mx5cartalk.com

Hi MX5 Brains Trust,

Just finished installing a 1.6ltr clutch and flywheel into my NB8A.

Started the car on the stands after putting everything back together, and there was a horrible metallic rattling noise coming from the gearbox area. When pressing the pedal in, the noise got somewhat louder but did not intensify any further as the pedal touched the floor.

We have since dropped the gearbox again, and it appears that the clutch was not disengaging, however can't seem to understand why, or what the noise was.

We noticed when comparing the 1.6 clutch and flywheel assembly to that of the 1.8, the 1.6 assembly sits roughly 1cm shallower than the 1.8. Could the thrust bearing be rattling off the end of the input shaft?

My friend and I are baffled.

Any ideas?

Cheers,
Giuls.

I should also add.

After dropping the gearbox the second time, we could confirm the clutch was the right way around, all bolts had been tightened, and clutch pedal feel was perfect after being bled.

Can also confirm the clutch was aligned with alignment tool, and when starting the car in gear, drive the wheels spun no worries but rattle was still prevalent.

Is it an oem 1.6 flywheel or an after market super light one? Alloy or steel?

I went the other way and put an SE clutch plate and flywheel into the 1.6. No dramas at all so should fit although I think the housing bolts were slightly longer.

It's an alloy fidanza flywheel.

I have used the same combination of clutch and flywheel in my old na6 a few years ago with 0 issues.

interesting. in my particular install on my NB8B i noticed that I now get a metallic resonance exhibited through the lightweight aftermarket 1.6lt (8lb) flywheel at low rpms. Some lightweight flywheels are known to exhibit noise at low and high rpms. This is because of their thinner, lightweight design. If you think about it they become almost like a cymbal from a drum kit and resonates noise from the motor. Its also possible that your are hearing noise on your NB8A version that you weren't hearing on your NA 1.6 because of a different motor design?. This is only an opinion though as your issue could be something different but I would recommend you do a bit of research on the lightweight flywheel noise as it seems fairly common on lightweight ones, especially alloy.

All opinions are welcome mate

The noise is definitely different to that of flywheel chatter. I did experience the resonance you speak of, so have a decent idea of what it sounds like.

This is more like a metal item is loose or out of position and rattling around...much louder noise.

Exhaust brackets on the left side of gear box? This has me curious now

clutch definitely not disengaging?
Mick

No issues with the exhaust bracket.

Mick, can confirm 100% clutch was NOT disengaging.

we recently installed a new clutch in my sons car (1. and struck a (small) problem in figure 3 of this http://www.exedy.com.au/assets/files/te ... /TN015.pdf
we took the assembly back to the clutch shop to check and he solved it with .015'' shims then checked clamp pressure was ok.

if your new assembly is 10mm shallower you may need to move the pivot point similar to what is noted in this.
http://www.exedy.com.au/assets/files/technotes/TNN.pdf
but you would have to make sure everything else is right first,hydraulics,pedal stroke.I can recall having to do this about 25 years ago in similar circumstances,i think it was with a lightened flywheel and heavy duty clutch on a Datsun..we were sure then that we had something else wrong.we had the gearbox in and out 3 times.hopefully someone who has struck this on an mx5 will chip in soon.
Mick

Mick that looks brilliant! Thanks for the info.

Will try and give it a crack this weekend!

just be sure its not something else.i've probably done about 30 car (and a few motorbike) clutches in the last 40 years mostly datsuns holdens galants etc (saying that makes me feel old,lol) but only had to move pivot post twice.maybe I was just lucky,or maybe I was just blissfully ignorant!
Mick

I have done no where near 40 clutches!! If a clutch does not disengage- esp on old motorcycles it was nearly always related to the mechanism needing adjustment- same deal for brakes the free play before engagement needs to be adjusted. The ball head adj bolt on the pivot is adjustable but not sure how much effect it will have. A 10mm height diff strikes me as a lot to the std unit.

recently had the same issue with a CI clutch

the shop supplied the wrong size throw out bearing and the race sat inside the fingers of the pressure plate.

the problem was with the clutch industries specs