Slant Six Forum
https://slantsix.org/forum/

Mazda RX 8 clutch for a slant?
https://slantsix.org/forum/viewtopic.php?t=54700		 Page 1 of 1
Author:  AndyZ [ Sun Feb 23, 2014 6:35 pm ]
Post subject:  Mazda RX 8 clutch for a slant?
Has anyone tried out the Mazda RX8 clutch on a Slant? These are a 9.25", 23 spline 1" shaft which looks like a possibility for a decent upgrade. Here is the link:

http://www.summitracing.com/parts/ctf-c ... /overview/

There are some more robust cclutches availqble in this size. Slant flywheel will likely become the weak link though...

Thanks all.
Author:  DusterIdiot [ Sun Feb 23, 2014 8:32 pm ]
Post subject:  You know...
Most likely if the disc will fit the input shaft, you will have to have our flywheel redrilled to accept the RX-7 clutch cover...

The easiest way to experiment would be to buy a cheap clutch kit from Rock auto, see if it fits your tranny and what the mismatch is on the cover bolt pattern, if it all fits then you can go for the Centerforce clutch or a McCleod for that type. Worst case, just buy the disc and see if it fits the tranny input shaft then see if it will fit under your stock clutch cover, and test run it.

-D.Idiot
Author:  sandy in BC [ Mon Feb 24, 2014 8:30 am ]
Post subject: 
What DI said x 2.
Author:  AndyZ [ Mon Feb 24, 2014 4:18 pm ]
Post subject: 
Thanks for the repies.
What are other slant six folks using for an upgraded clutch these days? Dont want to rediscover the wheel if possible. When I researched this 10 years ago, there was not alot out there. From what I can tell not alot has changed recently. I will be happy to try out the RX8 clutch if there are no other options.
AZ
Author:  DusterIdiot [ Mon Feb 24, 2014 4:48 pm ]
Post subject:  Stock bolt up...
Quote:
When I researched this 10 years ago, there was not alot out there.
If you are looking for a stock bolt up to your current stock setup, there isn't much...Modifying will get something more, going to a quicktime bell and small block flywheel opens up some other stuff...I converted the hpak duster to use a truck bell and 11" big block clutch since I got tired of wasting spec clutches..oddly after discussing with a local guy and his lenco alcohol burning car I am on the right track for keeping the clutch from burngin up (although he's saving weight using an SFi bell, I'm just doing a junkyard conversion for those who are cheap or just are power on the street). If you do go there, you'll be the first for the Rx-8 clutch...so that makes you a pioneer.

-D.Idiot
Author:  Joshie225 [ Tue Feb 25, 2014 8:23 am ]
Post subject: 
The metric 23-1" spline is supposed to be a little different than the SAE spline we have. That being said a clutch disc is pretty easy to have made. It's a good clutch cover we lack. Small clutches just don't take a lot of heat because they don't have much mass. Put the same amount of energy into a smaller mass and the temperature is higher. Drag racing is about the worst thing you can do to a clutch. I had a 9.25" slant six Borg and Beck clutch beefed up (full compliment of springs, Kevlar disc facing) for my road race car and kept it when I killed the 225 and changed to a V8. It held fine until I started drag racing.

Clutches are rated for torque capacity. Have you looked at the torque figure for an RX8? 159-165 ft/lbs. Stock (SAE gross) for a 225 is 215 ft/lbs.
Author:  AndyZ [ Tue Feb 25, 2014 2:48 pm ]
Post subject: 
Thanks for the reply.
What is somewhat interesting is that for the RX 8 clutches, there are a lot of different levels of performance, brands and materials. I will check a stock slant pressure plate against an RX8 pressure plate just to check the bolt circle dimensions. If a redrill of the flywheel only is needed and it is not too close to the ring gear, i will likely just try out a higher end kit with a higher pressure rating and better clutch material. I hope to abuse this setup this summer to see if it is worthy!
:twisted:
Author:  DusterIdiot [ Tue Feb 25, 2014 5:24 pm ]
Post subject:  What Josh said...
Quote:
i will likely just try out a higher end kit with a higher pressure rating and better clutch material.
If it's a multi disc clutch, it may not properly fit in the bellhousing, likewise there is a fitment issue if the splines are mm vs. in...

Another thing I've noted while drag racing, I've built up heavy heat with the kevlar facings and they just transfer it to the flywheel or retain it...typically the clutch started to fade bad when the kevlar got hot enough to soften and smear the lining facing the wheel...Hence the logic of using the bigger flywheel and clutch (also since I am launching a heavy late car, the heavier flywheel will have higher stored energy and will launch harder if I don't destroy the u-joints or driveline first....)

I worried about using the sintered iron disc that without a billet flywheel I'd miss my legs...In all cases Spec had promised they would hold up to a 300-400 ft/lb torque load....


-D.Idiot
Author:  AndyZ [ Tue Feb 25, 2014 7:45 pm ]
Post subject: 
I will look out for the 25mm vs. 1" diameter.
I will also check for overall height of the pp and bellhousing clearence.
This will be a street car that I would like to drag race a few times a year. Either way, I want to get it safe first. Right now I am getting some info on the stock RX8 clutch and pp that I hope to compare with the stock slant parts.
Author:  WagonsRcool [ Fri Feb 28, 2014 8:49 am ]
Post subject: 
Another thing to check would be the "dimensions" on the RX-8 flywheel. Many late model cars have stepped flywheel surfaces- the clutch disc contact face might be raised .020-.030" (or something like that) from the pressure plate mounting points. If you fit that type of pressure plate or cover to a flat-single plane flywheel you'll have slippage or very short clutch life due to low disc clamping force.
Author:  AndyZ [ Wed Mar 05, 2014 9:40 pm ]
Post subject: 
It appears that the RX8 flywheel is stepped, so this clutch/pressure plate retrofit does not look it is an easy or imexpensive mod to get hooked up.
I will likely get the Dart loaded with the 10" " Taxi" clutch for now. Before I go racing, I think DI's setup will be the most robust and safest with the 11" clutch plate and SFI explosion rated bellhousing. I dont need a pedicure when I am at the track.
Thanks all for the feedback. You saved me some time and money on this.

AZ
Author:  DusterIdiot [ Thu Mar 06, 2014 7:31 am ]
Post subject:  option 2
If you don' need that big of a fly wheel, you can step down a size and use a modified small block flywheel and the 10 1/2" clutch as welll...just check the bellhousing availability and starter position...

-D.Idiot
Author:  AndyZ [ Thu Mar 06, 2014 11:26 am ]
Post subject: 
The info is probably posted somewhere here but; Does a small block internally balanced flywheel bolt up directly to a 67 slant crankshaft? Are there any other dimensions, other than bellhousing clearances that will not work?

Thanks,
AZ
Author:  Junior [ Thu Mar 06, 2014 12:16 pm ]
Post subject: 
couldnt you use a custom thicker clutch disc to make up the difference in flywheels?
Author:  DusterIdiot [ Thu Mar 06, 2014 2:01 pm ]
Post subject:  Yes and no...
Quote:
Does a small block internally balanced flywheel bolt up directly to a 67 slant crankshaft?
It will bolt up except for one bolt hole that will need to be egged and welded to complete the installation...then you will need a bellhousing to fit the flywheel. Hopefully quicktime can help with a clocked bellhousing as the stock 318 and 11" clutch bells have low mount starter positions which does not allow for use of headers and requires a unique exhaust routing if using dutra duals...
Page 1 of 1 All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/