Grind/ rattle/ metallic grating at 2200 revs (AJP 4.5)

[Wolvesboy]

Well, sorted the gearbox, then the tick over now this.
Cruising on the freeway at 1800 revs and go up to 2200 and the above happens - very distinct, very obvious and I'm thinking "oh what now!" It is definitely in front of the gear lever and does seem very close to the flywheel area but really difficult to pinpoint when driving.
I have to continue, drop to 1800 and all ok. Every time I get anywhere near the 2200 revs mark in 5th (100 kph) it does the same, no loss of power just the noise. I realised that every time I went up to these revs it did the same. In fact, a slight grind would begin sometimes at about 1900 or so. Then once off the freeway and on normal roads I realised it would do the same in each gear and if I revved the engine but it is so loud that it is initially difficult to diagnose! I didn't realise at first as I always feather the car until it is properly warmed up.
As the car got very hot in traffic the noise actually did not occur sometimes but this was infrequent. Needless to say I'm now worried again and feel the need to rip off the heads to check the valves and cams. Or maybe it could be the exhaust but it just does not sound like it is (if that makes sense)!
Any ideas (again!)? Cheers.

[mac315p]

Given that you've just had the gearbox out and it didn't go back together 'well' what about clutch alignment (assuming there is no noise whilst in neutral and stationary at the revs you've mentioned?)

[Flashheart]

Over the years I've had 2 similar problems, both turned out to be exhaust related (as you've had them off). The first turned out to be the baffles inside the exhaust and the second (noisiest & hardest to find) was the brace that linked the 2 pipes together. One weld had snapped so at about the same RPM as you mention, the pipes would vibrate and the end of the brace would bang against the now-free pipe. Drove me up the wall for ages. I just broke off the brace in the end. HTH

[fatjon]

Did you forced the box on by tightening the bolts? Possible wrecked spigot bearing causing input shaft misalignment.

Or just pipes rattling on the bell.

[Montauge]

I too would start with the exhaust. I had pretty much EXACTLY the same problem after my clutch was done. It turned out to be one of the exhausts touching or vibrating a plate towards the back of the car (can't remember exactly now what). I spent ages making sure that the clearances from anything they could touch were bigger and the nasty noise disappeared. In my case the vibration must have been travelling up the exhaust to the gearbox and that was why it sounded like it was coming from the gearbox.

[Wolvesboy]

Thanks fellas for the info.
I got a friend to look underneath as I revved it and along with him sitting in the passenger seat - it then became an obvious exhaust issue.
I have now twisted the middle connections around as they must have been hitting each other when horizontal. They were actually touching before being moved! They now sit at 10 and 4 instead of 9 and 3 if you know what I mean?
All good now and she is running well. Such an easy fix when you now what it is! Relief!

[ukkid35]

fatjon said:

Did you forced the box on by tightening the bolts? Possible wrecked spigot bearing causing input shaft misalignment.

Or just pipes rattling on the bell.

Good to hear it was just the exhaust, because like fatjon I feared that the spigot bearing might have suffered.

[Wolvesboy]

She is running really well! The change is amazing and I was pretty concerned at one point!
I replaced the spigot bearing as recommended (grinding the other one off with a dremel) and the new one was a really tight fit to get back in.
All is good and blasting around Perth showing the Aussies some British culture!

[ukkid35]

Wolvesboy said:

All is good and blasting around Perth showing the Aussies some British culture!

Let's see some photos showing off the scenery as well!