The Exedy-Pink Clutch Cover issue and how to fix

The Exedy "Pink" DHC511HD uprated Clutch cover is quite a common item that has been fitted to many GTti's. Camskill sold lots of these in the UK a few years ago.

 

They were modified by Exedy Australia using the standard Exedy DHC-511 cover (same as factory fitted 31210-87708).

 

However, whilst they are uprated. They do not work as good as they should!

 

But don't throw it away, Recondition and reuse!

 

If you have one of these pink covers that is used. Chances are it's still going to be in perfectly OK condition to clean up and use again and work better than it ever did !  

 

 

The cover was usually sold by camskill as a "Fast road" kit together with a standard replacement GTti organic friction disc and release bearing.

 

To start with the clutch when fitted new seems to works well. Especially as most owners have quite modest bolt-on modifcations such as downpipe/exhaust and a boost pressure increase.

 

 

But, It doesnt take that many miles of driving before people notice that the clutch is already starting to slip.

The reason for this is that the Pink cover was made by Exedy Australia intended to be used with their 3 puck paddle friction disc.

 

The paddle disc has a thickness of about 8mm.

 

However a standard organic friction disc measures between 6.8 - 7mm thickness (when the marcel cushion spring layer in the middle is compressed flat)

 

Exedy made the pink cover with 1mm less clamp down height to compliment the 1mm thicker friction of the paddle disc. 

 

So when a standard thickness organic disc is used with the pink cover. The cover does not clamp down far enough to obtain the correct and optimum clamp with the diaphragm position. 

 

So as well as not clamping as hard as it should when new, You also have the same effect as a clutch which has already worn the friction down by 1mm. This is quite considerable. 1mm of friction disc wear is certainly a good few thousand miles worth of driving! 

 

Hence why it doesn't take a great amount of friction lining wear before the clutch starts to slip.

The fix is easy and does not cost much money...

 

Simply buy a new organic disc (I can supply). Or if your existing disc is in good condition should be no problem to re-use it. 

 

Send it away to any clutch specialist. And request that the friction is re-lined 1mm thicker. Expect to pay in region of £50 for this service.

 

A standard new disc measures as follows...

 

Each friction lining is 3.0 - 3.2mm thick, So together that makes between 6.0 to 6.4mm.

 

The wavy marcel cushion spring layer between the linings is about 0.6mm.

 

When uncompressed the standard disc measures 7.5 - 7.7mm.

 

When fitted and the lining marcel has compressed flat, The disc thickness measures 6.8 - 7.0mm

  

 

So the newly relined disc should be made to measure about 8.5 - 8.7mm uncompressed, And when the marcel layer is compressed flat it will then be about 7.8 - 8.0mm,...1mm thicker than original. 

 

To recondition the cover. First give it a good clean.

 

Put a straight edge across the friction ring to check the flatness.

You will find the ring is not perfectly flat, but warped lower on the inside diameter than the outside.

 

This occurs with normal wear and they seem not to be made perfectly flat even when new.

It can be corrected and made much better by hand, using a nice flat surface such as a piece of glass and some medium-coarse (200-300) grade wet&dry emery paper to rub the cover. Takes a bit of time/patience but it will clean up the friction ring nicely and makes it flatter.  

Using the staight edge and a feeler gauge to measure you want to aim to have less than 0.10mm warpage. 

The end result will be a clutch than holds stronger torque with longer lifespan than it ever did.

 

It will hold in the region of 150 - 160lbft torque , which is about the limit of the gearbox strength to stay reliable. Plenty for most !

 

Print Print | Sitemap
© Nathan Munns