Manual Trans Clutch Removal

[Tomnistuff]

I'm making progress on my 67 Italian 230SL restoration.  The engine is out and the transmission is removed in preparation for sending the engine to Metric for rebuild.

But I have a question about clutch removal.  I can, with time and effort, fabricate three hold-down clamps for "blocking" the clutch fingers, but would like to know if there is a "shortcut" method for keeping the clutch disk and fingers from moving while removing the clutch from the flywheel.  I've attached a photo of the clutch fingers with a sketch of a clamp on the photo to show what I mean.

One thing I do know is that it will be quicker to make the "hold-down clamps", as the BBB calls them, than to find them and buy them.  But is there an easier way?  Are they even necessary?

Tom Kizer

[Benz Dr.]

Well, a new pressure plate comes that way, with the fingers locked in place, but I've never put them back in if I remove one. The lock is a piece of heavy flat wire kind of like a big staple.

I usually install a new pilot bearing, clutch disc, throw out bearing, and pressure plate on all of my rebuilds. Flywheel should be ground not lathed.

[Tomnistuff]

Thanks, Dan.  I was so deeply involved in thinking about the body, chassis, and powertrain, I didn't even think about needing to replace the clutch.  I see that the Sachs Clutch Kits are pretty inexpensive at Rock Auto, at least by vintage Ferrari standards, and there aren't even any cross-border issues.

I'll twist up some coat hanger wire to get the right diameter and bend it into a square C shape, then use that to clamp the fingers, at least until I get the clutch apart.  I don't like spring loaded surprises.  A clutch spring would make a hell of a jack-in-the-box.

I thought there was probably an easy way, but I had an end-of-the-workday "senior moment".

Do you have a web site or a catalog?  I like buying Canadian.  Since I live here, even though I'm an American, I like to buy here, and especially from experts.

Tom Kizer

[Benz Dr.]

The clutch won't come flyiing out at you - trust me. Release the tension on the fixing screws a bit at a time on each one until there's no pressure.

No, I don't have a catalog. The pictures are often copied but are still copyrighted - I've had problems with MBC before so I stay away from those situations. Any place that has a catalog also has theirs copyrighted so it's not like you can use them for our own operation . It's very exspensive to have one done up properly. You can copy one but can't use it for sales.

I'm a K&K dealer so I tell people to use their site or catalogs as a reference. I take care of imports myself or I get my stuff from a supplier in Toronto. After 23 years in the parts biz, it's still never routine.

Contact me PM if you need any more help.

[tel76]

The last time i did this job(it was not on an MB) i used three 3/8 nuts placed between the outer cover and the centre in the position you see in your photograph,if you do not use something and the retaining bols are not long enough you could end up in A and E.

[Benz Dr.]

A and E? As in Arts and Entertanment?
Done the way I say to do it,  it won't fly back at you. The screws are more than long enough to release all of the tension before that would happen.

[Tomnistuff]

Dan was right.  Although I made the clips and installed them, there was more than enough thread to keep the clutch from springing off the flywheel.

In fact, in my case, you were even right in your suggestion, Dan.  Two things I noticed were that the clutch disc was stuck to the flywheel like it was glued on, and there was very noticeable wear on the pressure plate fingers where the throwout bearing contacts (as if the throwout bearing were stiff).  I suppose it's just coincidence that the three things that need to be replaced are the three things that come in a clutch kit, and that you said I should replace.  I don't know about the pilot bearing yet, but I'll replace it anyway, just for insurance - it's only about $6..

It's really comforting to get advice from someone who know what he's talking about.

Thanks again.

Tom Kizer

[GGR]

Flywheel should be ground not lathed.

I had an M116 3.5 flywheel ground. I then had to have the recessed area where the pressure plate bolts machined so that the difference remains the same. This had to be done on two different machines (in two different shops as none of the shops had the two machines). As a result the two areas were not exactly parallel, ie the pressure area of the pressure plate was not exactly parallel to the area where the disk sits on the flywheel. This was due to the fact that the second shop wasn't able to position the flywheel the same way the first shop did. There was no much difference and I was told the difference will disappear with wear. I was also told by the second shop that they have a customer with Porsches with the same issue so do both surfaces on the lathe. In practice they say it's just fine. I will have to have another 3.5 flywheel surfaced for another project. I am planning to do like the Porsche guy does. What is wrong in lathing rather than grinding a clutch surface?

Thanks for the help!

[Benz Dr.]

The flywheel grinder is a table that rotates and the disc that grinds the flywheel is cone shaped. The table turns slowly in one direction while the grinding cone turns at high speed in the oposite direction. The flywheel is mounted using a centering mandrel so that the flywheel runs true to the end of the crank shaft mounting holes.
Grinding is much prefered because it will remove all material regardless of how hard it is. Flywheels often get hard spots on them and the grinder will go right through those areas.
With a lathe the tool bit will tend to bounce right over the hard spots because it's almost as hard as the tool bit. By the time you remove enough material to get down to softer metal the flywheel will be machined past it's minimum thickness using a lathe.
 
I'm aware of what you refer to as a stepped flywheel. The two dimesions of pressure plate mounting surface and clutch plate running surface must be kept to a very strict distance so the clutch won't slip. The grinding machine will do both surfaces ( one at a time ) without removing the flywheel and will give you a prefectly flat surface in one pass.
By keeping these two dimensions at a pre set distance the pressure plate will be able to let the clutch disc spin when the clutch is pressed in yet still have full pressure when the clutch pedal is released.

[GGR]

Thanks Dan,

this is very useful, especially because these flywheels do not have much before ending out of spec.

The grinding machine will do both surfaces ( one at a time )

That's the thing. the recess is kind of a narrow grove and the gringing machine can't access there. Here is a picture of my flywheel installed after machining. You can see the markings made by the second shop:



I wonder if a grinding machine can get in there? If yes, why didn't the first shop do it?

[Benz Dr.]

What your picture shows is a stepped flywheel. The area with the cap screws is higher than the area with the markings on it. A grinder coud have done both of these surfaces without removing for a new set up so that both surfaces would be square to each other.

I imagine that they did't have a flywheel grinder or it would have been done that way.

[GGR]

What your picture shows is a stepped flywheel. The area with the cap screws is higher than the area with the markings on it.

No. the area with the cap screws is in recess between the disk area and the lip all around. The lip all around is used to center the cap.

[Benz Dr.]

Yeah, I think I see that now. I was referring to the standard six cylinder flywheel used on 113's. All of the V8's I've worked on have been autos - the 4 speed box is quite rare.

The main clutch surface could be ground but the lowered area might well have to be lathed. That area wouldn't normally have hard spots like the clutch surface area so it would machine readily. Not that familiar with this set up but it's like anything else - you figure it out once you get there.

[GGR]

Thanks. With what you told me I may do i again the same way or my other project. I dont want the lathe to take too much out as the spec limit is very tiny.