Rebuilt A998 - No upshift/only 1st gear

-
O

olei

Well-Known Member
Joined
Jan 3, 2015
Messages
88
Reaction score
54
Location
Norway
Hi all,

I have just done my first automatic transmission overhaul, and I seem to have messed up. :) The transmission is a A998 from my ´88 Dodge Dakota (electric controller lockup).

I used the performance rebuild kit (teflon seals for reaction shaft) from Oregon Performance transmission, along with a Sonnax servo piston and Transgo TF1 kit.

My problem:
I only have first gear, and it won´t upshift even if I go to 2nd. 1st gear works well in all gears (drive, 2nd and 1st).
It goes in and out of gear (from Park to Reverse and drive) better than ever, it just won´t upshift from first. I did one run where I gave it some revs, and when I went off the throttle and back on, I might have felt like it would have been in neutral for a second, before it was back in first gear. It pulls strong in first gear.

I have the throttle valve lever set to be at mechanical end stop when I have full throttle.

So, where do I start? I do have a gauge to check pressures. :happy1:
 
..........Had u checked the governor when u rebuilt it........pull ur kd linkage all the way forward and see if it shifts..........kim.......
 
I didn´t notice any issues with the governor when I had it disassembled.

I have Lokar kickdown cable, I can try to loosen it up.
 
pressure test the gov port. See if it registers as you run it up to 20mph. No pressure, gov is likely issue.
 
Try obvious things 1st. Fluid level-OK. Kick down adjustment-OK. Band adjustment can cause problem. As mentioned, pressure test. Check it at all ports & compare results with service manual. If OK there pull the pan & look for anything out of place. Band anchor strap, servo snap rings, band levers, loose valve body bolts/ screws. If you pull the valve body down check the servos for leaks with compressed air by blowing in through the pressure check port & looking for leaks(bubbles or hissing) around the seal rings. After that you probably gotta pull it back out & start tearing it back apart.
I hope this helps.
 
FredS said:
pressure test the gov port. See if it registers as you run it up to 20mph. No pressure, gov is likely issue.
Click to expand...
Will do!

Woods74 said:
Did you pressure test it before and after install?
Click to expand...
No, I did not.

Lonewolf3165 said:
Try obvious things 1st. Fluid level-OK. Kick down adjustment-OK. Band adjustment can cause problem. As mentioned, pressure test. Check it at all ports & compare results with service manual. If OK there pull the pan & look for anything out of place. Band anchor strap, servo snap rings, band levers, loose valve body bolts/ screws. If you pull the valve body down check the servos for leaks with compressed air by blowing in through the pressure check port & looking for leaks(bubbles or hissing) around the seal rings. After that you probably gotta pull it back out & start tearing it back apart.
I hope this helps.
Click to expand...
Fluid level is OK.
Band adjustment was done after rebuild, before the transmission went back into the car.


I will continue with pressure testing, thanks guys. :)
 
I got the governor pressure checked.

I don´t have a speedo at the moment (neither do I have a tacho in my instrument cluster). I had 0psi at idle, and the pressure gradually increased along with the speed and I stopped the test at 50psi.
 
I wired up a tachometer and did some more testing.

With selector in 1st gear at 1000rpm:
Line pressure was 32psi with throttle lever all the way forward, 80psi with throttle lever all the way rearward.
Rear servo pressure was 32psi with throttle lever all the way forward, 73 psi with throttle lever all the way rearward.

With selector in 2nd gear at 1000rpm:
Line pressure was 52psi with throttle lever all the way forward, 88psi with throttle lever all the way rearward.

With selector in Drive at 1600rpm:
Line pressure was 55psi with throttle lever all the way forward, 90psi with throttle lever all the way rearward.

With selector in Reverse at 1600rpm:
Rear servo pressure was 150psi with throttle lever all the way forward. When I pulled the throttle lever rearwards the pressure peaked to 160psi but dropped and stabilized at 150psi.

So, what´s my next step?
 
Guys,

I pulled the pan and valve body. I performed a air pressure tests, and here are the results: [ame="https://www.youtube.com/watch?v=r4QdFDv2EEg"]A904 - YouTube[/ame]
rear servo - ok
front servo - minor leakage (acceptable?)
rear clutch - minor leakage (acceptable?)
front clutch - massive leak!

I did have concerns regarding some leakage applying air pressure to the front clutch when I tested it on the bench before going in the car, but it was a lot less than now. After the bench test I disassembled it again, all looked good, reassembled again, and got the same results doing the air pressure test. I took a chance to use it, and failed!

Now, is there any specific seal/ring kit I should go for? What about my rear clutch/front servo leakage, is it acceptable?

Thanks!
 
On the massive leak, do you hear the clutch engage or just hear air?

It' hard to tell over the internet what minor and massive are to you.
 
I believe I can hear the clutch engage slowly. Possibly the teflon seals leaking?

Based on my issues with no upshift, do you believe my problem could be something else?
 
olei said:
I believe I can hear the clutch engage slowly. Possibly the teflon seals leaking?

Based on my issues with no upshift, do you believe my problem could be something else?
Click to expand...

Sounds like it very well could be the Teflon rings, as it is super easy to cut them going together.
I grease (assy lube) pack the heck out of the ring grooves and then press the rings down into them so they are basically glued in.
I have even bent the ends before putting them in the groove so the tapered ends don't stick up.

As far as that causing a no shift I don't remember, sorry.
I do know that a loss of fluid pressure in the circuit can definitely cause shift issue's though.
 
TrailBeast said:
Sounds like it very well could be the Teflon rings, as it is super easy to cut them going together.
I grease (assy lube) pack the heck out of the ring grooves and then press the rings down into them so they are basically glued in.
I have even bent the ends before putting them in the groove so the tapered ends don't stick up.

As far as that causing a no shift I don't remember, sorry.
I do know that a loss of fluid pressure in the circuit can definitely cause shift issue's though.
Click to expand...
Thanks for your reply.

The ATSG manual says that both a faulty front clutch and worn/broken reaction shaft support seals can result in no upshift.

Are teflon seals still prefered compared to the steel ones? Who sells the steel type?

What do you think about the hydraulic pressure test results?
 
olei said:
Thanks for your reply.

The ATSG manual says that both a faulty front clutch and worn/broken reaction shaft support seals can result in no upshift.

Are teflon seals still prefered compared to the steel ones? Who sells the steel type?

What do you think about the hydraulic pressure test results?
Click to expand...

When that front clutch engages you should hear a definite "Thunk" (not "I think I can hear it")

I have been out of the trans business so long I can't really comment on the pressure test other than it seems reasonable (can't get specific)

The one thing I always disliked about using Teflon was that it wears the steel and iron parts worse than metal rings.
Other than that I can't really argue that they work fine, just never liked the idea I guess.

Try www.transpartsonline.com and see what you come up with.
(they have really good prices also)
 
TrailBeast said:
When that front clutch engages you should hear a definite "Thunk" (not "I think I can hear it")

I have been out of the trans business so long I can't really comment on the pressure test other than it seems reasonable (can't get specific)

The one thing I always disliked about using Teflon was that it wears the steel and iron parts worse than metal rings.
Other than that I can't really argue that they work fine, just never liked the idea I guess.

Try www.transpartsonline.com and see what you come up with.
(they have really good prices also)
Click to expand...
Shouldn´t I have seen a increase for the rear servo pressure in reverse, when I pulled the throttle lever?
 
Your governor pressure sounds ok. Rear servo pressure is not affected by the throttle lever. It's at max all the time, which if it was only 160 that's pretty low. I listened to the air pressure test and over the internet it didn't sound like a massive leak to me. I've noticed that teflon rings don't seem too seal all that great when doing the air pressure test. IMO it sounded normal for having teflon rings. Even if the front clutch wasn't engaging I believe it would shift into 2nd gear as that is controlled by the front band and that servo applied good. Did you have the valve body all apart? If so is there any possibility that you could have got a couple springs switched around? I remember a couple yrs. back a fellow did that with the 1-2 shift valve spring and the torque converter clutch spring and it wouldn't shift out of first cause the TCC spring is a lot stiffer. If you didn't take the valve body all apart to clean it good there's a possibility that a piece of trash has the 1-2 shift valve stuck.
 
fishy68 said:
Your governor pressure sounds ok. Rear servo pressure is not affected by the throttle lever. It's at max all the time, which if it was only 160 that's pretty low.
Click to expand...
Thanks for your reply.

The ATSG manual says: "Rear servo pressure should read 145 to 175 psi with throttle lever forward and increase gradually to 230-280 psi as throttle lever is moved rearward."

If this is not correct and the rear servo pressure should be stable, what should it be?

I listened to the air pressure test and over the internet it didn't sound like a massive leak to me. I've noticed that teflon rings don't seem too seal all that great when doing the air pressure test. IMO it sounded normal for having teflon rings. Even if the front clutch wasn't engaging I believe it would shift into 2nd gear as that is controlled by the front band and that servo applied good. Did you have the valve body all apart? If so is there any possibility that you could have got a couple springs switched around? I remember a couple yrs. back a fellow did that with the 1-2 shift valve spring and the torque converter clutch spring and it wouldn't shift out of first cause the TCC spring is a lot stiffer. If you didn't take the valve body all apart to clean it good there's a possibility that a piece of trash has the 1-2 shift valve stuck.
Click to expand...
I did have the valve body apart since I also installed the TF1 kit. I will take it apart and double check everything.
 
IIRC the throttle pressure spring and the 1-2 shift spring can get swapped very easily.

Don't take that as gospel, but I do remember something about the springs looking real close to the same but having different pressures.
 
With the selector in Reverse your gauge will read the maximum pressure that the pump can produce, regardless of the TV as reverse is unregulated pressure. The pump usually puts out pressure well in excess of 230 psi. But no circuit requires this much pressure to operate. This reverse test just tells you if the pump is half-way decent.Yours seems low, but not dead.
BTW, nice video! Good work.
The servos are popping nicely, and I can clearly hear the Fwd clutch, feeding it's air pressure back through the apply hole after you released the pressure. Besides, if it was bad, you wouldn't have any forward gears at all,including low. On the roadtest;when you backed off and it felt like the tranny hit neutral, this indicates that the tranny was trying to hit second, and momentarily responded to governor pressure, by releasing the low servo.So it points to the VB.
If you had the VB apart I have some ideas; in addition to what has already been posted.
 
Thank you both.

I will see if I can get the valve body disassembled and inspected today.

The oil pump is new, and the clearance is within specs.
 
If the pump is "NEW", and in spec,then the low pressure points back to the VB and the mixing up of springs.
Waitaminute, that's not right. In reverse the pump runs wide open. At 150 your pressure is some 30% down.
Hmmmmmmmmmmmmmmmmmmm
Ok I checked my 69 fsm. There is a high-pressure relief system. I believe it has a 3/8 checkball . If someone accidently installed a 5/16 ball there,(as all the other balls are)it could effectively show up as a leak, and ensuing low pressure.If you do find a small ball there, I guess you would have to search for where the bigger ball is.

I reviewed post #9, the pressure post, and I did not see a report on governor pressure. So if gov pressure is not reaching the shift valves, there can be no shifts, with the selector lever in Drive. And with the TF-II, you still cannot have manual-second until gov pressure climbs to line-pressure.
So I guess I would be chasing that circuit down.If you did report on gov pressure and it fell in spec,but I missed it, then I would be chasing the 1-2 shift valve and it's associated spring.
FWIW: if the accumulator piston or bore was cracked, the band apply pressure could all leak away before it ever got to the KD servo.
 
Update.

I checked the valve body, and I found the cause. I somehow had the 1-2 shift valve installed the wrong way (I bet that´s the first time you´ve heard someone do that!).

I flipped the 1-2 shift valve and reinstalled the valve body. I did a short test run today, and it shifts through all gears (though a bit firm on 2-3 shift, and a bit sensitive kickdown/downshift).

I hope my mistake didn´t do any damage to any other components. I´m planning to redo the rear servo pressure test to see if the 1-2 shift valve affected this.

Sorry for wasting your time, and thanks for getting me in the right direction! :)
 
I thought of that, but when I checked the FSM, I looked and didn't see it as being possible.
Goodonya. No worries. When you learn,and are not too proud to report back, then we learn. And I, for one, am here to learn and share what I've learned.
You want me to tell you about the spinning earth theory?
 
I rechecked the rear servo pressure again, with engine running at 1600rpm and gear selector in Reverse. I got 150psi with the throttle lever all the way forward, and 260psi with the throttle lever all the way rearward.

It´s working! Thanks again all.
 
You must log in or register to reply here.
-

Back
Top