Clutch adjustment

[gugel]

Is it possible to adjust the clutch so that it engages earlier as the pedal is raised?

Mine engages almost at the very top of the pedal travel.  There's no slippage at all, but I'd like it to fully engage sooner.  (All parts were new just a short time ago).

Chris

[Benz Dr.]

You can adjust that out. What model do you have?

[gugel]

You can adjust that out. What model do you have?

1965 230SL, Euro model

[jaymanek]

When I changed my gearbox recently I found that the "pin" between the clutch yoke and slave cylinder was too long... this meant my new clutch was slipping.. It didnt look like the original, it looked more like a long bolt that someone has cut down... So i cut this down further and my clutch is now perfect.

[georgem]

You can adjust that out. What model do you have?

Dan,

How do you adjust it?

cheers

[Naj ✝︎]

The push rod on the 230 slave cylinder is adjustable.
The specs are in the owners manual and early BBB
Sorry, too long ago since I owned one to remember the spec.

naj

[ja17]

Hello,


Remove the clutch slave return spring and adjust the rod at the slave cylinder so you have  just a bit of play 1/16" to 1/8" (at the adjusment rod). You should be able to feel about 1/2" of play at the top of the pedal travel,  ( with slave cylinder spring back on)

As the clutch disc wears, the fingers on the pressure plate move outward making the distance between the throwout bearing and the fingers of the pressure plate smaller or gone altogether. As a result the freeplay at the slave cylinder rod disappears. At some point the throwout bearing stays engaged instead of fully moving off the pressure plate fingers.  Full pressure is no longer exerted on the clutch assembly. Results can be uneccessary wear on the  throwout bearing, and clutch assembly. Pedal action may also become  incorrect.  

Naturally it is important that the hydraulics are working correctly  also.  The rubber clutch hydraulic hose, will eventually  become restricted with age (like the brake hoses) causing a slow reacting pedal or a pedal whichh is too firm.

Since normal clutch wear will cause the rod adjustment at the slave cylinder to become tighter (wears tight),  the clutch adjustment should be checked at intervals to make sure it has not become too tight.

[Benz Dr.]

Joe,
I always thought that the clutch free play was self adjusting. After you have the base set up the slave piston will move out as the clutch disc wears. Since this is a very slow movement, it sort of self adjusts as the piston moves every time you press the clutch in and the base measurement always stays the same. Either that or I have it all wrong after believing this for years.

On a 190SL I can see where you would need to adjust it every now and then because it's all mechanical linkage. Even on those cars it's not very often that they need to be adjusted. Maybe every 10,000 miles?

[georgem]

Joe and Dan,

What about the pedal itself- probably the most complicated pedal mechanism I have seen (compared to MGs, Austin Healeys and Jags that is).  Is there any adjustment for pressure or travel?

Cheers

George

[jacovdw]

George,

There is an eccentric bolt (the one the pedal pivots on) on the pedal assembly that is used to adjust the clearance between the pedal rod and the clutch master cylinder.

It has a notch machined on the hex portion that indicates the point of maximum eccentricity. It is adjusted by loosening the hex clamping bolt on the opposite side and turning the part with the notch to achieve the 1mm clearance required between the pushrod and master cylinder piston, taking into consideration that the notch must face to the rear of the car.

While you are in there, you may as well clean things up a bit and give the cam bolt a bit of lube.

Be warned though, very awkward angle to work if you are a bit tall...

[ja17]

Hello Dan and George,

Thanks for the input. I do get some information mixed up from time to time. The mechanical clutch systems (190SL) do require a lot more maintenance and adjusting than the later hydraulic set ups which are nearly maintenance free.  

My thoughts are; since the clutch pressure plate fingers move outward pushing the throw out fork with it, the distance between the fork and the back limit of the slave cylinder does become smaller.  As you say the slave will self adjust. This self adjustment is limited to how much play is initially adjusted at the rod. It is imoportant to make sure some play is present or the clutch pressure plate and throwout will be under load when they should be at rest.

If you go to the early BBB  (Workshop Manual Starting Aug 1959) Job #29-6 you can find a very extensive adjustment procedure for the hydraulics and the mechanical clutch pedal excentric spring assembly (over five pages of info).

"In the case of the hydraulic clutch acttuating mechanism, the clearance between the piston rod and the piston of the supply cylinder and also the free play between the push rod of the extraction cylinder and the throwout bearing at the release levers of the clutch must be checked and adjusted."  


As George has indicated the excentric spring pedal assembly is complicated. I find that it is not normally the cause of any issues unless it has been tampered with. Most likely a problem with the clutch, or the hydraulics , or slave cylinder adjustment is the root of most problems.

I can see that increasing the play at the slave cyllinder will also make the clutch peda; engage lower to the floor, but an adjustment out of specs could cause the pedal return to react differently.  

[Benz Dr.]

Hi Joe,
that's the way I understand it to be. You need a small amount of clearance on the push rod coming from the pedal so that the piston will be at its full upper limit. If it isn't, the fluid pressure won't be able to escape and release once the pedal is fully retracted.
If there is too much free play or the fluid level is low allowing air to enter the pedal will go over center all the way to the floor. It's almost impossible to pull it back up unless you stop the car and do it by hand.

 Once the system is properly bled and everything is adjusted it will work without any problems. Fluid should be flushed out every year or the master and slave will start to rust inside which will produce leaking.