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One last thought on clutch plates

  • Thread starter Thread starter lecroy
  • Start date Start date
L

lecroy

Guest
This is for Ryan, but I figured I would toss it to the wolves and see if I get bit.

I switched from a 2-stage to a multi-stage clutch and doubt I will ever look back. Ryan is running a modified Busa multi-stage in his for now as well. He mentioned once (I can't find the original post because we covered this subject so many times) that I think what happened was the bikes reaction would slow over the course of the day. The next day racing things would be back to normal and everything was good. Seems like someone told him that the wrong springs were installed. I doubt I had any ideas at the time.

So Ryan, after all this time I was thinking about your little problem. Here is my thought.

I know your running a GS1100 engine same as me. So I took some ball park numbers from my setup.

The total height of the hub is 2.4"
Total stack height is about 1.780"
Steel plate is about 0.078"
Fiber plate is about 0.119"
Fiber substrait is about 0.070"

I use 9 fibers and 9 steels.

Fibers are from FBG and use an aluminum substrait.

Hub assembly is aluminum as well, so plate substraits and hub will have around
the same temperature coefficent.

So say 9 X 0.070 = 0.63" of aluminum
And 9 X 0.078 = 0.702" of steel

The growth is calculated using:
Delta L / L = temp coef X delta T

temp. coef. for Alum is about 23 X 10-6 / deg C.
temp. coef. for Steel is about 13 X 10-6 / deg C.

Say our engine cold is 30C and once we start making round robin passes at
the end of the meet we are up to 100C or a gain of 70C.

So 0.63 * 23 10-6 * 70 = 0.001" of gain in the pack due to aluminum.
and
0.702 * 13 X 10-6 * 70 = 0.0006" of gain in the pack due to steel.

This is a total growth of around 0.0016" which is wanting to add more load to
the pack.

However the hub is made of aluminum and will grow also. It has a total lenth
of about 2.4"

So 2.4 * 23 10-6 * 70 = 0.0032" which is more than the pack. So it actually
lost about 0.0016" which will reduce static load on the pack.

If you used APE or Barnett plates they have a steel substrait which will
aggravate this problem. Maybe 0.003" or so.

From working on my own bikes and that little RD of the kids, this sort of change could have a major effect. I just wonder if this is what your running into.
 
I kind of ignored the wrong springs comment. I'm guessing that came from someone who services the clutch every pass. Trying to run the same static from the first pass of the day to the last is where I have problems.

For me first pass of the day i ride up do a burnout, do a dry hop, and leave at 7800 rpm. clutch hits hard and jerks it out of the beam. Oh in fact I have a video. This is Saturday first pass didn't heat the clutch up enough to get it to leave right. Bad video, but you can hear it. My dad shot it for me.
http://media.putfile.com/clutch-25

This is a first pass at indy. you can hear it if you listen. Slight dip as the lockup comes in. Exact same clutch setup just more heat from riding it up to the starting line. 7800 lauch with a dry hop.
http://media.putfile.com/clutch2


Second pass of the day. Push it up, do the burnout, and leave at 7800 with no dry hop. clutch doesn't jerk so hard. Saturday the second pass it lifted and carried the tire out nice. No bog like the first pass

When they start hot lapping us I'll drop 100 rpm each pass from the 2-step and push it into the burnout box to keep the heat out of the clutch. Reaction time starts to slow down as I don't get the jerk as the clutch hits. if I don't take the rpm out the bike leaves real lazy. Doesn't pick up the front tire till the lockup comes in. had the 60' go from low 1.30's to 1.40. This is why I really want to try a slider. Tired of fighting with this lockup. With that said the multi stage is way better than the 2-stage. Will probably sell it on ebay. This winters project. http://cgi.ebay.com/ebaymotors/ws/e...m=130030114690&ih=003&sspagename=STRK:MEWA:IT

I've changed my combination alot. Tried all different static pressure. Too light on the static and I've actually seen the shift light before the lockup comes in.

Started editing the video. now the hard part of what gets left out.
 
Last edited:
Good to hear I am not the only one that flys in the face of advice.

What your saying makes sence. If I were to guess, I think taking out a few thou. of gap would help. The reason I say this is because the angle of the arm would not change as much as the hub grows, so the leverage point would remain more constant.

So, I guess I am saying that the 0.125 number is too much. Set the gap closer to 0.1 and see what you come up with. Er, I guess it maybe too late to try this now.

Now that I have a base line for mine, I called Kevin and asked about a shim kit but they have nothing. So, I am back to making my own. I have a 0.040 shim in there now and its not quite enough and I see a major drift in the 60 and clutch slip from run to run. I think 0.050 - 0.060 is the ticket for my setup.

I saw that slider out there. It looks like its in real good condition.

Ok, just a little advice for what it's worth. Send the hat in and have them install the larger studs (just to play it safe). The next problem is that you need, or at least we use custom tools to set these up. One tool is used to tighten the nuts without moving the tensioner. It looks sort of like a T handle wrench that fits in a long cylinder. The second tool has a micrometer built in that is used to set the stackup. This will at least get you to where you can play with it. Next, you need to get hooked up with someone that knows what the hub gap needs to be set at. We have a lot of shims to set this and it is more sloppy than stock. I have seen us knock off that little tit more than once.

I have heard of nightmares people have had trying to get these to work for them. I really don't know because it was all figured out before I ever saw one. When team Green converted, Tony set his up after they damaged the first unit. I could get you some numbers to try, but to be frank we don't have anything real close to your setup. The kids bike is the closest.

That said, with the kids bike there has not been any clutch problems but it has a small tire. The Suzuki car tire bikes on the other hand seem to need constant attention. Mostly broken plates. We blame this on the riders doing hops after the burnouts.

I think once you get it setup right, your going to find little drift in your 60's.

Looking forward to the video.
 
Listened to the two videos. It's stange if the engine was at the same temp, cold, that you would see that much difference. I would have expected Indy to bog just because of track prep. This is where the trusty logger comes in.

You have the buttons installed don't you?
 
yes buttons are installed. I think the slip I was getting at Indy was due to the heat in the clutch from riding it thru the pits to get to the starting line. We were pitted in the shutdown area way off to the side. Engine temp is about the same. or so says my hand on the side of the head.

Now I need a crank with an 1100 gear. or get mine changed over.
 
Yep, she's 18mm. I couldn't tell.


You can have one changed, but the prices are a little high now. For some reason I am thinking that the gear was a couple hundred now.

I thought you had a couple of cranks laying around?
 
I have 3 laying around. I may call GRC and see how much were talking to get a fresh one done. I could sell the crank in the bike now to recoup some of the cost. Only has one season on it since GRC did it.
 
Three?

Well, if the wife shoots me over this one, I can will it to you.

Hey, what do you plan to use as a button to go with that slider? I am still cleaning out my basement (like it ever ends?) and found one of Bruce's switches. This is supposed to be one of those ultimate killer buttons. Of course you need the shaved custom gloves to go with it that have the softer leather in the thumb area so you can "feel" the tension......

It was on my bike when I bought the chassis. I think Greg was using it when he was the terror of Osceola.

http://www.powerbysauer.com/products.htm

Anyway, if your interested in it, I will swap you for a couple of DVDs once your done editing.
 
I think its his alter ego account under his kids name. I wish I knew how many runs it had on it and how many times it has been apart. I could not get an answer from them on this. A brand new one with knife rods is around $3000. I think it's a little on the high side for the age without more details.

Good luck.
 
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