Clutching at straws

[Mr MXT]

The gearbox is coming out of Project MXT in the next few weeks to replace an increasingly dodgy 3rd gear syncro. The clutch is also starting to slip on emergency starts so it makes sense to do the clutch and flywheel at the same time.

I want to future proof it (Currently running 203bhp, 193 ftlb) but ideally don't want to end up with a clutch that operates like an on / off switch.

I've done my research, read the threads on Nutz etc, but to be honest I'm finding it pretty hard to come to any kind of descision.

So to the turbo'd guys: What are your recommendations? And what about flywheels? I'm happy to spend the £££ but obviosuly don't want to spend more than I need to.

Teh final target for MXT is approx 230bhp and whatever the associated torque figure is.

[_Batty_]

emergency starts
nothing carbon based if you like a smooth getaway...

[JonnyFive]

I see what you've done there.

[MX-5 Lazza]

I can't help much either. Somehow my car has managed to survive for over 6 years supercharged on the stock clutch so I haven't looked seriously into a replacement.

[GravelBen]

Mine has a 5-puk Exedy clutch and lightened flywheel (NA6 with 250+ bhp), tbh the flywheel is almost too light for easy use around town (just takes a bit more care and precision), but other than that its fine.

[Mr MXT]

GravelBen said:

Mine has a 5-puk Exedy clutch and lightened flywheel (NA6 with 250+ bhp), tbh the flywheel is almost too light for easy use around town (just takes a bit more care and precision), but other than that its fine.

Do you see much advantage from the ligtened flywheel?

[GravelBen]

Its hard to say as I've never driven another turbo one to compare with a normal flywheel - however the guy I bought the car off (who built it) reckoned it sharpened up the throttle response and reduced lag.

[Mr MXT]

So when you say its "almost too light around down", what do you actually mean? (Never driven a car with a lightened flywheel).

Presumably revs quick to drop making it easy to stall?

[Munter]

Mr MXT said:

So when you say its "almost too light around down", what do you actually mean? (Never driven a car with a lightened flywheel).

Presumably revs quick to drop making it easy to stall?

My understanding of lightened flywheels is that it makes it easier to stall. So if you get the clutch a bit wrong pulling away, you don't get a feeling of "chug", it just stalls.

[GravelBen]

Yeah revs rise and fall very quickly making it harder to drive smoothly, in fact when the car is cold and you're slow through the gears (until the box warms up a bit) I sometimes find myself giving the revs a blip even on upshifts to smooth things out.

Its not a big deal for me as I live in a small town and don't use the MX5 for that much round-town running anyway, but it could become a bit tiresome in a city.

I guess there are a few different weights of flywheels available, so whoever you're buying from can probably advise you as to the most suitable weight.

[Richyvrlimited]

I have a SPECII which is as light as stock in action if not lighter.

However the bed in period is a pain for some (no boost for 500 miles), and the bite point is in a narrower window to the stock clutch so smooth starts are a bit more difficult.

If you don't intend to up the power any more, and you really want to keep the easy smooth gearchanges I'd personally stick with a stock clutch. I find my dads car much easier to change gear smoothly as it has a stock clutch.

If your target is 230 and if you're turbocharged there's no way a stock clutch will last, torque is what kills clutches and turbo's make more peak torque and are more non-linear in their application of torque compared to a supercharger - which is why Lazza's clutch (and my origional clutch), has/had survived so long.

There will always be some sort of compromise, if it's not the action it'll be it's weight, or it's ability to hold the torque

Edited by Richyvrlimited on Monday 21st February 11:17

[GravelBen]

Richyvrlimited said:

...which is as light as stock in action if not lighter.

Should have said that about mine as well, its just the greater precision needed (a bit snatchier than a standard one) which is different.

[Mr MXT]

Ah ok thanks guys. I was worried I might need a left leg like Geoff Capes.

I've read good things about the SpecII clutches Richy, where did you get yours from?

[MX-5 Lazza]

My car does have around 200lb/ft which isn't bad though I know it's less than a 240bhp turbo would have. I do take it to a lot of track days though and also 3 trips to Santa Pod, all of which is pretty hard on a clutch.

I should add that my clutch was replaced when I first bought the car (before it was modified) because it had the dreaded Mk2.5 clutch judder and I have no idea what clutch they replaced it with or if they changed anything else in there. I've always assumed it was a new stock clutch and flywheel as I can't imagine Mazda fitting aftermarket items for a warranty job but who know, they tried quite a few different things to rectify clutch judder before they got it right and mine was fixed in one attempt. It was also done by Newbury Mazda who were one of the top MX5 dealers in the country at the time (gone downhill a bit since then sadly).

[piefacemate]

I've got an ACT clutch rated at around 300lb/ft's, extremely good clutch although a bit heavy for town use. It bites instantly and doesn't give much slip, but once you're used to it it's fairly easy to drive. Happy for you to try mine if we're at any of the same meets in the future.

[Mr MXT]

I've spoken to a few people and I'm looking at these, does anyone have any experience?

http://www.competitionclutch.co.uk/mazda-mx5-18l-1...

and if anyone can tell me the differences between the one above and this one i'd be much obliged:

http://www.competitionclutch.co.uk/mazda-mx5-18l-1...

Also probably going to go for one of these bad boys

http://www.competitionclutch.co.uk/mazda-mx5-19942...

[JonnyFive]

Don't know other than my friend is sponsored by them in the BDC.

[Mr MXT]

JonnyFive said:

I can get you Jonnyspecialprice becuase friend is sponsored by them in the BDC.

[Richyvrlimited]

Mr MXT said:

Ah ok thanks guys. I was worried I might need a left leg like Geoff Capes.

I've read good things about the SpecII clutches Richy, where did you get yours from?

I sat in a few cars and 'tested' the clutch action before I picked my clutch, the bed in time was well worth the light action IMO.

My mate had an ACT in his car, it juddered like a bh when setting off and had a REALLY firm pedal, you do get used to it apparently, but I didn't want to

I got my clutch from Phil at Performance5

[deviant]

If you are going for silly HP a multi plate clutch will be the way to go. They can handle big power put the pedal pressure will not be as high as with a single plate, you still will not be able to slip it without causing premature wear though.

You could also look at something like a hydraulic throw out bearing. As I understand it these can be set up to alter the ratio betwixt pedal and clutch...light pedal but with massive pressure on the other end.

I am told that the stock SE turbo clutch can hold decent power and torque but I have no experience of this.