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-   -   downshifts (http://www.peachparts.com/shopforum/tech-help/6746-downshifts.html)

Marc 03-18-2000 10:34 AM

My 83' 500sl seems reluctant to downshift under power so, I've been reading the posts regarding this behavior. The car seems to shift from 4th to 3rd normally, if I peg the throttle I can feel the kickdown switch depress and I will get 3rd but, I never under any circumstances (except shifting it myself) get 2nd. I've even taken the carpeting and padding out to make sure this had no affect. I saw the post with this symptom that had a pinched wire to the switch, I can see the connection to the switch but that is all, the floor seems to be covered with a hard rubberized material, unless this is something that has deteriated. I also saw the post on the kickdown/Bowden cable, is this relevant to this car. Does it have a Bowden cable?. I don't think there is a transmission problem. I have the 107 CD, should I start digging?

TIA

Marc

stevebfl 03-18-2000 12:41 PM

Yes, your problem is in the adjustment of the control pressure cable ("bowden cable").

You are going to have to change the length of one piece of linkage about an 1/8in., probably.

With the air filter off, look down between the fuel distributor and the firewall. Move the throttle (engine off)and look for the cable (it will have an accordian shapped rubber boot where it comes from its housing). The adjustment is in a rod that pulls the lever that the cable is attached to. There will be a 7mm wrench size screw pinching the sliding link to a fixed position. Loosen the screw and shorten the link. It will be in proper adjustment when the cable starts moving when the throttle does. Don't be fooled by linkage movement. The key is the throttle and the cable (and the slack of the cable isn't apparent - hinden by the boot - take it loose and felt the spring tention of the cable). OR just shorten it too taste. Beware; all your shifts will be later, probably a good thing. If you were only getting kickdown downshifts you probably are shifting too early for good power all the time.


------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

Marc 03-18-2000 02:27 PM

Stevebfl:

Perfect! I made the adjustment as you described, now I do have the correct downshifts and it does stay in each gear longer. Much sportier feel all around.

Thanks again for your help.

Marc

Nick Jamal 03-18-2000 02:38 PM

Just out of curiosity, does the 103 engine/transmission have a similar adjustment? The car is a 300E.

stevebfl 03-18-2000 05:45 PM


Just out of curiosity, does the 103 engine/transmission have a similar adjustment? The car is a 300E.

As it turns out, allmost every MB automatic has some form of control pressure linkage.
The exceptions are; pre1970 "klunk-box" used in 108/109/111/113 chassis, 722.1xx used 1980-81 123.123 and 123.130 diesels. The 722.00x and 722.1xx transmissions used linkages to a lever on the side of the transmission.

The 722.3/4/5 trans used in 1982-1995 cars have cable action. All use a similar adjustment theory (throttle and cable should start movement together.)

The 1996 cars start the 722.6 trans which is electronically controlled and no longer has a cable control.

This info is from memory covering a lot of territory; there might be some rough edges.



------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician

francis 03-19-2000 01:45 PM


I have a 603 engine. The Car is an 85' 300D W124 Euro Version. Here's what I feel when driving: When I hit the kickdown/or even maually shift down - on certain slight uphill roads it does not work, but sometimes from 4th to 3rd on a straight away it does. I feel like there's not that much response from the tranny. I would like to have that sporty feel.

I have a 77' 300D and I can feel more response.

Do I follow the same steps you explained for my 603 engine?

Thanks!

Francis


stevebfl 03-19-2000 04:31 PM

Yes, finding the adjustment won't be as easy though. Same conditions apply for the cable (accordian boot where it comes out).

I can't from memory describe its location though. Although the cable starts from the forward pass side of the trans and is easily visible from the bottom. Follow it to its end. The adjustment will be in the white plastic nut on the cable mount.

------------------
Steve Brotherton
Owner 24 bay BSC
Bosch Master, ASE master L1
26 years MB technician


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