Intermittent knocking problem

[Tanuki]

Driving along today, came down a short incline and needed to brake. After braking all of a sudden a knocking noise from what seems to be the transmission tunnel.

I drove along slowly for a bit and under power the noise went away, but when I pulled up again, the knocking noise returned. Clutch fully depressed, the noise stayed constant, engine at idle.

• Engine runs fine. No rough idle
• Seemed to happen after braking
• Clutch has been operating just fine with no slip
• Gears working fine, changing smoothly, no noises.

Got home and let it sit. Went and had dinner, sat down and got my head straight, went back out and and started the car. Knocking disappeared
Drove it round the block, did some braking, still no knock. Drove home and car quiet and well behaved.

What is going on?

Flywheel? Clutch? Brakes? Driveshaft? (By the way where is the driveshaft(s) on a front drive?)

I thought something to do with brakes maybe, because it happened right after braking, though the knock seems to be in the transmission.

Now it's gone, but I'm obviously concerned there is something ready to go if I don't work it out. I've got it booked into the garage but I'll bet I won't be able to reproduce it for them.

[Teutonic_Tamer]

Could be the rear engine mount!

BTW, update your signature, so we dont have to guess what car you drive

[passat boy]

Driving along today, came down a short incline and needed to brake. After braking all of a sudden a knocking noise from what seems to be the transmission tunnel.

I drove along slowly for a bit and under power the noise went away, but when I pulled up again, the knocking noise returned. Clutch fully depressed, the noise stayed constant, engine at idle.

• Engine runs fine. No rough idle
• Seemed to happen after braking
• Clutch has been operating just fine with no slip
• Gears working fine, changing smoothly, no noises.

Got home and let it sit. Went and had dinner, sat down and got my head straight, went back out and and started the car. Knocking disappeared
Drove it round the block, did some braking, still no knock. Drove home and car quiet and well behaved.

What is going on?

Flywheel? Clutch? Brakes? Driveshaft? (By the way where is the driveshaft(s) on a front drive?)

I thought something to do with brakes maybe, because it happened right after braking, though the knock seems to be in the transmission.

Now it's gone, but I'm obviously concerned there is something ready to go if I don't work it out. I've got it booked into the garage but I'll bet I won't be able to reproduce it for them.

A golf i once had, showed the same problem and it turned out to be the clutch worn(pressure plate not the friction lining)that set up a left to right type of wobble vibration.The clutch went on for 6 months before finally packing up.Driveshafts are the tubular bars running centre into your wheels to make it simple,just look under your car or remove the hubcaps/wheel trim and the big centre nut under is bolted into the driveshafts.Have you checked your barke pads/shoes/drums for ovalness and metal to metal wear as well as wheel alighnment and 4 wheel balancing.Generally the front wheels out of balance with worn brakes(pads worn on the point of the metal backing plate)can set up a judder and bad alighnment adds to your woes.All these faults wear the wheel bearings/suspension bushes/tyres/cv joints/stering rack etc out and can be dangerous on aluminium parts and ball joints.As you state it happend after braking,a clunk could indicate the brake pads as the pistons are pushed out almost their full lenght(shortening their life rapidly)and increasing your stopping power to danger point.Look at the calipers to see the condition of your brake shoe/pads(do a google search for info on descriptions of the parts you need to know about).

[Teutonic_Tamer]

Have you checked your barke pads/shoes/drums for ovalness and metal to metal wear as well as wheel alighnment and 4 wheel balancing.

Are you being serious? The OP said - quote "knocking noise from what seems to be the transmission tunnel" unquote! *** would ANY brake wear issue, or ANY alignment issue, or ANY balance issue have to do to create knocking near the transmission tunnel???????

Generally the front wheels out of balance with worn brakes(pads worn on the point of the metal backing plate)can set up a judder and bad alighnment adds to your woes.

Oh dear - what comics do you read???? None of this will create any "knocking" sounds!

All these faults wear the wheel bearings/suspension bushes/tyres/cv joints/stering rack etc out and can be dangerous on aluminium parts and ball joints.

You really are on cloud cookoo land - how TF can say a worn wheel bearing be dangerous on aluminium parts?????

As you state it happend after braking,a clunk could indicate the brake pads as the pistons are pushed out almost their full lenght(shortening their life rapidly)and increasing your stopping power to danger point.

What have you been smoking. I have never, ever experienced caliper pistons being pushed out more than 25% of their maximum travel - even when the pads have worn down to the metal!


You really have demonstrated you complete lack of any basic technical understandings of "real world" automotive problems. With people like you, who needs time wasters!

[passat boy]

Are you being serious? The OP said - quote "knocking noise from what seems to be the transmission tunnel" unquote! *** would ANY brake wear issue, or ANY alignment issue, or ANY balance issue have to do to create knocking near the transmission tunnel???????



Oh dear - what comics do you read???? None of this will create any "knocking" sounds!



You really are on cloud cookoo land - how TF can say a worn wheel bearing be dangerous on aluminium parts?????



What have you been smoking. I have never, ever experienced caliper pistons being pushed out more than 25% of their maximum travel - even when the pads have worn down to the metal!


You really have demonstrated you complete lack of any basic technical understandings of "real world" automotive problems. With people like you, who needs time wasters!

MMMMMMMMM.......so much for freedom of speech and democracy,sorry to offend you but were all entitled to our oppinion's and your's seems to be very verbal at present but that's good as it show's your'e intelligent to a point.Im not a proffesional mechanic and i assume you are,i speak from what ive experienced personally or seen and heard using good judgement also about what has been described about the problem and cure.
Put a smile on your face and stop working long hour's,look what it's turning you into!.

[seraph]

but were all entitled to our oppinion's

This is a classic case of the problem afflicted on forums.....separation of fact and opinon.

While we are all indeed entitled to freedom of speech, some threads of a technical nature require a high degree of accuracy and fact, thus theres little room for opinion.

Remember, lay people visiting these sites will rely on what they read, so it has to be accurate...

Nobody doubts what happen to you, but becasue it happened to you, doesnt make it inevitable in all other golfs!

[Teutonic_Tamer]

MMMMMMMMM.......so much for freedom of speech and democracy,

Ohh, good heavens - I would never want to restrict freedom of speech, and would be one of the last persons (my attempt to be PC!) standing to defend that said freedom.

But, with that "freedom", also comes responsibilities, and liabilities! If you do wish to stand on a soap-box, and state your cause, you must be responsible enough to ensure, to the best of your ability, that it is accurate. You must also accept that people will have the very same rights of freedom to challenge what you have said, particularly if it was factually incorrect.

I certainly didn't mean to offend you, but it is obviously clear that my "frustrations" were being vented, and I apologise if I did cause any offence!

sorry to offend you

Oh, no worries - no offence taken. I have pretty thick skin. I was more frustrated, if anything.

but were all entitled to our oppinion's

Again, I fully agree. But you might have been wise to use the accronym: "IMHO" (in my humble opinion), then the emphasis of your post would have been taken in a different light!

and your's seems to be very verbal at present but that's good as it show's your'e intelligent to a point.

OK, I'm not sure wether to take that as a compliment or not? I do however, feel that it is important that I can offer the "professional" experience, and technical know-how, if I can see "errors" that others (it wouldn't matter if they were a professional mechanic, an enthusiastic DIYer, or a complete mechanical ignoramus) have posted. It is what makes this such a good forum, in that people can offer professional and technical advice, and also have that advice judged by others too. It is really about giving and taking!

Im not a proffesional mechanic

Then perhaps it would have been wise to say so, in a simlar vein to the "IMHO" bit!

i speak from what ive experienced personally

There is nothing wrong with that (may we should use "IMPE" - in my personal experience).

or seen and heard using good judgement also about what has been described about the problem and cure.

But that is where it can get a little dangerous - rumor mills can be a real melting pot of anywhere between fiction and fact, and unless you are professionally trained in that specific area, you won't be able to truely deciper fact from fiction!

Put a smile on your face and stop working long hour's,look what it's turning you into!.

Oh, I can certainly smile, thanks, and as for "long work hours", thankfully those are a thing of the past (still don't know where all my 8loody time goes though ). What has it turned me into