Rear-end clunking when pressing clutch

[kjmac]

Hi all,

One of my car's more annoying characteristics is a certain amount of clunking that sometimes happens when pressing in the clutch. It tends to be quite notifiable at low speeds and seems to be coming from the rear of the car. Something not right with the diff maybe? A little while back I'd also attempted some brief sideways antics on works wet car park (not so keen on that kind of thing on public roads) only to find that the diff seemed to be very reluctant to lock up. Fluid change? Warranty issue?

The car's a 56 plate 6 litre VXR.

Thanks

[racebreed]

maybe diff mounts or something like that more likely just does it as a charecteristic

someone more qualified will be along soon

[kjmac]

Hmm, just scraped this from corvetteforum.com:

corvetteforum.com said:

PIP3896: Clunk Noise When Shifting More Noticeable At Low Speeds - keywords clutch manual throttle transmission - (Aug 28, 2007)
Subject: Clunk Noise When Shifting More Noticeable at Low Speeds
Models: 2004-2007 Cadillac CTS-V

1997-2007 Chevrolet Corvette
2005-2006 Chevrolet SSR
2004-2006 Pontiac GTO

Equipped with a Tremec 6-speed Manual Transmission

--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
While driving in a steady slow speed parade type situation a clunk-clunk noise from the driveline may be heard when depressing and releasing the clutch pedal, between shifts or quickly depressing and releasing the throttle.

Recommendation/Instructions:
The noise is a normal torque reversal in the driveline and a combination of axle backlash, front and rear drive shaft rubber isolation flanges, drive shaft center support, and a dual mass flywheel all working together. This is a normal characteristic and not a condition of operation concern. No repairs should be attempted.

Also reference the latest version of TSB 03-07-29-004 for further manual transmission operating characteristics.

The above sounds quite familiar, the Monaro's drive-train does feel like it's got a fair bit of slop in it

[ringram]

Mine was down to the rear cv joints in the shafts. If you grab them and twist there should be little to no movement in the front of the diff/driveshaft. Mine had about 1cm play in it.

[crisisjez]

That`ll be LSD lock up.

Sounds expensive but really easy to fix.

Little bit of molyslip diff oil ought to do the trick.
Give Roger at Monkfish a call if he`s near you.

[kjmac]

crisisjez said:

That`ll be LSD lock up.

Sounds expensive but really easy to fix.

Little bit of molyslip diff oil ought to do the trick.
Give Roger at Monkfish a call if he`s near you.

The bugger is that I'm near Liverpool! Does anyone know of any good independant specialists in the north-west? I'm guessing there's no magic to changing the diff oil? That being the case I guess I could get hold of some and ask if Oli at Phoenix Motorsports could take a look. Sadly to date he's about the only bloke I trust with my cars, although he's really a Lotus specialist.

Thanks for the responses

[ringram]

When the LSD mix needs looking at its normally only noisy when turning corners.

[racebreed]

kjmac said:

Hmm, just scraped this from corvetteforum.com:

corvetteforum.com said:

PIP3896: Clunk Noise When Shifting More Noticeable At Low Speeds - keywords clutch manual throttle transmission - (Aug 28, 2007)
Subject: Clunk Noise When Shifting More Noticeable at Low Speeds
Models: 2004-2007 Cadillac CTS-V

1997-2007 Chevrolet Corvette
2005-2006 Chevrolet SSR
2004-2006 Pontiac GTO

Equipped with a Tremec 6-speed Manual Transmission

--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
While driving in a steady slow speed parade type situation a clunk-clunk noise from the driveline may be heard when depressing and releasing the clutch pedal, between shifts or quickly depressing and releasing the throttle.

Recommendation/Instructions:
The noise is a normal torque reversal in the driveline and a combination of axle backlash, front and rear drive shaft rubber isolation flanges, drive shaft center support, and a dual mass flywheel all working together. This is a normal characteristic and not a condition of operation concern. No repairs should be attempted.

Also reference the latest version of TSB 03-07-29-004 for further manual transmission operating characteristics.

The above sounds quite familiar, the Monaro's drive-train does feel like it's got a fair bit of slop in it

mine certainly does this as well i wouldnt have thought its anything to worry about

[v8 beef]

racebreed said:

kjmac said:

Hmm, just scraped this from corvetteforum.com:

corvetteforum.com said:

PIP3896: Clunk Noise When Shifting More Noticeable At Low Speeds - keywords clutch manual throttle transmission - (Aug 28, 2007)
Subject: Clunk Noise When Shifting More Noticeable at Low Speeds
Models: 2004-2007 Cadillac CTS-V

1997-2007 Chevrolet Corvette
2005-2006 Chevrolet SSR
2004-2006 Pontiac GTO

Equipped with a Tremec 6-speed Manual Transmission

--------------------------------------------------------------------------------

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
While driving in a steady slow speed parade type situation a clunk-clunk noise from the driveline may be heard when depressing and releasing the clutch pedal, between shifts or quickly depressing and releasing the throttle.

Recommendation/Instructions:
The noise is a normal torque reversal in the driveline and a combination of axle backlash, front and rear drive shaft rubber isolation flanges, drive shaft center support, and a dual mass flywheel all working together. This is a normal characteristic and not a condition of operation concern. No repairs should be attempted.

Also reference the latest version of TSB 03-07-29-004 for further manual transmission operating characteristics.

The above sounds quite familiar, the Monaro's drive-train does feel like it's got a fair bit of slop in it

mine certainly does this as well i wouldnt have thought its anything to worry about

Mine seems to have the same on take up of drive just checked the prop shaft and driveshafts and diff they all seem fine no play. there does seem to be a about a 1/8th of a turn of backlash in the output of the gearbox and you can hear it too.

[davegreg]

yeah, my Ro does this too, particularly noticeable whilst crawling along in 1st gear anywhere. More noticable when the engine is cold..
I'll stop worrying about it now though.

This was in reply to the original message.

Edited by davegreg on Tuesday 26th August 06:48

[S600VXR]

Mine does this to a little, just a combination of backlask from all the joints etc. Nothing to worry about so long as its not to bad otherwise it could mean a damaged CV joint, diff gear bearing etc, mind you Id guess that would fail fairly quickly with the Ro's torque.

[ukvoyager.info]

Mine did this also. Got really bad at one point where below about 40 it clonked all the time... happened when not accelerating or braking (ie in traffic).

Anyway some diff modifier does the trick. Dead easy to DIY or any half decent garage to do. 10 mins work max.

[kjmac]

It's not too bad at the moment, but I'll certainly consider looking at some diff modifier. It's certainly all a world away from my VX220 which had zero slack anywhere. It also had the best shift action of any car I've ever driven, not something I can say about the ro.

That said, the ro is a much more viable daily driver! I'd used the VX in that capacity for over 2 years, no heater, ice on the inside of the windscreen etc! Cracking car tho.

[S600VXR]

kjmac said:

ice on the inside of the windscreen etc! Cracking car tho.

WTF!

Dont care how well it handles - thats just taking the P*ss!

BTW - have you got a rip shifter fitted? or AP's or coilovers...? all contribute to improving the Ro signifigantly.

[kjmac]

S600VXR said:

WTF!

Dont care how well it handles - thats just taking the P*ss!

BTW - have you got a rip shifter fitted? or AP's or coilovers...? all contribute to improving the Ro signifigantly.

Apart from the Wortec pipes the car's standard, I've certainly heard good things about the upgrades mentioned, but it all adds up! I certainly remember it being very easy to hook 1st gear instead of 3rd when I was new to the car - thankfully I didn't have any kind of high speed money-shifting incident. Sounds like a rip-shift might help there. I'll probably leave the car be, it's more economically viable to buy a modded car if that's the way I'd want to go!

As for the VX, did I mention that the locks would freeze too? There was also no filter on the demister so it would spray live insects into the (very confined cabin). Oh and my garage was so small that I had to get in and out by taking the roof off in the morning Er, and the interior was either made out of the cheapest possible scratchy plastic and foam or was just bare metal! Conversation at motorway speed was also near impossible. Awesome thing, the handling really was that good

Fingers crossed I'll get a bigger place in a year or so with parking for two cars, then I'll probably get some cheap bargain barge thing combined with something really stupid with no doors and no roof!

[ukvoyager.info]

I have to admit getting out of the 205 in to the Monaro is like chalk and cheese. You really understand what modern suspension and comfortable seats are all about not to mention torque.

[headhoon]

kjmac said:

Hi all,

One of my car's more annoying characteristics is a certain amount of clunking that sometimes happens when pressing in the clutch. It tends to be quite notifiable at low speeds and seems to be coming from the rear of the car. Something not right with the diff maybe? A little while back I'd also attempted some brief sideways antics on works wet car park (not so keen on that kind of thing on public roads) only to find that the diff seemed to be very reluctant to lock up. Fluid change? Warranty issue?

The car's a 56 plate 6 litre VXR.

Thanks

This is a well known issue with Holden in NZ and Australia (even the V6 auto Commodores do it). It's not a biggie but can be a bit annoying and some diffs do it more than others. My mate has the SV6 2006 Commodore auto and it does it all the time whereas my Monaro (6 speed manual) does it now and then. His car is still under warranty and all they do in this situation is put an additive in the diff oil (probably suet pudding)... Hope this helps.

Edited by headhoon on Thursday 28th August 02:12

[kjmac]

headhoon said:

This is a well known issue with Holden in NZ and Australia (even the V6 auto Commodores do it). It's not a biggie but can be a bit annoying and some diffs do it more than others. My mate has the SV6 2006 Commodore auto and it does it all the time whereas my Monaro (6 speed manual) does it now and then. His car is still under warranty and all they do in this situation is put an additive in the diff oil (probably suet pudding)... Hope this helps.

Cheers mate, I need new tyres soon-ish and might get it looked at while the cars in the garage. Knowing that it's a common quirk is reassuring!