Auto Transmission

[al11]

Hello,
I have a 68 280 SL that I use in the South of France. I drive it about 2 weeks a year. 4 years ago the auto trans started making noise. I found a local mechanic (old Alpha Romeo racing guy) that dismantled it. I drove it to Germany to this super reputable trans guys and exchanged it for a rebuilt one.
The Alpha guy put it back on. When I drove it away, I realized that it was not shifting properly and there was no kick down. The fuse was blown. I changed the fuse and heard it pop at the next kick down. I took the car back to the mechanic, he found out that there was some error from his employee and that the “cable” was improperly placed and stuck. I drove the car away and have been driving 6 weeks total in the last four years. This week after adding a bit of trans oil and driving it on 2 up a steep driveway ramp, I realized that the car is doing the same thing again. No kick down, late shift, and slipping. The fuse does not blow like last time.
I wanted to open the passenger side access to the solenoid but it seems that my car does not have one. I am also not sure which switch is on the the injection area. While I was looking around I found a disconnected wire. I think I know where it goes but I do not think it is related since they are eyelets at the end. I think the wire attaches to this( photo). I would appreciate your input! Thanks

[Pawel66]

The opening on the right hand side of the tunnel to see the three way solenoid is quite far in the front - where passenger's toes are. Maybe you were looking too close to the chair.

The part you are showing is the constant speed solenoid (CSS). It gets power from the fuse and gets ground from either of the two hydrauiic switches you find at the bottom of the tranny on both sides of it. The role of the CSS is to push the throttle linkage to increase rpm when the gear is selected so that the engine does not stall. It does not affect shifting directly, but it does influence the work of the throttle switch, that in turn steers the solenoid on the gear box.

It seems to me indeed that checking all the wire connections again and checking operation of the three way solenoid may be the first steps to take, but see what others say, I am not a mechanic.

[teahead]

Looks like your CSS is not hooked up (no wires going to it) like my car.

Wonder if they only hooked it up to AC cars (which mine is), or some mechanic removed it?  Gotta crawl underneath to see if there are wire going to the two solemoids.

Sounds like you need adjustment for your shifting problems.

Checkout the online manual on this site.

[ja17]

Actually, some cars without AC came from the factory with  a CSS which was never connected. Some of these models with the automatic transmissions used the vacuum dashpot on the intake to prevent stalling in gear. Make sure the wiring at the trandmission is connected properly and make sure the transmission linkage from the solenoid moves to all three positions.

[teahead]

Actually, some cars without AC came from the factory with  a CSS which was never connected. Some of these models with the automatic transmissions used the vacuum dashpot on the intake to prevent stalling in gear. Make sure the wiring at the trandmission is connected properly and make sure the transmission linkage from the solenoid moves to all three positions.

Interesting.

So those with automatics didn't necessarily use the CSS.  And dealer installed AC units, probably never bothered with it either.

I guess it wouldn't be too hard to wire it yourself.  Find a hot wire when ignition is on and use a relay from the AC compressor wire to trigger the negative side of the CSS.

[al11]

Thank you gentlemen,
I did find the access to the solenoid, as mentioned it was further towards the ankle area of the passenger. I turned the power on, the rod moves 1/2” or so backwards, I push on the gas pedal it moves almost to where it was when the car was off, and when I touch the kick down it moves another 1/2inch towards the front of the car. Is that ok?
As far as the unconnected wires to the css they are hanging on loose the side.......One is green/red the other black red... The car has AC

[Pawel66]

It sounds like the three-way solenoid operates as it should. Its movement from back position to middle position should happen when you touch gas pedal slightly - this is governed by the throttle switch and can be adjusted, but I would not touch it for now. Then it goes forward when you press kick-down.

On Euro car with no emission control and no AC: if you have power with ignition turned on on the black/red (or black/red/green) wire (the power then is from fuse 5) and if you have ground on the red/green wire when the forward or backward gear is selected while engine is running (need two persons maybe to check it) - these may be wires to CSS to prevent engine from stalling when a gear is engaged (the ground is delivered by either of the two hydraulic switches on both sides of the tranny). But it may be different in your case if you have an US car.

To me it sounds like your modulator pressure may need to be slightly adjusted or the throttle switch may need to be adjusted - but see what the more experienced Members are saying.

However

Even though I am not a mechanic, I know that for the tranny to work properly, as it is governed by vacuum that engine is producing, the engine needs to be in tune. Ignition timing, dwell, valve clearances, idle adjustment - all that may affect shifting if out of tune. So I htink it needs to be made sure all this is correct before getting to tranny work fixing.

[al11]

Hi Pawel66,
Thanks for your input. I saw in the technical manual that after checking the solenoid, one should check the switch at throttle. Can that switch, if bad, cause no kick down and late shifting on its own, while the solenoid works?

[ja17]

The intake switch will not effect kick-down. The switch on the floor under accelerator pedal activates the three position solenoid to cause kick-down. Late shifting can be an adjustment or internal problem.

[al11]

The late shifting and the no kick down appeared at the same time...

[Pawel66]

I am not an expert, but if you say that the three position solenoid works properly, then lack of kick-down and no shifting, as ja17 says, may be an adjustment issue or internal issue. I think ja17 may mean the modulator pressure adjustment.

This can be done by adjusting the length of the rod between three-position solenoid and the modulator (across all ranges) and/or by turning the adjustment screw on the side of the transmission. These adjustments are described in the Technical Manual on tis site as well as in numerous posts.

Here is how ja17 explained it to me, and I did it: https://www.sl113.org/forums/index.php?topic=22622.msg161736#msg161736

[al11]

THANKS,
I will work on it this weekend. It is impossible to find a decent mechanic in th South of France!

[Pawel66]

I know the pain - from my place...