clutch heat issues

B8 S4
#68

Alright so driving it around SF gridded aveneues with a stop sign at every corner, I’m breaking it in. After about 25 miles of this the clutch pedal now moves all the way to the floor. It had that infamous “pop”. At the same time the notchiness in the shifter went away.

The engagement feels nice and it’s extremely direct. When it clamps nothing slips.

The clutch pedal is still sticking about every 10th time. Seems to go away after a few pumps. Not sure if there is a spring in the actual pedal, which would benefit from replacing the whole plastic pedal arm?

#69

Having driven around in San Fran both in ubers and in a rental car I have to say it’s a nightmare for any clutch. Do you actually live there?

#70

I have done it before too, with my 5R. Will probably do it again too. Even though it sucks!

#71

Driving the car around purely to break it in before a track day on August 25 at Sonoma.

Yeah I live and work in SF. Have 3 parking spots - 2 at home and 1 at work. But I prefer to take the train. If you don’t leave by 7:30 the traffic sucks.

Boxster with base suspension clears the hills no problem and PDK with hill hold is nice. All 1st and 2nd gear. 1st is nice and tall. 2nd dogs a little bit from 5 MPH.

Cars are really for leaving the city. Uber is the best way to get around.

#72

Rented a house in Pot Hill. Fucking insanely hilly . Hard to believe they decided to build houses on this rock.

#73

Put a 3.5 amp trickle charger in the trunk. This one has a special mode for 12V lithium batteries. Also put a security camera to watch the car since this gilded city is a crime ridden shithole with the worst police to citizen ratio.

http://uploads.tapatalk-cdn.com/20160722/994ba7ea57490c3df75b2884cf277cb7.jpg

#74

So trolling around AZ anonymously since all of my accounts are banned, I found a few old clutch threads particularly for B7 RS4.

I think I need to get a few more break in miles on the clutch, and some issues like occasional pedal stick go away. I’m actually probably still only 30 miles on it.

#75

a camera would be a good investment on top of the charger.

I forgot how much did your battery weigh. and how is the clutch now that you got more miles on it.

#76

Clutch update

I haven’t had much time to drive the car. I’m still under 100 miles on the new clutch, but they’re hard city miles where driving 500 feet is 6 shifts.

The self adjusting clutch mechanism is pretty bizarre. Sometimes it moves the travel all the way to bottom of the pedal, like if I’ve been sitting at a traffic light. Then when I start driving it moves back to the normal spot. I’ve been in the habit of leaving the car in gear at a red light with the clutch pedal depressed, just to keep things normal. I wonder if I disconnect the clutch switch bypass if it will start acting normal again. Since I didn’t do the work, I don’t even know what to reconnect.

In spirited driving the car seems to do great. I can rev 1st gear all the way out, pop the clutch into 2nd, and it grabs like an on/off switch as I get back in the gas. If it works like this for an entire track session, I got what I paid for. Which is a motorsports clutch that acts a little wonky from a start in 1st gear.

But then a few minutes later everything goes to shit. The engagement point moves back to the bottom. The car is hard to get in gear. The clutch pedal travel is like air for the first 40%, then catches, then sticks at the bottom.

It looks somewhat ridiculous breaking this clutch in on city streets for hours, but there is so much weird shit going on in SF that I hardly stand out.

http://uploads.tapatalk-cdn.com/20160806/9cdf80de57cba8c6ff1335fc5c2e5491.jpg

#77

I wonder if I need a new clutch vacuum assist line.

[quote]There is a known problem on early delivery RS4s with the clutch vacuum assist line. This needs to be replaced. Basically the line is too week and colapses, pinching off the vacuum. One way to see if you have the problem safely is to place your transmission in neutral and depress the clutch petal twice rapidly in succession. If you have the problem, on the second press, the clutch petal will stiffen up and be almost impossible to press to the floor. But, any kind of change in clutch operation on the 2nd press is a problem.
[/quote]
It is back at the shop and we are going to try:

1/ reset hall switch to normal
2/ bleed slave line again

Any of you guys see anything else we should replace? Obviously we have done the master, the slave, the line in stainless steel, the throwout bearing, the pressure plate.

Maybe the actual over center spring on the pedal? I know the spring makes the clutch-in effort easier, but it also serves the function of returning the pedal.

http://www.jimellisaudiparts.com/showAssembly.aspx?ukey_assembly=746646

http://www.jimellisaudiparts.com/images/parts/Audi/fullsize/670721250.jpg

#78

Checking the vac assist line is a good place to start. Testing it wouldnt be a bad idea.

You can bleed the line and that might not be another bad thing to test.

#79

Does anyone have the vacuum system diagram for the B8?

What’s my worst case scenario with his job? Hook up the heavy duty clutch to the OEM dual mass flywheel?

#80

Looks like we have a brake (clutch) fluid leak. My guess would be the clutch master. If it’s in the bell housing I’m in trouble.

#81

That is worth looking into. a leak would obviously not be helpful.

The flywheel isnt going to change anything so I wouldnt go down that path.

#82

So maybe the slave cracked when I breaking it in. If so, replace here:

http://i64.tinypic.com/1zvyate.png

Here is the OEM clutch master:

http://i65.tinypic.com/qyclj7.png

The current wisdom is to modify it as such to move it closer to the firewall, so the hall switch bypass is not needed:

http://i66.tinypic.com/24l7whf.png

#83

That should put it a lot further in.

#84

This helps me reason about the problem better.

http://i63.tinypic.com/rjfggm.png

#85

I got confirmation it is indeed the slave cylinder that is leaking. So we are replacing the slave. Then we’ll pull apart the engine bay again, mod the clutch master so it inches forward, disconnect the hall switch grounding hack, and hopefully everything works normally again.

I don’t care if the slave cylinder becomes a consumable part. I’ll gladly replace it after every track weekend. I just want it to work while I’m out there.

#86

why would you do all that modding if a slave will fix it?

#87

Because it is dumb to leave the hall switch grounded and the finite state machine permanently confused. It injects wonky behavior. The reason the slave cylinder broke is because the clutch will only travel 70% of the way. Push it 75% and the slave sacrifices itself under massive force.

Fixing the master will allow full pedal travel as god intended.