a bet?🤔

luvrbus · June 20, 2019, 11:50:37 AM

Quote from: chessie4905 on June 20, 2019, 11:43:17 AM
Hope so. How big a bet?🤔

For you Chessie a new 4 inch grinder from Habor Freight

Tenor · June 20, 2019, 03:17:35 PM

I have access to an ht740 that was originally behind a 6v92. I am taking it out of an MCI 9, with shifter driveshaft, etc. The engine was being replaced with a Cummins, so the original engine is not available. The question has been raised by a supplier for a correct flex plate that told me I need to fit a 118 tooth flex plate and he is sure I need a different bell housing. He also says my current trans has a 102 tooth ring gear on the flywheel. So, let me re-ask the question better than I did the first time. How can I tell which bell housing I have, and if it will accept a 118 tooth flex plate and an ht740 trans and have the starter engage? Is there an external depth measurement of the bell housing I can make? As I've read here, there are 2 different internal depths, so I assume that would carry to the outside of the bell housing? Does someone know exactly which bell housing they have, and could they measure the external depth at the starter motor and report back? We could make a comparison that way perhaps? Thanks everyone!!

luvrbus · June 20, 2019, 04:03:34 PM

There are no teeth on a 740 flex plate where does he get that,all flex plates for a 740 are the same except for ply's for higher hp engines and the removable center hub for different engines ,if you have 24 bolts on the bellhousing you have a SAE 1 type bellhousing .you can measure from under the bus,the starter location if you can measure the top bolt should be 2-3/4 inch to that bolt to the engine block with the starter mounted at 9:00 then it works,the 740 starter ring gear should be the same location as the flywheel ring gear with a clutch for depth.I done a couple of the conversions from the Long clutch to the 740