kgorman

I need some advice. I am at the track, and my longitudinal slave cylinder let go again. Fluid is leaking from around the edge of the cylinder. I need a way to continue to drive. Here is my plan, anyone have any smarter advice?

plan a) remove connector on the actuator in the trunk area. This connector looks like a trailer connector with 4 pins. This disables the ABS, TC and AWD. My hope is that if I disable it, then no more brake fluid will spill out and I can continue to drive w/o ABS and TC (and AWD)

plan b) plug up the supply line going back to the rear of the car so no fluid can go back to the car. What I don't know is what to plug. I was thinking to plug it at the 'bomb' or perhaps the actuator?

Any other advice? Any relay I can pull? Is there a way to just disable the AWD but leave TC and ABS functional?

I don't have any docs/manuals here to reference so any help would be awesome!!!

Indycam

Clamp off a rubber hose , if there is one , that goes to the longitudinal slave cylinder ?

kgorman

Indy thanks for the quick reply. It seems that there is no rubber around only the high pressure brake lines. This thread seems to indicate that plan A is at least valid. https://rennlist.com/forums/showthre...ight=pdas+leak

However, I would like to retain the lateral slave and the ABS if I could. I know beggers can't be choosers, but I am having fun I don't want to stop!

Indycam

Are you willing to clamp down on a metal tube ?
Small vice grips across a metal tube leading to the leaking cylinder ?

kgorman

hmm, seems possible, but I think that might be plan c, I might be able to stick something into the output of the brake line if I knew which one to plug. I am still searching the archives, shoot I wish I had Adrians book with me. Note to self to add it to my kit.

Indycam

What track are you at ?

Indycam

Take the tube off of the cylinder , put in a bit of soft copper / alu , put tube back on and crank down tight ?
A BB makes a good stopper .

I hope you don't mind me spitballing ideas at you .

kgorman

Thunderhill. I am supposed to be here tomorrow too. ;-/

Perhaps I could disconnect the longitudinal accelerometer? Do the accelerometers work completely independently or does the brain make decisions based on a combination of both sensors? If disconnecting only the longitudinal removed just the center diff from actuating, then that might work too.

After this next run group I will post back how it went, and if I feel like I need to go to the next step.

kgorman

Ok, no fluid leak so I can keep driving. I miss the lateral PDAS, but it seems fine otherwise. I like it w/o ABS. ;-).

Thanks Indy for the posts, I will check back later after some more laps.

-kg

deep_uv

Kenny, I don't know anything about C4's, so I can't help, but I feel your pain. I'm at the track (TWS) with a broken car too. Looks like my alternator went out. I went and bought an extra battery and a charger and I'm making do by recharging and swapping them back and forth. Worked like a chrarm and have only missed one session because of it. Hope you get it figured out.

Regards,

Tom W

Kenny: Thank goodness for wireless access at the track! Glad to see it's working out - it's a glorious day here (60 °C and sunny) I hope it's the same there. The surf competition at Maverick's just ended.

I certainly thought about driving today, but my car is in more pieves than together and looks pretty silly with the roof cut off. Just wait though. The Turtle will be back breathing flames.

Ritter v4.0

Best of luck McGuiver, er, Kenny.

garrett376

Kenny, what a bummer!
If I was in your position, the easiest thing to do is to plug off all hydraulic supply to your solenoid block by finding someone with a spare bleeder screw and use that to plug off the entire solenoid block feed off of the accumulator, or "bomb." This will disable all hydraulic control to both differentials and prevent you from leaking all fluid out. It will allow you to maintain normal brake function. If you tried to plug just the line to the longitudinal slave, you will end up with an electronic fault disabling PDAS anyways - so it's pointless to try to retain function of just one differential when one has failed.

Depending on how much stuff you have access to, you can remove the longitudinal slave, and leave it off. Then remove the lateral slave and mount a plate with a bolt that goes into and contacts the actuating arm of the lateral differential - thread the bolt to provide pre-load on the differential and you've got yourself a pre-set limited slip differential but an open front differential which isn't much help for the front end traction. If you had even more supplies, you do what the C4 RS did - run a line from the lateral slave cylinder to a master cylinder that can pre-pressurize the slave cylinder - then you have a constant set pre-load on the differential plates which you can adjust in the **** pit! But, if you want ABS, you need to splice in a C2 ABS module connector and use a C2 ABS module... gets complicated and not really a track-side fix!

Good luck, and keep us posted!

garrett376

You want to disconnect and plug the lower of the lines seen on the left side of the accumulator:

garrett376

But remember the accumulator is usually charged, so find some way to vent the pressure - safest thing is to bleed out all the fluid from the bleeder screw on the top (will be like 16oz or so).