Endelig skal jeg få sett nærmere på 411 girkassen og problemene der, etter en helvetes tid med dødsfall, sykdom, jobb og arrangering av utdrikningslag osv..
Komplett kløtsj er bestilt av Dalhems (bra service) til ca 1800 kr og slavepumpe er oppdrevet, så i kveld er det ut med kasse og motor, har også en oljelekkasje jeg må se på. Fikk en lang avhandling av raygreenwood på Shoptalkforums om dette, i følge han, "drittslavesystemet". En fryd å lese. Mye kunnskap derfra. Kanskje andre kan dra nytte av infoen.
<I have been there and done this so many times over my years of driving...that I just hate the damn clutch slave system on this car.
A couple of things.
The master cylinder...as long as you have no rust pits in the walls...can be rebuilt simply by stealing the outer and one inner seal from any type 3 or 4 brake master cylinder...along with the brass compensation port flap valve. You apply these seals to your pistons. Then...DO NOT hone the cylinder. lap it with 1000-2000 grit paper or with felt and very ffine diamond paste. The object is a very smooth wall....not cross hatching. These are not piston rings. The smoother the surface the better.
Or.....
You can use the master cylinder complete from a Vanagon. By Vanagon...I mean...what...1979 to I think 1982...angular body....air cooled enegine. Either way...last of the air cooled with hydraulic clutch.
Its clutch master was the same diameter, stroke length and volume as the type 4. It mounted differently....but one glance at it and you will instantly realize that you can simply mate up an angle iron plate to it and bolt it into the type 4. Or...you can simply steal the guts from it.
The clutch slave is a different story. I'm working on something for this now. It may take a while. But...I have rebuilt several of these over the years from readily available SAE sized seals. Usually they are a little tight and not the optimum cup design...but they worked. The problem is getting thr proper seal material.
Your best best is to locate an NOS kit or a new or rebuilt cylinder.
that being said....it does not solve the issue that the lifespan of these slaves is short...and in a year or two you are back to square one.
If you pull out the piston, sit down with a beer and a caliper and look carefully....you will see the defects that kill it. I'll list them so you do not have to think or measure while you drink....
(1) Looking at the piston you will see that the seal is down near the bottom of one end of the piston. You will also note that the skirt of the piston or the thin end.....on the pressure side....is the exact same diameter as the main body of the piston :shock: :shock: :shock:
This should shock you...as it means that the only fluid that gets past the skirt to inflate the cup/seal....is NIL! This means that the seal has poor inflation and sealing pressure on the walls of the cylinder....and very poor lubrication. this makes for high wear.
The best fix for this is to have some machinist chuck the piston in the lathe and reduce the skirt diameter. Or....you can simply take a round file and make about 8 clean groves across the skirt so fluid can bypass to the cups.
(2) The long main body of the piston...is too long...and needs support. Bear in mind that both brake and clutch master cylinders operate the same way. The pistons themselves do not seal the bore. The cups/seals do that and also center the piston in the bore. In fact all of these hydraulic pistons have excessive clearance to the bore....by design. The pistons are simply the support for the sealing cups. The clutch slave is no different.
Because of the long body.....the outer end of the piston "droops"...and rides against the bore. On high milage pistons you can see the wear marks on piston and bore. This also causes the main seal to "@@@@" slightly in the bore...causing excessive wear.
The best solution I can think of...is to chuch that piston in a lathe...and have a band of material about .75" wide and about .020" deep taken off. You will then fill that band with a strip of etched backed teflon of .025" thick...adhered with epoxy. Its a low friction packing. It will keep the piston centered in the bore.
(3) The outer boot is poor. Its subject to too much heat and braking dust and is not high temo enough. It takes about 1-2 years and it gets crispy and pops loose...allowing dust in...that kills the bore and seal. It should be made of either thin silicone sheet wired on...or I can cast a stepped version that collapses into the bore on retraction.
One last thing that should be done.
The type of seal that is on the slave is s "shaft" seal. It has the inner seal collar just like the outer seal of a master cylinder to keep fluid from from bypassing.
There is a company here in the US I have done a good deal of business with in the past. They can make a duplicate of the seal. I have used their seals before to rebuild the slave. The problem is this:
In the past (early 90's) they did not have the correct materials. Life was short...though the seal worked great. They have the correct materials now.
The other problem is that their seals are relatively high durometer...because they are cut from block material in a CNC multi-axis lathe. They do beautiful work...but the seals will be stiff enough that getting them on teh piston...will destroy a number of seals. I destroyed four getting one to work.
The ideal thing...would be to have the machinist...remove the seat end of the piston...the skirt end...with a sharp tool. Them..we install it back on with a center mounted screw...and a locating pin. All of that can be done on a drill press at home. In this manner..the seals can be bolted right up.
To do this.....you are probably looking at about $125 initial cost for design and layout and about $8 each per seal in a batch of about 50-75 seals.
That equals out to seals at about $10 each...of the right materials and dimensions.
I can make the teflon packings for about ...oh...lets see.....about 30 cents each....or 61 per 24" x 12" of material....in about 30 minutes.
I can recommend silicone sheet for the boot....or get busy casting one if everyone is serious.
If enough people are serious about a solution.....I can organize a group buy, make the teflon strips.....and draw up the machine sketch. The only two steps I would have the machinist do to save money...is remove the skirt and cut the band area for the teflon packing. Most friendly machinist shops can do this for maybe $50.
I found that just adding grooves on the skirt works great...and you can do the bolt and drilling at home.
In this respect...we can have a rebuildable slave. Ray>
