What Is A Slipper Clutch | Do YOU Need One? [TECH NUGGET]


when it comes to getting fast and
consistent standing starts from a four-wheel drive drag car slipping the
clutch is one of the case the problem with this is that particularly when
you’re making a lot of power and you have a twin or a triple plate clutch for
the driver to be able to consistently and reliably slip the clutch the same
amount pass after pass it’s almost an impossibility the reason we need to slip
the clutches with a four-wheel drive drivetrain there’s a lot of grip
available and when we leave the line and sidestep the clutch it’s likely that the
car is going to do one of two things either it’s going to light up and wheel
spin and the engine will end up on the rev limiter which results in a lot of
smoke but not a lot of forward momentum or alternatively the car’s going to grip
up and this is going to bog the engine down bringing it off boost and making
for a very slow pass bogging the engine down like this also puts an immense
amount of stress on all of the drivetrain components and this is one of
the reasons why a lot of four-wheel drive drag cars have a reputation for
reliability problems for years the worst kept secret among for drive drag racers
has been a clutch slipper device now this is a valve that goes in the clutch
line between the clutch master cylinder and the clutch slave cylinder the idea
here is that the driver will manually disengage the clutch by pushing down on
the clutch pedal but that little valve will restrict how quickly the clutch can
release when the driver sidesteps the clutch and more advanced systems the
speed of release can actually be adjusted to suit the track conditions or
the amount of grip available with one of these systems in use the driver will
stage the car normally but then as the tree counts down and the driver side
steps the clutch the clutch may take as long as one and a half to two seconds to
fully come back out and fully engage so this allows the clutch to slip
particularly over that critical period the first 20 to 30 feet of the launch
now you may be thinking that that’s all well and good as the driver steps off
the clutch at the start line but of course if you need to use the clutch as
you go down the strip this isn’t going to be much use that very slow clutch
response when we shift from first to second to third etc that’s going to
really make the clutch slip and reel the cars time well that’s okay there’s
ways around this too first of all with a lot of the high performance jet cast
they will be running what’s referred to as a dog engagement gearbox and these
gearboxes once the car leaves the line don’t actually require the clutch to be
used for the gear shift this is all done through the ECU and all the driver needs
to do is pull on the gear lever the ECU will interrupt the engine talk allowing
the ship to progress so in this instance the clutch really doesn’t matter once
the car leaves the line however if you’re running a conventional
synchromesh box where we do need the clutch for each of the changes then
there’s ways around this to some of the devices such as the unit from Magnus
motorsport can be set up with a bypass now depending how you set this up this
could be done based on speed so that once the car exceeds perhaps 20 or 30
mile an hour and first gear the clutch system is disabled and then you can use
the clutch as normal the big downside with these clutch slipper units though
is because we are purposely generating so much slip in the clutch unit the
clutch will create a lot of heat and it will wear very quickly in some instances
a complete triple plate clutch may only last eight to ten passes before it needs
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29 Comments

  • Would this be useable on a 2wd application for slipping the clutch off the line?

  • Not all heroes wear capes! Some like to low key things with an HPA tee. Get yours here: http://bit.ly/MerchHPA – Taz.

  • Why bother with side stepping the clutch at all? Put a PWM on a button with a MPH trigger and disable the system once the car reaches a set speed at the end of 1st gear. Even more consistent.

  • Magnus motorsport ftw

  • Parker f200b valve and a line lock

  • Anyone using these in fwd applications?

  • Damn I don’t know this kind of thing even exist.

  • Turbo 400’s forever !

  • wow that is completely different to a slipper clutch in motorcycle world.

  • Wouldn't boost by gear fix this issue? Only a sufficient amount of hp off the line during the launch

  • I swear your vids are always timed perfectly for when I want to find out more about a particular mechanical device. Great stuff

  • I have this on my RB30 Skyline R33 GTR Vspec and my 20b FD RX7. I love it, it’s controlled by my Haltech Elite 2500. It only engages when I’m in 1st gear, between 0-7mph, and the engine is 75% throttle over 4500 rpms.

  • I didn't know they made these for cars

  • What about nissan gtr with dct? How do they do with the brake/clutch pedal?

  • Quite simply one of the best channels on you tube for content. I love it when the guy ask some of the really technical question to the build teams and you see the look on there faces, like ( I don't want to answer that / or how The fuck did you know to about that lol.. ) this guy ask the question I would be asking and he knows what the the answer might be. He can also smell bull shit a mile away. Great great work .

  • HPA let me tell you that I have been on this bandwagon for awhile now but only now have actually used a product. There is a lot here that I have said in response to other comments but once the cat is out of the bag, FWD, AWD it doesn't matter if they have a clutch and are manually shifted they will benefit from slipping the clutch and only go faster, with far less parts breakage. There are people in the Coyote Stock community that used to break T56 transmissions regularly but can go a whole season or two on the same trans with clutch slip. The clutch tamer has become so popular in that class that automatics have fallen out of favor, you can read about it the latest issue of Fastest Street Car Magazine that the NMRA puts out. It's also linked to Grant's website clutch tamer dot com.

  • How would a clutch slipper launch compare results-wise to a clutch-dump wheelspin launch with well-tuned traction control?

  • I'd just go auto

  • Not worth it imo if your clutch is cooked after 6-8 passes

  • 8-10 passes!!!

  • I have a question, does this affect classing?

  • Awesome!! This is what I need for my galant vr4!! Twin disk clutch is hard to launch consistently!!

  • Local street evo pushing 800whp has this, pretty crazy how he rockets out of the launch.

  • Could you make a homebrew version of this with a unidirectional damper attached to the clutch pedal itself? Seems like it might do the same thing.

  • Like a BMW then, in a SMG transmission

  • Nice 👌👌

  • Funny, BMW E90 models came with clutch delay valve like that from the factory. A little part in the clutch line with a smaller inner diameter. I guess to achieve some kind of softer clutching. Unfortunately it is a pain to drive.

  • So it's basically a clutch delay valve…

  • My 1957 fe Holden clutch pedal comes out at the same speed

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