C4inLA

Any C4 Owners ever experience sticky/stuck ENGAGED lateral slave cylinder?

In pariculiar sticking engaged with PDAS off .

I suspect it is possible to bleed slave okay, however, that would not preclude the guts, piston, spring, rod side having sludge, buildup, etc.?

Is the following scenario possible;

From a level flat, from dead stop, lateral diff lock stuck engaged, proceed with steering wheel all the way to one side for tight circle turn, because of outer tire needing more rotation, diff locked inner axles , SYMPTOM = car hops ?

What will happen or is supposed to in above scenario with or without diff locked and I unplug say inside rear wheel speed signal sensor before proceeding?

Enso

i got the valve kits from Ninemister to replace all seals other wise its replacing both valves and thats expensive
then bleed with a Hammer or i use the PDT 999 Diagnostic tool

best
glenn

C4inLA

+1. I have the kit from 9m for future use. I don't have anything leaking. At this stage diagnosing....

Anybody? I know you Drivetrain Guru's are out there ....

John McM

My car had that and I think it contributed to the cracked planetary gear. In my case the mechanic was able to free it up and get it working again. I think mine had seized from lack of use.

C4inLA

I am asking about lateral transverse slave rear diff lock. PTU (torque transfer unit) is effected by the other slave Longitudial and where Planetary gear resides. Kind of getting away from questions I asked in post . Anybody on my theories and diagnostic questions ?

John McM

My mistake sorry.

C4inLA

No worries. I just got caught up on "Herman's refurb", nice to see so much progress, got to be exciting seeing it come together. The pic of your gearbox in verticle position with clutch sleeve showing, do you think just the PTU unit by itself can be removed (engine in car) and sent out for inspection vs drop and full gearbox sent out? Another way to say it, if I wanted the clutch pack removed engine in car, can it be done? Otherwise, seems like a lot of effort to inspect something that may be perfectly fine

Matthew

John McM

Matthew, I wouldn't inspect the unit unless there was a known problem or the box was coming out for another reason e.g. New clutch. It's pretty tight under there and I'm not sure there's enough clearance. Plus you have to drain oil etc.

I would make sure your locks are operating and put a bulb in the PDAS alert so you know when the system is working, then wait for another need.

As for "Herman" it's coming to the exciting part. I collect the box this weekend and will mate it back to the engine, awaiting the body in a week or so.

tdiquattro

You could unplug the connector from the solenoid unit in the frunk that drives the actuators. That unit pulses the high pressure fluid through to build up the friction in the plates (20 pulses to full lock I think).

Not sure if the car will start with it disconnected tho.

With it unplugged the night before there shouldn't be any pressure on the actuators, tbh given the massive pressure they need to lock the plates I cant see how one could stick on without being activated? Or something mechanical has jammed in the plates/clutch pack?

C4inLA

Interesting, thanks. I was just reading a few of the articles tha Black Betty thread posted, one on Adrian Streather, who stated, on his first C4 the problem his mechanics at the time thought might me gearbox, turned out to be bad center diff slave .... He didn't state details, but I am real curious as to what can go wrong with these diff locks if not leaking issue In my case, car average mileage 2k a year for last 18 years...