I have aquired a MA6 HD dual disc clutch set up for a 68 427. Does any one have any install info / instructions for this clutch set up. Thanks

 

What company makes it should be able to find it online.

 

Cool!
OEM GM unit. Rare!
I have been talking to both McLeod & Ace lately about their dual disc clutches.
They both told they basically copied the original GM design. And supposedly improved upon it.
Their tech told me an air gap of .025-.035" on the bottom disc should give you a clean release. The top will probably be more. It is the bottom one that is the concern.
The finger travel to do this will probably be around .350" That's usually enough.
And you want 1/16" clear between the throwout bearing and the fingers at rest.

Hope that helps.
The McLeod uses solid hubs. The ACE uses sprung hubs. The GM used sprung hubs.
There are apparently some issues with certain combinations of flywheels.
The indented center register area of the flywheel must be big enough to contain the sprung hubs, some hit. So check that.
McLeod rec'd a flywheel with a center cutout of around 6-1/8" to 1/4" max. It needs to match the plate friction surface. The discs are only 10" dia,, but there are two.

 

The original GM twin disks are rare. A really rare desireable car is a 1970 SS454 Chevelle, all options including the M22 Muncie tranny (the rock crusher) and a twin disk clutch. Unless you have the original invoice or build sheet, an original 6 cylinder Malibu can be cloned into a SS454 and a great deal of expertise can be needed to identify a clone. A M22 with a twin disk can bump a clone into the big bucks range. In 1970, the SS454 Chevelle was just an option and there's no way to distinguish a 1970 Malibu from a SS454 with the VIN.

 

GM Dual Disk clutch diagram.

 

Here's a McLeod

 

I guess unless its a restoration I might shy away from a Clutch that is 50 years old. And if it is a restoration then the car is probably worth so much that it won't get driven much so it will probably work out.

 

Thanks guys clutch is NOS. Stingr69 where did you find that diagram of the clutch assy.

 

I remembered seeing this in my Haynes manual decades ago. It just stuck out in my mind. It is a rare setup for sure. Please post back once you get to drive it a few miles. We would love to hear about what it is like to live with it.

 

I have seen two original GM MA-6 clutches in my travels. Pics below.


The MA-6 requires a dedicated MA-6 flywheel. The McLeod twin disc is very very similar to the GM MA-6, as it should be, since McLeod admits to copying the old GM design

However Mcleod says they changed a few things to solve "issues" with that clutch. Two that I see are the McLeod uses solid hubs vs the GM sprung hubs. I am not sure that is an improvement and in fact the Mcleod is known for low rpm rattle because of this solid hub "feature". Also the GM hat design is a very deep one piece hat and the McLeod is a two piece. It has an adapter plate that bolts to a stock flywheel. They say it is an improvement but if you ask me there are a lot more bolts to cause possible issues. I am sure that they did it so that they can use a standard depth hat as a cost saving measure and not have to tool up for a deep one.

So I chalk the Mcleod up as having only one improvement. It bolts to a standard flywheel. The solid hub is a negative for street use.

I am currently investigating an ACE Racing Clutch Street King dual disc as an alternative to the McLeod.
https://aceracingclutches.com/product/rsk-306l/

ACE manufactures mostly racing clutches and this is the only street one they sell. No single discs at all. They have a lot of experience with multi-discs and slipper clutched for racing use. Much more than McLeod. The street king uses sprung hubs and a large deep cover/hat like the original GM version. So it is much more authentic to the original GM design.

Anyone have any experience with an ACE Street King?

 

I can say that the Mcleod " Street Twin " sold 15 years ago was terrible. To stiff to use in a C3 the Firewall is no strong enough, supper grabby. In other words it was a racing Clutch not to be used on the street. I messed around with mine for months trying to get it to work. The best thing I ever did was sell it. I understand the new design ones built in the last 10 years are a much improved.

 

I have a Street Twin, NIB, bought about 12 years ago. A few months ago, after reading several recent posts on these clutches, I called McLeod and specifically asked them about the reports of being grabby and the person I spoke with said given the date I bought it, I would not have any problems for my application. This post prompted me to take it apart today and see what I have and I sure am glad I did. Note the machining debris!

A you can see, I have the solid hubs which is now causing me to rethink this. GaleBanks80 - what did you change in your attempts to make it work for you? I am wondering if I can simply swap out the discs with a sprung hub design? I’m now thinking the McLeod rep thought I had sprung hubs.

 

I did a RST a few years ago in my 69 along with a Hurst shifter. First thing I noticed was the brake pedal would move as I pushed on the clutch pedal. Hmm..... maybe something broken because I never noticed that before. Looked and nothing broken or loose in the pedal box. Now onto the test drive. Lots of chatter on initial take off from a stop. After talking with McLeod about it, I was told about 500 miles to break it in. 500 miles on my car is over 5 years of driving. Out came the McLeod and I bought a Ram diaphragm clutch. I would rather have bought a vintage 69 GM clutch. I wasn't really happy with the Hurst shifter either. Stock shifter went back in. Sold them both.

 

Anyone have trouble with drivetrain rattle?
If so what combo or rpm?

 

For some reason or another Your Clutch Looks " Different " than I remember mine. I'm going to say yours is newer. I had a local Speed Shop install Pins in the Flywheel for the pressure Plates to slide on. They also went threw the whole thing and Balanced and Blue Printed everything. This was not my Idea it was a proven way to make it work. I must of talked to The Tech at Mcleod 20 times and came to the conclusion that he would tell You what ever You wanted to hear to make You go away.. Since all my efforts to make it work were working out to just the opposite of what a Twin Disc was supposed to be ( Use both Feet stiff and super Grabby ) I installed a stock replacement clutch just to see what would happen. All my problems went away instantly. Since this clutch was not going to cut it with my Engine I gave Mcleod one last call and asked if I sent them the Street Twin could they install lighter springs ? The answer was no and the next call was to Spec Clutch and I have never looked back. The Spec is a modern CNC Aluminum work of art compared to the Stamped Steel Mcleod . It also has its issues it chattered for the first 500 miles and when its depressed it sounds Weird. People ask what is that sound You must have a Twin Disc ? I think what is happening is that when depressed the inner Disc is bouncing back and forth as its not being held and is free to roam. Other than that its everything a Twin Disc is supposed to be. If You want to hear me gripe some more just ask me what I think of the Mcleod Scatter Shield. .

 

if this is NOS GM stuff i would keep it new and run a regular clutch.

 

If I understand correctly. the original Street twin comes with a dedicated flywheel and is rated for 1200 ftlbs TQ..
The RST uses a flywheel adapter and is rated at 800 ftlbs. It has only a 1800 lb clamp/plate load, less than the factory OEM 2000.

So I could see where the Street Twin would flex a C3 firewall some. It must have a stiffer spring/clamp load . A RST should not.