Another One...........

[Sumner]

   

Now I'm trying to find out who's car this is.  I can't remember where I got the picture from.  I don't think I took it.  I think I got if from someone's site.

I'm looking at different options to tension (take the slack out of) the chain on my lakester.  Anyone have any opinions.  So far I'm looking at an idler sprocket, nylon (or teflon) roller, and or nylon (or teflon) blocks/pads.  I think I'll set things up to maybe try all three.  I've heard good and bad about all of these methods.  The rear and the motor are fixed, so I have to do something.

Also any thoughts on chain type for speeds over 175.  I'm interested in hearing from anyone running chain drive, car or bike.  The chain I have right now is an EK530MVXZ that they they say is a SuperSport Quadra-X Ring Chain with lightening holes for heavy-duty OEM replacement & racing use.  It is an O-ring chain, which bothers me as I've heard stories of all the O-rings coming out.  Any Opinions (good time to shoot some arrows Slim) .

Looks like I should take a number of chains with me.  What about sprockets?  Do they hold up better than the chains?

BTW I have 'busa 530 sprokets on the 750 GSX-R motor.

Thanks for any input,

Sum

[Dean Los Angeles]

Chain is one of those things that we tend to overthink. It's a pretty simple horsepower transference device.

I would go with the idler sprocket. The teflon is just another disc brake. I know you have enough horsepower, but no sense giving anything away. Tension the chain up to get a lower wrap angle on the sprockets. Is the suspension going to change the length?

The smaller the sprocket the tighter the wrap angle and the greater friction and wear. I would run the largest sprockets you can fit on the engine. The chain has to be lubricated, and at high speeds centrifugal force cheerfully throws off all the lubrication in a hurry. I would put a chain oiler on it if you can contain the spray without leaking outside.

I wouldn't run more than once on a chain with the horsepower you have. It costs money but it's cheap insurance. Sprocket wear isn't an issue because of the short run time. If you are wearing the sprockets than you either have an alignment issue or the chain is too tight.

Having said all that, I would wait to hear from Rick Yacoucci. If he doesn't have the fastest chain on the planet who does?

[GeneF]

Thats a mini sprint set up in your pic. I used to race one and have some knowledge on their chain set up.
 
 In your application, I think a spring loaded chain roller or idler sprocket would be quite sufficient.

 A o-ring chain has inherent drag built in and I feel a well lubed std. chain sucks up less h.p. and is much cheaper.

 I never had much luck with the cir-clip type master links and prefered to rivet mine.
 
 In straight line racing, with a solid mounted diff., I don't think sprocket wear will be much of a issue
 
Do a search on scca sports racers and fsae formula cars, they all use a drive setup with m/c power like yours.

Hope this helps.

[hitz]

Sum,
 Idle spockets seem to work best. I prefer solid but adjustable on the return side of the chain.( the one with no load on it.)

  Bigger sprockets are always better for the chain as long as your ratio is right.

  On some of the old bikes with primary chains, a smaller sprocket at the crankshaft would make it harder to shift because it would slow the transmission down. It seed to be better by using a larger sprocket at the rear wheel when going up in ratio. When going up on ratio it seemed best to go bigger on the transmission output shaft.

  On your slack adjuster a bigger sprocket is better.

  Just my thoughts.  Harv

[hitz]

Sum, Mistake!!
  When going down on ratio you go bigger on the tranny sprocket.

  Harv

[bak189]

We have been using for many years with good success a nylon wheel off a skate-board (they have bearings)
mounted solid on the down side of the chain (no load side) The chain will wear a groove into it...and in time the wheel will need to be replaced....mount it close to the
rear-sprocket

[Sumner]

I really appreciate all the input here and hope I'll get more, especially what style chains you guys are running. Let me add some more fuel to the fire.  I was in the midst of making an idler sprocket for the bottom run when I got the following e-mail form Pete Moran, who is on the Isle of Man.  I hope he doesn't mind me sharing it as he has some really good observations based on his personal experiences.  His e-mail made me reconsider the path I was on and prompted me to start this post on the subject.

My next post below this one will be my thoughts, but for now here is Pete's excellent e-mail:

Hi fella, well done, I love the detail in you explanations and howl with delight at your methods.  I may be able to help with your chain idler, from experience learnt the only way - hard.  I race a supercharged 500cc single in drag and sprint, I built my chassis and modified or built every other  bit; the thing about powerful singles is the chain gives the tyre a massive kick followed by a long pause, whereas a 4 cylinder gives 4 smaller but evenly spaced kicks.  Here's what I learnt:

    Chains never snap on the top run ie the bit doing the pulling.  They
always snap feeding onto the bottom part of the sprocket and the reason why is the bottom run is slack, and develops a slight sideways waggle which can offer up to the sprocket on the chain plate rather than the roller and -Ping.  Then the end on the sprocket gets a vicious whiplash in the
direction of travel and flails off the top of the sprocket causing quite some damage, it can certainly cut steel.

    You must not run a tight chain.  It will not prevent that slack bottom
run and will maul the output bearing in the gearbox.

    As you are running a unit engine/gearbox it is sometimes easier to
picture the loads as the gearbox sprocket trying to wind in the rear of the
car along the top chain run, and design according

    Now, the tensioner.  Be very careful here, if you see a video of a chain
under full load you can see the bottom run is thrown off the drive sprocket
in a nice upward catenary fairly near the sprocket, then curves back to meet the rear sprocket.  Sense would suggest the tensioner should be above and near to the driver, and always on the bottom run.  Unfortunately the ideal position is not fixed and varies with revs, bumps and other minor variables. You cannot find the position, it will always be not quite right, and the problem is having the tensioner in the wrong position, because it imposes on the chains' natural harmonic and restricts it.  This sets off short duration unstable vibration, including the-to-be-avoided sideways waggle.  Further more, it is exceedingly difficult to engineer a mount for the tensioner that is exactly in line and vertical, to align with the rear sprocket.  Once more only consider a roller, never a sprocket for the job.

    Front and rear sprocket alignment must be as good as you can humanly
achieve, the point to particularly watch is the alignment of the bottom of
the rear, as this is where the chain must feed onto.  Looking at your
admirable chassis construction pics you shouldn't have a problem with
rigidity but visualize any possibility for that rear sprocket to deviate
from vertical, which is the obverse of the sideways waggle: the chain is
dead straight but the sprocket can move sideways, not loose mind, more a
slight rotation due to mount flexure.

    Always on the bottom run.  Tensioners on the top run deviate max pull
from the straight line and chew the chain, sap power, maul the gearbox
bearings, and expire too quick, no discussion I'm afraid.

    So they go on the bottom run.  Still not good, any change from full
power puts the bottom (slack) run into the driving run, as the rear wheel is
now trying to rev the engine, particularly on gear changes, and all the time
on engine braking; now all the problems mentioned above happen upside down, and a sideways waggle will throw the top run as it misfeeds onto the gearbox sprocket, as the top run is slack on engine braking.

    Seeing as how you can't tension the chain by moving the engine, or the
rear, you would have to be extremely lucky to get the chain length correct
for tension, so a tensioner it is.  It must be fixed, as a sprung loaded one
certainly takes up the slack, but again imposes restriction on the chains'
natural harmonic, and becomes dangerously slack on overrun, with too much loose chain wanging around the top on engine braking.

  My advice is to engineer a wide nylon roller, double bearing as wide as
feasible, on a substantial arm that you can swing up to take up the slack,
and lock off, and I mean lock off, with a separate strut rather than
tightening the pivot bolt, as my primary was always pushing the roller down on engine breaking until I strutted it.  Don't bother to profile the roller to the chains' width, it wont like it and prefers to find its own middle.
And finally install a 'catcher' about 3 inches above the middle of the rear
to catch the whiplash should she snap, or better still a top chain guard
that extends over the top half of the rear sprocket.  The roller will groove
over a few runs, don't let the grooves get deep as that means the rollers
are contacting the tensioner rather than the chain plates , as it rapidly
wears the chain, just swap the roller for a spare and reskim when you are
back in that excellent workshop of yours.  And all the very best, from over
the Atlantic, clean over Ireland, and straight into the middle of the Irish
sea _ The Isle of Man, where we appreciate original ideas and happily race
anything.

Sincerely

Pete Moran

c ya, Sum

[Sumner]

I would go with the idler sprocket. The teflon is just another disc brake. I know you have enough horsepower, but no sense giving anything away. Tension the chain up to get a lower wrap angle on the sprockets. Is the suspension going to change the length?

The smaller the sprocket the tighter the wrap angle and the greater friction and wear. I would run the largest sprockets you can fit on the engine. The chain has to be lubricated, and at high speeds centrifugal force cheerfully throws off all the lubrication in a hurry. I would put a chain oiler on it if you can contain the spray without leaking outside.

The rear is an IRS, so the rear sprocket is stationary (see the pictures).  I'll tension the chain from the bottom of the bottom run.  I'm confused about "Tension the chain up to get a lower wrap angle on the sprockets".  One thing is I'm really tight in this area and don't have a lot of options.

Thats a mini sprint set up in your pic. I used to race one and have some knowledge on their chain set up.....

.....A o-ring chain has inherent drag built in and I feel a well lubed std. chain sucks up less h.p. and is much cheaper.

 I never had much luck with the cir-clip type master links and prefered to rivet mine.
 
Do a search on scca sports racers and fsae formula cars, they all use a drive setup with m/c power like yours.

Hope this helps.

The mini sprint makes sense as I visited some of those sites.  Thanks for the info on the o-ring chain and the suggested links.  I found a couple good sites.  Neat cars.  I plan on running the rivet master link.  That is what came with the chain.

Sum,
 Idle spockets seem to work best. I prefer solid but adjustable on the return side of the chain.( the one with no load on it.)

  Bigger sprockets are always better for the chain as long as your ratio is right.

The rear sprocket I have should be good for a pretty good range of speeds with the different options I have for countershaft sprockets.

We have been using for many years with good success a nylon wheel off a skate-board (they have bearings)
mounted solid on the down side of the chain (no load side) The chain will wear a groove into it...and in time the wheel will need to be replaced....mount it close to the
rear-sprocket

Mike (ack attack) mentioned the skate-board/roller skate wheel to me the other day.  He also feels the idler sprocket like rick uses is a good option for me.  I think I'm going to set it up so I can use either of these.  I almost have the idler sprocket done (should be on my web pages in a couple days) and will work on making it so I can replace it with the skate wheels and try both.  I need to find some of those.  Do they come in "good" and "bad"?


 
This is a picture of what I have going on.  Not a lot of room to work with.  In this shot the chain is the slackest it will be and the tensioner as high as it will have to be.  If the chain was just a bit longer I could take out another link.  I worry a little about the angles coming down from the rear of the idler sprocket to the rear sprocket.

mount it close to the rear-sprocket

 
Is this too close to the rear sprocket?

   

I'm going to try running the car this way at first, but eventually I think I'll move the motor forward (I have about 2 feet in front of it now before the cockpit) and install a jack shaft between the motor and rear-end.  I think that will give me more options.

B.J. if you are reading this thanks for your help on the phone the other day .

[ack]

I would move the idler to the center of the chain run.  Does two things reduces the back bend of the chain and associated friction.  Second by moving it to the middle of the run you reduce the load on the idler bearing because the angle of the chain approach is much shallower.  As for chains if you use a high quality O ring chain I believe you will find them virtually trouble free.  When Jim True ran Jack's red car that Rick now has we used Diamond O ring chain and ran the whole season with the same chain. The idler was in the center of the run.  On our streamliner we run high quality O ring chain on the rear and it is virtually trouble free.  We've have run well over 200 high power dyno runs on the same chains.  I would follow the chain manufacturers recommendation as to chain wear limits and replace them at about half of the recommended service limit.

[Sumner]

I would move the idler to the center of the chain run.  Does two things reduces the back bend of the chain and associated friction.  Second by moving it to the middle of the run you reduce the load on the idler bearing because the angle of the chain approach is much shallower.  As for chains if you use a high quality O ring chain I believe you will find them virtually trouble free.  When Jim True ran Jack's red car that Rick now has we used Diamond O ring chain and ran the whole season with the same chain. The idler was in the center of the run.  On our streamliner we run high quality O ring chain on the rear and it is virtually trouble free.  We've have run well over 200 high power dyno runs on the same chains.  I would follow the chain manufacturers recommendation as to chain wear limits and replace them at about half of the recommended service limit.

 

Thanks for the input Mike and thanks for the time on the phone the other day .  In the picture above I moved it forward to almost the middle (I just have it wedged against a board for the picture).  That is about where I had planned on putting it before.  It is a couple inches further forward  than in the other pictures and will probably go about 1 more.  I set the motor up about the same distance from the rear sprocket as it would be in a bike, but now wish I would have gone further forward a little more, but I'll wait now until I decide to install the jack-shaft.  Like I mentioned in the other post this is the worst case position now as I'm close to the point where a link could come out and the idler moved down.

Ok you have me talked into the o-ring chain (what is in the pictures).  I plan on taking a couple chains with me though and also a nylon roller as a backup/substitute for the sprocket.

Hopefully this post will help out some other builders/potential builders also.  On the salt over the years I have not thought about a lot of things that I should have asked about and taken pictures of.  It was just last year I decided to go the bike motor route over a car motor and I hadn't been paying attention to the bike motored cars like I should have.

[Rex Schimmer]

Sum,
You should be able to get the skate board wheels on the net as there are a number of manufactures. They come in a number of ODs and most of them use a 5/16 inch shaft (it might be 8mm as there is only .002 inch difference). The 5/16 shaft should work if you make the mount so that the bolt is in double shear. The "good" wheels have the best bearings, most of them are shielded style and usually in the grade 5 or better area. The rubber,(plastic?) that they use for the wheel is very tough and should make have good wear characteristics , plus they should be a lot cheaper than making them. I used some on my "go cart" but never saw how they lasted as I couldn't keep the motor in it long enough! It's hanging on the wall in my shop now.

Having two sons that when through the skate board phase I have paid for lots of wheels.

Rex

[1212FBGS]

sum
don't waist your time with skate board wheels. been there done that. the material is too soft and will melt from the heat. our chains on the twin engine liner turn purple at speeds over 250 we finally went to a pressurized lube system for it. secondly the bearings are good for your mommas skate boards but wont take the loading and violent whipping action of a drive chain. we turned rollers out of delrin cuz it is harder than teflon and they seem to last 2 passes before we replace them. then we press in 4 hi speed un sealed bearings in the roller. I run RK 530 drag race"DR" chain it is the strongest (11,000 tensile strength) available. it has huge flat non dog boned side plates and doesn't stretch like light weight street bike chains. I use clip style links and never had a problem if ya install them correctly.

[Sumner]

sum
don't waist your time with skate board wheels. been there done that. the material is too soft and will melt from the heat. our chains on the twin engine liner turn purple at speeds over 250 we finally went to a pressurized lube system for it. secondly the bearings are good for your mommas skate boards but wont take the loading and violent whipping action of a drive chain. we turned rollers out of delrin cuz it is harder than teflon and they seem to last 2 passes before we replace them. then we press in 4 hi speed un sealed bearings in the roller. I run RK 530 drag race"DR" chain it is the strongest (11,000 tensile strength) available. it has huge flat non dog boned side plates and doesn't stretch like light weight street bike chains. I use clip style links and never had a problem if ya install them correctly.

Thanks Kent for sharing all of that.  I won't be over 250 for a long time, if ever, but I may as well try and set it up as good as possible.  I'll do some searches to see where I can find some delrin.  Will it machine with the same tool bits I use for either aluminum or steel?

Also you said you pressed in "4" bearings.  How wide did you make the rollers?  I was thinking of using "2" of the same type I"m using with the sprocket adjuster I'm making now (see picture).

   

Here is the info on it from my page on the parts I've used:

 

Bearing for Idler Sprocket -- Motion Industries Inc. -- 801/972-1036 -- SLC, UT -- SKF bearing #6303 2ZJEM ball bearing. 6303 is the size (Metric =17 x 47 x 14) .67 ID X 1.85 OD X .55 width. 2Z = metal shields on both sides (allows higher RPM than rubber seals. JEM = packed with high temperature grease. This bearing is good to 16,000 rpm and radial loads of 3040 lbs. At 250 mph the bearing would have a speed of 8300 rpm with a 21 tooth sprocket mounted on it. I hope this works. A MRC (800-MRC-7000) technician helped me with the selection of this bearing. They have good tech support. Cost $24.00.

For your pressure lube system, do you mean you were spraying lubricant on the chain and recovering it?  If so was this also an attempt to cool the chain? Mike mentioned spraying water on the chain as a coolant.

Thanks again for all the input from everyone,

Sum

[1212FBGS]

The roller is 2"wide it allows the chain to move around a little we have had chains jump off of idler sprockets and tear up stuff. if your chain is longer than 100 links I guarantee it will jump off that idler. your bearing speed looks good. our pressurized lubber is a 1 qt alum tank that is full of 90wt gear lube and is plumbed to our 100psi nitrogen air shifting tank. when i hit an up shift button it squirts oil onto our guides, yes we also run adjustable guides on the top run to stabilize the chain whip

[Dean Los Angeles]

The point I was trying to make earlier was the wrap angle around the sprockets changes with the position of the idler.

If there is no idler and both sprockets are the same size there is exactly 180 degrees of wrap on both sprockets. As the drive gear gets smaller there is more wrap on the driven gear and less on the drive gear, but the total is always 360 degrees of wrap. (It?s a circle with straight sections.)

If you look at the picture of the two chains on the left side, the idler is at the centerline of the tangent of the two sprockets (the dashed line). The idler is at the midpoint between the sprockets. The only difference is which side the chain wraps. Pushing out modifies the wrap angle for all of the sprockets but still equals 360 degrees.

Pushing in increases the wrap angle for all the sprockets and adds 39 degrees of wrap and friction.

The right two pictures show the idler pushed out/in the same distance. The out angle total stays the same 360 degrees; the in angle increases the total an extra 57 degrees.

It?s true about the oscillations of the chain. Every time the plug fires there is an explosion that sends a shock wave through the power train that shows up at the chain as a series of pulses. The pulses cause the chain to have waves of oscillation running through it. The frequency and amplitude vary with speed, sprocket size, distance between sprockets, etc. High speed video shows the chain looking more like a snake than a straight line. The same holds for belt drives also. Machinery Handbook under roller chain drive service factors recommends derating the chain 60 percent for internal combustion engines with high shock loads.

If the chain is turning blue it's running out of lubrication and is a huge source of friction loss. Spraying water will cool the chain, but potentially wash the lubrication off. I wouldn't do it. If the chain is getting lubricated it won't heat up.

Your idler bearing will take large radial loads but no thrust loads. The chains whipping will generate side loads that could cause bearing failure. Having two bearings spreads the load out laterally and is better at resisting thrust loads.