Lock Out/Lock-Up Tuning

[SlowerThanYou]

I have a? regaurding lock up arm clearance to the plate. What effect does this have on the clutch tune? Do you just shoot for a certain arm angle when applied for max pressure applied. I think the way to adjust it would only be by changing stack height but i might be wrong. I fully understand changing height will change base pressure.this is refering to a standard direct drive style.

 

I thought a similar question was asked a while ago about the same subject.

 

First, you need a minimum clearance this is usually around .100". If you don't have the min. clearance your clutch will not disengage when the clutch lever is pulled in.

 

Maximum clearance, I wouldn't stray to far from your min. clearance! Maybe .020-.040 max. If the max clearance is too much. The arms will not apply enough pressure to lock-up the clutch.

 

IMO, worry about the basics above.

 

We actually change our arm air gap with the clutch stack hieght & machining of clutch components. I consider this stuff for very fine clutch tuning. We have 2 settings we shoot for depending on the class of racing we are doing. Other than that, it's just something that's checked during maintenance/inspection.

[SlowerThanYou]

Here's how we measure our arm air gap. It's basically the same way you guys can measure yours, but you have to make sure your arms a parrallel to the pressure plate.

[Joejr915]

What the best way to measure the height of the spring? To get rhe installed height. Also what a good starting point on base presure of all the springs together? 240lb of spring pressure for 421 cub

[SlowerThanYou]

 

What the best way to measure the height of the spring? To get rhe installed height. Also what a good starting point on base presure of all the springs together? 240lb of spring pressure for 421 cub

 

This is best done with the clutch pack out of the motor. It can be done with it in, but it's a little more difficult. I will have to make 3 or 4 posts to get all the pics needed.

 

Below is a piece of tubing I cut on the lathe to set length.

 

[SlowerThanYou]

Here's the tube installed in the clutch pack.

 

[SlowerThanYou]

Here I'm using the depth gauge of the calipers to measure. You must subtract the distance from the top of the tube to the top of the inner hub stand to get dimension #1 of the installed hieght.

 

 

[SlowerThanYou]

Lastly, you have to measure the spring seat hieght on the lock-up, dimension #2. To get your spring installed hieght, add dimension #1 & #2 = installed height. 

 

 

[SlowerThanYou]

Also what a good starting point on base presure of all the springs together? 240lb of spring pressure for 421 cub

 

That's one of the most sought out questions for clutch tuning. I'm sharing a good amount of information on the subject as is. Right now, I choose not to give out baseline information.

[trickedcarbine]

Pretty fair of you Slow. I find the amount of info you have posted to be super helpful and I think it is done in a way that gives the knowledge to start and experimenting with your own set up to find what works. It is good that you leave out specific baselines out so that it makes people have to take the knowledge posted and apply it to actually learn their own bikes.

[SlowerThanYou]

OK, my next subject was going to be a launch limiter. Another post got started about an adjustable switch clutch lever used to activate the limiter. I thought it was needed for this subject in this thread.

 

 

I am looking to use a MPS or pingle adjustable switch clutch lever with a drl-300 and wanted to know if anyone has used this before and if so where is a good starting point on making the adjustments on the lever.  My goal is to get better and have more consistency with my 60' time. Any pointers or suggestions would be appreciated. Thanks

 

 

I was debating on replying to this thread or not, but I will not give up all the pieces of the puzzle. 

 

1st, you made the right choice to go with the adjustable switch clutch lever. Of course you need the switch adjusted to activate the launch rpm when the clutch lever is pulled in. That's the easy portion of adjusting the switch.

 

The harder part is the timing of the switch to deactivate the launch limiter. The timing of the switch deactivating plays an affect on 60' times. If it's totally out of whack it can cause a bog also.

 

We have a certain way of setting ours up & it works for our clutch set-up. The switch deactivation needs to be set-up/tuned for your combination.

 

There are some other tricks that can be done to the clutch lever for tuning purposes also. I choose not to share them at this time.

 

As for the rest of the above information. I was getting ready to post this in the Lock-up/lock-out tuning thread with the launch limiter subject.

 

 

Thanks Bryan for the reply.

I will hold off on the 2 step until I get my 60' to where I want it to be, once there I will add the 2 step in to my set up. I want to get a handle on my clutch set up before I go chasing my tail if the 2 step might be bring up other issues at the same time. Thanks again

 

 

I know it's a lot to process starting out with the clutch tuning thing. I was the same way when I started & it seemed overwhelming at times. Now it seems so easy for me & it does get easier.

 

IMO, I think you will chase your tail more on the clutch set-up without the launch limiter.

 

I'm a little worried about the drl-3000, it looks as if you can only adjust the rpm in 1,000 increments. You need to have something with a finer adjustment. You might want to check into that.

 

If you want PM me & I give you my cell # to talk this thru. The best option is to do this all at once!

[SlowerThanYou]

Sorry, been pretty busy with stuff & this topic got a little neglected. Reading an article in National Dragster today; "How to make key adjustments to a drag racing clutch." It talked a little about launch rpm.

 

Launch rpm, IMO the best way is with a launch limiter. It can be done with other things also. To me this needs to be added whenever getting serious about clutch tuning. It's considered another adjustment mechanism in the clutch tuning department.

 

Changing the rpm even 100 rpm can change the way the clutch acts on the launch. A lower rpm tends to load the clutch more & make it slip more than desired at the launch. A higher rpm tends tighten or slip less than desired at the launch.

 

How does this help at the hill, 300' or the track. It allows for an easy clutch adjustment using rpm & not have to change the lock-up set-up.

 

Note to myself for next subject on launch rpm, rotating inertia.

[SlowerThanYou]

I finally found the link for my spring tester with a little help from yamahaman126.

 

http://www.powerhouseproducts.com/ph/valve-train-tools/valve-spring-tools-page-2.html

[SlowerThanYou]

now normally i could careless about your clutch tuning thread or any other thread your in.

 

Seeing one of my good fans brought this up, LOL! I decided to bring it to the top with a little more information.

 

Note to myself for next subject on launch rpm, rotating inertia.

 

Besides leaving off with the clutch spring testing tool. The last item I shared was launch rpm/limiter rpm & how it can make minor changes to the clutch.

 

I was debating on even talking about the inertia subject. I'm not really smart on all the laws of physics, but I try to study them & apply them to racing.

 

We like to control our launch rpm for the clutch tune, but also for the stored inertia/energy. The rotational energy of the flywheel, parts of the clutch & the motor. Can be used to tune your launch & also applies in other areas down track. We will keep it to the launch/60'.

 

The spinning weight of all 3 items can be controlled a couple different ways & probably more. With rpm & changing the weight of the spinning items.

 

In most situations raising the rpm launch point will initially hit the tires harder/violently. The opposite will happen for lowering the rpm.

 

You can also adjust this with changing the weight of the rotational items. Let's take the Banshee flywheel as an example. People/builder's lighten these all the time. What happens when you do that is many different things, but for the launch. It lessens the hit at the drop of the clutch lever. You could actually increase the weight & increase the hit also. Yamaha & other's make mods for the 4 strokes to do that.

 

While directly/indirectly related to clutch/lock-up/lock-out tuning. It does play a factor on how your quad launches/60's.

 

[SlowerThanYou]

Note to self about primary gear ratio affecting clutch set-up.

 

We really got caught off guard with the primary gear ratio affecting our clutch set-up. I knew it would change our set-up, but I didn't figure this much. Anyway, our new primary ratio is a 2.54. We chose this for 1/4 mile primarily. We have ran 2.68s when we 1st started in 2005 & then switched to 2.86s around 07.

 

It's hard to find information on primary ratio changes affecting clutch basket speed. Most that I have talked with says going from a 2.86 to 2.68 to 2.54 etc. speeds the basket speed up. I agree with that, but a few say it slows it down. Also, in my studies I found that there's less torque being seen by the clutch, because of the change. That worries me & I found some of these results in our 1st track outing.

 

The 1st thing we noticed was the motor wanting to bog at the drop of the clutch lever. No big deal, I'll just take some base pressure out. Well, I kept taking & still haven't found the sweet spot yet. We were at a point of 40+ lbs. less base pressure than we ran on our Cub.

 

2nd thing we noticed was the motor rpms being pulled down 20'-30' out. The arm weights were coming in to fast.

 

While we made changes in the right direction on both areas, it was not enough.

 

The last part of the evaluation was inspecting the clutch pack after getting home. It can tell you your clutch tune-up; kind of like reading your spark plugs. There was not enough heat in the steels for it to even show. The type of hot lapping we were doing should have shown a slight brown discoloration, but nothing.

 

For me, this last information along with the above info. Gave me a pretty good insight to what the clutch was doing & really what it wasn't doing.

 

Note for myself: clutch changes made & reading the clutch pack.

[sprinklerman]

The last part of the evaluation was inspecting the clutch pack after getting home. It can tell you your clutch tune-up; kind of like reading your spark plugs. There was not enough heat in the steels for it to even show. The type of hot lapping we were doing should have shown a slight brown discoloration, but nothing.

 

For me, this last information along with the above info. Gave me a pretty good insight to what the clutch was doing & really what it wasn't doing.

 

Note for myself: clutch changes made & reading the clutch pack.

Not to derail your thought process, but im in for some of your thoughts on "reading the clutch pack". I looked at one of our clutch packs friday and noticed a significant amount of heat concentrated in the steels in the center of the clutch pack. Also the heat was concentrated along the outer ring/edges of each steel that showed heat. Upon further inspection, the steels affected that way were warped,,actually they were cupped if that makes any sense.

   Thoughts on that?