Better upgrade/replacement Miata clutch for less then OEM.
 

First the base price. Autozone clutch kit 1.8L Miata. 10-045 $194.99

Now here's how you get a bigger better clutch for less.

Order Autozone clutch kit NU31218 ('94 V6 MX6) for $109.99 then add the throwout 614079 for $28.99. $138.98 total. Saved yourself $56 bucks but it gets better. The V6 MX6 disc is 8.875" vs. 8.5" for the stock Miata replacement. The additional 3/8" of friction surface is at the outer edge of the disc and will completely cover your pressure plate and flywheel surfaces from edge to edge. The MX6 pressure plate fits the Miata's flywheel but I have no way to verify the clamping force vs. the Miata's pressure plate. I used my Exedy pressure plate when I installed mine. Being this kit is for a 2.5L V6 you can pretty much assume it'll hold more torque.

A couple notes... If you set the Miata's throwout on the fingers of the MX6 pressure plate it looks as if it -just- touches the tips but once the plate is bolted down it'll look much better. ;) You may also notice the spline/hub of the MX6 disc sticks out a little further towards the trans then the stock Miata hub but I verified there's plenty of clearance left on the input shaft of the transmission. Using a stock Miata disc there's -roughly- 3/8-1/2" of unused spline before the hub would make contact with the transmission (based on the wear marks on my input shaft). The MX6 disc is only about 1/8" further out so that leaves 1/4-3/8" clearance. That's plenty of room to allow for the disc to float away from the flywheel during disengagement. Almost forgot to mention... The pilot bearing is the same. :)

If I can figure out how to get pictures off my phone I'll upload them so you can see the differences.

These pics are from NAPA and it's a little hard to tell but you can kinda see the difference. NAPA's MX6 kit looks like rubber bumpers for springs. The AZ one has 6 springs in it.

https://www.miataturbo.net/forum/att...1&d=1269598838

https://www.miataturbo.net/forum/att...1&d=1269598841

So will it hold the turbo cars?

I remember hearing about this a few years ago on another forum but I can't remember how it worked out for the testers.

I'd be interested in hearing since this would be another option for aftermarket clutches too. Mx6ers turbo their cars and make a fair it of power so their high torque clutches might help out some on this board.

I'll use this infor for my daily with a clutch that slips at probably 70whp.

It would depend on how much torque the engine is producing. Even the stock Miata clutch can handle -some- boost but even with the extra friction surface of the MX6 disc it's still up to the pressure plate to squeeze it. I can't find any info about the MX6's engine other then some Wiki specs.

"The 2.5 L (2497 cc) KL family uses an 84.5 mm bore and 74.2 mm stroke. It includes the Japan-only KL-ZE, which produced 199 hp (149 kW) and 165 ft·lbf (224 Nm). Another variant, the KL-DE (also known as the KL-03 outside the USA, and fitted to 2.5 litre Ford Probes) was the worldwide version, with 164-170 hp in various applications."

So it looks like it's a 164hp engine.

Here's the MX6 8.875" and Miata 1.8L 8.5" discs side by side. It's almost like looking at a 1.6 and 1.8 discs.

https://www.miataturbo.net/forum/att...1&d=1269635104
https://www.miataturbo.net/forum/att...1&d=1269635104
https://www.miataturbo.net/forum/att...1&d=1269635104
https://www.miataturbo.net/forum/att...1&d=1269635235

Pretty cool. Nice find lazzer. nice to have you back btw.

Ok, a bit of a dumb question. Doesn't more surface area = less psi? That's why puck clutches are the way they are?

Greater distance from the center = more leverage.

So this is just about the diameter of the disc? Just wanted to make sure.

The puck design has different benefits. It doesn't get nearly as hot and therefore is way better in intense on/off uses. A full disc organic clutch can hold a ton of power as well, but once it heats up too much it's game over.

Just imagine if you cut off some of your brake shoe. Would your braking be worse? Ofcorse it would. It would take more force on the smaller shoe to create the same amount of friction. It would also create more heat in the process. The opposite is also true. More surface area is more friction area and with the friction spread over more area it should keep the disc cooler and less likely to fade. I'm going to pull numbers out of my ass here but say a pressure plate can clamp 1200lbs and the disc has 10sq-in of surface area. That's 120lbs per inch on the disc. Now say the disc has just 1sq-in more surface area at 11sq-in. That drops the force to 109lbs per inch on the disc. That should keep the disc cooler plus the fact that the disc now has more surface contact with the flywheel and pressure plate to transfer the heat away. There's also less force over more area so everything will last longer. The MX-6 was a 2.5L V6 and has much more torque then a BP so in general it's a better clutch. It's win-win-win in any case.

I posted my findings for those who may be replacing a stock clutch, need just a little more grab, or just want to save a few dollars. I didn't want to imply this is as as good as a puck disc but it's significantly better then stock for less money.

I really wish I had installed the MX6's pressure plate so I could compair. My Exedy clutch hardly held 15psi on the BP. As long as it didn't get hot it was ok but launching under boost and it was instant fade. I will be able to post my opinion as to how well just the MX6 disc performs because I kept the pressure plate I had when I did the swap.

Thanks Tim. I've been popping my head on now and then to see what's new. I've been too busy to say much though. Now that I'm replacing my engine I figured I'd try this clutch swap and see how everything fit. If it worked then everyone should know right? :)

Did some driving on the new clutch today. It's not broken in yet but the engagement is quicker which I like. It's handling boost with no problems. Pedal feels stock but it's definitly got more grip. No complaints at all.

How much boost/power is you car running? Have you broken it in and really tried it out yet?

I put a few 100 miles on it all city driving. Even before it was broken in it was holding 15psi without any slipping. It feels almost like a stock clutch as far as feathering to get the car moving but full engagement has much more bite to it then stock. It's really not a performance set but it grabs like one. I recomend it to anyone even as a clutch replacement. I wouldn't expect it to hold up to much drag racing but on the street it's great. For the price I don't think you'll beat it.

We are doing a 11.1:1cr Miata build in the next month and the driver is going to try this set up. That car will have alot more torque on the launches then I do because I don't launch under boost. I'll let you know what he thinks.

Incorrect.. if you halved the area of the pad but kept the same normal force applied to it, it would work better (discounting heat dissispation/fading). The only two things that matter are force applied and coefficient of friction. Here's a quote from a website that explains this in more detail... all you engineer/physics types need not read further.

"Standard friction equation
When a force is applied to an object, the resistive force of friction acts in the opposite direction, parallel to the surfaces.

The standard equation for determining the resistive force of friction when trying to slide two solid objects together states that the force of friction equals the coefficient friction times the normal force pushing the two objects together. This equation is written as

Fr = μN

where:

•Fr is the resistive force of friction
•μ is the coefficient of friction for the two surfaces (Greek letter "mu")
•N is the normal or perpendicular force pushing the two objects together
•μN is μ times N
Fr and N are measured in units of force, which are pounds or newtons. μ is a number between 0 (zero) and ∞ (infinity).

Applies to static and kinetic
This equation applies to both static and kinetic sliding friction. Static friction is the friction before an object starts to slide. Kinetic friction is the friction when the object is actually moving or sliding.

Static friction and kinetic friction have different coefficient of friction values.

Independent of area for sliding hard surfaces
An interesting result of this equation is that in the case of sliding friction of hard surfaces, the friction is independent of the area of the surfaces. In other words, it is just as difficult to move a 1 square-cm object as a 1 square-meter object, if they both are pressed to the surface with the same amount of force.

This is not intuitive. You would think that there is more friction when the surfaces are larger, but the friction equation states otherwise. You can verify this fact with experiments."


I'd imagine the MX-6 clutch would work better but it would be because of its larger diameter having slightly more mechanical advantage rather than the increase in area.

But back in the real world where friction creates heat and heat=fade, it wouldnt take a physics degree to see my point. Maybe I should have used tires as an example. But thank you. :jerkit:

As I had stated before but don't forget the cooling ability of more surface and more in contact, heat transfer, less fade, bla bla bla. Your more then welcome to do the math and prove something then to come here to discount this as an option. It works and it works well. I'm trying to save people money with a better solution. This economy is tight and anything helps.

wait you guys are just figuring this out now?

ive been running KL v6 clutches on my FWD bp since like 2006 :). i wasn't the first, either! aftermarket pressure plates (like ACT) have higher clamp loads than the equivalent BP model, too.

this is news to me... :(