What clutch are you running other than stock and does it chatter?

[FASTFATBOY]

I hate clutch chatter when backing out or leaving a stop light, drives me NUTS. Like driving a paint shaker at Lowes.

Please let me know if you have an aluminum or steel flywheel.

Thanks.

[Pops]

I had a Mccloed RST double disk clutch put in a few months ago. It is super for the street no chatter. My power ratings are very close to yours. The next level up was not recommended by my installer as it was more of a track clutch and would not be as smooth. I think it would be fine for limited track use. It is much more authoritative than a stock clutch. They also said to go with steel flywheel which I did.It is Mo,s Speed in Dallas Ga. if you want to get their input.Jeff runs the dyno. Hope that helps.

[FASTFATBOY]

Originally Posted by Pops

I had a Mccloed RST double disk clutch put in a few months ago. It is super for the street no chatter. My power ratings are very close to yours. The next level up was not recommended by my installer as it was more of a track clutch and would not be as smooth. I think it would be fine for limited track use. It is much more authoritative than a stock clutch. They also said to go with steel flywheel which I did.It is Mo,s Speed in Dallas Ga. if you want to get their input.Jeff runs the dyno. Hope that helps.

How is the pedal effort as compared to stock?

[Pops]

Pedal effort is about the same I don't have a difference . Its very easy and comfortable.

[Triple5even813]

Monster LT1-S. No chatter. More than 25k miles on it, plenty of racing, and all good.

[acammer]

McLeod RXT here. Been in for about 15-20k miles. It will chatter if you don't get your takeoff right. Mostly I can drive around it, once and a while it does catch me by surprise. I have a billet steel flywheel.

There are a few things that lead to that chatter on take-off with a clutch. The material used on the clutch has the biggest influence. Organic material, like that used on the factory clutch, Mcleod RST, and Monster "S" series clutches is very forgiving. Because it has a relatively low coefficient of friction, the discs are a "full face" which also promotes a smooth engagement. Finally, these clutch all also feature a "sprung" hub, which uses a series of torque dampening springs to help moderate any sort of spikes in torque delivery. That all combines to make for a clutch that operates smoothly, and has fairly gentle engagement characteristics.

More aggressive clutches, like the Mcleod RXT, use a ceramic material. This has a dramatically higher coefficient of friction, as well as much better heat resistance, which makes it ideal for handling big power and abuse. This type of material is arranged on a "puck" style disk to achieve the correct amount of contact area. The side effect of these performance benefits is that the engagement character is extremely fast and aggressive. You can slip a clutch like this, but the window within which you can do so is extremely narrow. These also are almost exclusively mounted on unsprung hubs to maximize their power transmission, responsiveness, and durability - but again that comes at the cost of a less desirable driving characteristic.

The flywheel material is altered to change the weight - the friction material is steel even on an aluminum flywheel, so the material itself does not impact clutch engagement behavior. However, with a light weight aluminum flywheel the engine can accelerate faster - and it also can decelerate faster. That sounds good, until you drive one on the street and find that it makes for a much more challenging take off. For drag raced stick cars, getting the 60' right with a very lightweight flywheel is a challenge, and I typically recommend to my customers to stick with a billet steel flywheel. This is already lighter than stock, but keep a little inertia in the flywheel makes the car easier to effectively 60', and the gain in performance there almost always outweighs the acceleration advantage an aluminum flywheel setup would have down track.

FWIW, here is some driveability video of my car with the Max Package 2.0, which includes a fairly good sized, aggressive camshaft, and a Mcleod RXT. You can see some of that tricky engagement behavior in a few places, but you'll also see that it's totally manageable with well coordinated feet.

[The_bald_eagle_machine]

Originally Posted by acammer

McLeod RXT here. Been in for about 15-20k miles. It will chatter if you don't get your takeoff right. Mostly I can drive around it, once and a while it does catch me by surprise. I have a billet steel flywheel.

There are a few things that lead to that chatter on take-off with a clutch. The material used on the clutch has the biggest influence. Organic material, like that used on the factory clutch, Mcleod RST, and Monster "S" series clutches is very forgiving. Because it has a relatively low coefficient of friction, the discs are a "full face" which also promotes a smooth engagement. Finally, these clutch all also feature a "sprung" hub, which uses a series of torque dampening springs to help moderate any sort of spikes in torque delivery. That all combines to make for a clutch that operates smoothly, and has fairly gentle engagement characteristics.

More aggressive clutches, like the Mcleod RXT, use a ceramic material. This has a dramatically higher coefficient of friction, as well as much better heat resistance, which makes it ideal for handling big power and abuse. This type of material is arranged on a "puck" style disk to achieve the correct amount of contact area. The side effect of these performance benefits is that the engagement character is extremely fast and aggressive. You can slip a clutch like this, but the window within which you can do so is extremely narrow. These also are almost exclusively mounted on unsprung hubs to maximize their power transmission, responsiveness, and durability - but again that comes at the cost of a less desirable driving characteristic.

The flywheel material is altered to change the weight - the friction material is steel even on an aluminum flywheel, so the material itself does not impact clutch engagement behavior. However, with a light weight aluminum flywheel the engine can accelerate faster - and it also can decelerate faster. That sounds good, until you drive one on the street and find that it makes for a much more challenging take off. For drag raced stick cars, getting the 60' right with a very lightweight flywheel is a challenge, and I typically recommend to my customers to stick with a billet steel flywheel. This is already lighter than stock, but keep a little inertia in the flywheel makes the car easier to effectively 60', and the gain in performance there almost always outweighs the acceleration advantage an aluminum flywheel setup would have down track.

FWIW, here is some driveability video of my car with the Max Package 2.0, which includes a fairly good sized, aggressive camshaft, and a Mcleod RXT. You can see some of that tricky engagement behavior in a few places, but you'll also see that it's totally manageable with well coordinated feet.

I have a Mcleod RXT clutch with a steel flywheel sitting on my shelf that I haven't installed yet. I'm making 530rwhp currently, potentially planning on a centrifugal cam in the next year or so...So if I'm lucky my max power gains would be around 600 rwhp. The car is essentially, only a street car. Never seen the track and only launch it every once in awhile when i wanna show off my car to someone. Is the stock SS clutch adequate? Is the RXT overkill for my application? If I had a few complaints about the stock clutch, the biggest one would be that it is really grabby in 1st gear cruising through a parking lot. Is there a better clutch option out there?

[FASTFATBOY]

Originally Posted by acammer

McLeod RXT here. Been in for about 15-20k miles. It will chatter if you don't get your takeoff right. Mostly I can drive around it, once and a while it does catch me by surprise. I have a billet steel flywheel.

There are a few things that lead to that chatter on take-off with a clutch. The material used on the clutch has the biggest influence. Organic material, like that used on the factory clutch, Mcleod RST, and Monster "S" series clutches is very forgiving. Because it has a relatively low coefficient of friction, the discs are a "full face" which also promotes a smooth engagement. Finally, these clutch all also feature a "sprung" hub, which uses a series of torque dampening springs to help moderate any sort of spikes in torque delivery. That all combines to make for a clutch that operates smoothly, and has fairly gentle engagement characteristics.

More aggressive clutches, like the Mcleod RXT, use a ceramic material. This has a dramatically higher coefficient of friction, as well as much better heat resistance, which makes it ideal for handling big power and abuse. This type of material is arranged on a "puck" style disk to achieve the correct amount of contact area. The side effect of these performance benefits is that the engagement character is extremely fast and aggressive. You can slip a clutch like this, but the window within which you can do so is extremely narrow. These also are almost exclusively mounted on unsprung hubs to maximize their power transmission, responsiveness, and durability - but again that comes at the cost of a less desirable driving characteristic.

The flywheel material is altered to change the weight - the friction material is steel even on an aluminum flywheel, so the material itself does not impact clutch engagement behavior. However, with a light weight aluminum flywheel the engine can accelerate faster - and it also can decelerate faster. That sounds good, until you drive one on the street and find that it makes for a much more challenging take off. For drag raced stick cars, getting the 60' right with a very lightweight flywheel is a challenge, and I typically recommend to my customers to stick with a billet steel flywheel. This is already lighter than stock, but keep a little inertia in the flywheel makes the car easier to effectively 60', and the gain in performance there almost always outweighs the acceleration advantage an aluminum flywheel setup would have down track.

FWIW, here is some driveability video of my car with the Max Package 2.0, which includes a fairly good sized, aggressive camshaft, and a Mcleod RXT. You can see some of that tricky engagement behavior in a few places, but you'll also see that it's totally manageable with well coordinated feet.

Long story but I got a Spec twin disc with aluminum flywheel that was installed wrong given to me.

I sent it back to Spec for inspection and had the discs changed to organic because I wanted zero chatter. I had to also replace the floater and the steel mating ring in the flywheel.

I was ASSURED it wouldn't chatter the many times I asked.

This MF'er is like a paint shaker at Lowes, I hate it.

I do my own work, I was a dealer tech for 12 years and have been doing car stuff all my life, but at damn near 60 years old my old bod is pissed it has to do another clutch.

The spec has an AEWSOME soft clutch pedal, grip is very very good but the drivability is shit. I can no lift shift it like butter. Make an outstanding road course clutch.

I have called Spec numerous times, I did the break in procedure. The told me to "be more aggressive with it" and I have, to no avail. It may be a tad bit better... maybe. Has about 3,000 miles on it now.

I am not going to mod the car anymore(I don't think) I like it at 600 wheel, fun and reliable.

A McLoed RST may go in it with a steel flywheel. I had one in my C5 Z06 and it never once chattered.

If I tried to do what you did in that video to take off without and added throttle it would die or shake your teeth out.

And FYI, the stock ZL1 clutch is 64Lbs, this clutch is 42 lbs, on a Dragy 60-130 in similar DA the car is not faster, although it feels like it is.

[Pops]

Very thorough and informative write up by acammer!!!!!

[CamaroDreams76]

I had my RXT for a little over a year now. The stock clutch went after heads cam (513whp/463wtq). Went to launch hard, blew right through it.

I was recommended the Mcleod RXT by Redline. It's definitely a learning curve and chatters a decent amount if you dont drive it correctly. It held the power and could take abuse. Still holding at over 800whp and over 700wtq.

[acammer]

Originally Posted by The_bald_eagle_machine

I have a Mcleod RXT clutch with a steel flywheel sitting on my shelf that I haven't installed yet. I'm making 530rwhp currently, potentially planning on a centrifugal cam in the next year or so...So if I'm lucky my max power gains would be around 600 rwhp. The car is essentially, only a street car. Never seen the track and only launch it every once in awhile when i wanna show off my car to someone. Is the stock SS clutch adequate? Is the RXT overkill for my application? If I had a few complaints about the stock clutch, the biggest one would be that it is really grabby in 1st gear cruising through a parking lot. Is there a better clutch option out there?

If you don't get along with the stock clutch, you're going to hate an RXT. It's good for about 850whp, so it's also overkill. I think the RST would be a good match for your intended power goal - the stock clutch will not hold there, but the RST will be fine at that power or even a bit more - especially if you don't have plans for any major racing.

A triple disk from Monster is also a super nice driving option, but is definitely overkill for your application.

When you're ready, and if you want to, give me a shout at andrew@gwatneyperformance.com and I'll get you sorted with a complete package of the clutch and the appropriate pieces that go along with it.

[acammer]

Originally Posted by FASTFATBOY

Long story but I got a Spec twin disc with aluminum flywheel that was installed wrong given to me.

I sent it back to Spec for inspection and had the discs changed to organic because I wanted zero chatter. I had to also replace the floater and the steel mating ring in the flywheel.

I was ASSURED it wouldn't chatter the many times I asked.

This MF'er is like a paint shaker at Lowes, I hate it.

I do my own work, I was a dealer tech for 12 years and have been doing car stuff all my life, but at damn near 60 years old my old bod is pissed it has to do another clutch.

The spec has an AEWSOME soft clutch pedal, grip is very very good but the drivability is shit. I can no lift shift it like butter. Make an outstanding road course clutch.

I have called Spec numerous times, I did the break in procedure. The told me to "be more aggressive with it" and I have, to no avail. It may be a tad bit better... maybe. Has about 3,000 miles on it now.

I am not going to mod the car anymore(I don't think) I like it at 600 wheel, fun and reliable.

A McLoed RST may go in it with a steel flywheel. I had one in my C5 Z06 and it never once chattered.

If I tried to do what you did in that video to take off without and added throttle it would die or shake your teeth out.

And FYI, the stock ZL1 clutch is 64Lbs, this clutch is 42 lbs, on a Dragy 60-130 in similar DA the car is not faster, although it feels like it is.

It sounds like something must be wrong with it, or something in the driveline, to be that bad. It is true that they take some break in, but it sounds like you've been making 60-130 hits, no lifting, it should be well broken in by now. I don't have experience with Spec's stuff, other than some MASSIVE ceramic single I used in a buddies AWD twin turbo car, which was a literal light switch on engagement with a pedal heavy enough to burst blood vessels in your left leg - but a full faced organic twin should be very smooth.

The Mcleod RST is a known great, smooth clutch, well suited for your power level. But, I'm hestiate to recommend it because it at least seems like the clutch you have now should be pretty similar, and it's giving you fits. You sound like you know you're way around a wrench and a car - so you've checked things like motor/trans/subframe mounts, carrier bearing, axle/diff play, etc I would bet. Maybe one last confirmation would be to put a different driver in your car that has some experience with a similar or more aggressive clutch and get their impressions just as a baseline. I'm not accusing you of being too sensitive, but I have had people just really not know what to expect, and I do think that when you're expecting a problem and sensitive to something like that, we tend to make it worse.

I know none of that is super helpful. I do think an RST fits your goals and build, so if you're set on changing the clutch, that would be my go-to. I'll even help you get one ordered if you want - but I think it's critical to make sure you've ruled out all other possibilities before going after the clutch.

[FASTFATBOY]

Originally Posted by acammer

It sounds like something must be wrong with it, or something in the driveline, to be that bad. It is true that they take some break in, but it sounds like you've been making 60-130 hits, no lifting, it should be well broken in by now. I don't have experience with Spec's stuff, other than some MASSIVE ceramic single I used in a buddies AWD twin turbo car, which was a literal light switch on engagement with a pedal heavy enough to burst blood vessels in your left leg - but a full faced organic twin should be very smooth.

The Mcleod RST is a known great, smooth clutch, well suited for your power level. But, I'm hestiate to recommend it because it at least seems like the clutch you have now should be pretty similar, and it's giving you fits. You sound like you know you're way around a wrench and a car - so you've checked things like motor/trans/subframe mounts, carrier bearing, axle/diff play, etc I would bet. Maybe one last confirmation would be to put a different driver in your car that has some experience with a similar or more aggressive clutch and get their impressions just as a baseline. I'm not accusing you of being too sensitive, but I have had people just really not know what to expect, and I do think that when you're expecting a problem and sensitive to something like that, we tend to make it worse.

I know none of that is super helpful. I do think an RST fits your goals and build, so if you're set on changing the clutch, that would be my go-to. I'll even help you get one ordered if you want - but I think it's critical to make sure you've ruled out all other possibilities before going after the clutch.

Had the stock clutch in the car, smooth as glass. This thing, paint shaker at Lowes.

Like I said, the steel flywheel RST I had in my 440whp cammed C5 Z06 never once chattered. Buddy just built a 600 whp C6 Z06 with an aluminum flywheel RST with no chatter and he is picky as hell, WAY worse than me. He would have told me if it even farted like a chatter.

When I pull it out I'll inspect it good and may even send it back to Spec.

Thanks a ton for your input.

[acammer]

Originally Posted by FASTFATBOY

Had the stock clutch in the car, smooth as glass. This thing, paint shaker at Lowes.

Like I said, the steel flywheel RST I had in my 440whp cammed C5 Z06 never once chattered. Buddy just built a 600 whp C6 Z06 with an aluminum flywheel RST with no chatter and he is picky as hell, WAY worse than me. He would have told me if it even farted like a chatter.

When I pull it out I'll inspect it good and may even send it back to Spec.

Thanks a ton for your input.

Sounds like you've made the right considerations and gut-checks, and to me it sounds like a problem with the clutch itself. Full faced organic should drive pretty much like stock, just like your buddy's C6Z06 does. Hopefully Spec can make it up to you somehow. I'd consider getting a different clutch in and validate your experience is vastly different with that before you reach back out to them.

Lot of work though, no doubt frustrating. I've had my trans in/out a few times, and I never once enjoyed the experience! I'm slowly v-banding more parts of my exhaust, as well as just removing parts of it, got a 1pc driveshaft with, remote bleeder, so it's definitely easier than it used to be at least!