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904 front drum differences 71-72 solved, new problems #2011914
02/14/16 06:14 PM
02/14/16 06:14 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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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 03:42 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
Re: 904 front drum differences 71-72 [Re: herkamer] #2011938
02/14/16 06:51 PM
02/14/16 06:51 PM
Joined: Jan 2003
Posts: 21,651
Rio Linda, CA
John_Kunkel Offline
Much ado about nothing
John_Kunkel  Offline
Much ado about nothing

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Rio Linda, CA

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.


I'm supposed to respect my elders, but its getting harder and harder for me to find one now.
Re: 904 front drum differences 71-72 [Re: herkamer] #2012039
02/14/16 09:15 PM
02/14/16 09:15 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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Perfect, thank you!


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
Re: 904 front drum differences 71-72 [Re: herkamer] #2012219
02/15/16 01:38 AM
02/15/16 01:38 AM
Joined: Jan 2003
Posts: 9,800
las vegas
70AARcuda Offline
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las vegas
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)
Re: 904 front drum differences 71-72 [Re: herkamer] #2015009
02/18/16 09:47 PM
02/18/16 09:47 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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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

20160218_173410.jpg

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
Re: 904 front drum differences 71-72 [Re: herkamer] #2015010
02/18/16 09:48 PM
02/18/16 09:48 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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Pic 2

20160218_173423.jpg

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
Re: 904 front drum differences 71-72 [Re: herkamer] #2015013
02/18/16 09:50 PM
02/18/16 09:50 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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Pic 3 with both drums

20160218_173617.jpg

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
Re: 904 front drum differences 71-72 [Re: herkamer] #2015165
02/19/16 12:35 AM
02/19/16 12:35 AM
Joined: Apr 2011
Posts: 280
GEORGIA
barracuda7199 Offline
enthusiast
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GEORGIA
Is the groove for the lip seal the same? Can you compare the seals out of both drums and piston?

Re: 904 front drum differences 71-72 [Re: herkamer] #2015211
02/19/16 01:56 AM
02/19/16 01:56 AM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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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
Re: 904 front drum differences 71-72 [Re: herkamer] #2016393
02/20/16 11:40 PM
02/20/16 11:40 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
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herkamer  Offline OP
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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
Re: 904 front drum differences 71-72 [Re: herkamer] #2016631
02/21/16 03:01 PM
02/21/16 03:01 PM
Joined: Oct 2005
Posts: 1,305
Lakewood, Colorado
herkamer Offline OP
pro stock
herkamer  Offline OP
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Joined: Oct 2005
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Lakewood, Colorado
bump

Anyone? Loctite bearing sealant? Can I stake it in?







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