Pagoda SL Group
W113 Pagoda SL Group => Drive train, fuel, suspension, steering & brakes => Topic started by: Por911t4 on June 04, 2019, 08:59:01
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Firstly thanks for the help, advise and input in connection with previous posts in relation to this ….
In short … the gear change is 'thumpy' between shifts especially under load. This has been confirmed by our auto transmission repair shop. They've removed and cleaned the throttle position sensor to no avail. So the 'box now needs to be removed. Car is a '66 230SL auto / 60,000 miles.
Can anyone offer anything to this and has anyone had previous experience of these symptoms ?
Thanks in advance
Barry (Glasgow Scotland UK)
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Barry, I cannot recall the previous posts now, but what I know is that before you take the transmission out, there are certain checks to do:
1. Level and condition of transmission oil
2. Oil and filter replacement if history is not known
3. Checking the 3-way solenoid operation (after fixing the throttle switch as well)
4. Checking and adjusting modulator pressure
5. Making sure the car is in tune - ignition timing, valves, linkage, idle, brake booster (automatic transmission will not work well if idle is wrong or brake booster is leaking air due to vacuum issues)
Done those?
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Barry,
It is worth checking the technical manual here, & the posts on rough changes, and following Pawel`s advice, before removing the box.
These boxes are not as smooth as a modern torque converter box,
Is any one local to you who knows these cars that could have a ride and an opinion ?
Keep well
Paul
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Barry, I cannot recall the previous posts now, but what I know is that before you take the transmission out, there are certain checks to do:
1. Level and condition of transmission oil
2. Oil and filter replacement if history is not known
3. Checking the 3-way solenoid operation (after fixing the throttle switch as well)
4. Checking and adjusting modulator pressure
5. Making sure the car is in tune - ignition timing, valves, linkage, idle, brake booster (automatic transmission will not work well if idle is wrong or brake booster is leaking air due to vacuum issues)
Done those?
Thank you Pawel,
In truth the car is now at our automatic transmission specialist who I have phoned and mentioned my concerns further to your reply (but I was unaware of your points prior to handing the car across to them). I have a situation where the 'box is now out of the car for inspection and can't check the points you highlight. However my plan always was to put the car in for a full service to an SL specialist further to the 'box fault being rectified.
Not ideal but its just the way events have unfolded .
Regards
Barry
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Hi Paul,
Thankfully our automatic transmission shop are a top end professional operation who are aware of the 'pagoda' model and have worked on two in the last two years . Ive spoken with the technician personally and he is very familiar with the 230 auto 'box and, while frustrating, hopefully we are near to pin pointing the issue .
I fully realise the box design is 55+ years old and the shift will not be silky smooth but there is no question there is an issue there and this has been confirmed by the technician . The thump when changing is quite alarming . Far to severe and rough even given the car is 53 y/o.
Thanks
Barry
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Barry, just to calibrate: the gear changes are almost silk smooth... not like the modern 9 gear Mercedes boxes, but surprisingly smooth.
In case your shop need any specs, you will find them here in the forum.
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Late reply. Have the same year with automatic. Please check that the rear differential has no play. This is the case with my car, thus the automatic seems to switch roughly, but it's actually the interplay with the rear differential...
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Barry,
Unless you bought this car new and drove only 100 miles a month for the last 50 odd years ( 100x12x50= 60,000?) As well as records to prove it, you have been conned or fooling yourself.
Trust me
Chris
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Or the car is like mine and been off the road for half it’s life.
As others have said the changes are not like a modern car but they should still be pretty good never the less and it sounds like there is something else occurring. Good luck with the outcome.
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I'm late to this, but the key to good shifting are correct trans pressures, and that's controlled by the modulator plus the 3-position solenoid. You can hook up a pressure gauge and check them, and will likely find they are off.
The BBB lists the pressures, but I don't recall them off the top of my head. There are three pressure setting, controlled by the 3-position solenoid. The higher the pressure, the harder and more abrupt the shift will be. Also the higher the pressure, the higher the engine will rev before shifting.
Low pressure is for down shifting so you don't get whiplash. Shifts are slow and soft.
Mid pressure is for normal driving. Shift are distinct, but not harsh.
High pressure is for hard driving and will typically cause a downshift and hard upshifts.
The three pressures are controlled directly by the 3-position solenoid, and this is often when problems occur. When depowered, like with the ignition off, the solenoid is in it's mid position. You should be able to grab the linkage rod and move it forward (high pressure position) and aft (low pressure position).
Now turn on the ignition and check for proper movement of the solenoid.
With your foot off the gas peddle, the solenoid should be shifted aft. Cracking open the the gas should cause it to shift back to the center position. Control is via a switch on the throttle body that closes when the throttle flap is closed. That contact energizes the solenoid to command low pressure.
Next check the high pressure position (forward). This is controlled by the kickdown switch under the gas peddle. When you depress the switch by flooring the peddle, the solenoid should shift forward.
With all that working, you can now do the same checks, but this time with the engine running and checking the actual pressures. In the three positions, you should see pressures consistent with what the BBB calls for (sorry, I can't remember the valves). If they are off, then adjust the solenoid linkage as needed. You may also find that the solenoid and linkages need to be cleaned and freed up to get full travel.
Making these adjustments on my car transformed a seemingly junk transmission (slipped and wouldn't shift) into a like new transmission. No parts, just time.