CAN THIS BE TRUE? 904 WON'T FIT AMC CRANK???

[SNOWMAGEDDON]

A GUY TELLS ME.............................................
HE SAYS...............................................

I HAVE A 904 TRANS COMPLEETLY BUILT WITH HEAVY DUTY DRUM, RACING CLUTCHES, ECT. IT HAS A BRAND NEW 3500 COAN STALL CONVERTER,TRANS MOUNT. I SPENT A LOT OF MONEY ON THIS TO PUT IN MY GREMLIN BUT MY MOTOR IS A STICK SHIFT ONLY MOTOR
THE CRANK WONT EXCEPT THE CONVERTER

i'M LOOKING FOR A 904 OR 998 AND THIS ( IF TRUE) WOULD MAKE A BIG DIFFERENCE WHAT/WHICH 904/998 I COULD USE - I'M FAR FROM A TRANS GUY AND THIS WILD CARD (IF TRU) NARROWS DOWN MY PICK OF CORE FINDS FOR A REBUILD - I PLAN TO GET A CORE AND REBUILD IT WHILE I STILL DRIVE MY DAILY - THAT'S HOW I RAN ACROSS THIS TRANS - LOOKING FOR A CORE

ISN'T IT MORE THE TRANS WON'T FIT THE 258 BECAUSE OF THE TRANS COMPONENTS INSTEAD OF THE OTHER WAY AROUND???
i'M COONFUSED - AS USUAL

HELP?

[mudkicker715]

What flywheel is on the motor.

[captspillane]

I second that. Don't use all caps.

There is no such thing as a "stick shift" only motor.

There is no difference effecting the transmission between the end of the crank for any AMC motor. There is a slight difference between a 4.2 and a 4.0, and even then it doesn't matter. You can even bolt a V8 flexplate on a 258 just fine, although a V8 crank is externally balanced while the 258 and 242 are neutrally balanced so it would vibrate terribly.

There are torqueflite flexplates (904/998/999/727) and then there are hydromatic flexplates for the rare TH400 transmission. If your engine came from a TH400 equipped full size Jeep it might still have some crazy spacer pressed into the crank. That spacer needs to be removed to install a pilot bearing or a torqueflite transmission.

You'll need 6 shorter bolts for a flexplate than you have for your current flywheel.

[BenM]

The only thing I could think of is if the guy had a older setup for the Borg-Warner automatics. That would be entirely possible with a 70-71 Gremlin, or a slightly later one if someone changed engines for some reason.

After AMC switched over to the torqueflite automatic things changed. That would be the same time that the short 199/232 six became the 232/258 tall six.

[carnuck]

There is a pilot bearing in the crank for the std trans, but that shouldn't interfere with the converter nub. Is your motor original? If not, some of the Jeeps ran TH400 trans missions and they had a thin sleeve in the crank hole to align the converter.
   What motor was that 904 from? Dodge ones only share internals.

[carnuck]

I second that. Don't use all caps.

There is no such thing as a "stick shift" only motor.

There is no difference effecting the transmission between the end of the crank for any AMC motor. There is a slight difference between a 4.2 and a 4.0, and even then it doesn't matter. You can even bolt a V8 flexplate on a 258 just fine, although a V8 crank is externally balanced while the 258 and 242 are neutrally balanced so it would vibrate terribly.

There are torqueflite flexplates (904/998/999/727) and then there are hydromatic flexplates for the rare TH400 transmission. If your engine came from a TH400 equipped full size Jeep it might still have some crazy spacer pressed into the crank. That spacer needs to be removed to install a pilot bearing or a torqueflite transmission.

You'll need 6 shorter bolts for a flexplate than you have for your current flywheel.

There actually was stick shift only AMC 6 cyl motors, but they went away in '71 when they changed the bell pattern to match V8s and put an alignment ridge on the crank flange casting. There is a '71 only 258 crank that no-one with a modern trans wants.

TH400 was available until '79 in Jeeps. The sleeve was used when they went away from the adapter ring between motor and trans and went with an AMC pattern TH400 @'74

[68AMXGOPAC]

I second that. Don't use all caps.

There is no such thing as a "stick shift" only motor.

There is no difference effecting the transmission between the end of the crank for any AMC motor. There is a slight difference between a 4.2 and a 4.0, and even then it doesn't matter. You can even bolt a V8 flexplate on a 258 just fine, although a V8 crank is externally balanced while the 258 and 242 are neutrally balanced so it would vibrate terribly.

There are torqueflite flexplates (904/998/999/727) and then there are hydromatic flexplates for the rare TH400 transmission. If your engine came from a TH400 equipped full size Jeep it might still have some crazy spacer pressed into the crank. That spacer needs to be removed to install a pilot bearing or a torqueflite transmission.


You'll need 6 shorter bolts for a flexplate than you have for your current flywheel.

"The rear flanges on all 1972 crankshafts are different than earlier ones,however,they present no problem when useing a manual transmission.If you are useing a 1972 crankshaft with an automatic transmission, use a 1972 and later unless you decide to modify the flange"-at least on a V8 it says.

[captspillane]

What year is your engine for your Gremlin, Snowmaggedon? If its a '72 or newer you won't have a problem. Since you specifically said 258 instead of 232 chances are it is. I thought it was only the 232 that had this problem but apparently the 1971 258's had it as well. If you have a 1971 motor I would start looking for a different engine before losing the transmission you already have.

[68AMXGOPAC]

I ran into it with my 68 - 390 wich was a standard T-10 4 speed and I wanted to put the auto off my 73 401 on it, and use the 4 speed on the 401. I have a mechanical drawing somewheres that shows the dimensional modification needed on the crank. I also thought this was only with the V8...............

[IowaEagle]

'71 and older AMC I-6 engines will not accept a '72 and later TF trans for several reasons.  The bell housing mounting is different, as mentioned earlier, they used BW transmissions and the starter is on the driver's side.  There was a '71 258 that did use the BW transmission.

[rollguy]

If the 904 you may be getting is for a 2 wheel drive, you will need some of the parts from a 998 to make it work in an Eagle.  The entire 2WD trans will need to be torn apart to install the output shaft for the 4WD transfer case.   You would be better off finding a 4WD trans core (from an Eagle or Jeep) to rebuild.

[DaemonForce]

If the 904 you may be getting is for a 2 wheel drive, you will need some of the parts from a 998 to make it work in an Eagle.  The entire 2WD trans will need to be torn apart to install the output shaft for the 4WD transfer case.   You would be better off finding a 4WD trans core (from an Eagle or Jeep) to rebuild.

Curious, could something similar be done to a 2WD T-5 transmission or otherwise familiar manual variation? I have a donor tail end from a 998.

[shanebo]

This is the first time I have ever heard of this kind of problem. Its good to know though as it could save alot of headache for someone else down the road.

[eaglefreek]

If the 904 you may be getting is for a 2 wheel drive, you will need some of the parts from a 998 to make it work in an Eagle.  The entire 2WD trans will need to be torn apart to install the output shaft for the 4WD transfer case.   You would be better off finding a 4WD trans core (from an Eagle or Jeep) to rebuild.

Curious, could something similar be done to a 2WD T-5 transmission or otherwise familiar manual variation? I have a donor tail end from a 998.

Nope not a T5. It requires a different case and different main shaft. It would require a total disassembly and reassembly. Would be much easier and a whole lot cheaper to find a 4x4 manual transmission.

[carnuck]

Curious, could something similar be done to a 2WD T-5 transmission or otherwise familiar manual variation? I have a donor tail end from a 998.

You would need the parts from a 4x4 T5 to make it work. CJs and some YJs used them (and blew them up with great frequency)

'71 and older AMC I-6 engines will not accept a '72 and later TF trans for several reasons.  The bell housing mounting is different, as mentioned earlier, they used BW transmissions and the starter is on the driver's side.  There was a '71 258 that did use the BW transmission.

Another small warning. Postal Jeeps used the '71 version almost till '79 in many models. If the starter is on the (normally) driver's side, pass it by!