2001CamaroGuy

iTrader: (6)

I'm getting to the point where I need to start thinking about the clutch for my project, so I need some input/advice.

My project car is a BMW Z4 roadster. I am in the process of building a 383 using an LS6 block, LS2 heads, and a factory LS7 crank/rods/oiling system. The goal is around 500rwhp (+/-). For a transmission, I'm using the standard F-body T56.

The car is a daily driver/weekend play toy. The goals are to have a sporty, excellent handling vehicle that is enjoyable to drive to work, go on weekend cruises, etc. IF it ever gets raced, it would be short track road course racing. With these goals in mind, I'm looking for the lightest (within reason) clutch setup that is reliable and reasonably priced (not looking to spend $2K for some exotic piece here).

My "default" is the LS7 clutch with an aluminum flywheel. I have used this setup in the Z28 and Silverado projects I did, and both were very drivable. I'm interested in/considering a multi-clutch pack that uses a flex plate, but I have zero experience with these so I don't know how they would work in my application.

Anyone with advice/guidance/etc. would be really appreciated.

Thanks,
Chris

BALLSS

I would look into the McLeod RST or RXT "twin" disc clutches if you are putting in a "LS" motor. you can get a aluminum or steel FW.

Your HP goal will go through a "stock" clutch so if you stay single disc you will have to get a more aggressive disc material. Monster is popular brand. SPEC 3+ may be another choice.

IMHO having been through a few single disc clutches of various brands and friction material, including supposedly enhanced PP with more clamp force, I just put in a McLeod Street Twin and steel FW. If weight is a primary concern a AL FW and single disc clutch will be the lightest set up

2001CamaroGuy

iTrader: (6)

An aluminum flywheel is a must (unless I use something that uses a flex plate). I don't need the mass of the iron or steel flywheel.

In the past, I had heard the McLeod twin discs were hard to setup/temperamental on their setup. Is that true?

SNLPerformance

iTrader: (15)

What kind of weight are you trying to stay around? With the clutch setup.

2001CamaroGuy

iTrader: (6)

Anything at/less than an LS7 clutch/aluminum flywheel combo. I have not set a 'number' since I don't have a lot of experience with ultra light weight clutch setups. I have always just used LS7 or SPEC 3 setups in my projects.

SNLPerformance

iTrader: (15)

Our Level 1/2 with the 18lb flywheel is 34-35lbs. IMO that is probably as light as I would go, and even still that has a 18lb billet steel flywheel.

2001CamaroGuy

iTrader: (6)

What's the difference (benefits/disadvantages) between your 11" and 12" clutches? What about your twin and triple disc setups?

Orange Juice

iTrader: (3)

I have had both a street twin and the RXT and the RXt is alot lighter feel with plenty of grab.

usdmholden

That 34-35 lbs on a stage 2 includes the 18 lb flywheel? Making the pressure plate and disk assembly about 16 lbs?

That's alot lighter than I figured it would be but it's about what I'm looking for.

SPEC-01

iTrader: (2)

An aluminum wheel should be fine though it's worth noting that the engine will respond differently with the reduced mass (you know this from your experience with other builds though). Additionally, what are you planning to make in terms of torque? This will provide me the ability to offer the best recommendation possible. Let me know and we can go from there. Thanks,

2001CamaroGuy

iTrader: (6)

Well, I expect the torque will be somewhere in the 450rw range (estimated based on past experience and research of other 383 builds). I don't expect it will being over 500rw (certainly will be above 400rw though).

I have always been very happy with the performance of aluminum flywheels on LSx based engines. Even my 4300lb silverado with a 5.3/t56 (NA with an LS6 cam) was very enjoyable to drive every day with an LS7 clutch/Alum flywheel.

I look forward to hearing your input.

SPEC-01

iTrader: (2)

Not bad at all. In truth a Stage 1 would be good for use with 450lb.ft at the wheels. But, having a little more clutch, for future mods, is always a good idea. If you are using this on the street only then a Stage 2 would be fine. Though, I am partial to our Stage 2+(I've used it in my last 4 cars with great results).

2001CamaroGuy

iTrader: (6)

What's the difference between the Stage 2 and Stage 2+? I agree with having a little extra reserve on tap. I willing to live with a little more peddle pressure, but do not want a lot of chatter (I'd take pressure over chatter if I had to choose).

I had a SPEC Stage 3 clutch years ago (near 10 years ago) and to put it frankly, I hated it (it would not disengage high/7000 RPM). I had installed a brand new LS6 slave and an adjustable master cylinder with the clutch, along with re-routing and wrapping the clutch line (to ensure it stayed cool). I pulled it for the LS7 clutch and the issue (not being able to disengage at high RPM) was gone. So I want to make sure I don't get a repeat of that experience.

SPEC-01

iTrader: (2)

Stage 2 uses a Kevlar facing on both sides of the disc whereas Stage 2+ has a hybrid disc that uses Kevlar on one side and our carbon-graphite-semi-metallic pucks on the other. Both will have the same pedal effort which is not excessive at all (within 10% of stock).

Without having seen the Stage 3 you reference it's hard to know the cause of your release issues. Lots of things can affect this (including hydraulic issues, a bent disc, an over machined flywheel, proper spacing relative to the slave or a plate related issue). We provide a measurement sheet that should help you insure that you are within the proper window of operation. Let me know if you have any further questions. Thanks!

2001CamaroGuy

iTrader: (6)

What's the advantage of having a dual material? If the carbon/metallic has a higher friction force, why not just run it on both sides?

What's the difference between the stage 2/2+ and stage 3?

BALLSS

I just put in a McLeod "Street Twin" and it was not difficult at all. The assembly comes marked in terms of how the FW, floater plate & PP align and each stand has specific shims set up by McLeod you need to keep in order...but that is no big deal. You also use a feeler gauge to measure between the bottom disc and floater plate to confirm if you are within spec (.020-.025) in my application.

I would assume any "twin" disc clutch assembly will weigh more than a single disc clutch. You can run a aluminum FW with either set up.

The single discs with "dual friction" surfaces like a 2+ or higher stages with non organic friction materials do hold better than organic disc material but can be prone to chatter.

I know McLeod offers both a organic disc and a ceramic disc in their RST or RXT twin clutches which can be used with a AL FW. I assume other companies also offer twin disc clutches for the LS platform. McLeod is the only one offering a LT platform twin disc clutch that I know of.

I believe the RST or RXT McLeod clutches use the stock LS FW which is available in both AL or Billet aftermarket

2001CamaroGuy

iTrader: (6)

How do you measure the space between the floaters and discs when it's all assembled? I assume the 0.020" is with the clutch released?

BALLSS

No, you measure when the FW, bottom disc and floater plate are bolted up BEFORE you put on the top disc and PP. Instructions are specific about doing this and not doing it while clutch assembly is laying flat on a bench. When right you can easily turn the bottom disc by hand but it won't have any noticeable 'front/back" play

pic shows .022 felt tight and .020 was just right. each clutch disc when made is slightly diffrent in thickness so shims are used to raise the floater plate to within spec. The clutch assembly from Mcleod came pre-assembled with the right shims. The directions just have you confirm measurements and if there is a problem to call tech line before proceeding