230SL Linkage adjustments and the effects on auto transmission shifting

[perry113]

I previously had written about issues I experienced on my 1965 230SL Automatic adjusting the idle stop on the venture throttle plate and then adjusting throttle linkage and then suddenly experiencing transmission slippage in all forward gears. Previous to this I never ever experienced any slippage. I then proceeded to study the linkage tour and as many linkage posts as I could reference and learned about first setting the pump linkage to the control shaft to 233MM. I then readusted the linkage from the opposite end of the control shaft to the throttle venture (with the throttle plate closed at idle) and got my transmission back (or so I thought).

Now that spring has nearly sprung in the northeast I decided to take the car for a nice ride on Saturday. I started to notice, however, when I slowed down from highway speeds to 45 or under and accerating again would create a transmssion slip for a second. Once you let off the gas when slipping then reappling gas the transmssion is fine. In fact , under load it feels normal. It also at times will slip upon initial start from standstill depending on how you intially apply the gas. Once you let off then reapply gas the transmssion is fine. During the ride I pulled the cover on the right side of the transmssion tunnel and had my better other half watch the linkage on the 3 position solinoid to see if it moved with the gas pedal. When cruising it would move to 2nd position. If you let off it would go back to position 1. If you resumed the trottle it would resume back to postion 2. I later checked the circuit on the 2 wire venturi switch and tried to adjust it by loosening the 2 allen bolts to get it to open the circuit a little closer than before. My test drive conclusions are as follows. Except for, on initial start from standstill all upshifts on acceleration feel normal. The transmssion, however on deceleration to 45 or uder followed by acceleration will cause a second of slip.

Today I helped a friend replace the 6 upper linkage pivots and control rod bushings on his 1963 230SL 4 speed (I would have never gone near his linkage with my above experiences with mine if his car were an automatic).  We were going to start by adjusting the pump rod to control shaft just like the tour said to 233mm, when I started to have a flash back regarding my car. I couldn't help noticing that his rods were identical in length to my 65 automatic, before we made any adjustments. His rods and my rods before making any changes were the following:

pump to control rod 240mm

center rod 144mm

throttle plate to control rod 310mm

We both thought this was too coincidental. Based on this we kept the pump rod at 240 mm. If you try to set this rod on the 63 4 speed and my 65 auto you find the rod is too long. You can only achieve 233 by loosing one of the locking nuts. We had to shorten the throttle plate rod to compentsate for the misadjusted throttle plate. Yes, his car like mine had the throttle plate adjustment screw adjusted so the plate was open at idle. (They always seem to mess with the throttle plate before you get the car.)
No where in the factory manual do you find length setting for these cars.

I realize one of my next steps in dealing with my transmssion shifting is to get a vacum gauge hooked up to the transmssion and check operation. But I want to revisit my linkage settings again to make sure I'm right at starting with a 233 mm lengh on the pump side. Please note the gas pedal operation works so the pump side hits both stops and the throttle plate is closed at idle and is open at full throttle.

Any thoughts or recommendations?

Peter Perry
1965 230SL Automatic
1972 911T Coupe

[J. Huber]

Hi Peter. Just measured things for a comparison. First off, I use a measuring tape (like a tailors), and there is likely some +/- of about 1 mm on each end. I shoot freehand for the center of the ball sockets. My linkage is tight and I went through the adjustment process last year including new sockets and bushings. All seems to be operating well...

233
147
300

63 Automatic 230SL (euro)

[ja17]

Hello,

Your automatic transmission is influenced by several inputs. Position of the three speed solenoid, engine vacuum, and engine rpms.

The linkage position can effect all three of these inputs.

The 233 mm measurement is a good starting point but can vary slightly as long as the position of the venturi remains correctly closed.  In other words, remove all linkages, when the injection pump linkage is on its stop, the venturi linkage must be all the way closed and be on its stop! Adjust the pump linkage to 233mm, next the long linkage at the intake should be adjusted and fall in place. The smaller linkage rod going to the linkage swivel on the block should be adjusted so that the venturi opens all the way at full throttle but still allow it to close all the way at an idle.

With the venturi all the way closed and the linkage on the venturi on its stop, the switch on the venturi should be activated so that the three position solenoid is in its rearmost position. The transmission linkage should move to the middle position as the engine linkage is moved and this should happen around 1,000 to 1,200rpms (adjust the switch to this spec).

The frontmost position of the transmission linkage (side of transmission, inside access cover)should only be achieved if the accelerator pedal is pressed all the way to the floor and the kickdown switch under the pedal is depressed.

If setting the linkage up correctly does not achieve the correct results you may have to check the modulator pressure and adjust and/or possibly addjust the transmission linkage (side of tranny).Along with the correct pressure readings you will need to refer to the specs on  the speeds for shifting up.

In most cases, if your transmission shifts too late or too abruptly, and the last downshift nearly jerks you out of your seat, a good correct linkage and venturi adjustment will do the job.

On rare occasions, modulator pressure adjustments are needed, especially if these setting have been altered in the past.

Keep us up to date!

[merrill]

Peter,
hi, I found that the measurements in the linkage tour are a good starting point.

I quickly found out that one needs to be careful when setting up the linkages as one small
change can throw something out.

I found this method worked ok.
1. take note of the distance the CSS moves when the car is in gear.
2. then disconnect the tb and inj pump linkages.
3 adjust the css adjuster (round thingey with lock nut) all the way in
4 adjust the vertical linkage from the side of the block up to the css pivot so you have reasonable clearance / throw.  (using the note from step 1)
5. then adjust the linkage from the pivot back to the cross linkage
6. after verifying the tb is set up correctly then set the linkage up to the tb
7 then set the inj pump linkage

once this is done the inj pump and tb should open and close at the same time
then start the car and set the css.
My measurements differ from the linkage tour but not by much.

Also, NOTE, any time you remove the cross linkage to say adjust the valves you validate the linkage set up.

[ja17]

Hello,

The further you get from the 233mm length,  the further the geometry of the linkages gets out of wak. Since the length of the linkage arms and their angles vary, the only reference point to start from is the stop on the injection pump, the closed position of the venturi linkage arm and the 233mm length which is the constant which ties these two variables together.

The BBB shows the factory linkage degree tools which can check to see if these variables are in sync.   Normally these degree tools are not needed unless the linkage  stop on the injection pump is moved or something else is modified.

[perry113]

I have new linkage ends and control shaft bushings on order. There is some marginal slop on the ones I have. I will rebuild the linkage and then reset the injection pump rod to a slightly longer length to line up the rear socket of the throttle body linkage to the hole that's cast into the intake manifold. There is mention of this hole on the linkage tour which is part of the control rod bracket on the 280SL but no mention on 230SL's. I was advised of this by a reputable source. I was told this hole is where the linkage needs to be lined up with. On my car 233mm does NOT line up.

I will update the tread of my results once all parts are in hand.

Thank you to all for your help thus far.

Peter Perry
1965 230SL Automatic
1972 911T Coupe

[J. Huber]

Here is a picture that might help?

[ja17]

Hello Peter,

This is a good point.  There are two distinctly different injection pumps on the 230SL. It may be possible that the earliest version does have a different length spec.?? We can survey this point at PUB 2009 when we have about thirty W113 cars on hand.

Huber, thanks for the nice photo with rod lengths. I think it clearly demostrates that the 233mm rod length and the alignment bore work together at least on the 230SLs with the later injection  pump like yours. One should realize that the 300mm rod is the variable in this case. In other words set the injection pump lever on its stop, set the venturi lever so the flap is closed and on its stop. Set the injection pump linkage to 233mm, confirm that the alignment bore is on target and then set the long linkage rod so it just snaps over the linkage balls without moving anything!

The last rod (147mm in photo) should be adjusted so that the accelerator pedal when fully depressed, oppens the venturi flap all the way. The slip joint on the firewall linage may also be used to adjust the final position of the accelerator pedal. Make sure those with automatics have it adjusted so that the pedal hits the kick down switch at full throttle. Lastly adjust the idle solenoid on the linkage to specs.

[ja17]

Hello,
It should also be noted that if the position of the injection pump linkage arm or it's stop  is ever tampered with at any time over the years, then the actual 233mm length of the linkage rod is no longer relevant and most likely is changed.

[bpossel]

On my 280sl, I have set the length of my ip linkage rod to 233mm which causes the throttle body linkage rod to not align with the bore hole.  It actually sets the linkage ball slightly behind the bore hole.  If I set the throttle body linkage to align with the bore hole, I then have to reduce my ip linkage rod to less than 233mm (forget exact length, maybe reduce length by 2-3mm...)

So the question is ...  on the 280sl, set ip linkage to 233mm and dont worry about the alignment bore, or set to the alignment bore and adjust ip linkage accordingly?

Thanks Joe and others!
Bob 

[perry113]

Here is a picture that might help?

Thank you for the picture. I'm awaiting my parts and some time this weekend to work in the shop,

[wwheeler]

Bob,

That is exactly what my '68 M130 280 SE linkage does. It kept me up at night wondering if I was doing something wrong. With the alignment bore, my IP rod is 231.5 mm. Earlier Joe had said he thought that that small amount of difference may not be significant. My Injection pump had been rebuilt sometime ago but the PO was a tinkerer. I just sent the pump off to be adjusted and checked out. It will be interesting to see if there is any change in the IP linkage length.

I am interested as well which adjustment would be the best to follow. Any thoughts?

[bpossel]

Wallace,

As you know, my IP pump was rebuilt last year.  I have had a bit of a cough issue thru the intake between ~1500-2200 rpms...(ip acted lean), which I curred by gradually adjusting and enriching the ip.  Tomorrow looks to be a nice sunny day in Memphis, so I may try and readjust to align with the bore hole.  Then do some driving.
I'll post again over the weekend the results...
Bob 

[ja17]

Hello,
The most important thing to remember here is that the venturi intake linkage lever must allow the venturi to close all the way and be on its stop and the injection pump linkage lever must be on its stop !   The 233mm rod length and/or the "bore" are only refference points to use for the next step. Never alter either lever arm position to accomodate positioning of the bore or the 233mm dimension.

If the injection pump rebuilder or a previous owner has moved the factory setting on the IP linkage lever arm at anytime over the years, the bore refference or the 233mm reference may never be exactly on again. My suggestion is make sure the linkage lever arms are correct, then get either of the refference points (bore and/or 233mm)as close as possible.

[perry113]

I spent some time over the weekend in the 230 laboratory working on both the 63 4 speed and my 65 auto. I'm still awaiting new bushings and link ends for my car, but I reset the IP linkage to line up with the control rod socket ball with the cast line up hole on the intake manifold.

The initial drive was good in that no slippage occurred of the line from standstill. I did not experience any slip when slowing down from highway speeds but did experience once an early shift from slowing from 65 to 40 whereby when slowing down then accelerating the trans jumped to 3rd then 4th in a split second.
 
I realize I will be able to get the set up that much better with new bushings and sockets. It's so critical to get both the throttle plate and injection arm to start moving off there stops together. Can't get it perfect with marginally worn sockets. I'm hoping I can fix the slight stumble the car experiences when you modestly push the gas from standstill. This doesn't always happen depending upon how gently you depress the gas pedal. I hope the linkage rebuild will resolve this.

My IP pump rod measured at 244mm lining up with the cast hole on the manifold. Many thanks to Dan Carron (Dr. Benz) for taking my phone call and spending more than a few minutes to advise me on linkage set up.

I will update again once a perform the linkage rebuild.

[perry113]

I wanted to let all that helped with my sort issues know that my transmssion slip ended up being in the center linkage adjustment with the gas pedal.

There must be alsolutely no play in the linkage so as soon as you put pressure on the gas pedal the control arm and all linkage starts to move which sets off the venturi switch that sends signal to the transmission solinoid.

It's amazing how we all at times including myself (big time on this one) can look everywhere except for where your problem lies.

Since adjustment the transmission is perfect. I 've run the car 600 miles since resolution and am enjoying the experience of owning an nice driving 230SL. I still have a slight hesitation when starting from standstill (worse when on an uphill incline) which could be an further fine tuning to get the throttle plate and pump to open at precisely the same time.