Very low bitting point

[plavis]

Hi everyone!

I'm new in this forum so let me introduce myself (and my car too).

I'm driving 2002 Jetta/Bora MK4, 1.9TDI with ATD PD engine (74kW) with manual 5speed PR-0EJ gearbox.

To cut long story short. Several months ago I changed clutch comletely (new DMF, clutch disk, pressure plate, release bearing, lever). Problem is that biting point is way too low, about half inch from floor and there is a small grind when shifting (especially 1st to 2nd). I changed master and slave cilinder, do the bleeding and after that it was fine. Biting point was around half pedal travel, gearbox shifting fine.

 

After some time, biting point was going down by itself and now is again near floor. Didn't noticed any leaking. Tried bleeding again but there is no bubbles. Pumping pedal is not changing anything.

Hi everyone!

I'm new in this forum so let me introduce myself (and my car too).

I'm driving 2002 Jetta/Bora MK4, 1.9TDI with ATD PD engine (74kW) with manual 5speed PR-0EJ gearbox.

To cut long story short. Several monts ago I changed clutch comletely (new DMF, clutch disk, pressure plate, release bearing, lever). Problem is that biting point is way too low, about half inch from floor and there is a small grind when shifting. I changed master and slave cilinder, do the bleeding and after that it was fine. Biting point was around half pedal travel, gearbox shifting fine. After some time, biting point was going down by itself and now is again near floor. Didn't noticed any leaking.

I also have another problem (noticed few years ago) that I never pay much attention but it can be relevant. Sometimes when pressing pedal, near the floor there is a some click, and there is a same click when almost depressed. I can't hear click but I felt it on left foot, and also on brake and acc pedal. After a day or two this problem dissapears.

I also post my problem on other forums but no solution so far.

Thanks in advance!

[cheshire_cat]

the only help (maybe) is that the book says it must be pressure bled   there is also some device not labelled between the master cylinder and the bleed off " T " may be worth a look

[cheshire_cat]

I would guess it's some sort of damper   with at least 3 seals and spring clips I would be surprised if at least one doesn't leak under pressure

[plavis]

cheshire cat, can you explain? I have new seals on pipes. There is no visible leaks and I haven't noticed air during bleeding.

[plavis]

I played a bit and here is update.

 

Pedal up - everything fine, no slip

Pedal pressed just about inch - slip on full throttle

Pedal about half inch from floor - begin of catching.

 

Could it be problem with hose? Maybe expanding under pressure?

[jme808]

Do you definately have the right grade of fluid in there?  And is it old (opened and left for a while etc) - possibly moisture in it?

 

If it's short hoses I can't see how one of them would expand enough to drop the pedal that far.

 

I've only worked on hydraluc clutch releases on motorbikes, but had the same symptoms which was due to a dead seal visably leaking.

[plavis]

When I chancged both cylinders I drained reservoir and filled with brand new fluid. After that everything was perfect, clutch was grabbing from about half pedal travel. During time (about 2 weeks), bit point goes down to near floor. I tried bleeding again but there is no single air bubble.

 

Hose is steel-rubber. Steel pipes are conected with cylinders, and rubber pipe connect two steel ones. I asked about expanding possibility because it just popped in my mind. I will look about that tomorrow, but I'm not sure how to.

[kentphil1]

Just because both cylinders where renewed, does not mean one of them has not developed a fault.

 

Is the bleed nipple seating correctly?, are there any cracks near the bleed nipple thread?, is there a possibility you may have overtightened it during bleeding?.

 

Best to recheck all the areas around the unions for hairline cracks if you can, preferably while someone operates the system.

 

Sometimes a crack can start in a metal line near the union as it tightened, but the leak may be so small it is being obscured by the union nut itself.

[cheshire_cat]

isn't that the one  with the clutch ----- which for want of a better description "operates backwards"   the problem could be at the gearbox release bearing end---worth a look and only a guess I've never  done one of those

[plavis]

chesire cat, release bearing, release fork and pin are new.

 

kentphill1, nipple is fine, I never overtight plastic screws. Pipe is just inserted into cylinder and secured with with ring. No nuts of any kind. Also, no leaking, fluid loss or bubbles in system.

 

I looked on other car and when pressing pedal rubber part of line is standing still and without eplanding. On my car pipe is moving significantly and with hand I fell expand.

[Oldfellah]

Are you absolutely sure you fitted the clutch plate the right way round? The boss in the middle of the driven plate (splined collar which slides on the crankshaft) is usually longer on one side of the centre line of the plate than the other, even though the whole assembly might seem symmetrical. The low biting point you describe and the clicking noise could be symptoms of this wrong fitment, because there isn't enough travel in the linkage from pedal to release bearing to bring the clutch plate far enough away from the flywheel. Only thing suggesting this might not be so is you say it did work fine initially.

 

Bad news is that if you didn't check plate was fitted right way round then there's only one way to find out and that's to take it all apart again . Given that it's years since I changed a clutch, I wouldn't want to set you off down this track without your taking professional advice first. Is that something you have considered?

 

Anyone else got thoughts on whether this might be the cause rather than hydraulics?

[plavis]

I am pretty sure that clutch is fitted right because it dmf, plate and disc came preasembled.

Clicking is not always, last month 0 times. And that happened with old clutch too, same way, just ocassionally

[Oldfellah]

Well that at least is good news if you're able to be sure. Really hope you can find the cause.

[jme808]

How does the pedal operate?  Is there an auto-adjuster for the pedal / bite point that could be at fault?  I'm assuming the pedal is a cable to the slave cylinder..

 

does the click sounds like a relay or possible an adjuster? 

 

That's the only other thing I can think of that could be at fault...  I'd be interested to know how it gets sorted - hope it's something simple.

[cheshire_cat]

any joy with this one?

[cheshire_cat]

bump :no: