Reward Offered - Help me diagnose a Clunking/Knocking noise from Satan

[Ghetto-Spec .:bayka:.]

Hi Guys, dead serious, I'm offering a cash reward to the first person to help successfully pinpoint a problem that is slowly killing me.

I am going to have to explain this in detail, so please bear with me, read carefully and dont jump to conclusions before you have read all the facts.

- - Executive Summary: The Problem - -
A mechanical knocking that can be felt and heard faintly under acceleration but is most prominent when the accelerator is lifted off and the revs are held at around 5000rpm (at minimal throttle). It can also be reproduced at other revs and similarly is most prominent when holding the revs at a point rather than accelerating or decelerating. The knocking frequency is around 2-5 cycles per second and increases with increase in rpm (dependent on engine revolutions). Most notable is the knock can also be felt through the chassis (ie pedals and floor). The knock was first noticed while driving in-gear. Once it is produced, if the throttle is used to hold the rpm, the knock can be sustained in or out of gear by either clutching or disengaging the gear to neutral. It does not happen when stationary and out of gear, and (heres the killer) it can be stopped instantly by applying the brake...

e.g. 2nd gear -> accelerate to 5000rpm -> hold revs at 5000 and the knock gets loud and clunky -> gently apply braking force with left foot -> knock disappears.

- - The Events in chronological order - -
-Serious engine rebuild (fine operation for ~4000kms)
-Lost driver side front wheel at 60km/hr (car grinded on ball joint underneith wheel hub)
-Two weeks after wheel was lost, the clunking noise started to emerg.
-We decided that with a clunk that can be felt so strongly thru the chassis and because we can make it disappear by applying brakes and we had just lost a wheel a few weeks ago: the problem must be drivetrain related.
-Replaced lsd box with non-ls gearbox and non-ls shafts (Perhaps the drive shaft rammed into the box when I lost the wheel and the box was damaged?)
-Replaced non-ls shafts with second pair of non-ls shafts
-Replaced both front wheel bearings
Problem still remained at each point.

What in fucks name could do this. Am I kidding myself about an engine knock?
Don't get me wrong, it was my first fearful assumption after a serious engine rebuild. I reproduced the problem to a good friend and he thinks the knock is too heavy to come from the engine, both driver and passenger can feel the knock through the floor. The engine revs smoothly and perfectly and is actually running the best it ever has with no power loss.
It just seems as though its ever since i lost the wheel.
It persists with two different gearboxes, completely different pairs of drive shafts and to eliminate another variable, I just replaced both front fucking wheel bearings (driver side had play).

Is it possible that the control arm was bent when i grinded on the hub after loosing front wheel, which somehow causes the knock?

I spun a big end bearing before the rebuild and the knock sounds completely different to that. The only other engine horror I can think of is a gudgeon pin - perhaps thats why the noise goes away when i apply the brakes - the brakes load the engine up which stops the loose vibration of an engine knock at low load (minimal throttle)? ((this is the shit i think about in the shower - seriously))

Fuck.
Please help
I cant do this alone anymore

[Jackel]

lift the back wheels up and put the car in gear and drive, if the noise is there it's engine/drivetrain if not it's the car

[oldcorollas]

does the frequency of the knock chenge when you change gears?

i guess i would start by...
changing up thru gears, see if frequency increases with road speed, or if the frequency goes down each time a higher gear is selected.
if it goes down, then it is between engine, clutch and input shaft/layshaft (if there is one in FWD box).
if it only increases with road speed, then it is between input shaft and wheels.

you say it sound stops when you brake?

what if you are driving at speed, then hold foot on clutch for say, 10 seconds (to make sure layshaft stops), maintain engine speed, and apply footbrake (with tricky footery)? what about if you use handbrake?

my guess for the money would have been the gearbox, ie something stuck on one of the teeth, on the side that is engaged during accel, that is hitting each time it goes around. if it is on layshaft, then it will be coupled to engine speed directly, and if it is on accel thrust side, then decel will stop the noise.

but you said you changed boxes? was the sound exactly the same between boxes?

if it is dependent on engine rpm only (but then it doesnt happen when stopped?), then you have ruled out most of the box, the shafts and hubs etc... but you need to be very sure it is not roadspeed based...
i think one of your clues is either incorrect, or not clear.

[oldeskewltoy]

check the suspenion carefully..... my bet is on something that occured when you lost the wheel. Since you have replaced gearboxes and such.... I'd say its time to replace the front end... at least the side that fell... but not knowing the impact or anything else about the wheel loss, I'd say swap it all out abd see if it remains......

[IN 05 NT]

what car??? im assuming your 4agse....

if its not making the sound when stopped in neutral, you can be sure that its not a bearing/or the motor,and mpst likely part of the driveline,

jack the front of the car up, put it on jack stands, (make sure its very stable!!!)

get in the car, start it up and start to make the noise as loud and clear as you can while you gt a mate to get under and try and locate the noise,

you can use a screw driver by placing the blade end on the gbox, and put you ear up against the plastic handle,(long screw driver, be aware of rotating parts!)

move the screwy over different parts of the box, till the noise is loudest,

by using the screwy, you can pin point the noise location, or atleast narrow it down,

let us know how you go, if you were in syd id say bring it down to the shop, would be happy to have a look,

blake

[TA-022]

lift the back wheels up and put the car in gear and drive, if the noise is there it's engine/drivetrain if not it's the car

LOL i can see his car through his garage door its FWD.

Have you checked brakes? straightness of hub etc?

[o_man_ra23]

Gday, I would back up the theories of replacing the suspension components on the dropped side, an impact like that is sure to bend something. However, this kind of knock, I would actually be having a careful inspection of the engine mounts, especially the front mount. Pull them off one by one and check them... a shagged out mount can cause a knock that will go through the chassis (subframe actually, your car doesnt have a chassis as it is Monocoque (Speeling??) design) at a low frequency. The inertia of the motor pushing on said engine mount when decellerating using the brake can cause it to hold steady and stop knocking, until you begin to use the accelerator again (or even just removing foot from brake may bring the noise back).

Other item I can think of is brake disks. I am guessing you have hat type brake disks. These could have been warped etc in the impact, or you could have a bit of debris behind the disk rotor, allowing the rotor to move slightly. The movement can be intensified by the harmonics of the engine causing an audible knock (without the wheel being loose). The rotor wont move around when your stationary or the pads are holding it steady.

Cheers, Owen

PS, Im not after a cash reward, just want your car to work properly... if I win, put the money to charity or something.

[madmont]

My wifes camry had a vibration which manifested at about 3500rpm. Turned out to be a broken bracket holding the exhaust to the motor . Mate of mine had terrible clunk in the drivetrain of his old sigma. Had a look and it was caused by no rubber left in the locating rod mount for the rear axle. Engine mount theory sounds good.

[IN 05 NT]

if the disc/s are damaged, or warped you would feel carzy vibrations thru the steering if thats the case,

engine mounts dont knock,..repeatedly like he is saying, to test the mounst anyway, put it in gear and load teh car up at a standstill and watch how far the engine moves,

when the wheel fell off, what was damaged? disc scrape along?

[ed]

heard faintly under acceleration but is most prominent when the accelerator is lifted off and the revs are held at around 5000rpm (at minimal throttle). It can also be reproduced at other revs and similarly is most prominent when holding the revs at a point rather than accelerating or decelerating.

thats a rod

the rest of your story, in particular the 'stops when i apply the brake' bit, also goes with rod knock

[WDE_BDY]

I'm thinking brake discs, maybe a stone or something hitting caliper or bracket. Doesn't sound egine related from the symptoms you describe.

Callum

[mr_unix]

Had exactly the same problem on an old Camry I used to drive, and it became progressively worse and worse. It turned out to be a screwed up engine mount, like o_man_ra23 said.

Apparently I was told by the mechanic that it screwed up when the Camry fell off the jack when I was replacing a tyre, it was on the passenger side.

Took the mechanic 2 solid days to find the problem, he thought it was a crap CV joint at first being a FWD car, then looked at the gearbox, then looked at the wheel hub and the front break. Purely by chance he had a glimpse at the mount when he was replacing the CV joint after giving up on everything else and bingo. He fixed the mount and noise was magically gone.

Jerry

[takai]

Check your wheel nuts as well, we had an old car which lost 2 wheel nuts and the other 2 were loose (stupid hubcaps with fake wheel nuts), and it made clunking noises under decel and braking, but not accel.

[o_man_ra23]

then looked at the wheel hub and the front break.

If you go to a mechanic asking for a break service, they will tell you they dont work their lunch hour. different story if you ask for a BRAKE service... you might be able to stop the car better after one of them.

Cheers Owen

[Talasas]

That's a tough one, the whole front end on these damn AE92s is a pandora's box when it comes to noises. However, being that it is a cycling sound it has to be related to moving parts (so rotors, hubs etc rather than struts) the way you can find out for sure (bear with me on this) is that if it is:

- A rotating part itself making the noise (e.g. bearing) it will make a noise and the duration of the noise increases as you slow down

OR

- A rotating the part causing the noise on something non-rotating the duration of the noise remains the same at all speeds (e.g. knocking)

So check that out to be sure.

When you replaced the hubs were they new? Because you might have gotten a dud one. It may also be that it is just low on grease, I had hub noise and applied some grease and it went away.

Otherwise I would also join the brake rotor bandwagon, The car falling off a wheel will surely hit the brake rotor even if it sits on the ball joint, was your brake dust cover bent/damaged? Then you know the rotor has been hit.