904 front drum differences 71-72 solved, new problems
#2011914
02/14/16 07:14 PM
02/14/16 07:14 PM
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Joined: Oct 2005
Posts: 1,305 Lakewood, Colorado
herkamer
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OP
pro stock
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Lakewood, Colorado
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Apparently I got a 72-up rebuild kit for my 71 904. Now it's open and non-returnable. Looks like the lip seals for the rear drum/piston are correct and went in just fine. Inner lip seal was the failure point last time, and I'll confirm when I can air test. That brings me to the front drum/piston/seals. Obviously this was a change between 71 and 72. Question is can I interchange a 72-up 4 clutch drum with no problems? Or do I need anything else? I have access to a bunch of used parts and there should be 72-up drums there.
This unit had previously been rebuilt so I can't assure that all the parts are the ones that came in it from the factory. Casting dates would lead me to believe they are correct.
Last edited by herkamer; 02/21/16 04:42 PM.
Matt 69 Dart Swinger 340 83 W350, Megasquirted with 46RH Old news: 72 Demon street/race mobile Latest: 70 Duster backhalf car and even more
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Re: 904 front drum differences 71-72
[Re: herkamer]
#2011938
02/14/16 07:51 PM
02/14/16 07:51 PM
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Joined: Jan 2003
Posts: 25,877 Rio Linda, CA
John_Kunkel
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 25,877
Rio Linda, CA
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Yes, '72 saw a change to the narrow lip seals in the front drum and, yes, you can install a '72-later drum in your '71.
The INTERNET, the MISinformation superhighway
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Re: 904 front drum differences 71-72
[Re: herkamer]
#2012219
02/15/16 02:38 AM
02/15/16 02:38 AM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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You can also buy the lip seals you need individually...
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: 904 front drum differences 71-72
[Re: herkamer]
#2015009
02/18/16 10:47 PM
02/18/16 10:47 PM
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Joined: Oct 2005
Posts: 1,305 Lakewood, Colorado
herkamer
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OP
pro stock
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Lakewood, Colorado
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Maybe I'm missing something. Got a drum assembly from my friends part stash. Took it apart and shows its a 79. Physically identical to the 71 parts with the 70 casting date. What's the possibility it is a newer setup? Pics attached for clarification. 71 unit is on the left in the pics
Matt 69 Dart Swinger 340 83 W350, Megasquirted with 46RH Old news: 72 Demon street/race mobile Latest: 70 Duster backhalf car and even more
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Re: 904 front drum differences 71-72
[Re: herkamer]
#2015211
02/19/16 02:56 AM
02/19/16 02:56 AM
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Joined: Oct 2005
Posts: 1,305 Lakewood, Colorado
herkamer
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Every dimension I mic'ed was the same. Lip groove is in the same place. The original seals looked the same.
Transmission build date is Jan 11, 1971. Not sure if this could have been a possible mid year change. And again I cannot 100% confirm those parts are original to the transmission, just that was in it when I took it apart. I don't want to burn this thing up again, it's getting too close to race season now.
Matt 69 Dart Swinger 340 83 W350, Megasquirted with 46RH Old news: 72 Demon street/race mobile Latest: 70 Duster backhalf car and even more
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Re: 904 front drum differences 71-72
[Re: herkamer]
#2016393
02/21/16 12:40 AM
02/21/16 12:40 AM
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Joined: Oct 2005
Posts: 1,305 Lakewood, Colorado
herkamer
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OP
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Lakewood, Colorado
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Guess it doesn't matter now, I upgraded to the later unit just in case.
So the next problem I am having is that I upgraded front pumps because the original reaction shaft bushing was loose. That ended up being part of the problem, it was the wrong year and had an extra hole. So I'm back to using the original if I can. New bushing fits in the reaction support ok, but it's not tight like I would expect it to be. What are my options besides finding a new pump?
Matt 69 Dart Swinger 340 83 W350, Megasquirted with 46RH Old news: 72 Demon street/race mobile Latest: 70 Duster backhalf car and even more
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