Why do we need a slave and master clutch cylinders?

[Totally 80s]

This is probably a really dumb question as I am no mechanic but I was working on my 66 VW Bus clutch line today and it begged the question. Why does a simple lever work on a VW Bus/Bug but not on a Delorean? Why couldn't the clutch on these cars be designed to simply move a cable to open and close the clutch pin?

The Delorean clutch mech is so clumsy and complicated (and stiff). Would one of you mechanical experts school me on why a simple cable wouldn't work on these cars but it does on a VW Bus?

[mark w]

the difference is 20 year plus of mechanical engineering between your bus and the D. Hydraulic systems wear less over time, and have good "feel".

hydraulic activated clutches are still in use today (when you can find a manual) while cable kinds are long gone.

why do you think its clumsy and complicated? its not...

the only bad thing was the use of the original plastic line easily remedied by use of a stainless one. Stiffer than the bus? well thats your perspective, mine is not. The more powerfull the engine, the more clamping force is required on the clutch thus usually a stiffer feel, but not always.

[Totally 80s]

My bus cable lasted 50 years and 80,000 miles my slave cylinder died at 25,000 miles not sure I am in agreement with the D wearing less over time.

By clumsy & complicated I was talking about the placement. It's a nightmare changing a slave cylinder. I wish the slave was easier to change and work on.

Your vintage VW bus clutch is stiffer than your Delorean? Mine is light as a feather. What year/model do you have?

I guess my question is would a cable driven clutch line work on a Delorean? Is the 130 HP too much for a cable system? Or was the car too luxurious to put an old fashioned cable system in? The cable set up is so incredibly simple it just made me wonder.

You are right about the "feel" The Bus has very little "feedback" where the Delorean you know right where that clutch grab is.

the difference is 20 year plus of mechanical engineering between your bus and the D. Hydraulic systems wear less over time, and have good "feel".

hydraulic activated clutches are still in use today (when you can find a manual) while cable kinds are long gone.

why do you think its clumsy and complicated? its not...

the only bad thing was the use of the original plastic line easily remedied by use of a stainless one. Stiffer than the bus? well thats your perspective, mine is not. The more powerfull the engine, the more clamping force is required on the clutch thus usually a stiffer feel, but not always.

[Gfrank]

My bus cable lasted 50 years and 80,000 miles my slave cylinder died at 25,000 miles not sure I am in agreement with the D wearing less over time.

By clumsy & complicated I was talking about the placement. It's a nightmare changing a slave cylinder. I wish the slave was easier to change and work on.

Your vintage VW bus clutch is stiffer than your Delorean? Mine is light as a feather. What year/model do you have?

I guess my question is would a cable driven clutch line work on a Delorean? Is the 130 HP too much for a cable system? Or was the car too luxurious to put an old fashioned cable system in? The cable set up is so incredibly simple it just made me wonder.

You are right about the "feel" The Bus has very little "feedback" where the Delorean you know right where that clutch grab is.

Mustangs still ran cable clutches up into the 00’s. Plenty more hp and much stronger clutches. Can’t say I’d want a cable that long in a Delorean. Likely be fairly awkward

[Rich]

Three additional points about these two types of clutch actuation.

1. Engineering: Routing the actuation system from the footwell are to the clutch - wherever it happens to be - is generally simpler with hydraulics.
2. Maintenance: Clutch cylinders fail mainly because owners don't manage to flush/fill the system every 2-4 years. Properly cared for they last decades.
3. Adjustment: Mechanical systems need to be adjusted so as to maintain the correct amount of free play at the top of the pedal travel. Hydraulic clutches don't need adjustment.

And, yes, the location of the slave cylinder in the D isn't great. Bleeding the clutch is something I'm happy to pay my local shop to do. Regularly. Half an hour of labor. No biggie.

[Totally 80s]

Three additional points about these two types of clutch actuation.

1. Engineering: Routing the actuation system from the footwell are to the clutch - wherever it happens to be - is generally simpler with hydraulics.
2. Maintenance: Clutch cylinders fail mainly because owners don't manage to flush/fill the system every 2-4 years. Properly cared for they last decades.
3. Adjustment: Mechanical systems need to be adjusted so as to maintain the correct amount of free play at the top of the pedal travel. Hydraulic clutches don't need adjustment.

And, yes, the location of the slave cylinder in the D isn't great. Bleeding the clutch is something I'm happy to pay my local shop to do. Regularly. Half an hour of labor. No biggie.

Number 3 is a huge disadvantage especially if you are trying to sell a luxury vehicle. In a VW it's just assumed you gotta adjust a bunch of stuff from time to time. So it was engineered to be as easy as possible to do so. It would probably be just as bad trying to adjust a clutch lever cable in a Delorean as it is replacing the darn slave.

[Ron]

+1 Rich
simpler = less moving parts to wear out too.

=====

Could be way off here, but it sounds to me like you (Alex) simply don't like the feel. Which brings up another point- You can probably get an aftermarket hydraulic MC/Slave set up with different bores/strokes/etc. to get closer to the feel you want...I'd say easier than re-doing it with a cable system, especially considering where a D's slave is located.

[DMCVegas]

My bus cable lasted 50 years and 80,000 miles my slave cylinder died at 25,000 miles not sure I am in agreement with the D wearing less over time.

By clumsy & complicated I was talking about the placement. It's a nightmare changing a slave cylinder. I wish the slave was easier to change and work on.

Cables go bad, and require adjustment. Where your bus was located, and what conditions it was operated in most likely have had a huge effect upon it's longevity too. Particularly when compared to the DeLorean.

And if you think the DeLorean's slave cylinder placement is bad, stay away from Ford trucks. Or you know what, take a look and see the nightmare that is the concentric slave cylinder to better appreciate how the DeLorean got the long end of the stick when it came to hydraulics.

Getting down to it though, cables require allot more brackets and adjustment points to implement in a vehicle. So that can drive up the cost and complicate the installation. Whereas a clutch line just needs some plastic clips to hold the bent or molded tube into place. Hydraulic systems also do not require all of the tinkering and adjustment that cable needs. The only prep needed is to bench bleed the cylinder, and then just bolt it all into place. Connect up a pressurized tank full of brake fluid and just bleed out the fluid until all of the air bubbles and old fluid is gone. That's it. Sure, you repeat it every couple of years, but it really isn't that bad at all.

Cables can have other issues such as freezing if water gets inside, and then eventual breaking. Again though, that's a factor that also depends upon the operating conditions. If you're in the desert, you'd probably never see that kind of issue compared to living in the rust belt.

[Bitsyncmaster]

It's really not bad replacing the slave if you pull the mixture unit. Pulling mixture unit takes about 30 minuets. Bleeding is a breeze if you have a bleeder extension like John sells.

[David T]

And if you have an automatic it is not a problem at all (other problems but not clutch problems!).