lets talk clutches...

[wankelbug]

I have a 1970 beetle with a turbo 13b rotary street/strip car. I have recently added the turbo and I had thought I have it enough clutch. Stage 2 Kennedy P plate with. Daikin clutch disc. When I set the clutch up it had 250+ ft lbs of break away. (that's as high as the torque wrench goes) last night at the strip on low boost it smoked the clutch through 1st gear if I tried to leave hard at all. Car is making low 300s horsepowr and probably mid 200s tq. On high boost 20lbs it should be flirting with 400hp/350 tq. In addition I am looking to launch at 5k ish rpm @5psi of boost.

What are people using in this power range?

I can either step up to a Kennedy stage 3 p plate and ??? Disc.

A puck clutch. But I know nothing about how these behave.

A sintered iron disc - I am not in love with this option as I street drive the Car.

The RLR rev 6- but the verdict is still out of it will even work with my cutom rotary flywheel. And it is $$$$$ going to follow up with Ron this week.


Thanks in advance.

[FJCamper]

Hi Wankelbug,

Our experience with puck clutches has been good. As a rule, a clutch disk slipping on a Stage 2 pressure plate will stop slipping on a puck disk. Get at least a four-puck disk.

I don't know how your clutch pedal assembly is set up, but consider this kit from Unique Parts.

http://unique-parts.com/?wpsc-product=n ... gn#more-96

This stops clutch cable hook failures.

FJC

[dragvw2180]

The other common problem has been warping of the pressure plate not allowing 100% contact . The repair may be as simple as resurfacing the pressure plate you already have plus a new disc. I still have my Rev 6 in my turbo street car , drove it yesterday matter of fact and it performs perfectly. Mike McCarthy

[Marc]

X2 on having the PP resurfaced - although you may not be able to find anyone local set up to do it...I once took one to a shop that specialized in brake & clutch component rebuild/reline work (mostly for commercial heavy trucks) and they quoted me more than the price of a new one. Some say that a "seasoned" one that's been resurfaced is even better than new, but I passed.

A non-marcelled disc like a "pucker" is difficult to modulate at the take-up point and can be quite "grabby" - if your street use includes ever getting stuck in stop-and-go traffic you're going to hate that.

[Bruce2]

As well as the pressure plate warping, another problem can be an improperly machined flywheel.
When you have the clutch off, measure the depth. The spec is 21.0mm, but I guarantee it will measure larger than this depth.
Here's why. The disc surface wears a slight amount. Then when the PO had the flywheel machined for his new clutch, the shop brought their stone down until it just touched the disc surface, then they zero'd it. They ground it down until it was all perfect then read off how much they took off. They went up to the surface for the bolts and took off that same amount, unknowingly preserving the error caused by the original wear. After repeating this 2-3 times in the last 40 years, your depth is way out now.
Get it resurfaced, then measure how deep it is. Machine the bolt surface until it's exactly 21.0mm.

Don't even think about the sintered iron disc for street use, it does NOT work with sychros. It is far too heavy and you will bend your synchros no matter how gentle you might be. After they're bent, all you get is grinding gears.

[Ol'fogasaurus]

Bruce's reply on the flywheel is very good! So many times the disc surface is resurfaced but the clutch cover's mounting surface on the flywheel isn't machined/ground to match any change in depth of the clutch disc's engagement surface.

While I run on the sand it can put similar loads on the clutch and disc. I lost a brand new disc (but the clutch cover wasn't affected) in less than an hour out on the sand just due to the loads that heavy, wet sand can put on the drive train. Talking to my VW engine guy he recommended a 4-puck with the stock cover which has held for over 10 years. I don't recommend a 4-puck on the street as it wants to be either engaged or not... no finessing (slipping) the clutch as it will tear away at the flywheel's surface.

Again, this is on the sand but other than the initial shock of dumping the clutch the sand's loading is probably as much or even more as it is a full time load. When getting stuck in the sand both of the turning brake's handles can be applied to the rear wheel brakes to cause the open diff to fully engage both wheels at the same time which, with 15 in wide paddle tires, does put an additional load on the clutch assembly.

For what it is worth.

Lee

[wankelbug]

The other common problem has been warping of the pressure plate not allowing 100% contact . The repair may be as simple as resurfacing the pressure plate you already have plus a new disc. I still have my Rev 6 in my turbo street car , drove it yesterday matter of fact and it performs perfectly. Mike McCarthy

the flywheel was resurfaced and balanced to the current clutch not long ago. i think i have good contact patch and grip as the car got the wheels off the ground when i left side stepping it but if i used launch control and built 5lbs of boost it was clutch spin city.

[wankelbug]

As well as the pressure plate warping, another problem can be an improperly machined flywheel.
When you have the clutch off, measure the depth. The spec is 21.0mm, but I guarantee it will measure larger than this depth.
Here's why. The disc surface wears a slight amount. Then when the PO had the flywheel machined for his new clutch, the shop brought their stone down until it just touched the disc surface, then they zero'd it. They ground it down until it was all perfect then read off how much they took off. They went up to the surface for the bolts and took off that same amount, unknowingly preserving the error caused by the original wear. After repeating this 2-3 times in the last 40 years, your depth is way out now.
Get it resurfaced, then measure how deep it is. Machine the bolt surface until it's exactly 21.0mm.

Don't even think about the sintered iron disc for street use, it does NOT work with sychros. It is far too heavy and you will bend your synchros no matter how gentle you might be. After they're bent, all you get is grinding gears.

thanks the flywheel was machined into spec recently and resurfaced luckily i have a seasoned vw machinist in town who can turn these around in 24 hours.

[wankelbug]

i am going to call ron lumas monday and see if his system will even work on my flywheel since it is a vw unit with a mazda hub integrated. if i cannot get that to work i will try a puck clutch. any specific brand you think i should look for? scat? kennedy? others??

[FJCamper]

Hi Wankelbug,

I advised puck type discs thinking you intended a race-only application.

Do not try and use one for the street. We call our pucks the "binary clutch" meaning it was on or off!

FJC

[wankelbug]

right on, anyone with the rev 6 able to chime in on the streetability of this unit?

[Piledriver]

The material matters.

I just put a new clutch in my TDi, after my daughter borrowed the car.
I went for overkill.

I went with a single mass flywheel, 228mm 6 puck copper ceramic and a "stage3" pressure plate
Supposedly rated to 450 ft/lb, which is good because the TDI can just about do that at 2K and 20 PSI.
OTOH it feels like a stock pressure plate effort wise (original was a. organic 200mm, hydraulic clutch, went 300K miles)

Not having the cush engagement of the marcel it engages different, but it is quite smooth (if you are) once it polished the mating surfaces up broken in correctly.

I'm pretty sure someone out there can make a similar friction disk for a T1, and it doesn't have to weigh a ton.
Shifting wasn't effected but I usually shift the TDI about 3K anyway, so its not comparable.

I only put it in a few weeks ago, but it drives nice, and the Rice racers and WCVW guys seem to like the friction material very, very much. It did require gentle driving until it smoothed out for the first 500 miles.(was noticeably smoother after a couple days in traffic with gentle, repeated slippage)

[dragvw2180]

I do have a Rev 6 in my street / race car . If this is something you want to drive every day this would not be my first choice , it is like driving a 4 puck style clutch so it is better suited for the drag strip . Having said that I have 400 plus dynoed HP and an incredible amount of torque on my turbo engine and I run a type 1 transmission so my options are limited. If my clutch does not slip slightly on a hard launch it will immediately eat the ring and pinion . I have personally tried many clutch setups and clutch management systems , this works the best of all the units I have tried. I have not broken my type 1 transmission since going this route , my results were repeated when we installed one in my friend John Toomeys car . I leave on my 2 step at 5800 and have a 1.35 60 ft without doing a burn out , I never do one except to break in new slicks neither does John in his bug. There are higher HP people out there that have setups that work as well or better for them but for us this works great. Mike McCarthy

[gbaker770]

Stage 1 and a 4 puck for me. If properly setup as Bruce stated earlier they will hold quite a bit. In my case it's held well over 370 whp many times. I've tried a ton of combos and I think the heavy disks just don't work in a race setup unless granny shifted.

[wankelbug]

I do have a Rev 6 in my street / race car . If this is something you want to drive every day this would not be my first choice , it is like driving a 4 puck style clutch so it is better suited for the drag strip . Having said that I have 400 plus dynoed HP and an incredible amount of torque on my turbo engine and I run a type 1 transmission so my options are limited. If my clutch does not slip slightly on a hard launch it will immediately eat the ring and pinion . I have personally tried many clutch setups and clutch management systems , this works the best of all the units I have tried. I have not broken my type 1 transmission since going this route , my results were repeated when we installed one in my friend John Toomeys car . I leave on my 2 step at 5800 and have a 1.35 60 ft without doing a burn out , I never do one except to break in new slicks neither does John in his bug. There are higher HP people out there that have setups that work as well or better for them but for us this works great. Mike McCarthy

This is the feedback I was looking for. The car will not see a ton of street miles but they will happen. The sticker shock of the rev 6 seems easy to stomach once I hear how well they perform and are able to preserve an expensive gearbox. 1.35 60 FT. WOW. I would love to cut a time like that. I was putting down 1.70 leaving on 0 boost heel toe launching @ 3500rpm. When i left on 2 step and the clutch just spun to rev limiter so I didn't do that again. Once I can get a clutch that holds I have another 10psi in my back pocket. Currently waiting on a call back from Ron , hopefully the rev 6 will work with my flywheel.