jeep 904 auto issues anyone want to take a crack at this please

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sparkie573

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Hi all. I thought I would try with everyone here before I got to digging into this real deep.

I have an 89 YJ wrangler with the 4.2 6 cyl and 904 auto, dana 30,ford rear 8.8 , and 35 inch tires... I am having an issue with the trans that I am having problems diagnosing. it is basically a stock 904 with a small shft kit and the transfer case has a slip yoke eliminator kit. other than that the drivetrain is pretty stock except for an aftermarket floor shifter....Any help would be great.
So, when you put it into drive or 2nd and drive around it is good. except that you can tell that it never uses 1st gear. when you pull up to a stop and then go, it starts off in 2nd and then goes to 3rd like normal and it also kicks down to 2nd fine. The problem is if I manually put the shifter into first, it feels like it is slightly pushing against something, it doesn't make any odd noises or anything else weird that I know of, its just that it seems that you have to use more throttle than you should and it feels again like I said that it is pushing against something or that something is holding it back or is not moving freely I 1st gear. then you put it back in drive or 2nd and it is fine again except it never uses first gear. I have driven it this way for a bit and not had any other issues but I may be putting it up for sale shortly and I'd really like to get this fixed. Again any input on helping get this diagnosed would be great.
Thanks again all.
 
I haven't at all. I haven't been driving the jeep to long. You think That would cause my problem? Any insight on that?
Thanks.
 
It's worth a shot, toss a new filter and adjust the front band while your at it. You've got to start with the easy stuff man. Also, make sure your linkage, and kickdown adjustment is good too.
 
-Hows reverse?Reverse and manual low share most of the same circuit.If reverse works perfect, then the L/R band adjustment is likely, fine.
-If the 2/3 shift timing is normal, then the throttle pressure, and the line pressure, is probably fine.
-If the tranny doesnt start in low, with drive selected; Ima guessing the KD band is not releasing. Then when you manually select low, you would feel that band dragging.
It could be a hydraulic issue or a mechanical issue. Since drive works ok, Ima thinking its a hydraulic issue. If it was mechanical, it would be dragging in drive as well, and that would make the engine sluggish, and mess up the 2-3 shift. So Ima going with a problem in the valve-body.I'm also guessing its been this way ever since the shift-kit was installed.

Unless the accumulator is broken. A broken accumulator would allow line pressure to sneak into the KD servo and apply that band.And so would missing hook rings, but I dont think broken hook-rings would do it, and the piston cant come up far enough to get out of the bores, and if it had come right out, second wouldnt work.But as long as its shuttling back and forth,it only affects first.
 
An 89 with a 904? Are you sure? More likely it is at least an A998 and possibly and probably an A999.

At any rate, 1st and reverse use the same stuff. How is reverse? Anything strange there?
 
Good call Rob, I was going to say A999...that's what my old roommate's 89 YJ had.

I'm with AJ on this one too--does reverse work? With my wife's car, one of the pistons was stuck in the valve body and it kept the trans from dropping down into 1st...it would do the same thing in reverse...felt like I was using a transbrake. Unstick the piston and it worked fine. After some test drives, I figured out it only happened when it would downshift under full throttle from OD to 2nd. If I left OD locked out or disabled it while cruising, it wouldn't do it anymore. Obviously the circuits are different and an A999 doesn't technically have OD (lock up), but you need to get in there and find out if you have some broken or stuck parts...
 
AJ/FormS said:
So Ima going with a problem in the valve-body.I'm also guessing its been this way ever since the shift-kit was installed.

Unless the accumulator is broken. A broken accumulator would allow line pressure to sneak into the KD servo and apply that band.
Click to expand...

You think maybe a piston installed upside down or can one do that?
 
Thanks all, I'll start digging into it. Yes, reverse seems to work fine and 1 to 2 shift seems ok also.
 
And I'm pretty sure it's a 904. When I got it and changed the filter and pan gasket I took them to the parts store. "A reputable one". And matched up the gasket and filter to a 904 which is what it also stated in his book.. What would be any difference in the other ones? I think I'll unhook the shifter at the trans and have my buddy manually put it in low to see if it still does it, that would rule out the mechanical part correct?
 
sparkie573 said:
And I'm pretty sure it's a 904. When I got it and changed the filter and pan gasket I took them to the parts store. "A reputable one". And matched up the gasket and filter to a 904 which is what it also stated in his book.. What would be any difference in the other ones? I think I'll unhook the shifter at the trans and have my buddy manually put it in low to see if it still does it, that would rule out the mechanical part correct?
Click to expand...

904, 998, and 999 all use the same filter and gasket and look identical in nearly every aspect. It's just that the 998 and 999 can be a lockup and have a lower gearset internally and hold more clutch plates.

IMO it's either a broken spring on the 1-2 shift valve (in the valve body), a governor problem, or very likely broken/leaking accumulator ring(s) like A/J mentioned. The only reason I can think that it'd start in second in drive and drag when you put it in manual low is a issue with the accumulator circuit leaking and applying the front band. Unhooking the shifter will not rule out anything cause a mechanical problem will be inside the trans.
 
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