TheAMCForum.com Homepage
Forum Home Forum Home > The Garage > Transmission & Drivetrain
  New Posts New Posts RSS Feed - Quick stupid question 74 401 to m12
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

Click for TheAMCForum Rules / Click for PDF version of Forum Rules
Your donations help keep this valuable resource free and growing. Thank you.

Quick stupid question 74 401 to m12

 Post Reply Post Reply
Author
Message
74Bubblefender View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jun/29/2007
Location: The AMC form
Status: Offline
Points: 2589
Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Topic: Quick stupid question 74 401 to m12
    Posted: Jul/20/2007 at 6:46am
I have laying in front of me a 727 flexplate and a m12 flexplate from a 1969 V8. I also have the torque converters. We are installing a 1974 401 in a 500 special (AMX) this evening and I am wondering if the 727 flexplate will work for this. The bolt pattern looks close but I personally havent done this swap. I believe I will need to make a adaptor for the converter spud. Anyone done this swap that can shed a little more light on this?
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
Back to Top
74Bubblefender View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jun/29/2007
Location: The AMC form
Status: Offline
Points: 2589
Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2007 at 6:52am
It looks like I just need to open up the mounting holes for the larger bolts on the M12 torque converter.
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
Back to Top
74Bubblefender View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jun/29/2007
Location: The AMC form
Status: Offline
Points: 2589
Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2007 at 7:03am
Ok so we have to bore out the center hole in the flexplate, leave a nice radius to allow it to fit on the edge of the end of the later crank. Make a bronze spud to allow the M12 torque converter to join with the later crank.
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
Back to Top
FuzzFace2 View Drop Down
AMC Addicted
AMC Addicted
Avatar

Joined: Jul/05/2007
Location: Angier, N.C.
Status: Offline
Points: 10343
Post Options Post Options   Thanks (0) Thanks(0)   Quote FuzzFace2 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2007 at 1:21pm

Some one does make an adaptor for this, One is a bolt in the other needs machine work-read crank has to be out. Think it might be the people in FL?

Dave ----

Back to Top
XJ-001 View Drop Down
Supporter of TheAMCForum
Supporter of TheAMCForum
Avatar

Joined: Jul/03/2007
Location: Minnesota
Status: Offline
Points: 193
Post Options Post Options   Thanks (0) Thanks(0)   Quote XJ-001 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2007 at 4:54pm
FF2 - You're thinking of the adapter for the early engine/crank in front of a TH400/727. MC and the car owner are trying to install a later (72-up) 401 in front of a M-12. The 71 401 flexplate has a very small center hole and the crank has the large diameter flange for the 400/727 stlye plate. They need to machine the 401/M-12 flexplate center hole out to the diameter of the late crank flange. The bolt pattern is the same on both cranks, so that won't be an issue. It appears from my discussion with the owner that the M-12 torque converter has enough of a recess to clear the crank flange without binding, but they need to make a special pilot bushing to adapt the M-12 pilot stub to the crank. IIRC, the pilot bushing on the later cranks sits deeper in the flange than on the older cranks, so they'll need to calculate the height difference and make the new bushing that much longer. Or they could take a grinder and grind the flange off the crank!Tongue

MC - You'd need to determine if the mounting areas on the 727 flexplate are the same height as the M-12 plate. I don't think they are. It might set the converter too deep into the pump.


Edited by XJ-001 - Jul/20/2007 at 5:01pm
1970 AMX 390 4spd

1970 Javelin 390 Auto (Project)

2002 Grand Cherokee Overland Edition

2002 Olds Intrigue (The Other Orphan)

Bloomington, MN
Back to Top
74Bubblefender View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jun/29/2007
Location: The AMC form
Status: Offline
Points: 2589
Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Jul/20/2007 at 7:36pm
Here is what I did. I made a steel insert for the back of the crank( slight press fit). I made a .753" hole in the insert for the M12 torque converter spud. I then took the original 1971 401 flexplate and machined out the center to match the later model crank. It went together beautifully! I have pics and will post them later!
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
Back to Top
348AMX View Drop Down
AMC Addicted
AMC Addicted


Joined: Jul/03/2007
Location: Massachusetts
Status: Offline
Points: 4165
Post Options Post Options   Thanks (0) Thanks(0)   Quote 348AMX Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2007 at 12:20am
Originally posted by 74Bubblefender 74Bubblefender wrote:

Here is what I did. I made a steel insert for the back of the crank( slight press fit). I made a .753" hole in the insert for the M12 torque converter spud. I then took the original 1971 401 flexplate and machined out the center to match the later model crank. It went together beautifully! I have pics and will post them later!
 
 While your in there you might consider upgrading the torque converter. The stock M12 depending on your engine combo gears and weight in most stock AMC cars anyway had a really low stall, like 1300 RPM, Continental converters has been making high stall AMC Borg warner Automatic converters for years. www.ctconverters.com.
Back to Top
74Bubblefender View Drop Down
AMC Addicted
AMC Addicted
Avatar
Charter Member

Joined: Jun/29/2007
Location: The AMC form
Status: Offline
Points: 2589
Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Jul/21/2007 at 1:05am
:) Nice!....7 hours too late but nice!
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
Back to Top
 Post Reply Post Reply
  Share Topic   

Forum Jump Forum Permissions View Drop Down

Forum Software by Web Wiz Forums® version 12.03
Copyright ©2001-2019 Web Wiz Ltd.

This page was generated in 0.156 seconds.
All content of this site Copyright © 2018 TheAMCForum unless otherwise noted, all rights reserved.
PROBLEMS LOGGING IN or REGISTERING:
If you have problems logging in or registering, then please contact a Moderator or