clutch disc 1 3/8" x 10 spline 12"

[MaSnaka]

I was under the impression that a McLeod 12" disc actually measures 11 1/2". You could call them and ask.

John

[Michael C Henry]

When I bought the car Hot August Nights 1999. It had a 7/8" dia. Tilton master cylinder for the clutch. It's volume would only afford a verry minor free travel and just barely release the clutch. That is how the adjustment got away from me in 2001. I've since stepped up tp a 15/16" dia Tilton master cylinder and I can now have a little more free travel and complete clutch release. Same pedal travel and a little more foot pressure. I'm looking through the new McLeod catalog and noticed their Street Twin disk for a Ford 427 1 3/8" x 10 says N/A all accross that line. In McLeods catalog the RST Street Twin series kits are said to not include fly wheel, saying that their kit will fit my fly wheel, but going to Summit website, McLeods RST Street Twin 12" disk kit #64304B-00-06 for Ford 427-429 1 3/8" x 10 includes a steel fly wheel and is supposed to hold up to 800HP and sells for $1,069.69. What happened to the concept of the RST Street Twin clutch kits fitting my existing flywheel? A diaphram pressure plate is shown in the RST Twin Disk setup. How does a diaphram pressure plate compare with the Long Style (Ford) pressure plate? Any insites?

[Michael C Henry]

I was out of free travel again. I jacked the car up and placed the four frame stands under it, and removed the clutch. I was in error, I have a McLeod 12"( Long Style) presure plate with 12 springs in the cover. It does have holes in the cover near the mounting bolt holes. I paid McLeod to machine for and install a 12" heatsheild in my alluminum flywheel. The big surprise to myself was I had a clutch disc with eight torsion isolator springs but only 11" accross. A good 1/2" of unused surface on my 12" pressure plate and heatsheild all the way around. If I noticed it back when I installed it all (2001), I do not remember it. Anyway, If I'm going back together with this I'll need a new 12" disc and throw out bearing. Or what about the RST Street Twin #64304B-00-06 maybe without the steel flywheel? I'll have to move one way orthe other soon as I have the garage blocked.

[blykins]

Michael,

I sell the twin disc stuff too.

If you want to replace just your clutch disc and TOB, then that's definitely the cheapest route.....around $250.

I can beat Summit's price by a long shot on the twin disc stuff, but the 1-3/8 application is not showing up in my catalog. I'll check into it more for you.

As for the 11.5"/12" stuff, McLeod's pressure plates are 11.5" and they are clearanced to fit a 12" disc.

The Long style pressure plates are generally associated with higher clamping forces and stiff pedals....where as the diaphragm plates are more street friendly.

Now if you pair a diaphragm plate with two discs, then you get the pedal feel of a new Mustang with 800hp holding capacity.

[blykins]

BTW, I just checked the link that you posted on Summit's site. It's for the McLeod Street Twin, which is different than the RST/RXT twin disc setups. The Street Twin products include the flywheels.

IMO, you don't need a twin disc setup, you need a steel flywheel, a new disc (and possibly pressure plate depending on how it looks -- if the disc is smoked, the plate can't be any better), and a new cam.

[patrickt]

He can put the new cam in over the winter. What sort of clutch do you have that slips a lot, but also grips when it's fully engaged?

[blykins]

Sintered iron, but he doesn't want that.

A steel wheel would help tremendously, 33# vs 14#.

[patrickt]

Originally Posted by blykins

A steel wheel would help tremendously, 33# vs 14#.

Yep, I agree with that. A heavier flywheel is definitely the answer -- and as much as I love aluminum flywheels for Cobras. Changing the cam is a PITA, I doubt he wants to pull the engine until after the driving season. But that's what he really needs to do.

[Michael C Henry]

Summit shows two versions of that 12" Street Twin disc

63304B-00-06 comes with an alluminum flywheel

64304B-00-06 comes with a steel flywheel

[blykins]

Michael, sent you two emails.

I'm going to contact McLeod and see what's up. Those part numbers in McLeod's catalog show a Long style pressure plate, but the links you show at Summit say it's a diaphragm plate. Let me verify and get back to you tomorrow.

[Michael C Henry]

The picture in McLeod's catalog PP 14 for the Original Street Twin Clutch Series show what they call a Borg & Beck Long Style. Which it lists for the 427 on pp 16 (BBL). It looks like the heaviest hat with Ford Long style fingers.
Also on PP16 last column 65-68 Ford 427 It shows the same assembly number but lists dbl. 10.5" discs but Summit says that number is dbl 12"discs. How harsh or ill mannered would it be for a small car like mine on the street?

[blykins]

The Borg & Beck is GM's version of the 3 fingered pressure plate.

If the discs are organic then there shouldn't be any chatter or instantaneous grabbing. If it's a B&B plate, then it depends on what the clamping force is. It could be comparable to what you have now, or it could have a little heavier pedal.

McLeod makes two Long style pressure plates, one is a street and the other offers a little higher performance. So depending on which one you have, you may notice a difference with the Street Twin or you may not.

To be honest, you don't need anything like that. These clutches are rated for 1000hp, for very high horsepower street cars. You're going to pay $300-400 more for this than a regular clutch setup with a new flywheel. I just don't see the justification for it. The only caveat would be if you were making more than 500hp and you wanted a stock-feeling clutch with no chatter.

However, I did send an email about it to clear some of their catalog info up. I'll keep you posted.

[Michael C Henry]

What do you figure the thicknes demension is on a new clutch disc, say perhaps a 260163? I just miced my old disc and it came up 0.312", How much material have I lost?

[blykins]

I don't know off the top of my head.

I wouldn't advise the 100 series disc though. It's only rated for 450hp and I would imagine that you're over that by a good bit.

[Michael C Henry]

I found that McLeod had written on the top of my 12"Long style pressure plate" 2,100lbs @ .300" ". Is that enough, usual, or what? I measured my old disc with my verneer calipers at 0.312"

What HP maximum would you rate the 500 series 12" disc at? should be 260563 wright?

[blykins]

McLeod has two Long style pressure plates. That's the weaker one of the two.

Depending on what disc you have, you're probably looking at a hp capacity of 400-500hp...ranging from a regular organic disc to a bronze/Kevlar disc.

[Michael C Henry]

It keeps sounding like I'm headed to the Street Twin again.
Last night I was over at another FE maniacs. He dug out an 11" Centerforce diaphram pressure plate and it appeared to have 9 bolts connecting to flywheel. Beats 6 bolts. How much more clamping force would be availabe in a 12 Borg & Beck long pressure plate?
Local Clutch shop offered to surface my pressure plate and double the springs. How much more spring pressure will it take.

[blykins]

Ford is a Long pressure plate. GM is a Borg & Beck.

The Street Twin is basically a GM pressure plate with a flywheel that's adapted for it.

It doesn't matter how many bolts hold the pressure plate to the flywheel. Trust me on this one, a Long style plate will have a lot more clamping force than a diaphragm. Again, the number of bolts to hold it on doesn't mean anything.

I have yet to hear your preferences and that's what I need.

Do you mind a stiff pedal? What if it's stiffer than the one you have now? Do you mind a little clutch chatter on a dead stop take off?

I need to know those answers, then let me worry about the clamping forces, the number of bolts to hold it on, etc.

I'm going to use the Street Twin as a last resort, because I honestly think it's overkill in both application and price for you. The ONLY reasons to use it are if 1. You're making 1000hp 2. You're drag racing. 3. You wouldn't mind a stiff pedal, but you absolutely don't want ANY chatter.

Here's how twin disc clutches work: You can get away with a sissy pressure plate because you now have two friction discs. The regular McLeod RST is a diaphragm plate with two organic discs. That means it's going to have a light pedal like a production street car, but it's going to grip....and it will hold about 800hp.

The Street Twin is going to have a 3 fingered pressure plate, and it's going to be stiffer than the one you have.....probably by at least 500 pounds of clamping force. I don't have the exact numbers in front of me, but the one you currently have is a baby pressure plate. So that means that it's not going to chatter because you have organic discs, but the pedal effort is going to be more than what you're dealing with now.

I can get you a brand new McLeod pressure plate, disc, throw out bearing, and billet SFI flywheel for under $700. You're going to pay at least $950-1000 for a Street Twin.

I would set you up with a 500 series disc, because I think you're making more than 400-450 hp. This disc has bronze pucks, so it *may* chatter, but I really don't think it would. I sell a lot of these discs to Cobra guys and I haven't heard anyone complain yet.

I have to tell a lot of people that they can't have their cake and eat it too. If you want a clutch that will hold the horsepower, it's not going to drive like a Honda. If you want a clutch that has a baby pedal, then it's not going to hold 500-500hp.

The RST clutches are much more cheaper, and if they had one for a big input Toploader, I'd be jumping up and down and pointing at it, as they're about $750 for a kit. However, the Street Twin is quite a bit more expensive.

[Michael C Henry]

My original Pressure plate is that Long (Ford )style .It still had the swirl marks from the conditioning pads. Any wear that was noticed was 2/3rds of the way outwards of the contact area. The wear marks fadded as you go towards the inside. You could see where the disc had made contact towards the inside but it was verry faint. Local clutch shop will surface my pressure plate and redo the springs for $45. I can't beat that. I'm am concerned how much more though.
Back to the Borg & Beck Long Style pressure plate used in the Street Twinn set up, does it use any more than 6 bolts to hold it to the flywheel? I could stand a little more foot to pedal presure and a little chatter is OK. I'm concerned about anymore rapid wear of the flywheel heatsheild as that would be another major deal tp repair. I'm going to break down and remove my flywheel and deliver it all to local clutch shop and have it all checked out for flatness.

[blykins]

Mike,

Not sure why you're hung up on the number of bolts that hold the pressure plate to the flywheel. Borg & Beck also attaches with 6 bolts and they (along with Long style plates) are the ones with the most clamping force.

Also, my advice again is to lose the aluminum flywheel.