LSx clutch disc information...

Regarding the LSx swap, the clutch disc that is needed is a 1" shaft, 23 spline disc, either 10.5", 11" or 12" depending on your flywheel fitment. I personally run a 168t flywheel with a 12" clutch disc, but other applications are adaptable as well.

Below are experts from the clutch how-to on PHB. I edited a bit, but can post all in full if anyone so desires.


- I found that a clutch disk from a 68 roadrunner with a 383 has a 10 1/2 clutch disk that works perfectly on atleast a 924 turbo...but should also fit just fine on 944's

- McLeod makes a 10.5", 11", and 12" disc with 1" x 23 spline hub. The truck bellhousing should work with either the 153 or 168 tooth flywheel. With the right 168 tooth flywheel you can use a 12" clutch.

- I've been casually looking for a FLAPS that I can get a disc at and have had trouble (easy to get at a clutch shop, but 45 minute drive). Nobody wants to sell a disk - everybody sells kits only (CarQuest, Advanced, AutoZone, one or two locals). Finally today I happened to be passing a NAPA (out of the way normally) and decided to stop in. They told me a 68 Roadmaster 383 has a 1x23 spline, but an 11" disc. I told him what I was after and the guy spent like 15 minutes trying different MOPARs from the 60's and 70's and found that up to '75 everything should have an 11" disc. I was surprised thier computer system actually listed the size and spline info instead of just make/model/part# like everybody else.

Final answer? 1976 Dodge Royale, and yes they sell disc only, $60. Side note, NAPA is also a VDO dealer.

- Wait..... Why cant you guys find just the disc?? I just went to autozones site and found this page using your info.

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They sell just the disc.

EDIT: that link doesnt take you to the page with the discs. But just select 68 plym. roadrunner. drivetrain. clutch disc. and 3-4 disc pop up.

Hell, they even list the size and splines etc.

Heres advance autos listings [You must be registered and logged in to see this link.]

Autozone CP4018
I nominate this one for the extended shaft splines.
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I'm concerned that these clutches won't hold the 350-400whp most of our cars will put down. Does anybody have any experience with these organic clutches at these power levels? Has anybody looked into non-organic clutch discs?

I am running a 168t flywheel with 12" Kevlar/ceramic clutch disc and ultimate street pressure plate from McLeod. As it sits, McLeod says that would hold 450+ to the wheels, 525 at the crank...

Sure, it wasn't the cheapest solution, but at least I have room for mods without having to tear down again. I'd like to plug McLeod too- my experience with their products and customer service (I've dealt with Jeff) have been nothing but top notch.

Sounds good. I'm about to put a McLeod twin disc in another car. I hope it goes well.

Does anyone have any information about a twin disk setup that will work on our cars?

I plan on a 550hp LS2 (Looking for about 450-475hp at the wheels) and I don't think just a single disk will hold it lol.

I'm sure my estimated hp is a bit high, but I don't want to do the clutch after the 1st burnout

m73m95 wrote:Does anyone have any information about a twin disk setup that will work on our cars?

I plan on a 550hp LS2 (Looking for about 450-475hp at the wheels) and I don't think just a single disk will hold it lol.

I'm sure my estimated hp is a bit high, but I don't want to do the clutch after the 1st burnout

Don't worry you'll be doing a tranny.

Nah....... I hope not anyway lol.

I plan on getting a turbo S tranny. They're tough as hell.

There are definitely streetable single disc clutches that that will hold 450whp+.

Here is an example: [You must be registered and logged in to see this link.]

You could probably talk to them about making one with the correct spline too. Maybe a group buy would make it worth their effort. BTW, these power ratings are for 3800lb F-bodys. Losing 800lbs should allow them to handle more power.

You are right though, a twin is awesome. I have a McLeod RXT twin being delivered today and installed tomorrow in my FD LS1. The reason I'm going with the twin is that I'm trying to get into the 9s on spray and 10s N/A with stock 347 cubes. I will likely need 700whp to get to the 9s and the twin is the best avenue.

You could also contact McLeod about put the correct spline in their RST/RXT clutch. It is about $750-800 and bolts to a LS1 stock or stock replacement flywheel. That is why it is much cheaper than other twins. It is supposedly as easy to drive as the stock clutch, works with factory hydraulics and will handle 800whp/1000whp.

The other nice thing about a twin is its a smaller diameter which should effectively free up hp. My FD is a dual purpose drag strip/open track car, emphasis on open track. I'm really just trying to win a friendly wager on the strip. It will eventually run NASA TTS/TTU.

Thanks for the info!!

I know you get a single disk to hold any HP you want, but then they become bad for the street. A brass friction disk engages so fast that unless you floor the throttle, you're going to kill the engine...

A twin disk setup lets you use regular friction material (that holds 400hp) on the disk so it feels like a stock clutch, but because there's 2, it holds 800hp.....

I can attest to the single disk holding up to 800hp but nto being very "streetable"!

I would love a twin disk setup but man it hurts the budget!