Rough Shifting Automatic Trans '98 NG900S

I have a 98 900S coupe that has an automatic transmission. I purchased the car used this past summer as a car for my daughter to drive back and forth to school in. She has a 45 minute urban commute each day from where she lives to her classes.

I got the car with just a little over 90k on it and it is in overall outstanding condition. I went through it entirely upon receipt and performed all the regular major service items (since I had no idea when they had last been done) including draining and refilling the transmission. The condition of the fluid was what would be expected if it had not been done in a while, but it did not have any serious metal filings or chunks in it. The drain and fill of the ATF was in an attempt to smooth the shifting out a bit.

She racked up 5k miles on it so I already did another oil and filter change and went ahead and changed the ATF again too. Still no big improvement.

From the time that I first drove the car I noticed that the transmission has a habit of shifting just a bit too hard into the next higher gear. It isn't horrible just something that concerns me a little. It does not always shift the same though. Sometimes it shifts just as you would expect and other times it's too hard. If I run it in "Sport" mode it seems to shift hard more often.

I'm just wondering if anyone has any similar experiences with the NG900 automatic transmission and what the outcome was. I'm also wondering if there are any decent additives that can be used in that transmission to smooth out the shifts. I've looked through trhe WIS and do not see anything as far as adjustments of Service Information Bulletins related to this unless I'm just missing it...

TIA,

Reply to
Malt_Hound
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Salutations:

On Tue, 01 Nov 2005 14:25:16 -0400, Malt_Hound not*yahoo.com">

Reply to
Dexter J

I also bought a NG900 for my daughter to drive, only I made the mistake of buying

the GM V6. The engine (if you call it an engine) is the reason I am selling it. However, I must say the automatic transmission has been flawless. I still prefer a C900 with a manual tranny and short shift kit, especially when it is teamed up with a Red Box turbo, but this is not the car for new driver.

Reply to
ma_twain

Fred one assumes knowing your posts that you have filled it correctly. At

90k the box if the car has been driven hard could be on the way out but I hope not. It could possibly be the tie up between the engine ECU and the gearbox ECU, as I believe the throttle is influenced whenever a gear change is made. Can you get a Saab specialist or automatic specialist to advise on this? Wish you luck. (Please advise outcome)
Reply to
John Hudson

Those ZF boxes are pretty good and are used in other car makes apart from GM Saabs. They should go for way longer than 90k without major problems.

Sounds like you might have trouble with the electric servo operated valves. Could just be varnish causing a valve to stick, or worse a broken or bodgy spring, or worn bore. You can damage the transmission pretty quickly operating it with faulty shifter valves.

Reply to
ShazWozza

I thought they were Aisin Warner on NG900's.Mine certainly is.

Reply to
John Hudson

Glad to hear it, and yes, received the shipping money by PP kust fine.

Reply to
Malt_Hound

Well, the good news is that it does not seem to be getting any worse. The bad news is that it does not seem to be getting any better even after 2 fluid changes.

Reply to
Malt_Hound

This is a 2.0 liter FPT. It's not so much the "new driver" syndrome. This daughter is 21 y/o and commuting to her internship (college). It's the route that she's driving that makes the auto box a good idea. Rush hour in the city anywhere in the Eastern US is gridlock.

But I must say that, having driven the car on the highway a bit, it is a very comfortable interstate cruiser as well.

Reply to
Malt_Hound

Thanks for the kind words. Yes, it is certainly filled to the right level. That was my hope initially, that the symptom was just low fluid level. I have even tried running it at different points on the dipstick within the "normal" range in attempt to see what it liked the best.

I am wont to bring it to a transmission shop as they usually give you the same diagnosis regardless of the actuals (rebuild). And I am boycotting the one SAAB specialist that I used to go to as he attempted to overcharge my daughter when I was away on business last year, even knowing that she was my daughter. Too bad for him.

I guess if the symptoms get at all worse I will have to find a new one (specialist, not car). In the meantime, I'll just be monitoring it closely.

Thanks,

Reply to
Malt_Hound

That's encouraging.

OK. That would be nice since those should be easy to replace in situ. But could you expound on how a sticky servo valve would cause the rough shifting? I am not really up on my automatic transmission theory, but I just figured the valves re-route the pressurized fluid through various circuits to affect the shift, and the shifting seems to happen at the right time(s), just not so smoothly when it does. To me, it feels as if the clutch(es) were a bit too tight, or not slipping enough.

Are there any diagnostics or tests one can run on those servo valves?

Reply to
Malt_Hound

You are correct - brain fart on my part dunno why ZF slipped out of the fingers. That same AW is also used some Toyotas.

The information about the valves is still the same.

Reply to
ShazWozza

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