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That NOS 904 on eBay
https://slantsix.org/forum/viewtopic.php?t=40456		 Page 2 of 2
Author:  Dave95693 [ Sun Jun 06, 2010 7:30 am ]
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By the way twali40....not sure what a heavy duty 904 is but if the one you have is a lock up, I can't imagine going wrong with the EBAY unit. But I do suggest that you research until your satisfied you'll be ok.
Author:  twali40 [ Sun Jun 06, 2010 12:15 pm ]
Post subject: 
Thanks for the replies (and I apologies for monopolizing the thread). One last comment: Does anyone know what "heavy duty" means on the 904 tranny out of a 78' Volare? I have looked around and I have not gotten any definitive results. Is it number of clutches, gearing (ratio or material), general materials (e.g. bushings, washers, gaskets)? The only external difference I have found is the mounting for the tail housing.

Thanks again,
Tom
Author:  wjajr [ Sun Jun 06, 2010 2:00 pm ]
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twali40,

I think the HD 904 has stronger guts, or 4 instead of 3 clutch plates & discs like a V8 build, that would be used for cop & taxi duty, or part of a tow package.


When ordering parts, call and ask about HD vs. standard duty. Have the transmission ID numbers handy when you call.
Author:  SlantSixDan [ Sun Jun 06, 2010 2:44 pm ]
Post subject: 
Quote:
Thanks for the replies (and I apologies for monopolizing the thread). One last comment: Does anyone know what "heavy duty" means on the 904 tranny out of a 78' Volare?
Clutch plate count (one additional) and torque converter stall speed. Everything else (gearing, gaskets, etc.) is the same.
Author:  twali40 [ Sat Jul 03, 2010 9:55 pm ]
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Okay, I bought the tranny off of ebay. It does look pretty good. The question I have is what is the tell tale on whether it is a lock-up or not? I thought that the input shaft on the lock-up had a step on it. The tranny I received does not have a step. I think that it has 23 splines.
I looked up the stamp number and it looks like it was manufactured somewhere between 1981-1983 and that it is a heavy duty trans.

Is there a way to check any of this without pulling the transmission apart or removing the valve body?

I am not tied to one or the other. I like the idea of getting better mpg. I really just want to make sure I get the right torque converter. I have also been waffling on putting in a Transgo TF2.

Thanks,
Tom[/img]
Author:  Pierre [ Sat Jul 03, 2010 10:04 pm ]
Post subject: 
The center input shaft of a lockup is hollow so fluid can be pumped through it. Non-lockup shaft is solid.

On a lockup the inner and outer shaft have different tooth count, off by one. Don't quote me on it but I believe it was 22/23, whereas a non lockup was 22/22.
Author:  twali40 [ Sun Jul 04, 2010 12:56 pm ]
Post subject: 
I believe that the inner shaft has 27 splines.
Attached pic of the ebay transmission's input shaft
http://image85.webshots.com/85/6/88/91/ ... wHO_fs.jpg

Image

Pic of what I thought the difference was between lock-up and non lock-up.
Image

http://image73.webshots.com/173/9/43/16 ... NNB_fs.jpg

The shaft is solid and the spline count 27. Therefore, I am going with a non lock-up converter...can i get a confirmation?
Is there anything that I should be concerned about here? My plan is to get a new converter, adjust the bands, swap the filter and pour in some ATF 4+.
Thanks for the help,
Tom
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