[BobS]

This may sound like a bunch of worthless babble to the long time users of this site but a few years ago a lot of us knew very little about what we had and what we needed. For the benefit of the new folks this should provide some information should they end up with a standard shift van. Soooooooo

This is an attempt to alleviate some confusion between the Borg-Warner T-19 flywheels found mostly but not always in the standard shift Ford vans and the elusive GM SM-465 flywheel found mostly but again not always in a standard shift Chevrolet vans. I first measured the thickness of each. The Borg-Warner flywheel measured out to 1.312 inches. The GM version measures out to 1.830 inches. This means the GM version is .518 inches thicker. The pilot bearing bores are also different. The Borg-Warner uses a 6303 double plastic sealed non relube type bearing. The GM version uses a 6302 double plastic sealed non relube type bearing. Do not use the metal sealed relube type in either application as they permit the grease to be expelled and dirt can then enter. Both of mine have the wrong type of bearing.

Overall the both flywheels have the same clutch mounting bolt pattern and are almost identical except for the overall thickness and the pilot bearing bores. Both are 13-1/2 inches in diameter with both center bore areas being 6-3/8 inches. The GM SM-465 is casting number 3913055; the Borg Warner T-19 version has the casting number 3906613. Flywheel to crankshaft bolts, Cummins 3901395, 8 each required.


The Ford/Borg Warner 11" set up:
Pressure plate: LUK #98202 This has a "dual mounting pattern" for either the 3 pairs or 6 evenly spaced mounting bolt pattern.
Clutch Disk: LUK #76500 11" x 1-1/16" x 10 splines

The GM/SM 465 12" set up:
Pressure plate: LUK #99400 This has the standard mounting pattern that GM used on the V8's clear back into the 1960's.
Clutch disk: LUK #97501 11-15/16" OD friction surface x 1-1/8" x 10 splines. Important NOTE the outside diameter.

If you ever need to use a Chevy disk with the Ford/BW set up the one from a 68 V8 with the 11" clutch fits perfectly inside of the Ford/BW dual pattern pressure plate.

All the GM location mounting holes [6 evenly spaced ones] are all the same mounting diameter to accept 3/8" fastening bolts.
The LUK PART NUMBERS are stamped on the parts; disk flywheel side PP rear cover, from the parts I have had on hand.

 

[rotty]

What about weights of flywheels, offset of crank flange to clutch surface?
Are the starter ring gear teeth the same number and dia?

Good job other wise. I was wondering myself what the differences were.

 

[BobS]

What about weights of flywheels, offset of crank flange to clutch surface?
Are the starter ring gear teeth the same number and dia?

Good job other wise. I was wondering myself what the differences were.

The back sides are look identical. The starter ring gears are the same pitch and diameter. Notice in the first picture the ring gears are "meshed" together because they are sitting on the same level piece of plywood. Both use the same starter so the spacing from the crankshaft mounting surface must be the same otherwise the starters would not interchange. To further confirm this I did a "rough" layout. The raised portion surrounding the crankshaft mounting surface is the same measured height for both as measured from the crankshaft mounting to the top of this machined lip. I laid a metal machinist straight edge on this surface and measured the gap it forms from the straight edge to the outer flywheel surfaces and both measured the same within .005" The same starter is also used in the ones with the TH400/475 automatic transmission versions. The GM version is heavier due to the .518 inch thickness difference. The GM flywheel weighs in at 62 pounds while the Borg-Warner tips the scale at 49 pounds.

 

[BobS]

What about the Bellhousings

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]

GM's Version of Chryslers A-833 Bellhousing Option

Since there have been a few discussions about using the GM version of Chrysler's A-833 transmission behind a 4BT I will include this picture of what I have nicknamed the GM 6.2L dual pattern bellhousing. This one is from around 1982 - 1984. Note the A-833 bolt pattern that GM used. It is the ones with the bolts threaded in. The other two holes are drilled and tapped but plugged with plastic inserts for a GM SM-465. Bellhousing index hole diameter is also 5.125 inches. This bellhousing has the General Motors casting/part number 14061655.

 

[BobS]

The GM Non-Overdrive 5 Speed

There were also some discussions last year on the Yahoo side about using a GM pattern non overdrive 5 speed transmission from a school bus or 21,000 through 26,000 GVW chassis behind a 4BT along with 3.08 gears. These are still common wrecking yards items. The down fall is you need the elusive Cummins to GM flywheel to use one. Here are two pictures of one that fits the GM bellhousing without any major modifications. Bellhousing index diameter is 5.125 inches. Input shaft is 1-1/8 inch x 10 splines with a stick out length is 6-1/2 inches. Note the lower threaded mounting holes. The trucks used mounting bolts that were installed from inside the bellhousing therefore the lower two mounting holes on the truck bellhousing were not threaded.

 

[bcowanwheels]

I Have Both Flywheels And The Pressure Plate Bolt Pattern Is Different.

 

[BobS]

I Have Both Flywheels And The Pressure Plate Bolt Pattern Is Different.

Interesting and good information. Do you have the casting numbers available? Does your Borg-Warner use the "Three pairs" bolt pattern with three release fingers?

I just rechecked what I have. I have two Borg Warners and the one GM version. All three of mine use the same Chevy pattern clutch.

 

[BobS]

The Borg Warner T-19 Setup

Most standard shift Ford chassis vans were equipped with the Borg Warner T-19. The T-19 is a fully synchronized 4 speed transmission. It is readily recognizable due to its two PTO covers unlike the T-18 version that usually only has one. The input shaft is 10 splines x 1-1/16 and has a stick out length of 6-1/2 inches. A local fleet mechanic in Ohio informed me that he was glad to see this setup get changed over to the TH 400/475 because the splines in the clutch disk failed whenever they got a new aggressive driver.

This is the Borg Warner T-19:

 

[BobS]

The Borg Warner T-19 Ford Bellhousing

This is one of the Ford "small pattern" manufactured bellhousings used with mechanical clutch linkage that was installed behind a 4BT. Unlike the pointed top GM version this one has a flat top with two mounting bolts spaced approximately 5-1/4 inches on center. The index hole measures 4.847 inches.
Ford Motor Company casting part number: E4TA-7505 DA

 

[BobS]

The Borg Warner T-19 Ford Bellhousing to Engine Adapter

This is the engine adapter that mates the 4BT to the small pattern Ford bellhousing. I have seen these mislabeled as an SAE adapter. Although the bolt pattern is somewhat round in overall appearance this is NOT an SAE adapter housing.

This is also the engine adapter that is used with the small pattern Ford ZF transmissions.
This adapter has the casting number 3910515 REV 004 and is 2.050 inches thick measured at the top cylinder head surfaces.

 

[BobS]

Starter Spacer

The GM SM-465 and the Borg Warner T-19 setup engine adapters both use the same starter and starter spacer. This spacer is 16 mm thick and provides the correct depth for the starter pinion and the ring gear on the flywheel to mesh properly. This same spacer is also used with the GM TH-400/475 transmission.

This spacer is Cummins part number 3906647.

 

[BobS]

The GM SM-465 Four Speed Manual Transmission

The GM SM-465 transmission could be found in GM truck and bus chassis rated from 7500 through 21,000 GVW. The input shaft is 10 splines x 1-1/8 inches and has a stick out length of 6-1/2 inches. Notice the heavy ribs cast into the side of the case. It also has two provisions for attaching a power take off.

 

[BobS]

So where does the .518" difference come into play?

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.

* (see below) 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

* NOTE: This has since been proven to work by a member here on 4BT Swaps:

the ford flywheel worked great, i was able to find one on ebay. i drilled the flywheel for a chevy pressure plate and made a sleeve for the pilot bearing. i used a lever style pressure plate and a short chevy throw out bearing. everything is working great THANKS 4 all the info.

No more Chevy flywheel shortage problems.

 

[cruiseroutfit]

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.

Excellent Tech!!!

While I'm not using the NV4500 (well, most likely not), I plan to mate the 4BT to a Toyota LC manual trans (H55F/H42) using an Advance Adapters bellhousing or a Marks Adapter bellhousing (also distributed by Marks). We've been an AA dealer for 15 years now... I'll see if they like me enough to send me some specs on both bellhousing

Theoretically I could shorten the front bearing retainer on the Land Cruiser trannies, its a very similar setup to the SM465

Another peice of the puzzle to consider. Do you think that the SM465's used with the 4BT had a different front bearing retainer than the regular SM465's found behind a small-block?

 

[LincTex]

My 4BT (Ford style adapter) came with a NP435 and a diaphragm clutch

 

[BobS]

Excellent Tech!!!

Do you think that the SM465's used with the 4BT had a different front bearing retainer than the regular SM465's found behind a small-block?

No, it actually looks like they just trimmed the length with a pipe cutter.

 

[cruiseroutfit]

No, it actually looks like they just trimmed the length with a pipe cutter.

Hmm, great info...

 

[dieselcruiserhead]

Bob, excellent tech, thank you.. I have been wondering about that (difference between the Ford and GM flywheels) for ages...

 

[cruiseroutfit]

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???