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Feeling detent is misleading Posted by Cmyles [Email]  (#1126) [Profile/Gallery]
(more from Cmyles) on Tue, 3 May 2011 15:08:48
In Reply to: When it was misbehaving..., Jeff Cullen, Tue, 3 May 2011 12:11:22 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Jeff,
That "braking" effect that occurs when the unit tries to upshift from first to second is most likely caused by application of the rear band when it shouldn't be. That wouldn't affect first in "D" except that you'd have traction (engine braking) that you won't notice unless you let off the gas and decelerate before the 1-2 upshift occurs. Then when the unit tries to upshift to second by applying the front band it will lock up and feel as if the brakes have been applied hard.
That can result from sticky control valves or a maladjusted shift control cable. Feeling the detent in the shifter tells you nothing useful about the state of adjustment of the cable. Saab C900s have detent at both the shift lever and manual valve (good idea huh?) and you are feeling the detent at the shift lever. If the two detents are not synchronized the shift lever detent will over-ride the manual valve detent (you'll never feel it) and the manual valve will be positioned between adjacent shift points. You can imagine the confusion that causes to the control valves and the ensuing misapplication of the friction clutches. That will eventually destroy the planetary gears, usually while cruising at high speed. So check the adjustment of that cable. The procedure is in the Saab 4.2 manual, maybe in the Bentley (I don't have a Bentley).
If the cable is adjusted right then the next best scenario would be that the control valves are just not moving smartly due to accumulated gunk and flushing and filling will hopefully get that corrected. It may be necessary to remove the valve body, disassemble it and clean it thoroughly.
There's really no good scenario after that. Any other cause (that I can imagine) will require that the unit be removed and rebuilt. Of course we've ruled out any cause external to the transmission because the car coasts OK and runs OK until it tries to upshift from first and when it does upshift it runs good in second and third (right?).
posted by 198.233....
, Tue, 3 May 2011 09:36:03, Tue, 3 May 2011 15:08:48 <-- Viewing This Message, Tue, 3 May 2011 15:10:31, Tue, 3 May 2011 15:34:57
, Tue, 3 May 2011 18:05:31, Wed, 4 May 2011 10:26:43
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