Author Topic: Sudden transmssion slip after performing idle & Linkage adjustment  (Read 16546 times)

perry113

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I have been working to sort a flat spot when I first start from standstill with my 1965 230Sl automatic. Timing and dwell are good.
Tonight I perfromed a linkage adjustment on the throttle rod and adjusted the throttle body butterfly and proceeded to adjust idle using idle air valve on front of intake and idle fuel setting on the pump. Previously idle adjustments were made eroniously by adjusting the set screw on the throttle body. I checked to see that the pump linkage went from stop to stop with gas pedal operation. I referenced the Pogada Basic Fuel Adjustment and Idle Adjustment Procedures in the Pagoda Technical Manual.

The only changes I made were the following:
Adjusted the throttle plate to closed position whereby, it sticks slightly when going to open.
I had to slightly shorten the throttle rod after adjusting throttle plate and set screw.
Taped into vacuum line from back of intake manifold to brake booster & installed vacuum gauge.
Adjusted idle air valve and watched vacuum (10 inch Hg).
Went 2 positions clockwise on idle fuel setting on pump.
Car sounds better, Idles better and starts better.

I went to road test car and suddenly found the transmission to slip when trying to accelerate. I immediately, ( I didn't drive 2 blocks) went back to my shop. I never tried driving faster the 20mph.

This car has only 56,000 miles. The transmisison has always been perfect. Fluid level is good and fluid is pink. It has never ever slipped until tonight. Reverse feels ok.

I must have changed a transmssion input by making the above changes. What have I overlooked?

I've called it a night here in Albany and look to my fellow friends on the forum to help guide my next steps and where to go next.

Peter Perry
1965 230Sl Automatic
« Last Edit: November 21, 2008, 03:03:44 by perry113 »
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

wwheeler

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #1 on: November 21, 2008, 06:20:53 »
Could the throttle switch on the throttle housing need adjusting after changing the position of the butterfly? The throttle switch is closed when the linkage is on the stops and is open when the linkage is just off the stops. The switch tells the transmission solenoid the postion of the linkage. 
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6

psmith

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #2 on: November 21, 2008, 06:27:52 »
I think it might be the throttle plate adjustment.  Manifold vacuum is related to the auto trans shifting.  I did some work on my linkage and although I put the linkage back to the previous dimensions, the car ran rich and downshifted with a loud Ker-Chunk.  I took it to a pro and got a valve job and linkage adjustment and now it shifts very smoothly.  Go through Joe's Famous Linkage tour and this link might help too.  http://www.sl113.org/forums/index.php?topic=1085.0

Good Luck!

DavidBrough

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #3 on: November 21, 2008, 09:49:25 »
Hi Peter,

I suddenly developed an intermittent slip in my auto box about a year ago. This only ever manifested itself at start off and most usually when cold. The transmission gave a slight slip then took off and seemed to work fine. I eventually decided I should do something about it and when the gearbox was taken apart it was almost totally shot. The repairer was able to save it in the end and did say these transmissions are surprisingly resilient to faults and wear which means that when they start to play up they are usually quite badly worn. I think the repair cost £1,000 in all, £500 to fix the gearbox and £500 to take it out and put it back. My fluid was good and clear at all times and I had no other indication of problems.

Unfortunately, I think any vacuum issues would not make the box slip but just make the changes early, late or harsh. If you’re sure it’s the transmission slipping and not an engine misfire, which can easily be confused, you may well have a gearbox problem I’m afraid and would suggest you let an auto transmission expert take a look.

« Last Edit: November 21, 2008, 10:02:02 by DavidBrough »

perry113

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #4 on: November 21, 2008, 11:50:25 »
Could the throttle switch on the throttle housing need adjusting after changing the position of the butterfly? The throttle switch is closed when the linkage is on the stops and is open when the linkage is just off the stops. The switch tells the transmission solenoid the postion of the linkage. 

How is this switch adjusted? I see it mentioned in the factory manual, but doesn't say how. I checked the throttle linkage and made only a change the to the throttle side. As far as inproper adjustment to the throttle plate, it says in the technical manual to adjust the plate to the closed position. I realize manifold pressure has alot to do with it. Could making major adjustments to the idle air valve cause this? I also know there is linkage to the transmission for kickdown connected to the middle rod.

My car was clearly set up wrong previous to my adjustments. The idle was dependent on the throttle plate being adjusted slightly open by use of the throttle set screw to maintian and idle.

I also noted more of a hissing noise around the air cleaner since adjusting the idle valve heard at idle. Originally I thought it was because now the car is using the valve and air from the line the connects the valve to the air cleaner.

I can't see how I could have a sudden transmission failure in 1 night when tuning the car.

As far as experts in my area, I know of none.

Peter Perry
1965 230SL
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

bpossel

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #5 on: November 21, 2008, 12:54:12 »
Hello Peter,

Here is some instructions that I saved from "graphic 66".  Hope it helps!  Note: throttle switch=idle switch

"Check fuse #3 - this power goes to the double acting solenoid unswitched. The solenoid is activated by switching the ground on and off at two locations, the kickdown switch and the idling switch.

Go under the car and find the kickdown switch just behind the gas pedal. Pull the 2 connector plug off of the switch, clean those contacts as they may be the culprit. Hook a continuity tester to the two prongs on the switch and push the gas pedal to the floor. The switch should make contact. If it doesn't it could just need adjustment. Go into the car and reach behind the gas pedal and push the plunger of the switch all the way in. If it now works then you must decide why the pedal isn't hitting it. The switch moves in and out by loosening the lock nut in the car and then go back under the car and put a socket wrench on the switch, it should turn in and out on threads in the floorboard. It' a good time to just unscrew it completely and clean and lube the switch and clean the threads. Then screw the switch in until when the gas pedal is fully depressed it actuates the switch.

Go under the car and with the ignition on and the car in drive and the gas pedal at least pushed halfway down as to activate the idling switch, put a jumper across the two wires in the plug you removed from the kickdown switch. The 3 position solenoid should move at this point to the forward most position. If it doesn't and you’re sure the gas pedal was depressed and the key was on it could be the linkage on the double acting solenoid is frozen or the solenoid is bad or your idling switch on the throttle body is out of whack. Try the switch first. It is a simple circuit with two switches, the kickdown and the idling switch which is located on your throttle body at the venturi control. It has two wires attached just like the kickdown switch and must not make continuity after 1200rpm and must make continuity under 1200rpm as to activate the double acting solenoid into the rear most position. You can test this by unhooking both wires and starting the car in park and hooking your tester to the two connectors and as you accelerate the motor at precisely 1200rpm the switch should open and you should not have continuity and under 1200 rpm the switch should be closed and make continuity. The switch is adjustable via two allen screws and it slides on its mount to adjust when it activates. Don't look for any voltage at either of the switches as the double acting solenoid has constant 12 volt power from fuse #3 and you are merely switching to ground with both switches you will not find power at either switch. You can test them with a test light by hooking one lead to the positive terminal on the battery and checking each switch lead for ground, one lead on each switch should have constant ground and one lead on each switch should only be grounded when the switch is activated. Also these switches work together and that is why your kickdown won't work unless the idling switch is in the open throttle position. It is a very simple circuit, 3 wires go to the double acting solenoid on top of the tranny, one from fuse #3 with 12 volt positive unswitched current, then a wire goes from the double acting solenoid to the kickdown switch and it switches the ground to activate the kickdown. The idling switch is wired to the double acting solenoid also and also switches the ground to activate the double acting solenoid. These switches work together and you must not activate them both at once, that is why you must have the gas pedal slightly depressed when testing the kickdown switch. Now the constant speed solenoid on the manifold to kick up the idle when in gear is supplied constant unswitched 12 volt positive power via fuse#5 and is activated by two oil pressure switches on the transmission each of which simply switches the ground on and off to the solenoid when the transmission fluid pressurizes the forward gear switch or the reversing switch. Remember all of these actions are activated by switching the ground and not the hot lead so looking for 12 volt positive power at any of the switches will not work. You must confirm they are actually switching the ground on and off and there are many many ways to do this depending on you equipment and personal taste. I have outlined some details here but not all, and there may be easier or better ways. Just remember, you are switching the ground on and off with constant 12 volt positive power on all the solenoids. The double acting solenoid is simply a 3 position solenoid, with the idling switch activated the solenoid moves rearward, when you go above 1200rpm the solenoid is totally off and moves in its relaxed state to the middle position and when you activate the kickdown switch it moves to the forward position."

Bob

ja17

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #6 on: November 23, 2008, 06:33:46 »
Hello,

The transmission slippage is most likely caused by too low modulator pressure.  i would guess that the three position solenoid is stuck causing the pressure to be too low. The engine linkages may have been set improperly in the past and someone may have altered the transmission to compensate. this linkage rod connects the three position solenoid to the modulator pressure unit on the transmission. Remove the access plate on the tunnel inside the car (passenger side).   You will be able to view the linkage rod on the side of the transmission, from the three position solenoid. At rest the linkage rod should be in the rearmost  position.  When the accelerator is pressed the linkage rod should move to the center position. When the acclerator is floored and the kick down button is engaged, the linkage rod should move to the front most position.

If the linkage rod is not moving correctly, it may be stuck.  Use plenty of penetraning oil and excersise it manually till it frees up. 

If someone has tampered with the actual modulator pressure on the transmission, in the past, you will need to go through a modulator pressure adjustment. Sun Valley Mercedes Dismantlers have given a very good set-up procedure on their web site;

Hopefully these modulator adjustments will not be needed. I sure we can get back with you with this information .
« Last Edit: November 25, 2008, 01:13:31 by ja17 »
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

perry113

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #7 on: November 23, 2008, 13:41:00 »
Thank you all for your comments and suggestions. The community of enthusiasts within this forum is fantastic. There are many always willing to take the time to help others when we cross rocky roads.

Here is what I've done so far since my original post.

I checked the idle switch on the throttle body and its working as designed. The loop is closed (power at both wires) when throttle is closed. It opens once you open the throttle.

I watched the linkage for the solinoid on the transmission thru the tunnel cover. It moves to a 2nd position with throttle halfway and a 3rd postion on kickdown. I didn't have much time when I did this so I need to review this carefully again.

The car runs and starts much better after my original listed above adjustments. There's a hole cast on the back side of the intake manifold.  Should my linkage ball for the throttle be perfectly aligned with this hole? I know it differenent on later 250 280SL, whereby the control rod bracket accomidates such a hole. I'm wondering if need to check and adjust the pump rod to match the hole and readjust from there. Maybe that's thrown off the center linkage that relates to modulator pressure.

Maybe by strike of lightning my tranny finally gave out, but it would just be too freaky to drop just like that. It feels like it just fades away once you try to accelerate over 20mph. Prior to these adjustments the transmssion has performed exceptional. This car for an automatic has been the best shifting one I've experienced compared to half dozen other 112, 113 automatics I've experienced. The car must have been set up wrong to compensate the incorrect idle adjustment.

When more time is alotted on my end for 113 workshop time, I will have to go to the next level and car goes up in the air to perform complete throttle and transmssion system checks including vacuum. I need to look at Sun Valley's website to review their setup procedure. I also will rule out possible vacuum leaks by replacing the old vacuum lines from the back of the manifold to the master cylinder.

Peter Perry
1965 230SL Automatic
1972 911T Coupe Albert Blue






« Last Edit: November 23, 2008, 13:46:18 by perry113 »
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

ja17

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #8 on: November 25, 2008, 01:07:24 »
Hello Perry,

Yes I would be suspicious that you may have changed a setting in this case.  Possibly someone in the past did a misadjustment to compensate for something else  and you simply set things back to the cporrect setting throwing off another adjustment.

http://www.mercedesdismantlers.com/16BoltInstallationInstructions.html

Yes this Sun Valley link gives a quite good description. check it out.

Make sure that your fluid level is correct. Check it with the engine warm and running and the car on perfectly level ground.
« Last Edit: November 25, 2008, 01:10:44 by ja17 »
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

glenn

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #9 on: November 26, 2008, 03:13:45 »
Perry113, Should solenoid move to 2nd position as soon as the throttle first moves(1 % open)???

perry113

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #10 on: November 26, 2008, 03:52:16 »
Perry113, Should solenoid move to 2nd position as soon as the throttle first moves(1 % open)???

I can't wait to find out. I'm close to finishing this other car (MGA) in my shop so I can get the 230 into position to check the solinoid movements and to also check the linkage from the center rod to under the intake and back to the transmission. I'm hoping its is a rod adjustment which can affect pressure. The change has to be close to where I was mainly the linkage. I should be there by end of Sunday to report more findings.
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

hands_aus

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #11 on: November 28, 2008, 12:27:15 »
I also know there is linkage to the transmission for kickdown connected to the middle rod.
another reference ...........the 230 into position to check the solinoid movements and to also check the linkage from the center rod to under the intake and back to the transmission.

The 113 auto transmissions do not have a solid linkage rod back to the transmission from the throttle linkage.

The pressure modulator is connected to the solenoid by a short linkage rod.
The solenoid is operated electrically.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

perry113

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #12 on: November 28, 2008, 20:10:28 »
The 113 auto transmissions do not have a solid linkage rod back to the transmission from the throttle linkage.

The pressure modulator is connected to the solenoid by a short linkage rod.
The solenoid is operated electrically.



How does the transmission know where the throttle is? Is it from just the the idle venturi switch on the throttle plate or are there other inputs?
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

hands_aus

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #13 on: November 29, 2008, 02:34:05 »
it is from the throttle idle switch as you suggest plus the kick down switch under the accelerator pedal.

You can test if the idle switch is working correctly by turning the ignition switch to the start position, put the gear lever into any forward drive position.

you should not be able to start the car because of the neutral safety switch.

listen carefully. without your foot on the pedal, you will hear the solenoid operate to the back position.
Apply your foot to the accelerator pedal and hear the solenoid move to the centre position.
Push the pedal to the floor in the kick down position the solenoid will move into the forward position.

You can do the same test for visual inspection.
Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

wwheeler

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #14 on: November 29, 2008, 04:01:56 »
I was confirming the operation of my transmission's three position solenoid today. All of the functions work but my question is the travel of the solenoid. The solenoid travels about 3/8" to 1/2" from center (neutral) position to the rear position when the linkage is at rest. But it only travels 1/8" from center to the forward kick down position. Is this normal?

My guess is the travel should be the same. The kick down works for the most part but occasionally will not function. Does the trans linkage need adjustment?

Thanks for the help! 
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6

hands_aus

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #15 on: November 29, 2008, 09:26:40 »
I think the amount of travel should be the same.
Perhaps cleaning and lubricating the rod ends and giving the solenoid a bit of attention
I wouldn't change the linkage.
The kickdown switch is behind the pedal. maybe a clean and adjust the carpet position will sort it out.

Bob Smith (Brisbane,Australia)
RHD,1967 early 250 SL #114, auto, ps , 717,717
best of the best

perry113

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went back to original settings and got a transmission again
« Reply #16 on: November 30, 2008, 21:50:52 »
Well the good news is that I have a transmission again. I went back to the original settings, whereby I disconnected the throttle linkage and opened up the throttle body with the set screw then slightly lengthed the rod. I leaned the pump 1 notch. The car doesn't run as good, but its similar to where I started prior t making any adjustments. The transmission feels normal again. Kickdown works. The transmssion feels strong.

Previous and afterwards I observed the solinoid arm for the transmission and this what I obseved:
Car is off and key is turned to power position, solinoid moves back slightly. If floored solinoid goes to furthest position forward.
When running at idle solinoid is in rear most position. Once you start to give it gas it goes to center position.

This whole experience is perplexing. I feel it could either:
1. in the idle switch adjustment in the throttle body. I tried to loosen it previously and it doesn't really move that much.
2. in adjustment of modulating pressure by adjusting the counter nut and screw on the modulating pressure transmittor.

My gut feels it all boils down to the engine's intake manifold vacuum pressure changing when setting the car up properly. Isn't the vacuum pressure within the intake another input to the equation for proper transmission shift modes?
« Last Edit: December 01, 2008, 02:42:27 by perry113 »
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

wwheeler

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #17 on: December 01, 2008, 05:02:23 »
Peter,

I remember when I adjusted my throttle switch it didn't move much (1/8"?) but it is very sensitive. 

I think it is best to adjust the switch with the throttle solenoid engaged. The solenoid engages when in drive and bumps the throttle linkage to keep the engine speed constant.
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6

3523pleigh

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #18 on: December 01, 2008, 16:35:44 »
I also have a transmission adjustment problem. I have taken the car to a transmission company. The mechanic need an electrical diagram of the solinaoid to see if it wired properly can anyone help with the diagram. thanks Phil

perry113

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Setting pump linkage to 233mm solved the problem
« Reply #19 on: December 04, 2008, 02:18:03 »
I finally achieved the results I was looking for. When I originally set up the car I assumed the linkage from the pump to the control rod was ok basing it on it stop to limit matching up when the gas pedal operation. WRONG!

I checked the linkage measurement from the pump to the control rod and found it to measure 240mm. I reset it to 233mm and reset everything else from there and got the car running nicely and got the transmission to operate nice and smoothly. Strangly I had to slightly shorten the pump linkage to achieve an adjustment of 233mm. Both ends bottomed out at 236mm. No question my car has been out of wack for many years.

My car no longer has a stumble when first starting out. I still need to perform slight adjustments for warmer weather with the idle valve and the solinoid that compensates the idle whe car is placed in gear.

I'm absolutely delighted with the knowledge I've gained from the technical manual and with this forum. I urge those who have not joined as full members to do so not only to gain full access to the technical manual but to support this organization.

Peter Perry
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car

graphic66

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #20 on: December 04, 2008, 02:29:59 »
You are absolutely right. I haven't kept up on my dues. Wow, that was too easy. I like the Paypal link. This group is the best.

perry113

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Re: Sudden transmssion slip after performing idle & Linkage adjustment
« Reply #21 on: December 04, 2008, 02:37:03 »
You are absolutely right. I haven't kept up on my dues. Wow, that was too easy. I like the Paypal link. This group is the best.

Amen
Peter Perry
1970 911T Bahia Red
1972 911T Albert Blau
1963 220seb coupe barn
1965 230SL Light Ivory automatic
1966 230SL Havana Brown 4 speed Barn Find
1970 280SE living 3.5 donor car