Noise from rear

[uriel]

Hi,

I'm new to TVR ownership, having just aquired a 280i.

All is well and I'm having a blast except the car sometimes makes a scary noise.

It sounds like a kind of roaring sound, very hard to describe. I assume it's the gearbox (or something related) as it happens at fairly high revs and pressing the clutch stops the noise immediately. It only happens when I come off the power, under power the sound goes (and not just masked by engine/exhaust) and once the speed drops a bit it will go. Seems to happen in all gears. At first I suspected exhaust since the noise sounds much more like something an exhaust would make as opposed to something in a tranny.

Any ideas what this is? Please tell me it's normalor at least something simple and cheap to put right
Thanks in advance

>>> Edited by uriel on Tuesday 27th May 15:32

[wedg1e]

Could be a differential bearing maybe? Or gearbox bearing. Probably not a universal joint though, unless the noise is accompanied by vibration.

Hard to tell without driving it, I'm afraid. Just realised you're in the NE, whereabouts roughly? I'm in Stockton...


Ian


>> Edited by wedg1e on Wednesday 28th May 00:47

[rus wood]

This sounds as though it is unburnt fuel igniting in the exhaust on the overrun. Does it sound like lots of backfires? My 390 has been doing this since day one (sometimes accompanied by flames). For example going downhill in 3rd gear at 4000 rpm and you lift your foot off the loud pedal, does it start popping until the revs get lower? Can you record it and put the sound on the PH site so we can all hear it.

[uriel]

Thanks for the replies.

Hi Ian, I'm up in South Shields. I've joined the club and am waiting for the next monthly meeting to go along and make introductions. Will you be there? It would be good to have more experienced TVR folk around.

BTW, I have a friend that says there is a wedge in South Shields round the corner from his house. A light blue convertible. Is this anyone on here??

Rus: That could be what's happening. It's more of a continuous sound rather than a repeated popping though. I guess if it was popping quickly enough that it became like one sound, that could be it. When listening to it, it definately sounds as though it's coming from the exhaust. Also the fact that the conditions you describe are the same suggests it could be the problem. I can try to get a recording, not sure what it'll come out like though. I have a mic from my computer and a minidisc recorder. I'll see if I can get a sample tonight.

What's causing it and is there a solution?

[rus wood]

It is caused by overfuelling on the overrun. I think it is to do with cam timing and the state of tune of the engine. I like the noise, on my 390 the pops and bangs are about half a second apart depending on the revs, the noise is not continuous. But if you want to get rid of it don't let the engine overrun, declutch and let the brakes do the work.

[wedg1e]

uriel said: Thanks for the replies.

Hi Ian, I'm up in South Shields. I've joined the club and am waiting for the next monthly meeting to go along and make introductions. Will you be there? It would be good to have more experienced TVR folk around.

BTW, I have a friend that says there is a wedge in South Shields round the corner from his house. A light blue convertible. Is this anyone on here??

One of the first guys I met when I got into TVRs was Bob Noble from up that way: however I seem to recall his car was white (not sure though!); also this was '96 and he was retired even then, so he must be ageing a little now.
I don't get to the Newcastle meets: in fact there was some suggestion of a Teesside meet a while back: we had one night and nothing's been heard since!

Back to your car: I don't know why I didn't think of the over-run exhaust noise... doh...

Ian