Drag Racing Clutch and Trans setups on the street

[tall69]

For you guys who run slipper clutches (e.g. soft-lok) and face plated\pro shifted transmissions, how usable are they on the street?  My Torino is 90% street, but I like to hit the track on occasion.  As setup now, my Mcleod street\strip clutch creates a dead hook situation and will slip badly on occasion.  My car has turned a best time of 11.905@116MPH with a 1.71 60'.  My car is not consistent, and my 60' is primarily the reason.  Most of my time slips have 1.90 and 2.0 60's and ETs in the 12s.  In addition, with 550lb-ft of torque and 2-tons of vehicle, I'm at the edge of what my clutch and driveline can tolerate without failing.

I'm just thinking out loud what the pros and cons would be of having a slipper clutch and\or a pro shifted toploader.  I've read a fair bit about it, and most people do okay on the street, but you have to not be an idiot (with the clutch).

[jayb]

I've never run one but I have a friend (HemiJoel on this forum) who has, and if I recall correctly he says that a different clutch adjustment is required for the street than the track.  I think he said he has a hole punched in his bellhousing so that he can reach in with a socket and adjust the clutch easily, either at the track or on the street.  Seems like if you could do that without much trouble it would be a workable combination...

[e philpott]

I run a sof-loc .... I have it turned up to 1100 pounds for street ..... mine is adjustable from 200 to 1100 pounds .... worse thing on it is a stop sign/traffic on a hill , it will screech when you take off from a dead stop and I'm talking about a toe curling screech that everyone in a 50ft radius can hear/feel ( street gear 3.70 with 30 tall tire ) , I also had to double up my block plate to get everything to fit in my QT bell housing and REMOVE the clutch center spring to get the pedal to return as quick as my foot can let go ..... my trans is simular to pro-shifted but with the synchronizer cut , I knew it wasn't going to hold on street so I installed stock synchornizers until I have it face plated

[tall69]

I should have separated the two topics, as I think running a slipper clutch and pro shifted transmission on the street pose significantly different challenges.  I'd see the slipper clutch as potentially more difficult on the street, but more effective on the strip when you compare the two.  True?

I haven't read were others have dealt with that sort of noise and grinding running a soft loc on the street.  Are there different friction materials used that would make that more pronounced?  Such as sintered iron vs kevlar?  You say 1100 pounds, what's a typical street clutch setup?  2200-2500?  Maybe more?

When I rebuilt my toploader last year, I had Tim Hyatt rework my Mcleod pressure plate and flywheel.  I had warped the pressure plate and broken some disc springs.  He recommended I move away from a dual friction setup and provided an organic disc that he thought would be less prone to slippage when hot.  It definitely seems more grippy than my old setup.  It has worked well on the street, maybe too well on the strip.  He steered me away from a centrifugal setup at the time due to my heavy amount of street use.

[Hemi Joel]

In have run Mcleod and Advance soft locks, and also proshifted and face plated transmissions on the street and on the strip. It IS doable, but there are a lot of drawbacks to using them on the street.  My opinion is if your car is only 10% dragstrip, neither is worth the hassle. On the strip, you set the soft lock clutch loose. it slips at launch, and the heat created by the slippage increases the coefficient of friction on the sintered iron disc, thus locking up the clutch. It's an awesome drag race clutch, effective and durable. Running down the street with the loose setting, it will  cool off and slip in high gear. So you have to tighten up the spring pressure to the max. Then it is very grabby when you have to slip it maneuvering around a parking lot. Also noisy. And you need to adjust it for wear a lot and adjust it tight for street or loose for strip. There are 6 adjusters on the back of the pressure plate. So you adjust #1 thru a small hole in the bellhousing, then turn the motor 60 degrees, adjust # 2 , and so on. It's a high maintenance piece.
On the faceplate and proshifted transmission, they shift great on the strip. On the street too, but you can not make any slow, relaxed shifts. you have to slam it every time to avoid grinding off the edges of the engagement lugs. High maintenance parts, you take it apart and have the engagement lugs resurfaced every so often. And there is backlash, or slop, between the drive and driven side of the face plate or lugs. When you are trying to go slow, like in the pits or a parking lot, or stop and go traffic, the surging of the engine is not dampend much because of the light flywheel, and so you feel a jerking of the car and a slamming inside the trans as the backlash in the transmission transfers back and forth.
All of this stuff you can live with.  But its not worth it unless you really do a lot of drag strip stuff. Good luck, Joel

[tall69]

Thanks Joel.  I hadn't read it explained that clearly.  As I'm not wanting to be messing with it all the time, I'm thinking these are not good choices for me.  Not to mention the significant cost of switching to this setup.

Thinking about a couple other options.  Do you have any experience with mechanical dampeners that slow the release of a traditional clutch to introduce some slippage?  There's a member on the UMTR forum that sells, what basically amounts to a screen door pneumatic dampener.  I would think it would create a bunch of heat and prolonged use would damage the flywheel or pressure plate.  Maybe with more experience I could manually slip the clutch on launch, but I doubt that it would result in consistent 60 foots.

The other option is to introduce more controlled tire spin.  I had attempted to do that by increasing my tire pressure to 21-22 psi.  I run 27x10.5 hoosier QTPs.  It would still dead hook, although I didn't attempt to launch it at 5k+ RPM.  On my fastest run, I launched at 4700, which seemed to create some tire scrub.  Maybe I need a narrower tire with less contact patch or just hit it at 5500 RPM.  That sounds like a recipe for broken parts.

[My427stang]

I have never ran a soft lock clutch on the street, but I did have a couple of years with a Doug Nash Pro-shift kit in my big in/out Toploader before I swapped back to synchros and ultimately a TKO-600

Keep in  mind, I grew up a diesel mechanic and was shifting quad box and triplex 2 stick Macks and any diesel tranny out there clutchless.  I also have no issues shiftinf an NP-435 or the TKO part throttle clutchless, although it really shouldn't be done.

I could not happily and consistently shift that damned crash box on the street unless I did the WOT hard shift that it was designed for.  I couldn't time a shift, I couldn't double clutch, it always ground a little, and sometimes a lot. 

That being said, at WOT you could click them off like a pro racer   and some guys can deal with the crunch, but in my case, I didn't like it

[e philpott]

I bought mine from Tim Hyatt too ... the way he explained it too me was .

1 ... you need light enough base pressure to spin the tire one revolution at the launch then dead hook

2 ... then you hang just enough arm counter weight to prevent slippage at high rpm ( roughly 60ft on )

3 ... abort any pass that has clutch slip immediately or risk burning up the disc , add base or counter depending on what happened , tire pressure , track prep all play into clutch setting

so far after maybe 600 miles on street I have yet to need a adjustment , is it worth it for street ??..... maybe not but it doesn't bother me ..... if I ever did go back to conventional disc and PP I would for sure keep the 13 lbs flywheel on the engine , on street the aluminum flywheel helps the tire recover from spin much easier than a heavy wheel

[tall69]

I run a heavy steel flywheel (about 35#).  I'm not sure whether or not this changes things.

[Hemi Joel]

  Do you have any experience with mechanical dampeners that slow the release of a traditional clutch to introduce some slippage?  There's a member on the UMTR forum that sells, what basically amounts to a screen door pneumatic dampener.  I would think it would create a bunch of heat and prolonged use would damage the flywheel or pressure plate.  Maybe with more experience I could manually slip the clutch on launch, but I doubt that it would result in consistent 60

The "hillbilly softlock"!  I like the concept, but have never tried it. The idea is to have a consistent, easily adjustable engagement speed. I would think that .25 to .5 second from disengaged to engaged would be about right to cushion the hit, but not roast the disc too bad. One of these days, I'd like to experiment with it.

[tall69]

The issue, as reported by others, is that it doesn't disengage so it affects shifts 2 thru 4 as well.  Pedal-less shifts are the answer I suppose.

[Hemi Joel]

If you think about it, there has to be a way to disengage it after launch. You just need to invent it. Something with an electric solenoid controlling its engagement to the pedal or to the under dash mount.
Or you could drill and tap into its hydraulic cylinder and run a bypass line by to the hydraulic tank. Then put a line lock in the line, and a handy way to control it so it is only active at launch.
Well there you go, try it out and let us know how it works. 

[tall69]

If you think about it, there has to be a way to disengage it after launch. You just need to invent it...

I could make up a bunch of excuses about it being too hard, expensive, or time consuming, but I'm guessing that mentality doesn't fly on this site.

How about the slippage impact on a street clutch?  Heat, wear?

[IDOIT4SPEED]

 is this the kind of street use you are thinking about? if not don't go there, stick cars are a hard road to travel. at this event there was not enough traction  for the clutch to work right. pro shift an face plate transmissions suck on the street. https://www.facebook.com/100011481633674/videos/vb.100011481633674/284746161918103/?type=2&theater   

[FE Jonny]

I went Mcload dual disk as it isn't a leg killer and is small diameter. Expensive but effective, would post pics but it's in boxes waiting for the rest of my engine to get put together a piece at a time.