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car sounds like its driving over a cattle grid?


liam1

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got myself a z4 auto before xmas, not drove it at all since I bought been away for xmas, now I know its sat on the dealers forecourt for a couple of months took it out this week and I noticed a few times a loud noise from the rear which sounds like your driving over a cattle grid, going to bmw next week wondered if anyone experienced this before.

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new discs and pads fitted all round so far noise has not returned.

 

- - - Updated - - -

 

 

don't say that lol, I traded in my range rover for it because that was so unreliable.

 

Could it be that the rear discs had started to go rusty from being parked up and now with a few miles they are now nice and shiny again?

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From my experience sounds like it could be the Autobox itself.

Have had similar sounding symptom on early and late model Lexus LS430 and GS430 when the Transmission cooler (integrated into the Engine cooling Radiator) corrodes and mixes Engine Coolant with Transmission fluid.

Even after a basic flush of Valvebody/ solenoids/ cooler pipes/ and filter change of the Transmission (without full dissassembly/ or removal of the Autobox) at certain speeds or loads this driving over a cattle grid noise/ symptom occurs.

Suspect possibly due to contamination of the clutch plate linings/ brake bands inside the transmission causing them to slip or damage to planetary gearset bearings to create a resonance/ noise.

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From my experience sounds like it could be the Autobox itself.

Have had similar sounding symptom on early and late model Lexus LS430 and GS430 when the Transmission cooler (integrated into the Engine cooling Radiator) corrodes and mixes Engine Coolant with Transmission fluid.

Even after a basic flush of Valvebody/ solenoids/ cooler pipes/ and filter change of the Transmission (without full dissassembly/ or removal of the Autobox) at certain speeds or loads this driving over a cattle grid noise/ symptom occurs.

Suspect possibly due to contamination of the clutch plate linings/ brake bands inside the transmission causing them to slip or damage to planetary gearset bearings to create a resonance/ noise.

 

is it an expensive job? checked the warranty it covers repairs up to £500.

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Have you checked the rear springs? They are a common problem on Z4s but dont usually make any noise. It could be the smaller portion of the broken spring rattling around over bumps?

 

its booked in next at my local bmw dealer for road test and health check hopefully its nothing major and the £500 the warranty pays will cover it, will post up what they find wrong next week.

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is it an expensive job? checked the warranty it covers repairs up to £500.

 

Would be/ could be quite expensive r.e Transmission repair/ rebuild, and possibly around that figure, if not more than the allowable warranty payout.

 

Would be worth first having the Vehicle Chassis, Powertrain & Drivelines checked first (like an MOT Style inspection) for anything obvious (as easy for some garages to overlook the obvious and go in guns blazing replacing this that and everything else / or solely rely on a Diagnostic tester computer to come up with an answer creating more problems than solutions etc..).

 

Confirm where and how the symptom occurs to get a better idea of what area it could be and why. Possible use of a Chassis Ear (Stethescope jobby for cars) to see if it can help pinpoint a location for the symptom and then carry out a closer inspection of the conditon & operation of the Driveline, Powertrain and Chassis components to confirm the source of the issue, process of elimination.

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