odd trans shifting - PeachParts Mercedes-Benz Forum

mdisav · #1 01-09-2006, 11:36 PM

On my 87 300D only when I have the kickdown switch fully engaged it will shift 1st to 2nd fine(4900rpm) then shift from second to third(4900rpm), then immediately back to second and shift into third at 5100rpm. It will then stay in third and shift fine into fourth. This is all with the pedal to the floor and never lifting my foot off the kickdown switch. It is doing it every time like this only when the kick down switch is engaged.

It shifts fine in all gears when the switch is not engaged. It shifts properly in all other ways.

I have replaced the klima kickdown relay, kickdown switch, and over voltage protection relay. The kickdown cable is just slightly tighter than nuetral and looser or tighter does not change this symptom.

Any ideas? B2 piston? K1 spring kit?

It does take a little longer to go into drive and reverse than normal but not that long. This trans does have 299K plus and is all original. The fluid and filter has been changed recently and the level is correct.

Thanks for your ideas and suggestions!

Pete Burton · #2 01-10-2006, 12:36 AM

Full throttle upshift is adjustable on the valve body, left rear corner. Those shifts should occur at lower RPM.

mdisav · #3 01-10-2006, 08:37 AM

Thanks Pete, but why would it all of a sudden decide to shift back down into 2nd then right back into 3rd and then proceed to finish shifting as normal?
Will that adjustment lower the shift point and then eliminate this symptom? I have had the car for a year and has behaved flawlessly at those shift points.

Hatterasguy · #4 01-10-2006, 09:50 AM

4,900 rpm at WOT is about where a 603 should shift.

Pete Burton · #5 01-10-2006, 10:43 AM

Quote:

Originally Posted by mdisav

Thanks Pete, but why would it all of a sudden decide to shift back down into 2nd then right back into 3rd and then proceed to finish shifting as normal?
Will that adjustment lower the shift point and then eliminate this symptom? I have had the car for a year and has behaved flawlessly at those shift points.

perhaps your K1 clutch pack is worn. If you find that it operates OK at 2/3 throttle, you might get a lot more use out of that old transmission if you drive it that way. Hint, hint.

mdisav · #6 01-16-2006, 10:24 AM

So is the K1 clutch pack responsible for the 2 to 3 shift? It does shift nice and firm with no flaring. Any clues why it would behave this way once and when it shifts into third for the second time very firmly it keeps third and does not do it again? I unplugged the kick down switch for now. Since I have the full load adjusted on the pump and intercooler, it is not like I have much of a power loss without it. Although there is no substitute for that full throttle 1 to 2 scream and snap you back kickdowns. Thanks for you input.

Hatterasguy · #7 01-16-2006, 10:37 AM

I was reading my FSM the other day and it seems 5,150 is the max rpm for a 603. Go figure I guess our's shift early.