Ok so this is really hard to explain, so ill try my best, hopfully y'all can give some thoughts. The first is a vibration in the rear. I had the shaft balanced but still had a vibration, just slightly different. I took it back and they spent the whole day looking/re balancing the shaft and found nothing (free labour ) He said all the joints, bushes and bearings are in good condition and can't be the cause! It's speed rated (70 through to whatever). One thing that may give a clue is when I'm at 60, and I lift off the throttle then press back down there kind of quickly, will be a clunk sound from the rear area... This will happen every time I do so in a fast action. Any ideas? The next noise I get is so very annoying and could be something bad slowly failing this is throttle related, only at speed (90 +), metallic sound, and in the engine bay direction. It kind of sounds like a bearing in a way. And will make the sound when I'm on the throttle (holding speed) lift off, and the sound will go until you apply pressure again. This sound will not happen in lower speeds, and won't do it if you have the bonnet up to try and hear for it! Grrrr What could this one be? Lol These are things I want to fix as it wrecks the driving experience, plus I'm worried its signs of something bad will soon happen
Guess #1: Have you checked the rear wheel balance? Guess #2: Similar problem with mine - after three rebalances of the 2-piece shaft was only eliminated by fitting a 1-piece shaft. Guess #3: ...clunk sound from the rear area - universal or CV joints? (even tho you say bushes and bearings OK) Guess #1: Manual gearbox - thrust bearing (remote) Guess #2: Auto gearbox - the vibration could be the torque converter, although that is related more to engine speed rather than road speed.
You need to replace all 4 diff mount bushes. Solid aluminium set are $70, I think from AMS. Poly set are $155ish
First question. Could be diff mounts as suggested. But also diff backlash. When driving it will mesh fine, then when coasting at speed then back on the pedal, the pinion/crown mesh loosens then snaps back giving you your clunk. Could also be uni joints but unlikely as they would make noise all the time. Lastly it could also be your gearbox mount. Which if also knackered too much could be dropping the front of the drive shaft too far out of alignment giving you a wobble/vibration. Second question. Could be a thrust bearing if you have a manual. Or it might be your front wheel bearings. Sometimes you won't hear a noise at lower speeds but as you rotate it faster the harmonics change and you would pickup on the wear. Do your normal wheel bearing checks and see if there is movement. Brake pad indicators?
Thanks for feedback guys. Car is an auto, which is freshly built w/mounts and all. I don't remember the sound to honest before the rebuild, but I took it back and they said alls good the sound if very precisely throttle related like something is "dingling" around when hold speed on the throttle, them nothing when off! My first car (a vr commo) had backlash, but would always give a clunk when you go from park to reverse. Could still be backlash of a different sort? Mounts I've been told need replacing as they are hard now, so ill put that on the list.... Tyres, brakes and all just recently done, balanced and aligned so I don't thinks that's the vibration....I don't really want to chuck a one piece in just in case that's not the issue -_- I'm stumped on both theses issues, ill get a vic zedder to come for a ride on the tech day so they can hear this stuff
i agree that all roads sound like they lead to Rome... and if not Rome then a rear sub frame housing issue etc.. mounts and so on...
+1 to Dougie's analysis(with the addition of possible Ring Gear/Pinion Gear wear/backlash in the Diff).
A one-piece Tail-shaft is a very worthwhile upgrade(as it eliminates one more variable in the never ending hunt for problem sounds and vibrations). Do it right..do it once!:zlove::zlove:
What your describing could be caused as a result of having no absortion (rubber cushioning) between engine/transmission and the chasis. Years ago I had an XU1 that had a vibration and transmitted a whole heap of drive train noise through the car at about 3 grand and above. It started directly after I replaced the clutch. Drove me crazy, had the clutch and flywheel balance, tailshaft and wheels balanced and was about to pull the engine and box out when I found that I had inadvertantly fitted a slightly longer bolt into the rear gearbox mount. It would touch the bottom of the gearbox when the engine torqued up at 3 grand and above. Shortened the bolt and problem solved. Regards Ivan
Could be, could be... The vibration I'm sure I could find and eliminate.... But the sound coming from the front is precisely throttle related... So I cant think of what would make such a sound apon throttle??? On top of that, as I said its only at 90+ aswell... Not lower speeds or stand still! So annoying!
Ok, so as an update, I jacked the rear end up so I could work out where the 'slop' is. With one wheel on the ground and the the other with out a wheel, I twisted the rotor back and forth....Found there to be 4-5mm of play. Is this correct? What other checks should I do to know for sure I need a reco Diff? There is a definite clunk when rolling at 60km/h, and by removing pressure of the petal then back on it will do so. I believe it could be the vibration i get?
That 4-5 mm are you sure that's not just the rotor spinning on the hub. They're not secure and the holes for the lugs are a fraction larger and allow them to move...
Well I grabbed hold of the studs to move it back and forth... I could easily see the shaft moving. I marked the rotor and marked the dust shield, then measured the play in the diff....seems al ot, or not?
Ok cool. Just some people I've seen grab the rotor and give it a wiggle not entirely realising what's happening. As for what you're describing. It might be an exaggeration of the diff play. As there are cv joints on the shaft that would have a certain amount of free play too. Not much, but just enough to notice. 4-5 mm I would think is pretty tight. If you can, take a photo of the diff mounts/bushes and also the cradle bushes. Let us eyeball them and their condition. I have a funny feeling you're problem is purely worn out undercarriage components. And as for your vibration. Gotta be the centre bearing and of rear transmission mount. The thudding would be from the centre bearing worn rubber flexing too much and hitting the steel outer. Having a new mount holding the back of the box all tight and in position might have thrown the worn equilibrium out. Ie, worn saggy trans mount is dropping the box and adversely tail shaft down, at which is lowering the centre bearing lower into its housing. To a point it's driving fine up until you've realigned it with end new mount, old rubber isn't coping. Take a pic of the centre bearing too and let see how central it looks. Should look bang on in the middle of the steel outer.
Also that jingling sound. Might be your exhaust heat shield. If your box was removed and serviced, they would have removed the exhaust, then heat sheild, then tailshaft. They might have put it back on slightly off key and the resonance of the exhaust, vibrations is making it jingle...
I havnt got time now to take photos sorry, but from what your saying, does go along with what other people/mechanics are saying.... Your right though I reckon, seeing as though the trans was rebuilt and it's rubber mount swapped out for a new one, its changed the aligmment.... I know the diff rubbers are probs old too and need to be replaced aswell. What would you suggest, new centre bearing or one piece shaft? I made close attension as to what was moving when I was checking out the play on the diff... It was all play in the diff an nowhere else. I've just recently had a balancing center root around under there to find the problem for a whole day, and didnt find anything he said the bushes and such where fine, but just old hardened rubber mounts. There is a definite clunk back there though!.... Lastly, it's funny you mentioned the shielding because the automatic place said the same thing when I complained, as it seemed to of appeared after their work I thought yeah....right! Because its not that type of sound, and only in particular situations.... But two people saying the same thing is enough for me to pull them off and try it Thanks for your help
Alright, I took off the tin wear from around the exhaust system....that scratchy, dingling metallic sound is still there at speed and throttle related! grrrr so annoying.
Ok, so i have been informed that my issue is "pinging" of the engine....Funny enough it was mum who said she recognised the sound from years ago, told Dad and from what ive heard its defiantly pinging!! Im a bit worried now, ive been putting it of for some time as i couldnt work out the issue. What are my steps to resolve this? I have a brand new S2 PTU, Injectors recently serviced and Brand new spark plugs. Thats about it for the ignition side of things. Do i need to take it to get dyno'd/tuned? or can i fix this issue at home? Funny thing is i have noticed the power is down lately....
