Clutch Questions

[Blake_DFSAE]

Hi, I was just wondering what sort of clutches you folks use.

I've been thinking about it and with a huge contact patch in comparison to a bike as well as grippier tires that a bike clutch would smoke out almost immediately with a good, hard launch.

Am I right in thinking this? I'm finding it somewhat tougth to get empirical data on alot of this stuff because we don't have the measurement equipment at our disposal as some teams do. That and our engine isn't running at the moment.

And let me know if I'm asking too much - I see alot of new teams like ours are using this board a bit too much and asking for almost complete designs, and I don't think that's what this place is about.

Thanks all,

Blake

[Blake_DFSAE]

Hi, I was just wondering what sort of clutches you folks use.

I've been thinking about it and with a huge contact patch in comparison to a bike as well as grippier tires that a bike clutch would smoke out almost immediately with a good, hard launch.

Am I right in thinking this? I'm finding it somewhat tougth to get empirical data on alot of this stuff because we don't have the measurement equipment at our disposal as some teams do. That and our engine isn't running at the moment.

And let me know if I'm asking too much - I see alot of new teams like ours are using this board a bit too much and asking for almost complete designs, and I don't think that's what this place is about.

Thanks all,

Blake

[KU_Racing]

stock f4i clutch, built into the tranny housing. remember, our clutches dont have to last as long as a bike clutch, and a stock bike clutch is a multi-plate wet clutch, probably the toughest design there is short of a multi disc carbon-carbon f1 unit.

[UTA racer rikki]

Blake,

I echo KU here. We have used stock clutches on almost all of our cars, to my knowledge. The only exception may be the 250's we ran in '98 and '99. If there is any question to the durability, we have launched at 1 g on the wonderful Topeka, Kansas Nationals Concrete and the clutches continue to work great!

[Erich Ohlde]

same here. stock f4i clutch. Contact patch size doesn't really matter here because the motor is still barely putting out stock torque numbers (unless you go turbo, then i dunno what the torque numbers are). but on the 600s (all i have experience with) go with the stock clutch

[Nick McNaughton]

If you get the launch right, the heat load on the clutch is huge. Yet they survive...

The worst we've done to a clutch was during repeated launch control testing, despite giving it ~20 seconds to cool down. When we pulled the engine down the steel plates were slightly discoloured in some places from the contact points on the friction plates. We've not had issues with slippage or heat related fade, despite what we try and do to it.

[VFR750R]

Motorcycles have more weight transfer and are geared higher...both harder on clutch. My VFR averages 1.15g's to the 60ft mark slipping the clutch the whole way.

On the dyno is another thing, we've burned up plenty of clutches there.

[Erich Ohlde]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Nick McNaughton:
If you get the launch right, the heat load on the clutch is huge. Yet they survive...

The worst we've done to a clutch was during repeated launch control testing, despite giving it ~20 seconds to cool down. When we pulled the engine down the steel plates were slightly discoloured in some places from the contact points on the friction plates. We've not had issues with slippage or heat related fade, despite what we try and do to it. </div></BLOCKQUOTE>

Same here, we checked all our clutches back to 03 and they all have the discoloration, but zero slippage or heat fade

[nick roberts]

Like Erich said we have torn down several engines in the past and all of the clutch plates that had any extended FSAE use were discolored. In the worse case we saw, the plates were almost solid with heat dicoloration. The only thing we noticed with that car was a little more clutch drag when it was disengaged due(we think) to the plates actually warping and putting pressure on the clutch discs...However, as long as you dont completely tear on the clutch from sloppy launches all day long, you should be fine.

By the way...I just thought of something...we use a CO2 shift/clutch setup so on a typical launch we dont slip the clutch as much as some of you might...Just thought id add that for clarification. I wouldnt think you would be in much danger as long as you take care of the clutch.

-nick roberts

[twpvw5]

Here at the University of Missouri we have never had any problems with clutches, i.e. slipping or fade. I've had the clutch pack out of nearly every car we have and there is no discoloration or signs of un-due wear.

[VFR750R]

Someone doesn't make any power http://fsae.com/groupee_common/emoticons/icon_wink.gif

[Jersey Tom]

Ouch.. burn...

Not like we make any power either.. in an effort to save weight we decided to drop the F4i and power our car with mouse traps and rubber bands

[KU_Racing]

Tom.. you stole my idea. Ass.
I checked our clutch from last year. No discoloration, since the plates are aluminum, but they definately showed massive wear- im not a drivetrain guy, but i would guess that they were about halfway to the point of uselessness.

[twpvw5]

Hey it's fine that we "don't make any power" or maybe we just know how to drive http://fsae.com/groupee_common/emoticons/icon_wink.gif

[B.K.]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VFR750R:
Someone doesn't make any power http://fsae.com/groupee_common/emoticons/icon_wink.gif </div></BLOCKQUOTE>

God, those Cornell guys are DICKS.

[Erich Ohlde]

I'd just like to let everyone know that KURacing, is NOT a member of KU, his school is Kettering. Didn't want anyone getting confused

[KU_Racing]

I see how it is. Didnt want anyone assoiciating me with Kansas eh. lol.

[Erich Ohlde]

pretty much http://fsae.com/groupee_common/emoticons/icon_wink.gif

[KU_Racing]

ouch... what did I do?

[Erich Ohlde]

lol

[Blake_DFSAE]

Thanks for the help all, really appreciate it.

Although I'm still quite surprised a stock clutch can handle a two racing slick launch. That's pretty awesome.

[VFR750R]

The point is, a two racing slick launch (applies to low CG FSAE cars only obviously) actually isn't all that much to handle.

[RonBurgundy01]

We took the restrictor off our car and replaced it with the standard 4 Carb system of the CBR 600 then took the machine to a local drag meet.

After 3 launches at a good rev range all that would happen was the rear wheels would smoke up half way down the track, so as for the clutch being an issue, i'd have to say no.

This is not a process i would like to undertake on a repeated basis though!!

[murpia]

Generally, a good launch will minimise clutch slip. You want to fully engage the clutch with just enough torque to be traction limited in your launch gear (of course this depends on your torque curve following a typical shape).

Simulating the process and plotting tractive force against time and or distance is very useful, and not too difficult. There is an earlier thread on this...

Also, has anyone measured the clutch slip torque as a function of release travel for a typical wet-plate moto clutch? Or found this online? It's conceivable this is highly non linear which a) invalidates what I just said above and b) should help you further optimise final drive ratio for launch.

Regards, Ian

[KU_Racing]

Ron Burgundy is down and it is NOT good!!!

you put the stock carbs on a cbr in ur FSAE Car?!? You totally did what I have wanted to do for awhile. If you dont mind me askin, how did the car run?

[UTA racer rikki]

Just another side note.

DON'T let the guys who are practicing for acceleration run fifteen or sixteen of these in a row without letting the clutch cool down. You WILL have a problem then. Just remembered a nightmarish day when I heard someone practicing launches over the phone. The same person was still practicing launches 5-10 minutes later when I showed up at the practice track. No cool downs between runs. He would launch back and forth from one side to the other. One would think a team with experience wouldn't let this happen, but apparently we all have to make easily avoidable mistakes sometime. http://fsae.com/groupee_common/emoticons/icon_razz.gif

[KevinD]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">One would think a team with experience wouldn't let this happen, but apparently we all have to make easily avoidable mistakes sometime. http://fsae.com/groupee_common/emoticons/icon_razz.gif </div></BLOCKQUOTE>

thats the understatement of the century erick http://fsae.com/groupee_common/emoticons/icon_wink.gif