6 replies to this topic

[rsk289]

Car is a '68 Cooper S, with 4-synchro box.  I've not used it for a year or so, but took it out for a run today and noticed a fairly loud metallic clicking/ticking noise at idle.  This goes away when I press the clutch, and reappears when I release it.  There's no untoward noise whilst driving, and everything seems to be working normally in the clutch and gearbox department.  I fitted a new flywheel, clutch (driven plate, pressure plate and release bearing about 1500 miles ago, and the engine and 'box were rebuilt 5000 miles ago.  Any ideas - could such a noise be the idler gear, and does it need urgent attention?

[hhhh]

I think it's more likely to be the throwout bearing.

[Swift_General]

Can't see it would be the throwout/release bearing as the noise is not present when clutch pressed (i.e. when the release bearing is loaded and spinning). My money would be on the idler gear endfloat being too big. If this is the case it does not need 'urgent' attention, but will need looking at.

[hhhh]

Every time I've had a throwout bearing on the way out, it would get quieter when I pressed the clutch, probably because it takes up the play causing the rattling. If it's really shot, it may grind louder.

[Dusky]

Will have to take the flywheel wok of anyway to either fit a new throwout bearing or take the engine out to correct the idler clearance. Dont Risk it chattering, it ll destroy the whole motor.

[Spider]

Although we go to some trouble to shim these up just so on assembly, often the casings are not that well aligned from the factory. They do have dowels for this but they are seldom spot on, most are close and on a few, out quite a bit.

 

Usually, if it starts chattering early on following a build, this is usually the cause.

 

The earlier cars, like yours, fair better in this regards as the thrusts have a bigger surface area.

 

I'd suggest leaving it for now as it may have just settled and found it's home, but definitely keep a keen ear to it and if you find it getting worse, it will need attention. look for the wear in the thrust faces on the transfer housing and gearbox it one part is deeper than the rest and that will in fact confirm that it is a misalignment issue.

 

Sadly, re-shimming it isn't the answer, re-alignment is what's needed. While it's very easy to modify the dowels (and well lend themselves to this), measuring and putting the cover exactly where it needs to be isn't so easy done. I found the best / most reliable way was to make dummy shafts (Idler and first motion, pull the dowels, fit the dummies and then the transfer housing, then rebore the transfer housing dowel holes to the alignment of the gearbox case. The original dowels are stepped (and this is where I mentioned the well lend themselves to 'adjustment') the Gearbox side being 7/16" and the Transfer Housing being 3/8". I clocked up the Case to these dowel holes, then bored through the transfer case, then fitted straight 7/16" dowels.

[rsk289]

Thanks for the advice chaps.  I'd be surprised if it's the throwout bearing as it was brand new 1500 miles ago, and the noise disappears completely with the clutch down.

 

Realignment sounds to be out of my field of expertise - whilst I've done a lot of spannering, I don't have boring facilities beyond a drill.  If that really is the case I'm going to have to find someone near Cambridge who can do this kind of work and maybe knows the problem.  I suppose I need to pull engine and box and see what it looks like.