Gearchange 'Clonk'

[zcacogp]

Chaps,

'Nother problem with my beloved S2. Crossing over 200,000 miles a couple of months ago has brought all the maladies out at once it seems. The last four times I took it out it has broken in some way or another (starter solenoid, gearchange linkage (outside the gearbox), passenger window coming off the runners, something else (can't remember what)).

The latest is that it is making a 'clonk' noise when changing gear. It's noticeable from within the car and sounds heavy (as opposed to a light 'tap') but isn't a very big noise. I am fairly sure it's associated with the changing of gear as opposed to the depressing of the clutch or the releasing of the clutch. It is associated with changing along the box (i.e. 3rd to 4th) as well as across the box (2nd to 3rd). It very occasionally seems to do it when going over a bump but this could be other noises.

I don't think it is CV's; I had a look at them and one of them had a split boot so I replaced it this afternoon, and the noise is still there.

I haven't yet checked (or changed) the gearbox oil but will do this as soon as I get some (probably in the next day or so). However it was done in the last 3 years or so.

Does anyone have any ideas, inspiration or wisdom to offer? I'm inclined to wonder whether it is something to do with the gear selectors but I don't know if they are even capable of being noisy. The box is not overly loud in other respects and the feel of the change is fine, but it does have a smidge over 200,000 on it now. The other possibility is the gearbox mount and I have read the thread about filling it with goo with interest and may well have a go at this sometime soon.

All suggestions welcome, thanks.


Oli.

 

[blade7]

My old mk1 Golf GTi did something similar when the gear linkage needed adjusting.

 

[Monkeythree]

Get it up in the air and give everything a good push and shove and see if you can find anything. Sounds mounty to me so I would start by seeing if the gearbox is moving about but also worthwhile giving the engine a good shoogle in case its an engine mount gone.

 

[Cater_Racer]

Oli,
While it's up in t'air take the rubber inspection cover off the rear gearbox bell housing and you can get yer hand inside and feel for play in the TT. That's what I did on the black one and I could turn it easily by hand . It should feel smooth and no slack or play.

Gerry

 

[zcacogp]

Chaps,

Thanks for the suggestions. I'll order some more gearbox oil, give the torque tube a spin and see if I can shoogle the engine today or tomorrow. I'll update this thread when there is more to know.

I'll also endeavour to use the word 'Shoogle' more often in day to day conversation as I think it's a criminally under-used part of the English lexicon.


Oli.

 

[robdimond]

Mine does the same and I'm fairly convinced it's the gearbox mount. Hope to try the urethane trick this weekend.
Also think the TT bearings are on the way out...

 

[edh]

My gearbox mount was shot & the symptoms were a difficulty in selecting gears under heavy braking, but no noise.

Does sound like something is shunting around, so a quick shoogle is probably the best bet...

 

[944Scott]

Rob make sure you mix it very well for several minutes preferably with something like and old fork and leave it to cure as long as possible before refitting.

 

[zcacogp]

I've been back to this one and discovered the following;

- I've changed the gearbox oil and it made no difference
- There is slight play in the CV's but no more than I'd expect
- If I remove the inspection hatch on the bottom of the rear bellhousing and have an assistant (mrs zcacogp!) press the clutch down then the torque tube will spin freely and smoothly but there is a noticeable 'clunk' when you start to move it in either direction. If the gearbox is put into gear then there is an appreciable amount of play in the drive. That's to say that you can turn the input shaft a good portion of the turn before there is any movement in the driveshafts. How much of a turn? I don't know but would guess it's 30degrees or so. It also seems to make a noise very similar to that which I am trying to solve.
- With the gearbox into neutral and the clutch pushed down there is much less play in the system (practically none at all)
- I tried to slide the joining sleeve back to disconnect the torque tube from the gearbox but despite undoing the bolt at each end I couldn't make it slide at all

This raises several questions;

- Does this point to gearbox failure?
- Does this point to Torque Tube failure? (I ask this separately as both could be on the way out)
- Is it possible to remove the Torque Tube without dropping the rear suspension?
- Does anyone have any tips to make the joining sleeve move?

Thanks for any advice - it's appreciated.


Oli.

 

[zcacogp]

Here's another question; do the bolts have to be entirely removed from the clamping sleeve that sits between the gearbox and torque tube for the clamping sleeve to slide?

Thanks.

 

[944Scott]

I don't think the sleeve pushes back far enough to free it from the gearbox, there's not enough room on the splines in my opinion and yes you would need to drop both the suspension and the gearbox to remove the torque tube but it sounds to me that your problems lie within the transmission area. If it was rumbling or vibration then I'd say it might be your torque tube but a clonk suggests gearbox, ring and pinion maybe ?

 

[edh]

The sleeve is tight - I'd suggest giving it a tap to start it moving. IIRC it slides backwards onto the gearbox shaft.

 

[zcacogp]

Scott, thanks. I'm thinking along the same lines as you - it's a gearbox problem.

Ed, thanks also. Do you need to remove the bolts entirely from the sleeve to slide it back? I gave it as much of a tap as I could manage but it didn't budge at all.


Oli.

 

[edh]

I removed the bolts I think but I don't see it would make a big difference.

It does sound like the problem is in the gearbox but I know nothing about what goes on in there...

Fortunately s/h boxes are quite cheap still

 

[944Scott]

Actually re thinking it the sleeve does clear the gearbox shaft by about 3-4mm My torque tube is still out of the car so I took this picture for you, this will give you an idea how far back it will slide on the shaft.

I also rotated the output shafts on my gearbox (no drive shafts connected) and I have about 2mm of slack on each before pick up, I couldn't check the input shaft as its sitting face down at the moment.

 

[zcacogp]

Scott,

Thanks for doing that investigation - I appreciate it. If you still have your camera ready then could you take a photo down the end of the sleeve, along the shaft? More for my curiosity than anything else.

I took the car into my local under-the-arches Porsche place yesterday afternoon (Tower Porsche, just by Tower Bridge). They took the car out for a drive and proclaimed the gearbox to be 'fine - in fact very good indeed given the mileage'. They thought the noise could be linkage-related, probably one of the bushes getting loose and wobbly, although I replaced the bushes about 6 weeks ago. They certainly didn't think it was anything to worry about - I asked them whether I should take it on a 5000 mile European tour and they said no reason other than that the French speed cameras will now trace UK-registered cars and you'll still get fined ....

So I'm perplexed. There is a noise. It's not one that makes me happy but the car works fine. Should I buy another gearbox and keep it in case the noise gets worse? Should I take all the CV's off and re-pack them with grease? Should I stop fussing and just drive the damned thing? I'll probably settle for the latter.

Thanks for your input chaps. All other thoughts welcome!


Oli.

 

[944Scott]

Do you still want that picture? it may be worth repacking the CV's with grease and whilst they are undone see how much play is in the output shaft.

 

[zcacogp]

Scott,

If you could send that picture over then I'd be grateful - thank you.

Yes, repacking the CV's is no bad idea. However having driven it a fair bit this evening I can distinctly identify the different elements of the noise. It happens twice - once on coming out of gear, once on going into the next gear. I am really wondering whether the bushes on gear selector forks can ever fail and if so what their mode of failure is.

Thanks again,


Oli.

 

[944Scott]

Ok it will be tomorrow evening now.

 

[944Turbo]

Chaps,
It very occasionally seems to do it when going over a bump but this could be other noises.

Oli.

Check the spare wheel well, the battery, the boot cubbys for something loose? Don't you have an amp back there?
Renew break down cover, relax and enjoy!
Tony