Lock up clutch tuning





#1
So I'm new to lock up clutches. I have a single stage locker and have been playing with it on the street for the last couple weeks, and will be using it for the first time on the track this weekend.

My question has to do with multiple stages of boost. If you are running 20psi on the back end, and launching with 7psi, you of course have to add enough weight to keep the clutch engaged at 20psi, but won't this cause the lockup to engage too early coming off the line, since you are only running 7psi?

Or is it simply, it'll start engaging as soon as it sees some boost and stay there?

Am I overthinking this?
 
#2
for multiple stages of boost you really need a multi stage a single stage is going to control the launch and one set pressure. its really made for more all motor bikes or set boost pressure. if you really wanna run it your going to find a happy medium between your stages but youll probably just end up smokin the clutches. jc
 
#3
Either way you set up your clutch (2stage or multi stage) your clutch will be totally locked up (as much as it can) within 100'. If you don't have enough weight down track you obviously have to add more. So basically you want as light a static as you can use (without to much slip off the line) and have the weights bring it in the rest of the way to hold the power down track. That why the mutistage works so much better, you can delay the arms coming in. Another part is are you trying to more of dump the clutch or slide it out to 60' two totally different ways to set it up for each??


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#4
thanks guys. I just "assumed" that you set up a lock up to dump it on the line. I was trying to remove the human error (and with me involved, its a big variable
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) on the launch. If I still need to feed the clutch off the line, then I probably should have just left the clutch the way it was before the lockup.

I have no problems with going through clutches if it greatly improves my times and consistancy....
 
#5
You can setup a 2 stage to do that, it just depends on the power your making and the weight. If your making 300 or so you can go light static then offset the weight per arms (different amounts on different pairs of opposing arms).


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#6
well took it to the strip, didn't even bother tuning it, just left it on the settings I had for the street, which were pretty dang loose on the spring tension with the weights making it lock up around 6K RPM's.

Actually worked pretty well, shaved .2 off my 60' time. I still need to practice with it some more, no doubt.

But it ended badly. 3rd run my motor seized at the end of the track. Little excitement for me. Nothing bad happened though.

#3 and #4 conrod sized on the big end. Thankfully the pistons, head and cylinders are fine. I have a spare engine ready to go....but I think I'll make some modifications before putting it on. See if I can reduce the amount of oil that bypasses the crank. Not sure if thats the problem I had or not, but figure its worth the effort.

But....that bottom end did last me quite a while. The crank had 118K miles on it. The bottom end hasn't been opened up in 40K miles, which was when the con rods were installed. All of it was turbo'd miles. Can't complain.

I just hope the new setup lasts as long.....
 
#11
I saw 18psi on pump gas for quite some time. Mostly keep it around 15-16psi. I've never yet made a run on race gas simply because, I think that would push the turbo well outside of its effeciency

The con rod didn't fail. If a stock rod can live through the abuse I've subjected it to, I see absolutely no reason to spend a grand on rods that will do me nothing....can't even see the bling!
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