Late 411/early 412 clutch slave cylinder kits (44.5mm)

[raygreenwood]

OK....bear with me for a minute here.

Over the years I have found an even dozen ways to get replaceable seals for our late 44.5mm clutch slaves...what few of us use them.....mainly by looking for another clutch slave that we can slap in with minor mods.

1. Virtually all of them will take at least a mounting plate bracket...no big deal.

2. Virtually all will be a smaller diameter piston and higher clutch pedal pressure...yeah...probably even better. As smooth as the late slave cylinder is...it gives and almost limp pedal feel even though it works perfectly.

3. virtually all of them will require some work to the throw length to get the stroke right...still no big deal.

4. About half will require a different size or type of fitting.

Lately...the best contender for a readily available clutch slave that can be installed with minor work has been the Golf/Jetta Mk 5 and 6 slave. A quality one can be had for about $116 for genuine VW, About $79 for Dorman and a few like Febi for $50.

These will require a plate and some shims to install and set stroke and a fitting adapter.

So that answer is a bit of work. It will not drop right in but should work well. It does not look stock...but should function well.

So lets say if you could get a kit that would would fix your existing 44.5mm core....so it drops right back in....and it would give you factory fresh bore surfaces, a new piston and seal (and lets say even a spare seal) and a new outer boot (made of much better silicone so it would last for ages)....would about $90 to $100 be fair for that?

Yes...I'm trying to judge interest here.

So....the same company that made 100 ATE caliper half o-rings for me of proper EPDM about 4 years ago (superb work and great price).....can and will make the 44.5mm seal for me.

They will be $12.80 each if I order 25 and $10.22 each if I order 50.

The problem(s):

1. The seal they can make is identical in every measurement (44.4mm OD X 32.0mm ID X 9.27mm Height)....but it does not have the inner cuff like the stock slave cylinder seal has.

This is what they can make in the correct size...with no set up charges. Its a stock size.

These slave seals are just like the outer seal on brake and clutch master cylinders. They have a standard U-cup profile with a single lip that rides on the cylinder bore....but have an inner "cuff" that seals tight to the shaft.
All clutch and brake master cylinders have this type of seal on the outermost piston. The clutch slave has it for the same reason.

It is a combined piston and shaft seal. It keeps fluid from migrating through the center along the ID of the piston when pressure is not on it. It keeps air from seeping back in and protects things like clutch linings and power brake units.

An inner master cylinder piston seal...which is similar to the profile they are suggesting. Only one lip and no inner cuff

The outer "double lip" master cylinder seal. Out slave seal is like this...kind of.

This is an actual slice of one of our slave seals nextto a drawing of the seal groove for dimensions.

Now...I have put 10s of thousands of miles on the same type of seal they are offering...no inner cuff like the one above.... in my 411 and 412 slaves...and they work excellently......but what it does is begin to seep just a little bit by about 2-3 years and 25-30k miles.
It does not suck air per-se...but it basically begins to seep fluid around the center ID of the seal due to normal slight rubber shrinkage. You slowly start to get fluid in the boot.

But....I will also list the company name.....and they can always make this seal in ANY quantity...its just a $100 minimum order. So its replaceable. Need seals....get a group buy of 4 people and everyone gets 2.

I can also have them make it 0.5mm smaller on the ID and it will last a longer time but is also harder to install. I had this done years ago and even added a packing 0-ring.

2. I measured two brand new/NOS slave bores I have and they are .0045" and .005" larger than the piston. Virtually all of the 10 cylinders I have are somewhere in this range.

This explains a lot really. Pistons like these have the same tolerances as master cylinder piston to bore tolerances.

Ideal is between .002"minimum and .0035" best. Tolerance of .004" to .0045" will work fine but leaves no margin for rebuilding or an odd piston kit...and .005" will function but will leak as the seals age...and is technically the wear limit.

I actually do not want to put new seals (that will be prone to leak slightly from the center in 2-3 years) on old pistons in old bores that may be at the limit for bore leakage already.

So...if I am going to make this kind of change....getting replaceable seals but making a "soft" compromise......what else or how else could I fix it?

Lets say we are staying with the 44.5mm:

Method #1:

OK....so as mentioned before..... I can plate the bores with nickel back to better than stock and hone them with 800 grit. If you never scratch them they will last until after you are dead. Hard as a rock and no rust.

Plating a batch of 10 cylinders will cost $25 each give or take a few pennies.
The seal...$12.80 X 2....because I'm giving you a spare. The outer boot will be about $4-6. Call it $6 for now.

Thats about $56.60. Thats just baseline parts and chemicals etc. It may be slightly higher. Call it $70 per cylinder at most.

I'm not here to make any profit. I want parts three spare cylinders with seals for myself from my pile of stuff...and me paying right alongside with the total.

HOWEVER........thats a lot of work I am willing to do to be able to get help to pay for the seals and parts.
The plating chemicals are about $250 with shipping. Its $320 for the seals...about $35 for the high temp silicone casting and a few dollars here and there to make molds.

and....its still the same limp pedal.....

Method #2:

Mind you...this will be the same seal profile without the cuff...meaning about every 2 years...you should just spend and hour and a half liter of fluid and change the seal.

I can get any size seal in this profile. So....bear in mind that the original 411 slave piston was exactly half the diameter...22.25mm. It had a slightly different leverage point...but ran with the same master cylinder.

I could....have press in or shrink in stainless bore tubes machined....to reduce the bore diameter. Let say to 35mm. MUCH better pedal pressure.

I can have new pistons machined from aluminum....same linear dimensions ..length...seal groove...just a smaller ID and OD....say 35mm OD and 23mm ID and 9.27mm seal thickness.

I would hand hone the bores to match each piston in the .002"-.003"...before pressing them in.

I'm looking into this....but...it would probably be from speaking to some machinists...about $30-40 for each sleeve, about $35 for each piston....add in the $25.60 for two seals and $6 for a boot. I should add in an extra boot for $6.
So about $100 to $112...possibly less...for a cylinder that drops right in...has stainless bore....new piston and tolerances...and a replaceable seal....and MUCH better pedal feel.

Both cylinders would last forever...just needing a new seal about every 2-3 years.

Or.....Method #1....plus having the correct double lip seal made which along with CAD design...might double the seal price at least in the short term. But it would be about the same price in the future but will still have to be made with minimum orders of $100

Your thoughts?

Ray

[vwrenault]

COUNT ME IN I HAVE 1 MORE SPARE ..

[raygreenwood]

Part 2

So....sitting in another airport now....been working the possibilities over for 2 days.

So interesting revelations:

1. The only reason I am keen to change to a smaller piston is....because the 44.5mm is just a really poor pedal feel.

But...... 2 nights ago....I was watching a write up on the 2018 VW Golf R. They noted that the inputs on the car are so processed.....that even the clutch pedal release timing is augmented to be flawless.

So.....hmmmmm. So I thought.....if all I am bitching about on the 412 is the pedal "feel" and not the "function"....why not cook up a spring that mounts on a bracket under the dash on the pedal cluster.....to augment the pedal feel...make it stiffer...just at the point where the release bearing starts to move the diaphragm? It would be easy to make adjustable so that you have a "break point" feel on the pedal. Thats all I'm looking for.

2. So with that in mind....I'm staying with the stock diameter...44.5mm. That makes things simpler and cheaper.

The cylinders still need to be honed and then plated back to stock specs.
Since I will be doing electroless nickel on the bore....I will also be doing several clutch master cylinder cores at the same time and probably a few brake master cylinders too.

The object of plating the bores it two fold....and very important in my opinion.
A. It brings the bores back to stock specs.

B. and makes them 100% rustproof. And since this plating will be baked and then final brush honed to exact size and surface......This means that as long and you never scratch through the plating..........the cylinder will NEVER rust and NEVER need to be honed again. The pistons do not touch the bore so they will not wear through it or wear out.

So every few years...whether its a brake master, clutch master or clutch slave....you may need to install a new seal.....but thats it. Call it a "forever cylinder".

3. So...back to the 44.5mm. Talking to the guys that make the seals....if I install an EPDM "backing washer"....or packing disc.....which goes where that lower shaft seal cuff would on our original seal.....it can prevent inner bore leakage for the most part.

It also costs pennies.

4. The other company I know can CNC machine these seals just like the factory seal.....but they have to be made of a higher durometer (harder) EDPM. That means the back of the pisyin will have to be made removeable.....machined off and installed with a center stud....easy to do....I outlined it in my other thread last year......but waiting on a cost estimate for that one.

4. I also noted last year in my other threar that these pistons have the issue of wearing the edges and leaking because they "cock" in the bore.
Part of this is the oversized bore tolerances....and the issue that the piston bores are close to oversized even new....but also due to the fact that the seal is so far to the rear and the nose of the piston is so long....and the pushrod to the clutch fork moves at an angle due to its arc....and rattles the piston in the bore.

So.....Since the seal company can offer me nylon "guide/wear" rings for only a couple bucks each.....I am thinking of having the pistons chucked in a lathe and have a 0.065" wide groove about .080" deep cut around the outer end of the piston ahout 1/4 from the end....and snap in a nylon centering guide. Keeps the pistons centered and straight in the bore.

Then.....I found a shop that can give me a good price on hard anodizing the pistons. This makes them last forever....really. and will bring the bore tolerance up by about .001"....which makes the nickel plating less....and cheaper.

So these cylinders will be zinc plated outside....nickel plated inside....hard anodized stock piston.....with centering/glide ring....new seal and backer packing X 2....plus a new high temp silicone boot.

Thinking maybe in the $80 ish total range. Ray

[raygreenwood]

An update to my update:

Sorry I was in the airport posting from my phone so I had no access to my pictures.

From my earlier post: