Upgrade clutch question.....need advice please.

[Mad Kiwi]

Hi Guys

I have posted this on the miata USA forum but some local knowledge will not go amiss....

This is either a case of the internet being dangerous (and my misreading) or bad advice from the clutch supplier.....

From what I have gathered, if you install an 1800cc flywheel and matching clutch on a 1600 you gain better clutch performance with no or little additional pedal pressure...and it is a bolt on, easy as mod....???

Can someone please correct me if i am wrong or fill in the gaps for me....

I am replacing the clutch on my NA '89" 1600 with turbo and want to beef it up a bit from standard whilst in there, so to speak....

While we are at it, can the standard 1800 flywheel be relieved of a little weight? (seems silly not to when it is away getting refaced at the machine shop....)

Cheers
Mark

[m4vr1k]

Correct. The 1800 flywheel and clutch have a larger diameter, so more friction surface, better grip.
Don't go messing around with taking weight out of the standard flywheel, spend the money on a proper chromoly one, that way you don't run the risk of it flying to pieces at 7,000rpm and really ruining your day. And ankles. And legs.
I can get Exedy clutches for the right price. PM me if you are interested.

[WideOpenThrottle]

Hi - i put an 1800 flywheel and a exedy HD clutch kit in my 1600 NA and it works a treat with no noticable pedal pressure.
I would also like to lighten my flywheel but only to take off enough so it doesnt fly apart if thats at all possible-the chromoly ones are pricy too!

[Mad Kiwi]

Thanks Wide Open, good to hear from someone who has done it to confirm.

I can't understand the concern re lightening a flywheel, well I can but back in the day you had to, as after market parts for Rx2's and 3's, escorts, cortina bro etc just weren't easily / affordably available and it was common practice to lighten and balance a flywheel.

Of course the horror stories abounded about people who went crazy but I really can't see losing a small amount (within reason) to jeopardise the integrity of the part......

Actually a friend of mine did lose one through his bonnet but he over revved a Periperal Port 12a to over 12,000 at a drag strip by accident....(it was a very thin plate of which we were somewhat dubious of at the time...) he was incredibly lucky to walk away....it chain sawed through the bell housing, gearbox tunnel and bonnet area straight up, never to be found again...

I will do more research.

[WideOpenThrottle]

it chain sawed through the bell housing, gearbox tunnel and bonnet area straight up, never to be found again

Thats why they call them FLY wheel then??

[WideOpenThrottle]

Found this on the net

Flywheels

1.8 fits 1.6 and allows use of larger 1.8 clutch

BSP has a lightened one (by 4 pounds) for $185.

A machine shop could only get 3 pounds off a standard 1.8 flywheel

1.6 is 18lbs stock
1.8 is 19lbs stock
1.8 FM 10.5 lbs,
1.8 Fidzana 8.3lbs
Jun do one at 5kg = 11lbs

B6-ZE 4.6kg #2001M-Z001 Y40,000 .

BP-ZE (NA6CE) 5.0kg #2001M-Z002 Y50,000 http://www.takakaira.co.jp/

Trust 1.6 =#12458 NA6CE B6 4.8kg

"Toda racing do 1.6 one. (8.4 lbs vs 17.7lbs claimed for 1.6t) but the quality and workmanship is stunning. They have artfully machined away the back surface of the flywheel, and added holes all around the perimeter to reduce moment of inertia. Looks like a good buy to me, cheaper than most aluminum ones in my case($420).
Machining a stock 1.6 will only get you to about 15lbs.
The aluminum ones are in the 8-12 lb range, Aluminum Mazda comp/tilton(I think) 9 lb

8 lb Mazdaspeed chromoly flywheel. 1.8 style


"It seems that, as a *very* rough approximation, lightening the flywheel by about 5lb is equivalent, in 1st or 2nd gear, to lightening the car by a hundredweight. Not bad" Carrick, M. (Mike)

"compare the kinetic energy in you flywheel with the kinetic energy in your car;

flywheel (disc) - J = 1/2 * M * r^2 say M 20kg and r 15cm gives 0,225kgm^2 w at 6000rpm this is 100Hz so w is 630rads/s energy = 1/2 J w^2 = 44650joules

Car M = 1000kg at 100kph v = 27.8m/s energy = 1/2 * M * v^2 = 386420joules

the flywheel energy is just over 11% of the overall kinetic energy. 6000revs at 100kph is a bit higher than 2nd gear. A lightened flywheel at one half standard weight (!) would thus accelerate about 6% faster in 2nd gear. "Robert Carter

"Loss of driveability is a non-issue. Noise does increase, mainly on decel in lower gears (mostly first) and at idle with air on. How much noise will depend on the clutch selected. The stiffer the center section, the more possible noise. We have our Fidanzas spec'd out slightly heavier than everyone else's to try to combat this." Bill Cardell

[RMS]

I recently installed an exedy HD clutch + 1.8 cro moly 'D2 Racing' cromoly flywheel (This is what they call 'F1 racing' in the states)

very happy with it, didn't weigh the flywheel but it is a bit lighter. I was happy with the quality of it.

I do notice that the HD clutch is heavier on the pedal. It actually surprised me how much of a difference this made but it's not something that I find problematic.

That said.. I fitted the clutch with my car on a wooden ramp which is slightly too low for me to stand upright under. So standing around fitting clutch/lifting gearbox in and out with bent legs for an hour or two really took the strength out of them!

Got everything from NZ Automotive Distributors on trademe and made sure I got the alignment tool thrown in, it makes things that little bit easier.