adam73bgt
Club Retro Rides Member
Posts: 4,867
Club RR Member Number: 58
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Aug 31, 2015 12:04:37 GMT
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Hi, Bit of an odd one this, but I've noticed that sometimes after driving my 750 that when you come to a stop there will be a single thud/'dong' noise coming from the rear end of the car Its just a single noise and seems to happen after the car has sat for a short while after coming to a rest, for example after there has been time to turn the engine off etc. Any ideas/ guesses as to what it could be? The car had the EDC suspension fitted from new so I'm wondering if it could be something to do with that? Or do these have self levelling rear suspension which might be doing something odd after the car comes to a stop? Any suggestions welcome, it doesn't seem to be affecting how the car drives but if its something amiss, I'd like to catch it before it gets worse Cheers  |
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E38s are great at eating bushes, does it have noticeable negative camber? If so, the control arms may need changing... They also love breaking springs...worth checking!
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Sept 6, 2015 12:23:32 GMT
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Alternative suggestion, has it got a valve in the exhaust? Seem to recall some BMW's with twin pipes (specific example for me is E36 328i) having a valve in one, possibly vacuum operated. Think it was to help with drive-by noise regs or catalytic convertor warm up. Could be this springing shut, hence the single noise and 'dong' sound.
Other suggestion is a coil spring settling, particularly if it's got a bit broken off.
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adam73bgt
Club Retro Rides Member
Posts: 4,867
Club RR Member Number: 58
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Sept 6, 2015 17:56:51 GMT
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Camber looks to be about normal and I don't know if its a bush thing as I can't hear knocking over bumps etc. its just odd that it seems to make the noise after it comes to a stop Broken spring could be a possibility, I shall have to get a wheel off and have a look I don't think theres any valves in the exhaust although I could be wrong as I'm just presuming cheers for the replies guys |
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Sept 6, 2015 18:11:44 GMT
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No ideas about the noise but i can confirm the car should have SLS, rear shocks are pressurized by the power steering pump, i did away with it all on my last 750 and fitted standard shocks and springs.
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72 Pontiac Firebird Formula 400. 95 BMW E34 525i Manual. 80 Lotus Elite, sold  86 Mk4 Escort RWD V8, sold |
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Sept 6, 2015 18:36:43 GMT
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I'd check the fuel tank ventilation system...if its blocked it can cause a vacuum in the tank which results in a bong sound as the tank expands and contracts.....its a common thing and is covered on the 7 series register- the worst case scenario is a cracked fuel tank....
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adam73bgt
Club Retro Rides Member
Posts: 4,867
Club RR Member Number: 58
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I'd check the fuel tank ventilation system...if its blocked it can cause a vacuum in the tank which results in a bong sound as the tank expands and contracts.....its a common thing and is covered on the 7 series register- the worst case scenario is a cracked fuel tank.... Hmm just had a listen to some E38 tank 'popping' noises on youtube and its not too dissimilar I think, though I've not heard the noise on my car from outside of the car yet The car has had at least one replacement fuel tank in its life so if I can stop it needing another one by sorting the venting system, I'm all for that! |
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