When a clutch goes...

When a clutch goes...

Author
Discussion

whitevanman88

Original Poster:

1,012 posts

149 months

Saturday 23rd January 2010
quotequote all
does the biting point get higher up the travel, or closer to the floor?

I was of the opinion that it gets higher up the travel? 'mechanic' seems to think otherwise...?

bananapieface

403 posts

143 months

Saturday 23rd January 2010
quotequote all
Does it matter?

When it slips it's fooked.

whitevanman88

Original Poster:

1,012 posts

149 months

Saturday 23rd January 2010
quotequote all
bananapieface said:
Does it matter?
Yes.

Mafioso

2,315 posts

183 months

Saturday 23rd January 2010
quotequote all
bananapieface said:
Does it matter?

When it slips it's fooked.
So the guy asks a serious question and you give him a response like that!?

lankybob

1,593 posts

159 months

Saturday 23rd January 2010
quotequote all
Yeah, I need to know this too.
My clutch biting point is about 3/4 inch from the top of the pedal travel!

whitevanman88

Original Poster:

1,012 posts

149 months

Saturday 23rd January 2010
quotequote all
lankybob said:
Yeah, I need to know this too.
My clutch biting point is about 3/4 inch from the top of the pedal travel!
Same. Mine seems to alter depending which gear I'm in too? (downshifting)

TheEnd

15,370 posts

157 months

Saturday 23rd January 2010
quotequote all
The biting point comes higher,
they operate by a movable pressure plate attached to the flywheel with a gap inbetween.

inside that gap sits the clutch disc on the end of the gearbox spline.

if everything is getting thin and worn, you'll only need to move the clutch pedal a little for it to release the plate.

at least, that's one theory...

Eggman

1,253 posts

180 months

Saturday 23rd January 2010
quotequote all
Depends what we mean by 'going'. If the reason for failure is worn friction material, then I would agree with your version - the biting point would move towards the top of the pedal travel. (Think of what happens inside the bell housing: once the clutch starts slipping, the pedal 'doesn't come far enough up' for it to get to the biting point).

If the slave cylinder is failing the biting point might move down - but I wouldn't expect much slippage there unless the cylinder leaks and contaminates the clutch, and even then I'd think it more likely for juddering to be the first sign that something wasn't right.

jaybkay

488 posts

189 months

Saturday 23rd January 2010
quotequote all
Yep, a high bite point is a sign of a worn clutch - a low bite point indicates problems with clutch release.

mat205125

16,261 posts

182 months

Saturday 23rd January 2010
quotequote all
jaybkay said:
Yep, a high bite point iscan be a sign of a worn clutch - a low bite point indicates problems with clutch release.
EFA

It doesn't have to always mean a problem with the clutch itself, or necessarily the release mechanism.

Is the clutch on a cable or hydraulic? Could be an issue with the adjustment, air in the system, a stretched cable, worn self adjuster .... etc etc etc etc

eldar

16,986 posts

165 months

Saturday 23rd January 2010
quotequote all
whitevanman88 said:
does the biting point get higher up the travel, or closer to the floor?

I was of the opinion that it gets higher up the travel? 'mechanic' seems to think otherwise...?
Could be the clutch wearing, could be the release mech getting tired. Does the clutch slip in normal use? If you provoke it a bit?


Superhoop

4,576 posts

162 months

Saturday 23rd January 2010
quotequote all
Tradionally, yes the biting point of the clutch would move upwards in the pedals travel as the clutch disc wears. I say traditionally because a lot of newer cars have a self adjusting device built into the clutch cover.

Think two opposing tapered rings, which rotate (they are pulled round by spring pressure) as the clutch disc wears. It's only real purpose is to keep the biting point the same, regardless of clutch wear.

Jag-D

19,633 posts

188 months

Saturday 23rd January 2010
quotequote all
Just from my experience, I remember when the clutch was slipping on our BMW E34, it wasn't the clutch itself, but the master cylinder seal which was followed by the peddle hitting the floor and not returning.

*Al*

3,830 posts

191 months

Saturday 23rd January 2010
quotequote all
I've generally found the biting point does get higher.Another sign of a worn clutch is the lack of sharpness at the biting point (can't feel the absolute point of engagement if that makes sense?)

Tunku

7,701 posts

197 months

Saturday 23rd January 2010
quotequote all
Higher in my experience, gets so high eventually, that you don't even have to press the clutch to make it slip. If the pedal is hitting the floor and you can't change gear, the cable/hydraulics etc is fooked, which is just about the exact opposite.

thunderbelmont

2,982 posts

193 months

Saturday 23rd January 2010
quotequote all
When a clutch goes, the vehicle does not drive, or it slips making driving difficult.

Anything else is adjustment (or cable replacement), with the exception of the Clutch Cover getting saggy to the point where it doesn't or hardly will, disengage (see Triumph 2000/2500/2.5Pi or Ford Transit with dual-mass flywheel as common miscreants)

There is also the possibility that the clutch is in good condition but the vehicle suffers slip because either the rear main, or the gearbox front oil seal is defective.


V6Alfisti

3,230 posts

196 months

Saturday 23rd January 2010
quotequote all
Stick it in 5th, start the car. If it stalls then the clutch isn't slipping, if it doesn't stall it's gone.

Clutches are so variable car to car, my mother runs a little Micra K11 and even when the clutch was replaced the bite point was still right at the top (despite trying to adjust it). Just the way that particular Micra was made, another Micra bites at a totally different point.

Eggman

1,253 posts

180 months

Saturday 23rd January 2010
quotequote all
TBH, there are a number of things that can go wrong. I had a release bearing collapse and every time the clutch was depressed the remains of it set about machining their way through the fingers accompanied by tremendous metallic shrieking noises. By the time I got round to fixing it they were nearly there. On another car the slave cylinder punched it's way through the release arm.

In both cases, the fix was the same - gearbox out and replace everything inside the bell housing so the job won't need doing again anytime soon. If you put anything back in, you can guarantee it'll fail almost immediately just to teach you a lesson.

RV8

1,570 posts

140 months

Sunday 24th January 2010
quotequote all
I bought a Scirocco with a really crap clutch I was able to make a huge difference just by adjusting the clutch cable.
My mum's Rav 4 has very noticeable DMF judder. My defender judders in reverse but I've found I can ballence the effects of this with clutch control, infact many cars I've driven new or old seem to judder if being reversed up hill especially if every seat is occupied.

The Nur

9,168 posts

154 months

Sunday 24th January 2010
quotequote all
V6Alfisti said:
Stick it in 5th, start the car. If it stalls then the clutch isn't slipping, if it doesn't stall it's gone.Clutches are so variable car to car, my mother runs a little Micra K11 and even when the clutch was replaced the bite point was still right at the top (despite trying to adjust it). Just the way that particular Micra was made, another Micra bites at a totally different point.
I am intrigued. When you say start the car in fifth, do you mean with the clutch up or down? The reason i ask is that the clutch on my girlfriends car has a reasonably high bite (Mk3 Golf). Whilst driving there is no slip at all. Clutch job or cable adjustment?