C4inLA

My curious questions on slave cylinder function, indulge please;

A) When rebuilt on shop table, can you actuate full travel of piston? Curious, what is full travel (retracted/extended), appx mm?

B) ever try to engage diff and test wheel rotation by simulating slave rod, ie well matched philips screw driver?

C) assume purpose of spring (extends on PDAs lock commands, Spring then recoils, necessary when hydraulic pressure is released to pull back rod?

Goughary

The piston just slides out under pressure. And gets pressed back by resistance from the clutch pack. There isn't anything to it. Look at the parts in the pictures. It's a very simple devise w no brain. If it moves and doesn't leak, it's fine.

tdiquattro

I believe the factory adjustment calls for exactly that; a certain travel on the rod should give a certain required friction in the clutch pack. It is documented in the porsche service notes.
There is a special tool that bolts up to the hole I think.

Then the clutch pack is assembled with a range of packing plate thickness to give the required resultant friction.

The actuator is pumped up by the system in operation, the very high pressure hydraulic fluid is turned on and off. 20 times is full extension I seem to remember, so the system gradually applies full lock depending on conditions/slew/wheel rotation. I found that interesting as I always assumed they were either on or off. I wonder what the light on the dash signifies? some operation/full operation?

Goughary

Light on dash is "any operation". It's either on or off letting you know it's doing something. They took it off because it's on every time you hit a bump due to the accelerometers...

FlyinTomato

Rob, I ordered the koni kit to redo my suspension. what else shoud I do while at it? dont want to turn to a big project tho

Goughary

Depends on what a big project is...

Gimmie a shout this week and we can discuss

Goughary

I didn't write anything yesterday. Did some painting of some parts and some cleaning...

Did the brake lines, switching them all to Goodridge braided lines.



And then we decided it was a good idea to replace the oil pressure sender seal. The o-ring came out shrunken, and like a hard piece of plastic. This thing was spitting oil everywhere. So that was a pretty easy job. We took out the airbox weeks ago for the struts to come out. And so all we had to do was to take out the right side intake and the ac bracket. And aside from some extensive cleaning before removing anything, it just came right out with ease. We then broke the old brittle oring off and put the new one on and buttoned it up. Done. I was expecting more to go wrong, but it was all pretty simple.

C4inLA

I saw a reference to the "20" actuations in the test tool. Can pulse one at a time up to 20. Not sure how that works with evaluating the result per pulse.

Perhaps in 2016, a C4 owner somewhere in world will do a teardown of the torque transfer unit specifically, so we can get an up close visual of all the parts and pieces including the inspection and assembly of that suspect planetary gear section. Of course, this would mean they may have mushed it

MikeP.

Looking forward to getting some of the parts in that are holding up reassembling the lobster rocket. Must REALLY be missing the car, because I ran across and bought a '91 C2 Targa yesterday. Looking forward to doing a little sprucing up on this one owner car and driving it this summer.

I hope no one makes me an offer I can't refuse Rob.

Porschenut_Lee

Congrats Mike! Sounds like Rob gave you the 964 sickness!

Goughary

i found this today -

http://www.406coupeclub.org/Files/Ho...0callipers.pdf

he says its "essential" to use thread locker on the bolts that hold the spring plates in - Ive read elsewhere that guys are using copper antiseaize on the same bolts to make it possible to remove them to clean behind the plates on the next pad change - thoughts? I get it - that you don't want the bolts backing themselves out - but would they? could they?


any brake-rebuild experts wanna chime in?

gavonder

That's a great article. In the past, I've rebuilt many calipers, but never Porsche ones. So, I've never come across this & didn't even know about this design until you pointed it out to me.
Judging by what you've explained to me & the article, I would say yes to the thread locker due to the different metals & their properties. I think if the screws did back out, (combined with the corrosion issues) it would cause just as much if not more problems.

Just my opinion.
By the way, how is that heater working out with the colder temps?

Gregg

Goughary

Yesterday was brutal till the place heated up. Takes 3 hours to get comfortable. Problem really is with propane you have to let the garage vent. So every so often, just as a precaution I open the door. But basically once the stuff in the garage has come up to temp, it stays nice and I can lower the level of the heater and get on w it...

Shop is closed today. Too many other things to get done. Waiting now on rigid collars, another set of brake rebuild kits from racingbrake.com and new heater tubes. In the meantime I've been working on painting parts and finishing the de-rusting of the engine tins, and all that jazz. We are so close to assembly. Can't wait to drive it.

HalV

If I'm reading it correctly, the use heat and thread lock in the article is consistent with what's in the shop manual, page 47-03.

JasonAndreas

When you buy them from Porsche they come pre-lubed with Loctite 207. In very few (actually almost no where else) does Porsche say to use a threadlocker.