A few lockup questions

lowandslow08

lowandslow08

Registered
Last week was the first time trying out the lockup at the track and I had some issues with it. I bought it used and it came with a new billet outer basket, quick access cover, springs, and the lockup. I started out running the springs it came with and had nuts and bolts with two washers (on three arms only) leaving at 8000 rpm and it acted like it was was not slipping much at all then it would lock and bog or the front would pull up. I ended up pulling the washers off the arms but it still acted about the same. A few days later I tested all the springs that were in it and they four of them were 47 pounds and the other two were each 70 pounds(=328 pounds). Then I measured the stock springs and they were 47. 5 pounds each. Im assuming it should be set up with lighter than stock springs but what should be a good point to start with? Now the total spring weight is 258 pounds and a total of 29.1 grams of weight on the arms. Id like to set it up to dump the clutch off the line or at least close to that.
 
How does a clutch configuration question get categorized in the "Turbo" section :dunno: may have better luck putting it in a closer section as engine modification or getting some setup tips from the drag racers in the 1/4 mile section..
 
What brand clutch?

You may have to buy a tuner kit, especially if the previous owners combo is not close to yours.

I had an MTC Multi in mine. Stock engine, with N20. I did not spray from the launch. Ultra soft springs. No washers on the arms. No static shims, either. 63.5" wb I want to say I had 3 #9 and 3#11 springs on the arms
 
Its a RPM 2 stage lockup, I have a bunch of different springs to set the static pressure, bolts, nuts, and washers with a scale to weigh everything. Just looking for a good starting point.
 
lankeeyankee said:
How does a clutch configuration question get categorized in the "Turbo" section :dunno: may have better luck putting it in a closer section as engine modification or getting some setup tips from the drag racers in the 1/4 mile section..
Click to expand...

Well judging by him saying he's launching at 8k tells me it's a turbo bike. :poke: setting a clutch up for a turbo is diffrent then any other bike.

Back to the question, if you wanna just toss the lever you'll need a multistage lock up. You can get a 2 stage to get pretty close, but you'll never be able to just dump it without bogging a little.
 
Static, first 60 ft controlled by springs under lockup. Soft springs to begin with and either shim them till you get it to go 60 ft without lifting front tire or blowing tire away. or change every other spring by a small amount..

Arms, have nuts and bolts for weight control pressure after 60ft, the lighter the arms, the longer it takes to lockup. You want it to slip long enough to get wheel speed up without hitting and lifting front wheel or locking up to early and blowing tire away. Add weight gradually till it tries to lift front wheel..


work on one part at a time till you find a happy medium with the two stage as you won't be able to just throw it away... Good Luck....
 
Tried it out today but it will take more time since I only had three passes before eliminations. On the first run it had less the stock total weight on the static which resulted in a crappy 60ft because the static pressure was to low. The second pass was all stock springs and a nut, bolt and washer on three of the arms and fourth and fifth gear felt like it was slipping. The third pass was a little more static pressure and a washer was added to all three arms and it resulted in my best pass. During the eliminations I felt the clutch starting to let go in the upper gears so quite a bit of weight was added to the arms just hoping the clutch would hold up. It finally let go in the finals. Last year with four pounds of boost, a stock clutch, and stock shock it ran faster eighth mile times than its running now but Im working on improving that.


timeslip 003.jpg
 
It made 405, this is my second time at the track with a lockup and a re-valved shock its about double the hp of last year and still running slower in the eight than with four pounds of boost:rofl:. Im going to put the stock shock back on it and try that because Im having no luck with the new one...either the spring is to stiff or the valving is not correct. Hopefully going to a test and tune on friday so I can get more aggressive with the boost controller.
 
It's your bike and do what you want but when testing here is what I do. Work one part at a time till its right then move to next one. You then know what affects the bike. Change three things on bike at once, which helped, which didnt?
 
I agree 100% with you about making one change at a time which is what I did today with the lockup only. The re-valved shock is not working for me and its already been sent back twice and both times it came back it was just to stiff for me. Last year it was running about a tenth and a half quicker 60ft with the stock shock so I just put it back on and will try it out at an actual test and tune so I wont get just a few passes then run eliminations.
 
He means that you are changing static pressure and throwing weight on the arms at the same time.

Which one helped? Or did one help a lot and the other hurt a little? You don't know, because you did more than one thing.
 
I ran a 2 stage lock up all last year. I would 1.38 60ft with it. You can set it up to through it but not as good as a multistage. Use soft static springs with no shims and no weight on the arms. work on getting the bike to launch first. You need to either datalog or use a gopro camera to watch your rpms during launch. Your rpms should drop no more than 1000-1300 or so during launch. If they drop more than that, add a shim to the springs. Start off with 50 thousandths shim. Once you get the bike to 60ft consistantly( 1.40-1.45), then start to add weight to the arms. Add equal weight to all the arms...not just 3 of them. Its not a multistage. Any change that you make, do it equally on all the arms or the springs. Changes to half the arms or springs are used for fine tuning. You are not there yet.

Dont forget that you only need a decent front half on a turbo bike. You make your money on the back half.
 
I just saw your video. Your rpms are dropping way too much on the launch. This could be because of gearing, the clutch, or you not going full throttle early enough. Do you have a boost controller? 405 hp may be to much to launch with. Turn the boost all the way down in every gear until you get the clutch right. There's no need to add boost until the clutch is right. Youre just gonna eat clutches. Your bike isnt trying to wheelie at all on the launch. This tells me that you can be alittle more aggressive. Add shims to the springs and it should be more aggressive on the launch. This will also stop your rpms from dropping so much.
 
Thanks for the good info, the bike has a boost controller. Im trying to do to many things at once and all that's getting accomplished is burnt clutches, also having rear shock issues which makes the whole situation worse. When the 2 stage was purchased my plans were to run about ten pounds of boost but over the winter I decided to get pistons and rods while the motor was apart. In the video it was bogging down in first gear pretty bad because of to much weight on the arms...if that much weight is not on the arms it wants to burn through the clutches on the back half. So far Im not even close to finding a happy medium. In the process now of buying a multistage.
 
Went back to the track today and ran my best time so far, the stock shock was reinstalled and I was leaving around 5000rpm because the front end would not stay down. In fifth gear the clutch started noticeably slipping. I red lit in the semis so decided to see what it would run. The shock and clutch are so far from where they should be but it will get better with time.

852 008.jpg
 
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