Grassroots style "clutch slipper": Grassroots Motorsports forum: Grassroots Motorsports Magazine

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May 26, 2011 10:58 p.m. weedburner New Reader

Here's an experimental clutch slipper control made from a $12 hydraulic storm door closer. The cylinder connects to the clutch pedal on this bracket. The cylinder was modified by adding about 4" of 5/16" threaded rod to the end of it's shaft...

Turning the black knob adjusts the release rate, adjusting the nut on the threaded rod moves the point in pedal travel that the cylinder becomes active...

I'm using this slipper control on a Ram diaphram pressure plate, and using a Ram sintered iron disc. The hope is to come up with a more street-friendly alternative to the high-maintenance McCleod SoftLoc clutch which uses a Long style PP that needs frequent adjustments of the pressure springs and occasional pressure plate shimming. My version can easily be adjusted from the driver's seat, and does not effect normal street driving.

I broke 5 Saginaw 4spds last year. Over the winter i dreamed this up and added a 175 shot...so far this year, no broken trans

I'm almost tempted to put a T5 back in the car just to see how much more i can get out of one of those.
May 26, 2011 11:00 p.m. JoeyM SuperDork

definitely grassroots
May 26, 2011 11:12 p.m. former520 New Reader

It looks more like an adjustable dampener like they have on the slave cylinder of the EVO. Are you trying to keep your clutch from engaging all the way without having to use your foot?

A slipper clutch on a bike it to keep a bike from locking up the rear tire from a hard down shift under aggressive riding. I always kind of liked a little bit of lock up to slide around. My SV650 did it pretty good.
May 26, 2011 11:36 p.m. HiTempguy Dork

former520 wrote:

It looks more like an adjustable dampener like they have on the slave cylinder of the EVO. Are you trying to keep your clutch from engaging all the way without having to use your foot?

I think it is a similiar idea to what Subaru does on their cars; since it is a hydraulic system, it basically slows the releasing of the throwout bearing even if you've completely removed your foot from the clutch pedal, allowing the clutch to take the wear rather than the tranny.
May 26, 2011 11:42 p.m. Derick Freese Dork

My only concern would be temperature change. I guess it's not a big deal since you set it up to be adjustable from the driver's seat, but I know I have to adjust my storm door closer twice a year, and I'm using it for its intended purpose.
May 27, 2011 6:19 a.m. Giant Purple Snorklewacker SuperDork

That is clever and interesting... but a "cleaner" way to do this might be to get a Clutch Delay Valve off any modern BMW and install it just before the slave.

Pictured in red. http://www.zeckhausen.com/CDV.htm
May 27, 2011 6:30 a.m. 44Dwarf Dork

If it hydrolic all you need is a one way flow control valve. http://www.surpluscenter.com/item.asp?item=9-7960-4&catname=hydraulic cheaper the a door closer too.
May 27, 2011 7:02 a.m. Tyler H Dork

Nice 44...I'll file that away somewhere.
May 27, 2011 10:18 a.m. weedburner New Reader

The problem with that hyd 1-way valve is that it slows down the entire release stroke of the pedal...very hard to cut a good light with that setup.

With the storm door closer, the active point is adjustable. Basically it's a hydraulic timer that controls only the last part of clutch engagement...a 2 stage clutch.
May 27, 2011 10:20 a.m. z31maniac SuperDork

Pretty inventive, nice work!