CGT gearbox / clutch problem

[84CoupeGT]

Unfortunately I didn't have time to do anything, it happened just before I was due to go home (car is stored at my parents house about 100 miles from where I live), it was already getting dark so after limping it back I just swore a bit, stuck the cover on and went home!

[Hanuman]

26years of non use, or very limited use, and the original clutch?

There could easily be a compound of things in there- clutch assembly, the fingers no longer having much spring left may have resulted in limited movement during release and bite, and maybe a position partway between. This is what was happening on my UR when I eventually had its clutch done.
The bearing was moving fine, but the clutch disengagement was not even, and incomplete, with especially harsh reverse selection. It was a case of push the pedal, and wait a little longer than normal for the residual drive to stop, then gently select reverse.

[K Simmonds]

Originally Posted by Hanuman

26years of non use, or very limited use, and the original clutch?

There could easily be a compound of things in there- clutch assembly, the fingers no longer having much spring left may have resulted in limited movement during release and bite, and maybe a position partway between. This is what was happening on my UR when I eventually had its clutch done.
The bearing was moving fine, but the clutch disengagement was not even, and incomplete, with especially harsh reverse selection. It was a case of push the pedal, and wait a little longer than normal for the residual drive to stop, then gently select reverse.

This....

[84CoupeGT]

Very interesting, thanks. No idea if it's the original clutch, but 120k miles, odometer still working, so I would say probably... Or at least a decent possibility!

Was your UR sitting for years also? What did you replace?

I know mine wont necessarily be the same, but it's all good info to give me clues!

Cheers

[K Simmonds]

If you have to take the box out you replace everything you can, full clutch kit, release bearing/guide sleeve, input shaft seal and the the rear crank seal. Unless you know the other parts have been recently replaced. Which in your case they obviously haven't.

Doing otherwise is crazy as most of the cost of changing a clutch is the labour involved in pulling the box out and putting it back in.

Personally I also have the flywheel refaced and balanced and replace the spigot bearing in center.

Do it right, do it once.

[84CoupeGT]

Good to know, cheers. Keeping my fingers crossed for something simple

If the gearbox does have to come out, I'll do it myself, so there won't be a financial labour cost and hopefully I'll enjoy it! I'll start looking into where to get the clutch kit and everything else from in the meantime.

Cheers

[84CoupeGT]

Managed to get back to have a proper look at the car yesterday. There is a small bush missing in the gear linkage underneath, which I guess probably crumbled and fell out while I was driving. It's the ball socket one which attaches the part of the linkage with the support arm from the gearbox. I also noticed the gear shift does seem looser than before (I hadn't noticed this previously, probably so focussed on just getting the car back!). It seems from reading online that this can make gear selection difficult, however whether this is the full story or whether there are other issues remains to be seen. It doesn't seem to account for the "rattling marbles" sound at idle in neutral it was doing when hot, although I couldn't seem to recreate it this time (didn't drive as far though).

Missing bush...


I also had a look the clutch cable and measured approx 20-25mm free play at the pedal, which is slightly over spec. I tried to adjust it but unfortunately snapped the adjuster, so looks like I need to get that repaired or a new cable made up (can't seem to find them for sale anywhere!).

Anyway, I've ordered the ball socket bush and will fit that and do some more driving to see how that goes.

In better news, I resolved the vibration coming from the rear which turned out to be rust in the groove of drums dragging on the backing plate. I was concerned I'd messed up fitting the wheel bearings, so checked and loosened those slightly first, but after scraping the rust accumulation off the rear wheels now spin silently

Also, the car now starts up much better hot and cold, and is willing to rev almost from the off, just needs one slow blip before it's happy to play! So, well happy the warm up regulator rebuild did the trick finally.

Cheers

[Hanuman]

Sorry, I’ve been a bit busy the last few days.

Yes, once the gearbox was dropped, I did replace everything, or rather, I got a very good deal on having everything done.
Clutch, release bearing, rear crank seal. I think the gearbox had some attention to the input shaft, too.

[84CoupeGT]

Morning all

I've finally had a bit of time to have a better look at the issue and drive the car again.

I replaced the ball joint bush which was missing from the gear linkage. I also removed and disassembled the linkage, most of the grease was dried out so I cleaned and greased everything up (I used brake ceramic grease so hopefully that's ok!) and replaced a protective cover which was split. The linkage certainly moves more freely and the gear change in the car feels a bit tighter.

I also adjusted the clutch so there was almost no play in the cable, my thoughts were that if the clutch was dragging it might be possible to improve slightly by doing that.

The upshot is that the issues are still there. I took the car for a fairly long (20 miles) drive, there was initially the occasional crunch (mainly reverse and third), but found this happened mainly with leisurely gear changes and if I changed quickly it didn't crunch. Some changes were fine, but sometimes it wouldn't go in and I'd have to "persuade" it / retry. The same happens with the car stationary, with the engine running or not, and even when the car is cold, and (if engine not running) with clutch in or out. It seems to "stick", but when you do get it into a gear it will then go through the gate fine until the car moves again or is left for a while.

I then took the car up to a higher constant speed (about 60mph), after that it was very difficult to get into or out of any gear. It didn't improve much (if at all) the next day when cold again. I also noticed when downshifting, on releasing the clutch to give engine braking the car judders quite a bit (does seem to back up what you guys have said about perhaps the clutch engagement/disengagement being uneven).

There is also the irregular metallic rattling noise, only when it's very hot after driving at speed. I took a video which you can see here, although the camera doesn't pick up the noise very well...

https://youtu.be/5pPgyKm81t0

So, it looks like I will be pulling the gearbox out! My question before I do that, is do you think it's worth changing the gearbox oil first? I have checked it, it was full and very clear. I know they are supposed to be "filled for life", but I guess the Audi engineers weren't envisioning a 38 year life span! Could the severe symptoms when very hot be because the oil has degraded and is not providing enough lubrication at higher temperatures? Or is that just wishful thinking and should I just crack on with removing the gearbox and clutch?!

Cheers

[84CoupeGT]

Bump! Anyone get chance to have a look/listen to the video in my post above? Any thoughts as to whether is worth changing the gearbox oil... Or should I now be resigned to pulling the gearbox out and replacing the clutch, bearings etc??

Any thoughts/comments welcome!!

Cheers