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Date: Wed, 02 Nov 2005 07:21:45 -0500 From: Malt_Hound <""Malt_Hound\"nospamm-me not*yahoo.com"> Subject: Re: Rough Shifting Automatic Trans '98 NG900S
ShazWozza wrote: > Malt_Hound wrote: > > > >>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... > > > 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. That's encouraging. > > 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. > 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? -- -Fred W
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