Multi stage lock up help, please!

[chunk1340]

I am using a MTC multi stage lock up on a stock motor. I am running 1.6 60’s launching at 7500rpm with a launch controller. Prior to fitting the lock up I ran a best of 1.47 60’ launching at around 6500 with no launch controller. I only changed to the lock up for consistency and as I will be fitting the turbo in a few weeks.
I seem unable to reduce the sixty foots with the new clutch set up. The bike will either wheelie as it is just out of the gate, or start to wheelie at approx 60 feet out. The trace on my logger show that the rpm rises to around 9,000rpm after I dump the clutch, rpm dips slightly and then rise to the limiter, drop and then rise to the limiter again before dropping and this where I believe I get real traction, bringing the front up. All of this is on full throttle.

I have messed about with more base, more/less weight on the arms etc. I have tuned a multi stage clutch before but this has me a little stumped. I believe I need more base to stop it flaring through the clutch. Any ideas?

I am also making a few chassis mods to try and stop the wheelies/wheel stands.

Pic below shows the point of "real" traction!

 

[Wayneovich]

Hmmm sounds like things are going to get nasty with that turbo. That pic is badass got a highires version hopefully those chassis mods will calm it

 

[Shaft]

nice bada$$ pic, I want a high res one too. Good luck on the mods. You're in for a treat with that turbo.

 

[Draco1340]

Can you post your log files. Might be able to help you then. Are you also logging boost?
What is the spring / weight setup for each of the stages.
Have you measured your base preload.

 

[chunk1340]

I will get the data and post it later. Thanks for the reply.

 

[chunk1340]

Can you post your log files. Might be able to help you then. Are you also logging boost?
What is the spring / weight setup for each of the stages.
Have you measured your base preload.

Hi Draco

The setup is as follows:

Stack height: 49.6mm
Installed spring height:28.3mm
MTC soft springs (34.5mm length uncompressed)
Turret springs are #10, #17 and #21 on opposing arms (setup as per previous owner)
Weight on arms is 8gms on #10 and #17 springs and 6.2gms on #21 springs.

Looking at this clutch data I think I know what to try next but I will appreciate your input.

Log file pic attached, hope its clear. Was full throttle launch and I kept it pinned. Throttle position isnt logged as output is utilised for another function. I short shifted 1st to 2nd during wheelie.

No boost logged as I dont have the turbo fitted yet. Thanks.

 

[Ludicrous Speed]

That seems like a strange combo of springs and weights to me, but I am not really well-versed with lockups.

Three different springs on the arms?

 

[Draco1340]

Nothing can substitute for professional expertise, so contacting the folks at MTC for clutch support is always a good idea, but my .02 as follows. Your datalogger shows you burning the clutch for 2.3 seconds before it locks and pops you up. Ouch. Its taking way to long to lock up, and when it does its doing it violently. 1.1 to 1.3 seconds to get the clutch to lock is a better target for a streetbike to shoot for, and a smooth lock transition, but first things first.

First get your static set. I would recomend adding more static until the chassis cant handle the hit when you throw it away. Once the bike starts to come up or blow the tire 10 feet out, then back off the static. These first ten feet will give you the biggest impact on your 60 ft. Remember that that static will only work for a given pack hight. 49 mm seems a little thin, but the important thing is to measure it, and then come up with some combination of plates and fibers that gives you that same hight every time you rebuild it. Guys who are very serious measure the exact hight for each new pack and measure each spring at its compressed hight and shim them to get the exact same static load. I'm a hack, so I just try to get the pack hight close.

With the new static values set, only then can you sort out the next 100 ft. Obviously the lower spring numbers come in first, the higher spring numbers later. Those spring numbers seem high to me, but I'm probably wrong...

Lets look at it again after you get the launch working. One more thing. You may want to go through that clutch pack and rebuild or replace. That log indicates a bit of abuse.
Tom

 

[chunk1340]

Nothing can substitute for professional expertise, so contacting the folks at MTC for clutch support is always a good idea, but my .02 as follows. Your datalogger shows you burning the clutch for 2.3 seconds before it locks and pops you up. Ouch. Its taking way to long to lock up, and when it does its doing it violently. 1.1 to 1.3 seconds to get the clutch to lock is a better target for a streetbike to shoot for, and a smooth lock transition, but first things first.

First get your static set. I would recomend adding more static until the chassis cant handle the hit when you throw it away. Once the bike starts to come up or blow the tire 10 feet out, then back off the static. These first ten feet will give you the biggest impact on your 60 ft. Remember that that static will only work for a given pack hight. 49 mm seems a little thin, but the important thing is to measure it, and then come up with some combination of plates and fibers that gives you that same hight every time you rebuild it. Guys who are very serious measure the exact hight for each new pack and measure each spring at its compressed hight and shim them to get the exact same static load. I'm a hack, so I just try to get the pack hight close.

With the new static values set, only then can you sort out the next 100 ft. Obviously the lower spring numbers come in first, the higher spring numbers later. Those spring numbers seem high to me, but I'm probably wrong...

Lets look at it again after you get the launch working. One more thing. You may want to go through that clutch pack and rebuild or replace. That log indicates a bit of abuse.
Tom

Thanks Tom

I was thinking that the pack height was low and as such was reducing the installed spring pressure too. I intend to go to 51mm and go from there, I agree that the first 100 foot is the most important to get right, the rest just follows on.

I check the pack after each run, where possible. After the Quarter finals we generally get turned around quickly, so there is often not too much time.

Thanks for you advice. Martin.