Rattle on over-run
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firman

Original Poster:

1,407 posts

216 months

Wednesday 9th March 2011
quotequote all
Just got the 5 back from having the clutch done and now when pushing on or on over-run there is a rattle coming from the back end somewhere, Only just noticed as just had it out for the first time, anyone got any ideas what it maight be so I can have a look in the daylight tomorrow. Ideally want it to be fixable myself save me from trekking back over to the mechanic.

TIA

anonymous-user

77 months

Wednesday 9th March 2011
quotequote all
Is it definitely from the rear? There's a common issue whereby changing the clutch or disturbing the PPF (the big metal girder thing that holds the gearbox in place) can lead to a fairly loud rattle from the gearbox.

I've had this on my 92 Eunos since I changed the clutch (and spigot bearing) a few years ago, mostly it's a loud rattling sound (like marbles down a drainpipe) when engine braking, but I can also hear it when accelerating gently. So far nothing has blown up, and it gets fairly well thrashed. Did loads of research when it started and it seemed very common in Miatas according to various forums, with no real solution but no real problems caused either, other than the noise. Some people had changed the gearbox, diff, spigot bearing etc.. and still had it.

General view seemed to be that it was vibration on one shaft in the gearbox caused by the slighly changed alignment of the drivetrain following the clutch change.

In mine it sounds like the noise comes from the passenger footwell.

If the noise is at the rear then the obvious things to check would be that the propshaft is securely bolted to the diff, and that the bolts on the PPF are all done up tight - IIRC there are a few very long bolts that hold it all together, some on the gearbox and some on the diff, but its been a while since I put mine back together.

PPF can be seen here:
http://flyinmiata.com/projects/installation_photos...

Edited by anonymous-user on Wednesday 9th March 22:48

Richyvrlimited

1,870 posts

186 months

Thursday 10th March 2011
quotequote all
JimSuperSix said:
Is it definitely from the rear? There's a common issue whereby changing the clutch or disturbing the PPF (the big metal girder thing that holds the gearbox in place) can lead to a fairly loud rattle from the gearbox.

I've had this on my 92 Eunos since I changed the clutch (and spigot bearing) a few years ago, mostly it's a loud rattling sound (like marbles down a drainpipe) when engine braking, but I can also hear it when accelerating gently. So far nothing has blown up, and it gets fairly well thrashed. Did loads of research when it started and it seemed very common in Miatas according to various forums, with no real solution but no real problems caused either, other than the noise. Some people had changed the gearbox, diff, spigot bearing etc.. and still had it.

General view seemed to be that it was vibration on one shaft in the gearbox caused by the slighly changed alignment of the drivetrain following the clutch change.

In mine it sounds like the noise comes from the passenger footwell.

If the noise is at the rear then the obvious things to check would be that the propshaft is securely bolted to the diff, and that the bolts on the PPF are all done up tight - IIRC there are a few very long bolts that hold it all together, some on the gearbox and some on the diff, but its been a while since I put mine back together.

PPF can be seen here:
http://flyinmiata.com/projects/installation_photos...

Edited by JimSuperSix on Wednesday 9th March 22:48
PPF alignemnt causes gearbox lash on the overrun, plenty of places that change clutches miss it. Hell one 'specialist' calaimed I was talking utter bks and that there was nothing to align.

Except it's in Mazdas service manual:

http://boostedmiata.com/servicemanual/92_servicema... (right click save as please)

Showing them that soon shut them up wink

anonymous-user

77 months

Thursday 10th March 2011
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Thanks for that download link - it mentions 66mm +/-5 for the PPF to be aligned, i'll have to check mine and see if i got it anywhere near that.

LukeBird

17,170 posts

232 months

Thursday 10th March 2011
quotequote all
Mine has had a bit of an on/off rattle from the rear which has recently become a bit more noticeable.
It sounds to me like a heat-shield. I've not had anything moved or un-done at the rear of the car.