Author Topic: Motorcycle cush drive q's  (Read 9212 times)

0 Members and 1 Guest are viewing this topic.

Offline Vishnuatepork

  • Full Member
  • ***
  • Posts: 79
Motorcycle cush drive q's
« on: February 16, 2011, 11:51:12 PM »
  To all the motorcycle rider;

I am looking at shaving weight off my Land speed bike.
Re cap;
Shaft driven Suzuki VX800,
liquid cooled V twin
custom pistons
custom ignition,
custom rods,
custom drive shaft and drive hub,
shrink ported heads,
36cv to 41fcr carbs,
SS exhaust with super trapp exhaust

So here my dillema....

The stock rear wheel is about 25#
I have found a light weight front wheel (3.5" as it dont want to mod the swing arm, the swing arm houses the drive shaft).
It has the same bolt pattern as the drive splines. With minimal fabrication it should fit. 
It doesnt have any cush drive.

What does the cush drive do, and is it possible to run without it?  The wheels are from a `08 gsxr 600 and I figure (crude math not engineering numbers)from a race perspective, it sees as much force in deceleration as it would in acceleration (375# decelerating from 260kph in race form vs the acceleration of 475# with 70hp).

The bike when all said and done wont have massive power  ~ 70hp.

Cheers
Alan

suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline Vishnuatepork

  • Full Member
  • ***
  • Posts: 79
Re: Motorcycle cush drive q's
« Reply #1 on: February 17, 2011, 12:01:14 AM »
  To all the motorcycle riders;

I am looking at shaving weight off my Land speed bike.
Re cap;
Shaft driven Suzuki VX800,
liquid cooled V twin
custom pistons
custom ignition,
custom rods,
custom drive shaft and drive hub,
shrink ported heads,
36cv to 41fcr carbs,
SS exhaust with super trapp exhaust

So here my dilemma....

The stock rear wheel is about 25#
I have found a light weight front wheel (3.5" as it dont want to mod the swing arm, the swing arm houses the drive shaft). It weighs about 12.5#. So a 50% weight reduction.  I have heard that removing a pound from a wheel is like removing 2# from the chassis, true?
It has the same bolt pattern as the drive splines. With minimal fabrication it should fit. 
The wheel I found doesnt have any cush drive. The stock does.

What does the cush drive do, and is it possible to run without it?  The wheels are from a `08 gsxr 600 and I figure (crude math not engineering numbers)from a race perspective, it sees as much force in deceleration as it would in acceleration (375# decelerating from 260kph in race form vs the acceleration of 475# with 70hp).

The bike when all said and done wont have massive power  ~ 70hp.

Cheers
Alan


suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline Beairsto Racing

  • Full Member
  • ***
  • Posts: 257
Re: Motorcycle cush drive q's
« Reply #2 on: February 17, 2011, 12:19:25 AM »
Alan,

There are several aftermarket rim manufacturer's that do not even have a cush drive.

The argument for them is that they reduce shock loads from possibly damaging the transmission. Imagine on pavement, the rear wheel spinning and then in an instant, gaining traction...quite a jar.

No, I do not believe it will be an issue for you with @70hp and your plan to run on the salt. Remember, the salt can be slippery.

You have made quite a bit of progress on your VX800!  :cheers: Time to post some more pictures?
Good luck.

Cheers,
Scott
2 Club since '02
Sponsored by: Turple Bros.,
Palliser Chevrolet, Hose Headquarters, Bentley's Motosicle Pain Tin, The Window Man

Offline Vishnuatepork

  • Full Member
  • ***
  • Posts: 79
Re: Motorcycle cush drive q's
« Reply #3 on: February 17, 2011, 01:07:22 AM »
Scott,

I'll try to dig up some pics from the file.

I wont be running on the salt but on the tarmac, I'm headed down to Mojave. Prolly in Oct.

Thanks for the 411, I appreciate it.  I guess it boils down to what bolts I use?  Dont want them breaking!!!!!

Cheers
Alan
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline wobblywalrus

  • Hero Member
  • *****
  • Posts: 5503
Re: Motorcycle cush drive q's
« Reply #4 on: February 17, 2011, 10:55:29 PM »
The drive system from the crank to the rear wheel is designed to reliably convey an amount of power with some sort of safety factor.  We hop up the bikes and we are taking advantage of the added strength that is designed into the drive system.  Removing the dampers also introduces more loads into the system.  Shock loads.  This can be a problem for us that run a bike that is not commonly raced.  We do not know how much extra load the drive train can withstand without problems.

This is what I do.  I look at the advantages the change might give me, speed wise.  Then I look at the chances it will work.  I look at the cost of blowing the bike up because I overstressed something.  Last I look at my finances.  As much as possible I try to put some actual numbers to these four items.  Almost always, after systematically looking at things this way, I get an answer to my question.

An example.  Some folks recommend an ignition module for the Triumph with radical spark advance.  It might give me 3 to 5 mph, I estimate.  There is a 75% chance it will work, as a guess.  25 percent odds to fry the motor.  Triumph parts are very expensive.  Some racing parts I have I might not be able to replace.  They are not available.  My money is really low.  A blow up would put me out of the game.  The decision is easy.  The small gain is not worth the big risk.  No major spark advance angle.  I will work on something else, like aero.

I hope this helps.     

Offline Seldom Seen Slim

  • Nancy and me and the pit bike
  • Administrator
  • Hero Member
  • ***
  • Posts: 13158
  • Nancy -- 201.913 mph record on a production ZX15!
    • Nancy and Jon's personal website.
Re: Motorcycle cush drive q's
« Reply #5 on: February 18, 2011, 06:44:23 AM »
Weight can be your friend at Bville, although you probably won't be putting out so much horsepower that wheelspin will be an issue.  For the higher powered vehicles -- it's darn near universal to gain speed at the top end when weight is added.  For a personal instance - on my nitrous bike I gained about 6-7 mph when I put 70# of lead on the swingarm.  The back tire was (before) spinning up from too much power, and with the extra weight it didn't spin (well, didn't spin nearly as much).  Even on the short course - which you'll be running - you've got two miles before you even get to the beginning of the timed mile, and that, you hope, wil be enough to get you to top speed.
Jon E. Wennerberg
 a/k/a Seldom Seen Slim
 Skandia, Michigan
 (that's way up north)
2 Club member x2
Owner of landracing.com

Offline wobblywalrus

  • Hero Member
  • *****
  • Posts: 5503
Re: Motorcycle cush drive q's
« Reply #6 on: February 19, 2011, 02:51:16 AM »
Alan, rear wheel weight is a big deal in road racing.  A person is flipping the bike from side to side and braking and accelerating hard many times a lap.  The inertial and gyroscopic forces from a heavy wheel are a handicap.  That is the basis for saying light wheels are good.  A hefty rear wheel does not make much of a difference in LSR.  The cush drive does reduce shock loads on the drive train.  This is important in LSR and especially on pavement.

Usually I am very reluctant to trade off reliability unless there is a clear benefit.  Experience has shown me this.  Sometimes things do not go like planned and it takes a whole lotta runs to get everything working good enough to take home a record.  Lots of hard miles on the bike.  The rider gets tired and does shift, etc. just right.  Everything gets hammered pretty hard.  Reliability saves the day when this happens.         
 

Offline Vishnuatepork

  • Full Member
  • ***
  • Posts: 79
Re: Motorcycle cush drive q's
« Reply #7 on: February 20, 2011, 03:02:57 AM »
Hmmmm,

you guys make some compelling arguments either way.  I am going to go ahead with the wheel, more as an engineering exercise than anyhting.  On this project I have created alot of 1st time stuff like high comp pistons and custom maps for the ignition module etc.  IF I can get the wheel to fit, it'll be the coup de grace.  As for running it down the tarmac...who knows, If I can successfully shave a full 50 pounds off the bike, I may run with it, if its only 30...we'll see.  I am starting to add up all the parts added and all parts taken off,...I have to do some due diligence first as it will require some fabrication......

Cheers and Thanks.
Alan
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline Vishnuatepork

  • Full Member
  • ***
  • Posts: 79
Re: Motorcycle cush drive q's
« Reply #8 on: February 24, 2011, 03:51:23 AM »
Thanks for the advice,opinions and messages.

So I finally did the math, and it will fit but it wont work. 

On the stock Suzuki wheels the driven splines are recessed approx 3cm below the rim lip.  I am going to investigate the RC Components wheel sets as they do make some for the VS1400 intruder, but I know the hub width is wider......  So it looks slim. As well when I did talk to RC Components, they were none to helpful in identifying the lightest wheel in their offering.


I would like to run with my wheels inline, as stated in the rule book.......

Cheers
Alan
suzuki vx800, 41mm FCR, shrink ported head, mega cycle cam, singh grooved head, custom headers, Supertapp exhaust, Ignitech ignition module, vs1400 drive hub, nology coils, magnecor wires, 12:1 cp pistons, carillo rods

Offline John Noonan

  • Hero Member
  • *****
  • Posts: 3606
  • 306 200+ mph time slips. 252 mph on a dirtbike
Re: Motorcycle cush drive q's
« Reply #9 on: February 24, 2011, 05:18:51 PM »
Hmmmm,

you guys make some compelling arguments either way.  I am going to go ahead with the wheel, more as an engineering exercise than anyhting.  On this project I have created alot of 1st time stuff like high comp pistons and custom maps for the ignition module etc.  IF I can get the wheel to fit, it'll be the coup de grace.  As for running it down the tarmac...who knows, If I can successfully shave a full 50 pounds off the bike, I may run with it, if its only 30...we'll see.  I am starting to add up all the parts added and all parts taken off,...I have to do some due diligence first as it will require some fabrication......

Cheers and Thanks.
Alan


Do you know what "Coup de grace" means..?

Good luck with your Deathblow  :wink:

Offline johnneilson

  • Sr. Member
  • ****
  • Posts: 502
Re: Motorcycle cush drive q's
« Reply #10 on: February 24, 2011, 06:00:11 PM »
Hmmmm,

you guys make some compelling arguments either way.  I am going to go ahead with the wheel, more as an engineering exercise than anyhting.  On this project I have created alot of 1st time stuff like high comp pistons and custom maps for the ignition module etc.  IF I can get the wheel to fit, it'll be the coup de grace.  As for running it down the tarmac...who knows, If I can successfully shave a full 50 pounds off the bike, I may run with it, if its only 30...we'll see.  I am starting to add up all the parts added and all parts taken off,...I have to do some due diligence first as it will require some fabrication......

Cheers and Thanks.
Alan


Do you know what "Coup de grace" means..?

Good luck with your Deathblow  :wink:

Doesn't the crowd have to ask for "Mercy" first?
As Carroll Smith wrote; All Failures are Human in Origin.

Offline 4-barrel Mike

  • Hero Member
  • *****
  • Posts: 3173
  • Any fool can drive a V8
Re: Motorcycle cush drive q's
« Reply #11 on: February 24, 2011, 06:01:32 PM »
It's one of those fancy 2-door Cadillacs isn't it??   :mrgreen:

Mike
Mike Kelly - PROUD owner of the V4F that powered the #1931 VGC to a 82.803 mph record in 2008!