Juddering under acceleration in low gears.

Hello everyone
My name's Alex and Im a recent member to the forums. Its a pleasure to read the advice from such an enthusiastic group of Alpine fanatics, so I wonder if I might ask for some myself.
Ive noticed a slight juddering under moderate acceleration at around 2-3KRpM a few faint clicks and knocks coming from the transmission. Preliminary inspection of the underbody doesnt show any obvious oil leaks, and Id like to hope the symptoms were those of a tired clutch part, (Ive recently spent two saturdays negotiating London traffic to get the water pump and pipes renewed by the excellent Paul Sage, which must have stressed it somewhat.)
Any thoughts people might have are appreciated!
Alex B

Hi Alex

Where are you based? When you say juddering, do you mean from the engine running (ie a misfire) or mechanical?

If its mechanical it could be a slight clutch failure waiting to happen (ie centre plate breaking down/spline centre etc) or maybe a driveshaft problem.

It could also be suspension based, wishbones bushes moving underload, gearbox/engine mounts etc.

Can you be more specific?

Hi David, thanks for your quick response.
The engine seems to be running smoothly both at idle.
When I engage first or second for example in a junction there is a gentle low frequency vibration when I accelerate; Paul mentioned the front suspension was looking a little tired.
Ive been reading clutch diagnostic pages (and scaring myself silly at the range of potential issues) which suggest a warped clutch componant due to overheating, consistant with a lot of sluggish traffic driving and the recently failed waterpump.
By the way Im based in Coventry, so some distance from South London where i had the most recent work done; is a failure in the transmission something a skilled non-Apine mechanic would be likely to attempt closer to home?
Thanks again

Sorry I meant to write the engine is running smoothly at idle and when engaged.
A couple of other smaller problems are the coolant temp guage is giving incorrect readings and the digital fuel guage shows a slowly decreasing quantity of fuel remaining which does not reflect the actual level in the tank.

Hi David, thanks for your quick response.
The engine seems to be running smoothly both at idle.
When I engage first or second for example in a junction there is a gentle low frequency vibration when I accelerate; Paul mentioned the front suspension was looking a little tired.

Are you feeling this through the back of the car then, or the front. It does sound like the gearbox or enigne mounts or some people comment on this symptom a short time before the clutch fork arm pin snaps!

Hi David Im not describing the symptoms very clearly am I? yes the shuddering does seem to be coming predominantly from the back of the car or from the driven wheels.
If I could ask a favour could you set some questions that I'll answer as accurately as I can, as Im afraid my discription might be misleadingly vague.
Im reluctant to drive her more than necessary in the hope I to get her back to London unassisted as soon as possible but with an idea of what to listen and look for I should be able to more accurately explain whats happening.
Really appreciate the help so far!
Alex

From your posts it's unclear as to whether it's when you're engaging the clutch, or when your foot is off the pedal completely?

If the former, the clutch needs replacing. These clutches tend to judder quite a long while before they start to slip, usually because one or more of the splines have worn through on the pressure plate and when you push the pedal down, you aren't applying an even pressure across the drive plate.

If it's when you're off the pedal, I'd be more inclined to think CV joints than gearbox internals or clutch.

Hi David Im not describing the symptoms very clearly am I? yes the shuddering does seem to be coming predominantly from the back of the car or from the driven wheels.
If I could ask a favour could you set some questions that I'll answer as accurately as I can, as Im afraid my discription might be misleadingly vague.
Im reluctant to drive her more than necessary in the hope I to get her back to London unassisted as soon as possible but with an idea of what to listen and look for I should be able to more accurately explain whats happening.
Really appreciate the help so far!
Alex

1. Is it when you first pull away and lift the clutch (ie, taking up drive) -? (very common fault on GTA, and most likely)

2. Is it when the clutch is fully engaged, driving along (low speed) and your applying more throttle.?

3. Any decrease in performance, or low end torque..?

4. Any clunks as you come on and off the throttle (at low speeds)>

Hi David and SM
Okay here goes

1. Is it when you first pull away and lift the clutch (ie, taking up drive) -? (very common fault on GTA, and most likely)

Not noticably, however I will check this more carefully and report back. The clutch seems to engage smoothly.

2. Is it when the clutch is fully engaged, driving along (low speed) and your applying more throttle.?

Absolutely, yes. Roundabouts and other 20-30mph manouevers are where its most apparent. It almost feels like a fuel issue but the engine is running smoothly throughout.

3. Any decrease in performance, or low end torque..?

I dont think so; I did a rough count of accelerative times and it seemed the same as the numbers I clocked when I last used the car. However there may have been a slight gradual decrease I had not spotted.

4. Any clunks as you come on and off the throttle (at low speeds)>

Yes. I explored the time when the clutch was engaging and it seemed to come up smoothly when I wasnt on the the throttle. However when accelerating there is a clunk which has grown louder.

2. Is it when the clutch is fully engaged, driving along (low speed) and your applying more throttle.?

Absolutely, yes. Roundabouts and other 20-30mph manouevers are where its most apparent. It almost feels like a fuel issue but the engine is running smoothly throughout.

Right, will it do it round roundabouts and low speed if you dip the clutch and coast (yes will mean confirming its a suspension problem, not drive - but not ruling out an engine issue...)

The clunk you get when taking up drive, is it just one, or a constant clunking with when rotation?

Could be a knackered driveshaft/joint. Easy way to check is just to get under the back of the car, grab the middle of the drive shaft with you hand and give it a hard wiggle in all direction. If there is any noise or slack, then it needs replacing.

Also, have a look at the lower rear wishbone where it bolts to the chassis (side nearest the back of the car). You will see a bracket with two bolts, but these brackets regularly snap, meaning the rear wishbone can move on load, round bends, and clunk when taking up drive.

Otherwise, you say it could 'feel' like a fueling issue but the engine is running smoothly? Does it do this with all manners of fuel tank levels? Does engine temperature make any difference, stone cold or hot?. Just trying to rule things out..

Hi David
Im in the office at the mo, but I will have a good poke around the car tonight.
There seems to be a single clunk when I come on the accelerator, and a quieter one when I let go and the fuel level does not appear to make a difference. I dont drive the car hard until its at temperature, but I'll do a thorough test tonight.
As always, much appreciation for your help!! Simon suggests I might be able to give you a call when I know a bit more; do you think this might be possible? Your knowledge of the car is clearly absolutely terrific and Im keen to learn as much as I can before I make any decisions.

Yes, no problem, 24hrs (some people do )

You're a legend, is any time best? I promise I wont call at rediculous hours! Also I think a box of beer or something would be the least I can do for your assistance!
Im crossing my fingers the problem might be a suspension or engine mount issue but preparing for the worst
Making sure she's spot on for the summer is priority; she's such a fantastic car these little issues are easy to forgive arnt they? I was driving accross Waterloo Bridge on Saturday with the city all lit up and laid around me and a guy in a Gallardo pulled alongside and gave me the thumbs-up; not bad for a car that cost £4500. Im 24 and this is the first sports car Ive been able to afford to maintain properly but Ive been feeding my addiction to slightly leftfield machinery for ages (Alfa 164, Opel Monza, Volvo480T ) so the vaguaries of these things seems more natural than the eerily flawless Honda R's my friends drive. Long live classic cars (I hope)
Sorry got a bit caried away there!

Hi Guys
Just got a note from PJA suggesting Paul had noticed the clutch was loose and a new clutch kit and fork would be required; quote circa £900 or so.

£750 .........................I'll get me crane out