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A904 No Forward Gears
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Author:  Chris [ Wed Jun 26, 2002 8:51 am ]
Post subject:  A904 No Forward Gears
I just finished a 904 rebuld and have an interesting problem. I have no forward gears! I have park, reverse, and neutral - but no drive, 2 or 1. I am going to take some pressure readings soon (hopefully this weekend) but until then - anyone have any suggestions? The linkage seems to be in the right place... Does anyone know of any websites relating to the Tech's of the 904? I'm working on a 65 - any help would be appreciated.

cbrunner@nexant.com
Author:  Dobie [ Wed Jun 26, 2002 11:17 am ]
Post subject:  Re: A904 No Forward Gears
Got ya beat- my '64 904 has everything but 3rd (drive). No upshift past 2nd. Similar problems?

dobie79423@yahoo.com
Author:  Chris [ Wed Jun 26, 2002 11:20 am ]
Post subject:  Re: A904 No Forward Gears
Quote:
: Got ya beat- my '64 904 has everything but 3rd
: (drive). No upshift past 2nd. Similar
: problems?


That sounds like a linkage issue. I'd check the controll linkage first, make sure it's all adjusted properly - if so then move on to check the bands in the tranny - if those are ok then it's time to dig in deeper.

Chris

cbrunner@nexant.com
Author:  Charlie Schmid [ Wed Jun 26, 2002 12:05 pm ]
Post subject:  Re: A904 No Forward Gears *PIC*
Quote:
: I just finished a 904 rebuld and have an
: interesting problem. I have no forward
: gears! I have park, reverse, and neutral -
: but no drive, 2 or 1. I am going to take
: some pressure readings soon (hopefully this
: weekend) but until then - anyone have any
: suggestions? The linkage seems to be in the
: right place... Does anyone know of any
: websites relating to the Tech's of the 904?
: I'm working on a 65 - any help would be
: appreciated.


There are 2 clutch packs in the trans. one is for all forward gears, the other for high gear,only. It sounds like the forward clutch pack is not engaging. It is possible to remove the valve body, and apply air pressure the the correct port,on the trans case. if you hear a solid "thumk", it is applying correctly. If you hear a lot of air leakage, it could be a broken seal ring, or bad lip seal. The checks can all be done without removeing the trans, the repairs, different story. The factory service manual, or trans manual, it will show you the correct port to apply air pressure. (see below)

Charrlie_S

Image
flturbo6@aol.com
Author:  Chris [ Wed Jun 26, 2002 12:38 pm ]
Post subject:  Re: A904 No Forward Gears
Quote:
: There are 2 clutch packs in the trans. one is
: for all forward gears, the other for high
: gear,only. It sounds like the forward clutch
: pack is not engaging. It is possible to
: remove the valve body, and apply air
: pressure the the correct port,on the trans
: case. if you hear a solid "thumk",
: it is applying correctly. If you hear a lot
: of air leakage, it could be a broken seal
: ring, or bad lip seal. The checks can all be
: done without removeing the trans, the
: repairs, different story. If you have a
: factory service manual, or trans manual, it
: will show you the correct port to apply air.
: My scanner is not working.
:
: Charrlie_S


So even if reverse is working (and rather well I might add) it means that the clutch packs may not be installed properly? I just put the darn things in and that's not really news I wanted to hear (I was hoping more for too much or too little hydrolic pressure).

Chris


cbrunner@nexant.com
Author:  bud L. [ Wed Jun 26, 2002 4:35 pm ]
Post subject:  Re: A904 No Forward Gears
I agree with Charlie, sounds like high gear clutch is gone. That's a pretty common symptom/diagnosis.
For Chris, it's more than that I fear. Did you take apart the valve body? Like Charlie suggested, first check the clutch with air pressure. If that checks out, look to the valve body.
Quote:
:
: That sounds like a linkage issue. I'd check the
: controll linkage first, make sure it's all
: adjusted properly - if so then move on to
: check the bands in the tranny - if those are
: ok then it's time to dig in deeper.
:
: Chris



fglmopar@aol.com
Author:  FOPAR [ Wed Jun 26, 2002 7:08 pm ]
Post subject:  Re: A904 No Forward Gears
Quote:
: I just finished a 904 rebuld and have an
: interesting problem. I have no forward
: gears! I have park, reverse, and neutral -
: but no drive, 2 or 1. I am going to take
: some pressure readings soon (hopefully this
: weekend) but until then - anyone have any
: suggestions? The linkage seems to be in the
: right place... Does anyone know of any
: websites relating to the Tech's of the 904?
: I'm working on a 65 - any help would be
: appreciated.


Had the same thing when I rebuilt my 904.
Hate to tell you this take the trans out and back apart. The Piston (the one with the seals) in first, then the spring plate (with the ears) against the piston, the spring plate goes with the raised center fingers against the small raised center part, so that it has something to push against. Look at the way the piston will pack the clutchpack using the spring plate.
I only thought I could do something so simple, shows that you must always think about how it works. Good luck

dbjerklund@hotmail.com
Author:  Chris [ Mon Jul 01, 2002 2:05 pm ]
Post subject:  Re: A904 No Forward Gears
I tried the air pressure tests outlined below (and also checked line pressures). The trans passed air pressure tests, and line pressure at 1k rpm was 90PSI. While doing the air pressure tests, I found the last one who was in the trans before me put some kind of restrictor plug in the forward clutch pack hole - maybe it just wasn't getting enough fluid to engage tightly (the tires would spin, just not move the car). I'm going to fix the line pressure and put everything back together tonight.

I'll let you all know how it goes.

Chris
Quote:
:
: There are 2 clutch packs in the trans. one is
: for all forward gears, the other for high
: gear,only. It sounds like the forward clutch
: pack is not engaging. It is possible to
: remove the valve body, and apply air
: pressure the the correct port,on the trans
: case. if you hear a solid "thumk",
: it is applying correctly. If you hear a lot
: of air leakage, it could be a broken seal
: ring, or bad lip seal. The checks can all be
: done without removeing the trans, the
: repairs, different story. The factory
: service manual, or trans manual, it will
: show you the correct port to apply air
: pressure. (see below)
:
: Charrlie_S



cbrunner@nexant.com
Author:  bud L. [ Mon Jul 01, 2002 4:09 pm ]
Post subject:  Re: A904 No Forward Gears
Quote:
: I tried the air pressure tests outlined below
: (and also checked line pressures). The trans
: passed air pressure tests, and line pressure
: at 1k rpm was 90PSI. While doing the air
: pressure tests, I found the last one who was
: in the trans before me put some kind of
: restrictor plug in the forward clutch pack
: hole - maybe it just wasn't getting enough
: fluid to engage tightly (the tires would
: spin, just not move the car). I'm going to
: fix the line pressure and put everything
: back together tonight.
:
: I'll let you all know how it goes.
: Chris


I am no auto trans expert, but it sounds like you have the remnants of a trans shift kit installed there. I believe they often ask you to drill the separator plate and add/subtract/change check balls in the valve body, also. So you might want to check that out, too. I really don't think those trans kits are necessary if the line pressure is increased and everything else is right.
Does anybody have some recent firsthand experience in this?



fglmopar@aol.com
Author:  Doctor Dodge (Doug Dutra) [ Tue Jul 02, 2002 8:35 pm ]
Post subject:  Re: A904 Shift Kits
Quote:
: I am no auto trans expert, but it sounds like
: you have the remnants of a trans shift kit
: installed there. I believe they often ask
: you to drill the separator plate and
: add/subtract/change check balls in the valve
: body, also. So you might want to check that
: out, too. I really don't think those trans
: kits are necessary if the line pressure is
: increased and everything else is right.
: Does anybody have some recent firsthand
: experience in this?


Shift kits can firm-up the shifts but you need to follow the instructions and have a good working trans to start.

If you ever suspect the valvebody has been "kitted" and there are shifting problems, it is best to swap back to an stock valvebody for a baseline then try a different kit if you need firmer shifts.
DD
Author:  CRANKSNAPPER [ Fri Nov 01, 2019 3:22 pm ]
Post subject:  Re: A904 No Forward Gears
GOOD CALL Charlie Schmid !

AN ASIDE: THE A904 OUTPUT SHAFT BEARING IS OBSOLETE (FAG 2A836) I.D. 1.1645" [/u] O.D. 2.44" W. .63'. SNAPRING

ALTERNATIVE WORKS WELL: (6206) NO SIDE SEALS I.D. 1.181" O.D. 2.44" W. .63" SNAPRING

https://www.ebay.com/itm/1-pc-6206-open ... 8122!US!-1

YOU CUT 3.5" LENGTH OF .008" FEELER GAGE AND SLIDE IT BETWEEN SHAFT & I.D.

https://www.ebay.com/itm/008-Thick-1-2- ... SwMmBVpBc2

N-O-W EMERSON BEARING HAS 4 ORIGINAL BEARINGS LEFT. I SCOURED WORLDWIDE AND FOUND SOME FROM GERMANY (FAG 2A836's)…….

BUT I LIKE MY ALTERNATIVE BETTER...….$9...….INSTEAD OF $54. SINCE I BUILD RACE A904's THIS IS A GOOD SETUP.


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