[BobS]

Bob,

I've read this over and over and I appologize if you covered this (I have a thick skull at times).

While I understand the pilot bearing bores are different, is their location, relative to the back of the crank, the same?

Example: Say I was using the same bellhousing & transmission. Assume I don't have a pressure plate, disc or clutch for in the assembly. If I have a transmission that will mate with the SM465 flywheel, could I put the T19 flywheel in its place, and still have the same transmission & bellhousing???

The flywheels are identical as far as O.D., Ring gear, and from memory the "web thickness" of the area of the flywheel to crankshaft mounting bolts are the same. The thickness area of the pressure plate and disc is thicker on the GM version as shown in this thread. The pilot bearing bores are different. You could get around this by machining an adapter out of steel and boring the center to accept a press in oiltite bronze bushing. This may work using an AA adapter in you case provided your input shaft stick out would be correct.

 

[slorocco]

Bob, it looks, from the first pic in post #4, that the starter pocket on the SM465 is considerably smaller than the adapter. Do they all run like this? If all the 465's ran like this than I guess I should be ok with my SM420 bellhousing that I asked about in a different post.

Dan

The P30 vans that came with the GM SM-465 transmissions used this adapter and bellhousing. This was from a 1979 retrofit. Notice how the point of the bellhousing is off center between the adapter mounting bolts which tilts the engine to the right when viewed from behind. The Borg-Warner T-19 set up looks totally different. Also note the clutch linkage ball threaded into the engine adapter in the second picture. The bellhousing index hole diameter is 5.125 inches. SM-465 input shaft stick out length is 6-1/2 inches. This bellhousing number is General Motors 460486 (casting number) and uses clutch release bearing fork – General Motors part number 14066235.

 

[BobS]

That bellhousing and adapter were both removed from a 4BT - SM465 adapter set that I have. You need to measure your bellhousing index hole diameter as the SM420 may be smaller. In that case you could machine a spacer ring to fill the gap.

 

[slorocco]

You're right on the index hole. I'm fine there. This is the bell housing that came on the 420. I was concerned about the starter pocket on the bell housing. However, as I look at your pic, mine looks the same. I was just surprised it didn't match up to the outer profile around the starter, on the GM/Cummins adapter plate.

 

[LincTex]

I was just surprised it didn't match up to the outer profile around the starter, on the GM/Cummins adapter plate.

GM used two different diameter ring gears on their flywheels, just like Ford. Did your starter from the old engine have a staggered bolt pattern or a straight across bolt pattern?

 

[slorocco]

Hmmm, the starter and flywheel I have are what was on the running 4BT when it was pulled.

Were there two different GM flywheels used on the 4BTs? I thought it was just one, and that it was different from both of the normal chevy/gm 153 or 168 tooth flywheels.

 

[BobS]

There is only one GM 4BT flywheel. The starter bolts to the engine adapter and the bellhousing bolts to the rear side of the adapter. There were two different GM GASOLINE ENGINE flywheel sizes. The early cast iron GASOLINE engines had two different bellhousing sizes and the early starters mounted directly to the bellhousing using 3/8" hardware. One was for the big block which had the bigger flywheel and one was for the small block. I believe the aluminum 4BT GM bellhousing that I have pictured fits the big block Chevy engine.

 

[slorocco]

Bob, thanks for the additional information. The aluminium bell housing in your pic fits the starter area exactly like the cast iron bell housing I have pictured in my SM420 thread, so I'm thinking I should be ok.

I don't think it's the same as the big blocks though. Looking at your pick and comparing it to mine, they seem like they are the same size, and I can tell you that mine fit perfectly on the back of the small blocks and the 4.3 V6, I haven't tried it on a big block.

 

[poolmike]

I just got off the phone with Cummins. The parts guy tells me that #3913055 is not a good/active part number and transferred me to a sales rep. He found the Chebbie flywheel number to be 3913056. He says there a lots of them in the Memphis warehouse for $891. Dear god thats almost $1,000 after tax. If I don't locate one used in the next month, I will have to spend the big $$$$$.

 

[BobS]

I just got off the phone with Cummins. The parts guy tells me that #3913055 is not a good/active part number and transferred me to a sales rep. He found the Chebbie flywheel number to be 3913056. He says there a lots of them in the Memphis warehouse for $891. Dear god thats almost $1,000 after tax. If I don't locate one used in the next month, I will have to spend the big $$$$$.

Which is why I have said for the upteenth time this is the most expensive route to take. Also earlier in this thread I presented a way to possibly use the $100 T19 (AKA Ford) flywheel with an AA conversion bellhousing.

 

[poolmike]

Yeh, I know....I was just trying to assist with the part number. I think I might the T19 flywheel/AA bell on my next swap. I don't want to use my Jeep as a 'lab rat', which could potentially cost more than the $1,000 flywheel if it doesn't work:rasta: NV4500's aren't cheap to repair. Right now, I can possibly recover some $$$ if I sell the TH400/flexplate/convertor that was bolted to the engine when I got it.

 

[cruiseroutfit]

I just got off the phone with Cummins. The parts guy tells me that #3913055 is not a good/active part number and transferred me to a sales rep. He found the Chebbie flywheel number to be 3913056. He says there a lots of them in the Memphis warehouse for $891. Dear god thats almost $1,000 after tax. If I don't locate one used in the next month, I will have to spend the big $$$$$.

I could have spared you the run-around on the part number
http://www.4btswaps.com/forum/showthread.php?t=2575

 

[poolmike]

If you take a closer look at the GM SM-465 you will notice the front input bearing retainer looks a bit stubby compared to the B/W T-19. This is because during the retrofit it was trimmed back to around 3.630 inches in length to expose more of the input splines. This permitted the clutch disk and pressure plate to be mounted more rearward toward the transmission. I did a rough measurement from where the pilot bearing rides on the input shaft to where the clutch disk shows a slight amount of wear on the splines. The B/W is around 1.300 inches from the transmission side of pilot bearing where as the GM version is close to 1.725 inches. The approximate distance from the end of the pilot tip to the beginning of the splines are: GM - 1.025 inches B/W - .985 inch so the B/W is .040 inches shorter.

In unproven theory what does this all mean?

It could mean there is a possibility that an Advance Adapters #712576 external linkage type bellhousing for a NV-4500 to Chevrolet (the one GM never made) could be used with the Borg Warner T19 flywheel (BUT NOT WITH THE GM SM-465 FLYWHEEL) as a bolt in system. A custom machined pilot bushing would be required. See: http://www.advanceadapters.com/instructions/712576.pdf


No more Chevy flywheel shortage problems.

I am really interested in proving this theory(right or wrong). I just ordered the A.A. bellhousing #712577 for my '95 NV4500. I'll have to hunt around for the BW flywheel for this experiment. Anyone in the NE region have one that I can borrow/buy for some test fitting??

 

[rayjon]

any update on this??? BTW has anyone thought about having a flywheel made???? not cheep but better than 891$

 

[bigorangecntry07]

bob i think this would be best as a sticky.....my2cents

 

[rayjon]

bob i think this would be best as a sticky.....my2cents

I second that

 

[BobS]

This thread has been in the "Topics Index" sticky for about the last year.

 

[Jakey]

Info that may be of some help, sourcing a pilot bearing for the Ford adapter.
I noticed that 6303 is a common input bearing for alternators.
First noticed this on a Ford 3G I was going to use.
So sourcing one from an alternator repair shop gives another avenue of purchase where it should only be available in the prelubed double sealed version.

 

[jrjeepparts]

flywheel

bob is right about using the ford flywheel with the chevy tranny.the mechanic from the bread company wher i buy my trucks told me they have used the ford flywheel with the chevy trans.
how they do this is by installing a spacer in the pilot bearing hole to use the chevy input bearing.then they redrilled the presssure plate bolt holes to match the chevy pressure plate.
to make this work with the difference in thickness of flywheels they used the chevy long throwout bearing.the short chevy throwout bearing is used from the factory.he said it was much easier to get the ford flywheels.
i have one of the flywheels that they modified if someone wants some pics i will be glad to post them.

 

[LincTex]

Could someone give me a tooth count of the ring gear? I need to know tooth count for my Dakota Digital tachometer sensor. When I did my swap, I did it in one week and tried to keep the pace up. I seem to remember 146 teeth.