Author Topic: Restoration Difficulty Level (Read 895773 times)

Larry & Norma · « **Reply #1675 on:** December 30, 2015, 10:14:05 »

Is one of those arms round the wrong way? The bottom one looks to be different than the other two.

andyburns · « **Reply #1676 on:** December 30, 2015, 18:45:28 »

Hi Larry. Thanks for that good spotting, it does look different in the photo. Not sure. I do know with 100% certainty that I never disassembled the plate. Just cleaned it up the best I could which is why it had rust on it.

Benz Dr. · « **Reply #1677 on:** December 30, 2015, 19:37:07 »

Arm is installed correctly.

andyburns · « **Reply #1678 on:** January 14, 2016, 04:52:42 »

made a start on removing the gearbox. Feels bloody good to be back on the tools again. First time in over ten months. Just like riding a bike. No chance of getting it ready for the car show this weekend but a start. Feeling much better

Tyler S · « **Reply #1679 on:** January 14, 2016, 16:17:28 »

A seized Pilot Bearing can also cause this. The trans input shaft gets seized to the engine. You mentioned bearing noise when the clutch was pushed in. Chances are your release bearing is seized or intalled backwards and finally ate its way through the clutch fingers.

andyburns · « **Reply #1680 on:** January 15, 2016, 20:55:18 »

Pick the problem. Was immediately obvious. Looks like just incredibly bad luck..

andyburns · « **Reply #1681 on:** January 15, 2016, 22:50:21 »

I have just had a really nasty thought. When I replaced the slave cylinder the one that was supplied to me was longer that the one I took off the car. If you remember I had issues fitting it and had to source another shorter push pin. I have just noticed on Buds site that there are two cylinders, one for the 230/250, and a separate one for the 280. This matches up to the difference between the pressure plates for the three models as well..

If you look at the damage to my pressure plate it would be explained by the hydraulic system over throwing the clutch fork and loading up the pressure plate. I am wondering if the 280 pressure plate has more travel than the 230/250

It kind of makes sense that with a longer body the new cylinder has more travel. Kind of works that way with hydraulics doesn't it?

Can we open this discussion up to some of you experts out there. I will go back to the vendor and see what they say.

Note the first two are of the damage finger mechanism. The last is of one of the remaining intact one for your comparison.

Benz Dr. · « **Reply #1682 on:** January 16, 2016, 19:37:39 »

I have to say that I've never seen this in the 40 years I've been working on these cars. I'm working on a 230SL right now that has a 280SL pressure plate so it would seem that some parts can be mixed and matched like this but I think you have to stay with the right slave cylinder relative to the throw out bearing you are using. A 230SL trans will only fit a 230SL style throw out bearing. The 280 throw out bearing fits to a larger boss on the input cover of the 280 trans and these to versions are not interchangeable.

My own car, uses a 280SL pressure plate, a 230SL throw out bearing, and 230 slave cylinder. It seems that the ZF 5 speed only uses a 230SL set up which is more than adequate for compressing the heavier 280SL pressure plate. When I first bought the car it still had the 230SL flywheel and clutch parts but it wouldn't hold the torque from my fresh rebuild on the 250SL engine that had already been installed when I bought it.

Not that I have any intentions of selling my car but I can just imagine anyone tying to order parts for it.

andyburns · « **Reply #1683 on:** January 23, 2016, 02:39:01 »

New Sachs pressure plate obtained. After quite a bit of research on am now sure that my new master clutch is correct 230sl but the new slave supplied by the same vendor is looking like a 280sl. Really don't want to clamp it back on of it was the cause. As Dan pointed outout this is a pretty unusual problem. Gut tells me there will be a reason. Everything else was textbook. The old clutch plate was new. As was the pressure plate having only done a thousand k. I set the free play on the pin to mercedes recommend 2mm when I put it on. My mercedes parts guy here in nz looked at my slave and thinks it's aftermarket. Do I ditch it and go oem?

GGR · « **Reply #1684 on:** January 23, 2016, 03:14:05 »

The length of travel of the piston in the slave cylinder is linked to the amount of fluid pushed in by the master cylinder. So no matter the length, the important factor here is the relation between the master cylinder diameter and the one of the slave cylinder. The bigger the diameter of the master cylinder, the more fluid it will be sending. The smaller the diameter of the slave cylinder, the more the piston will travel and push on the pressure plate. Diameters are noted in the workshop manual. You should check them both.

Tyler S · « **Reply #1685 on:** January 23, 2016, 03:15:48 »

Andy, Earlier before all of this, You mentioned bearing noise when pushing the clutch in. What does the throw out bearing look/feel like?

Benz Dr. · « **Reply #1686 on:** January 23, 2016, 08:24:21 »

The clutch on our cars is self adjusting and once you get the free play set up correctly it will always stay adjusted until the clutch plate wears out. On a mechanical linkage set up ( like a 190SL ) the free play needs to be adjusted once in a while to take up plate wear.

I know this info isn't part of this thread but I feel it's noteworthy.

tel76 · « **Reply #1687 on:** January 23, 2016, 10:48:58 »

Quote from: Benz Dr. on January 23, 2016, 08:24:21

The clutch on our cars is self adjusting and once you get the free play set up correctly it will always stay adjusted until the clutch plate wears out.

What you have indicated above is not correct, the early system (the type with the return spring) does require adjustment on the slave cylinder through out its life, failure to do so will result in a slipping (knackered) clutch.
The later version (from 67/68?) does not have a return spring and is self adjusting. There is a procedure with the later system that enables you to ascertain when disc replacement is required.
You may like to amend your post.

Benz Dr. · « **Reply #1688 on:** January 23, 2016, 19:39:44 »

I'm not sure about that. I agree that there's a place to adjust the free play to get your initial set up on a 230SL. I've seen a number of 230SL cars that didn't have a spring on them and they seemed to work OK so that's where I'm coming from. I assume the spring is there to pull the throw out bearing back away from the fingers on the pressure plate and may well pull the piston to the bottom of the cylinder but is it really needed?

Wouldn't the slave piston on a 230SL act in the same manner as that on a 280SL? Free play is set at the clutch pedal eccentric and on the push pin on a 230 but not a 280. Once the system is properly bled and adjusted a small amount of brake fluid will enter the system to take up for wear. The piston in the the slave cylinder will move out in the cylinder and come to rest in the desired position ready for the next shift you make and is therefore self adjusting.

Tyler S · « **Reply #1689 on:** January 23, 2016, 22:15:50 »

On models with a return spring on the slave, The fork will always be pulled back to the same position regardless of wear so on those you would need to adjust the eccentric bolt at the pedal. That is once the slave cylinder pin has been adjusted properly, with the piston at the bottom of the bore, It will always end up at the same place so no additional adjustment of that area will be required.

tel76 · « **Reply #1690 on:** January 25, 2016, 20:53:48 »

TS, I still maintain that on the early type slave cylinder with return spring you have to adjust the free play at the slave cylinder during the life of the clutch assembly for the following reason (or you will have slippage) -
With the clutch system at rest and with the return spring in position the slave cylinder piston is at the bottom of the cylinder and will go no further down the bore, you then remove the spring, push the clutch operating fork until the throw-out bearing comes into contact with the pressure plate fingers (it is worth noting that you cannot see this visually you have to do it by feel), you then adjust the length of the operating rod to give you the required free play (approx.: 1/8 inch, the correct figure will be in the workshop manual), you then replace the return spring.
With this work completed you will have a small gap between the throw-out bearing and the pressure plate fingers .
In service when the clutch is in use the friction material will wear and the gap between the pressure plate fingers and the release bearing will decrease, eventually the fingers will come into contact with the throw-out bearing, this will result in the clutch starting to slip and if the push rod is not adjusted the clutch friction disc will burn out. So it is very important that at the recommended service intervals this free play is checked.
The later type without the return spring is different there is no adjustment on the operating rod, the slave cylinder's pistons position in the bore is reliant on the length of the operating rod, with the later system it should be noted that when the piston is in the slave cylinder bore it is not at the bottom of the slave cylinder and also the throw-out bearing is in light contact with the diaphram type pressure plate.

Naj ✝︎ · « **Reply #1691 on:** January 25, 2016, 21:04:07 »

Eric is right.
You will find the clutch free play instructions in the 230SL Owner's Manual, maintenance section.
The push rod should be 2 piece, a solid rod drilled and threaded with a bolt to adjust the effective length and of course lock nut.

naj

Tyler S · « **Reply #1692 on:** January 25, 2016, 21:13:55 »

I see what you mean. I was thinking about it backwards.

Benz Dr. · « **Reply #1693 on:** January 25, 2016, 21:22:21 »

So, if you remove the spring it should respond in the same way the 280SL unit works. Right or wrong?

tel76 · « **Reply #1694 on:** January 26, 2016, 08:29:04 »

Wrong

Benz Dr. · « **Reply #1695 on:** January 26, 2016, 18:59:47 »

OK.... Why?

tel76 · « **Reply #1696 on:** January 26, 2016, 20:41:43 »

The return spring is fitted to return the piston to its resting position at the bottom of the slave cylinder when the clutch is not in use ie when cruising , this will ensure the gap remains constant between the throw-out bearing and the pressure plate fingers, this results in there being no contact between the fingers and the bearing(the bearing is stationary)
As I am sure you are aware there is a residual pressure existing in the hydraulic system, if there was not the rubber seals would not function.
If you were to remove the return spring this residual pressure would allow the piston to move forward forcing the clutch fork to move forward (plus normal driving forces will allow the throw-out bearing to move forward ), this would in turn allow the throw-out bearing to come into contact with the pressure plate release fingers, the bearing and the fingers are not designed to be in constant contact and would accelerate wear on both items.
The later diaphragm pressure plate has a flat surface that the release bearing can come into contact with, both items are designed and manufactured so they can be operated for extended periods in LIGHT contact with each other (when the clutch is not in use ie when cruising), not so the early type with fingers, if you were to operate the early system in this way you will get premature failure.

andyburns · « **Reply #1697 on:** February 03, 2016, 02:17:09 »

Can anyone tell me the torque setting on the bolts that secure the clutch pressure plate.

WRe · « **Reply #1698 on:** February 03, 2016, 14:17:49 »

Hi,
I didn't find any torque settings for the clutch pressure plate neither in the Mercedes table books nor in the workshop manual ("just tighten"). Maybe this general info will help you: http://www.torcup.de/index.php?id=104.
...WRe

Tyler S · « **Reply #1699 on:** February 03, 2016, 18:34:33 »

No torque spec, as stated above.
Going back to the original problem with the clutch, Is it possible that the orientation of the pressure plate was installed differently then when it was removed? There was a question above about one of the fingers not looking correct. 25-1/3 of the BBB shows that an adjustment of the 3 clutch fingers is needed when installing the pressure plate. Is it possible one of these was too tight and broke from the stress of not being even with the other 2, or reaching the end of its travel? Attached is the page out of the book. See the "Note" section. This is just a thought.

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Author Topic: Restoration Difficulty Level (Read 895773 times)