1986 transmission trouble
 

I'm the not so proud owner of an 1986 560SL, that will not upshift, 1-2,until the engine revs to 2500 rpm. What could be the problem?

Thanks in advance for your help.

Janal

try checking the transmission fluid level....

Mis-adjusted control pressure cable?

M.B. DOC
 

Could you tell me more about the misadjusted control pressure cable problem that I'm having. Do you have a manual that describes this adjustment?

Any help is appreciated.

janal

Normally your car should start in second gear and there should be two shifts as you come up to speed. Are you really starting in first?

MB Doc is referring to the bowden cable that attaches to the throttle linkage back by the firewall and runs down to the transmission. The cable should be adjusted to be "at rest" when the throttle is closed and move when the throttle moves.

There are several posts on adjusting this cable.

Chuck:

I see that you are located not far from where I live. I'm wondering if you have any recommendations for shops in your area that do repairs on vintage vehicles such as mine?

Iv'e got several repairs that need to be accomplished (replace timing chain and rough idle to name a couple).

Attempted contacting someone at American Service in order to determine if they had personnel that were familiar with older mercedes, but, was not successful.

Appreciate your help

janal

Members:

In regards to my comment/question about the upshift from a stop to the next gear, I've finally had an opportunity to locate the Bowden cable and do my best to adjust the upshift. However, my best only resulted in a reduction of 200 rpm.

What other system could be causing this problem?

Many thanks for the advice and suggestions.

Janal

Did you ever determine if you are starting in first or second? If you really are starting in first, the problem might be that the kickdown switch is stuck. Follow the cable from the switch to the solenoid and see if you have 0 volts with the pedal up, and 12 volts when the switch is depressed.

And are you sure that you have a just a little slack in the bowden cable with the throttle in the idle position?

Other causes from my book:

- low governor pressure, replace centrifugal governor if too low
- service control pressure valve

This is stuff that a good transmission shop can check. It's a very standard sort of transmission.

Chuck:

Sorry for not clarifying that point, but, yes the car does start out in 2nd gear and upshifts to the next gear at about 2200rpm.

I tried various settings from no upshifting at well above 3000rpm to now shifting at 2200rpm. Not much of a change, but thats as good as I could achieve. I think your advice is good concerning locating a good transmission shop. There are a couple shops in Rockville that I will contact.

I appreciate you and others sharing your thoughts and advice. And I will let you know how this all works out.

Again, many thanks.

Janal

If you are acclerating hard enough to get the car to kick down to 1st than a 1-2 upshift at 2500 is pretty normal.

Douge:

No I haven't done a hard acceleration, I start out at a normal rate and increase the rpm until the tranny upshifts to the next gear (2200rpm).

I tested the kick down switch while driving yesterday. It apparantly worked just fine.

Janal

a leaky vaccuam modulator on the A/T or the hose connection.
mak

Members:

The saga of the none shifting transmission (2d to 3rd gear@ 2300rpm) continues.

Vacum pressure at the mod valve is 19 in hg.
I've replaced and adjusted the modulator valve. (hard shift/soft shift)ok.
I.ve adjusted the bowden /pressure cable with no evidence that any of the adjustments have had any affect on shift timing.

Does anyone know of adjustments that can be made to the transmission end of this cable? Is something broken on the cable inside the trans?

Any help as always is appreciated.

janal