Clunk sound with clutch engagement

[BamaQLD]

Hey,

I am after a bit of advice and wondering if anyone has had a similar experience. My polo is growing old and has hit the 175k km milestone. The OE clutch is still installed and when I go to engage the clutch upshifting (or from a standing start) I get a clunking noise around the lower middle section between the foot wells. This only happens when I attempt to release the clutch pedal a bit too 'fast', if I release slowly and very gently there is no clunk.

It also only happens when accelerating, as I can aggressively let the clutch out deaccelerating with no noise. I have read other posts and some have suggested it is the clutch/flywheel? I have crawled under the car and checked all the engine mounts and control arm bushes and they seem fine. I also have a grinding noise when revving out first gear which I suspect sounds like a buggered throw out bearing.

If it turns out to be my clutch/flywheel are there any recommendations? I am looking at the BFI stg 2 from ECS. My mods and info related to my suspension set up are detailed in a previous post (BamaQLDs its getting there). Haven't contributed to the post for a while as my ass has been broke... keen to keep the polo alive.

Thanks in advance..

[sambb]

could just be a shagged dogbone bush. But given the age of the clutch your not incorrect in thinking about what to do re a replacement. You definitely want to do a single mass flywheel conversion. This means buying a kit that includes a flywwheel, clutch, pressure plate, all the relevant bolts and throw out bearing. My car is Stage 2 and gets tracked a fair bit (with an LSD which means more traction therefore more work for the clutch to do) and I've run the stage 1 ECS kit with the lighter of the available flywheels. At each hillclimb event it gets 5 good burnouts and then 5 good hard launches after that sometimes boosting it up against the handbrake at the friction point and the clutch is still going strong. In reality this kit is something similar to a G60 flywheel (the ecs lightest flywheel is lighter than that though and steel) with a VR6 PP and clutch. So you can buy in kit form from someone like ECS or Brian at GTIimports can sort you out with a kit built around the G60 flywheel. I dont thinkyou could get a clutch kit sorted cheaper off anyone else than him. PM me if you want his details. When I'm ready to put my new box in, i'll be doing it with identical gear except for an uprated PP - a transporter T5 pressure plate for a bit more clamping force to combat the traction of an even better diff. I do suspect though that the stage 1 ECS kit is more than adequate for a stage 2 car for a long time. The clutch pedal is even lighter on a stage 1/vr6 than the stock dual mass. The single mass will shudder a bit more around friction point as you hillstart, that kind of thing but otherwise you can't separate it froma dual mass. Maybe a tad noisier in general but they are so much lighter you'll love the way it revs up and engine brakes.

[BamaQLD]

Hey Sam,

Thanks for your reply and recommendations. I have recently replaced the (large) bush in the dogbone mount, is it common for the smaller bush in the dogbone to go? Seems to look and feel relatively solid still.

Keen to go ahead and replace the clutch/flywheel etc. How hard is the job to do. I only have a small garage but probably all of the equipment/tools to carry out the job myself.

As mentioned this is the kit I have my eye on $1300AUD landed. Seems to be good quality and BFI seems to have a good reputation? I noticed you mentioned Brain from GTIimports as a potential source in OZ. I might get in contact with him and see what he offers for that price range.

https://www.ecstuning.com/b-black-forest-industries-parts/bfi-stage-2-clutch-kit-lightweight-228mm-single-mass-flywheel-1185lbs/bfi18228st2~bfi/

Cheers

[sambb]

yeah its normally the big end that goes and/or is just too soft from factory.
Its a decent sized job. Nothing is hard technically its just many steps and its pretty awkward to maneuver the box into place as space is very tight. I'll see if I can dig out the workshp manual for the process as it does help massively first time around and has all the torque specs etc.
Sorry your link didn't open. Tomorrow I'll dig out Brians number as I'm pretty sure he could source you the bits even delivered up there for cheaper than that. He cant do the lightest ECS flywheels but he can do the G60 ones that are maybe a pound and a half heavier than ECS's steel one, although it'd be the VR6 clutch/PP which would be considered stage 1. My transporter PP and VR6 clutch plate would be stage 2 I guess and he can get that too. Its just that I haven't installed mine yet so cant vouch for it personally like the ECS stage 1/VR6 kit.

[BamaQLD]

Hello again,

I have still remained stumped on my 'clunk' sound coming from the center/passenger footwell when accelerating. I crawled under the car to inspect/eliminate the dogbone mount/bushes. I replaced the large rear bush only about 9 months ago and the small front bush seems okay albeit a bit worn. Everything else seems to be tight externally around the motor gearbox but when I turn the unweighted wheels back and forth there is a bit of play and a knocking sound coming from the gearbox/diff/drive shaft. I am guessing this may well be the problem and I was wondering if other polos have the same play/knock when moving the wheels back and forth?

At this stage I am looking at taking it to Nerang Differentials services as they seem to have pretty good reviews.


I have also ordered a new ECS stg1 clutch I am hoping to get fitted soon to eliminate the clutch as a cause.

[sambb]

There normally is a fair bit of play if you rock a wheel back and forth, mostly in the CV's. If you are on a steady light throttle cruise in a 4th at 50kph and you just give it a tiny bit more throttle and in that instant get a clunk, then often the same as you get out of that bit of throttle you just added - just one clunk as you change the load on the engine, then in my experience that can be the dual mass. If its a bit different to that I'm not sure.

[BamaQLD]

Thanks as always for your reply Sam.

Had the new clutch installed today and the clunk is still evident. The mechanic seems to think it is the gearbox mount. I had suspected this as I had the metal in it tear a little while back (long story...). Because I needed it fixed asap I had to go to a local ultra tune who got the mount welded up as they struggled to find a speedy replacement.

I have now ordered a new one so fingers crossed this is the problem. Has sounded like a mount from the start but seeing as though I had the gearbox mount 'fixed' recently and it visually looked okay, I put this towards the bottom of potential causes.

Re: The new clutch, I am assuming it will need some sort of running in?

[sambb]

metal in the dogbone tore ?Que?

yeah drive around normally for a while without line launches is good, just to get all the surfaces bed in. Hmmm if it wasnt that then yeah the dogbone would be most likely (if it is a mount) or could even be strut top bearings.

The single mass brings a new set of noises, or at least it did with mine. My release bearing was noisy fromm the start and you generally get more vibration related noise from single masses but I'm sure you'll notice it'll spin up and rev quicker with the lighter drivetrain.

[BamaQLD]

So I finally received and installed a new gearbox/LHS engine mount... problem solved! No more clunk, no more grinding noises. Car feels like so much more power is hitn the wheels now. Very happy with the result, car feels great with the combination of the mount, single mass and lightweight flywheel.
I ended up going with the vibra-technics mount. Quite expensive when postage is included but looks like a quality part and I was hearing some bad reviews on the local standard mount produced here through supercheap.
Few pics to close of this thread.. Will be adding it to my slow build thread. Thanks Sam for your replies and advice.

[Alex993cc]

hows the vibration in the cab afterwards? any increase?

[BamaQLD]

There is a very slight increase in vibration when idling, but nothing major at all. Makes sense to have the engine solidly mounted, feels better when accelerating.

[Bijoy K Jose]

Hi @BamaQLD,
My Polo 1.5 TDI has got this issue now, which is 6yr old and ran for 78K KM. I get the same clunk noise as you reported, when I release my clutch. This happens in 1.1-1.3 RPM range. If I release clutch slowly with bit high acceleration, I get no issues.

I went to a nearest mechanic. He said issue is with the driver side engine mount. I'm planning to visit nearest VW showroom in coming days. Can this issue be sorted just by checking and replacing engine mounts. Clutch and gear mount change are really needed here? Please could you clarify. I haven't got clutch and gear mount issues yet. So haven't changed anything related to clutch and gear boxes yet. So I assume issue is just with engine mount here.

[sambb]

If its the gearbox passenger side mount then it cant really be checked with eyes on. your battery and airbox = labour $, all have to be removed to do a visual. Best way to check it would be someone lying under the car or with their ear to the passenger side wheel well (tyre removed would be best with the caron a solid stand, not a jack) while another rocks the engine as hard as they can forward and backward to see whether the noise can be generated and if its coming from that area. If its the dogbone mount that runs between the subframes cross member and the gearbox underneath at the back of the engine, that can cause the same noise - if the bush material is gone you'll get it further up the rev range though. If its' bolt that goes into the subframe is loose you'll get the clunks at low revs like you described. So get under the car safely and tighten up that bolt and then see if you can diagnose a sound from the passenger side gearbox mount.