Landracing Forum

Tech Information => Technical Discussion => Topic started by: Koncretekid on November 18, 2011, 11:58:02 AM

Title: Resistance Forces Other Than Aero
Post by: Koncretekid on November 18, 2011, 11:58:02 AM
We all know that drag forces are about 2/3 caused by aerodynamics, but we may not pay enough attention to the other 1/3, such as transmission losses, bearing drag, and tire deflection.  This was brought home to me when BAK posted that Bob Barker told him that the CanAm 125 that he set records with back in 1973, seized up  before the last timing light, but still set a record of 135 mph + and coasted three miles back to the pits!  He said that the rear wheel, with the chain in place, would spin for 4 minutes when spun by hand.  So I went out to my shop and because my landspeed bike was not in the shop, I grabbed the back wheel of my BSA B50 road racer which was on a rear stand and spun the wheel.  It rotated grand total of 5 seconds.  Obviously, there are some transmission losses here.

I had an old CB350 Honda front wheel under the bench, which is the drum brake equivalent of the front wheel on my Landspeed bike so I set it up in an old swing arm in a vise and tried the same thing.  It spun an amazing (or so I thought) 4 - 1/2 minutes.  The bearings are Japanese Koyos, and might even be the original bearings, which are sealed on one side only. So I popped off the outer seals and tried again.  This time the wheel spun for 9 minutes 47 seconds.  At this point I noticed that the wheel was not well balanced, so I wrapped some solder around the spokes on the light side and spun it again.  The result was over 11-1/2 minutes before it stopped spinning, and I had to watch it carefully to tell when it actually stopped.

Now these experiments are not very scientific, but because I got an order of magnitude difference by just removing the seals and re-balancing,  the results are significant.

The BSA rear wheel will never rotate very freely, because the design of the drive sprocket, which is mounted on a sleeve gear, which in turn runs on a bushing on the mainshaft, and which also rotates the layshaft and all the attached gears, has a huge amount of drag.  Luckily, when in high gear, the mainshaft and sleeve gear rotate at the same speed, so the transmission losses are confined to spinning the gears and shafts on ball and needle bearings.  Not much that can be done here without cutting the gearbox off the motor and substituting a more modern transmission, torque converter, or what have you?

The drive chain is another potential horsepower eater, but I don't know what would be better.  If I were starting over, I would go to 428 chain (from the present 520), but that would require another whole set of rear sprockets and custom made front sprockets.  Other than that, would a belt drive be more efficient?   Also, a belt drive primary is available (with some modifications to fit the B50), which might help.

Tires are also part of the equation, and I'm presently using a radial 110/70-17 front tire on the back (running counter direction to the intended direction), and a 80/90-17 bias ply on the front, both with tubes, and running 50 psi tire pressure.

So I would be interested in hearing from others on what I could do (or what you have done) to reduce these other power losses.

Tom
Title: Re: Resistance Forces Other Than Aero
Post by: Milwaukee Midget on November 18, 2011, 12:54:20 PM
I know we've discussed oil in the transmissions before.  I'm aware that the Subaru Justy that I believe still owns the Production record in I/PRO used automatic transmission fluid in place of the gear lube in the transaxle.

A trick the BMX Bicycle guys have done is to use Vaseline on their wheel bearings, and they repack their bearings every race.  Might not hold up to motorized applications, but maybe it might?  Don't know.  It would be kind of a hassle, but if you're looking to minimize your rolling resistance, that might be something to look in to.

On cars, something that gets overlooked is the straightness in the drive axles and drive shafts.  As Koncretekid noted, out of balance issues eat power, even those that might not be perceptible to someone driving a vehicle.

I would think checking the concentricity of the wheel sprocket would be a good idea.  When I rode bikes, I always assumed that they're straight, but we're looking to minimize power losses, so maybe that needs to be checked.

Crank trigger versus a distributor puts less drag on the engine.

It's chasing a lot of little issues, but if there were a silver bullet, we'd all have them in our holsters.
Title: Re: Resistance Forces Other Than Aero
Post by: fredvance on November 18, 2011, 12:54:48 PM
I run ceramic wheel bearings in my bike. I trim the seal lip off that rides on the axle. The rusults from trimming the seal is more noticable than the high dollar wheel bearings. :?
Title: Re: Resistance Forces Other Than Aero
Post by: Dean Los Angeles on November 18, 2011, 02:23:38 PM
At some point you have to evaluate your budget.

If you are going all out then everything is a consumable that gets replaced every race.
Ceramic bearings not only in the wheels but the engine also. Expensive.

The drag from the seals is real and trimming them counts for a lot. Oil viscosity creates drag. Use the lightest oil you think you can get away with. The trade off is wear and potential failure.

Out of balance creates drag. Make a test fixture and spin the wheels up to maximum speed. If you can't keep a glass of water on it, then re-balance. The tires should be trued so there is no run-out. The tires should be shaved to the minimum. High pressure to reduce rolling resistance.

Search for the discussions on chain wear and drag. There has been a lot of discussion. Here is two:
http://www.landracing.com/forum/index.php/topic,6295.0.html (http://www.landracing.com/forum/index.php/topic,6295.0.html)
http://www.landracing.com/forum/index.php/topic,5718.0.html (http://www.landracing.com/forum/index.php/topic,5718.0.html)

Oh, and lose weight. No point carrying excess weight.  :-D
Title: Re: Resistance Forces Other Than Aero
Post by: Rex Schimmer on November 18, 2011, 02:25:19 PM
Koncrete Kid,
I agree with you that when you have limited horse power you need to make sure that most of it is used to make you car, or bike in your case, go fast and not waste it on parasitic losses like chains and bearing seals. I did a search on roller chain efficiency and the numbers are 91 to 94% efficient and that is assuming good lubrication, and new chain and sprockets, going with something like the new Gates GT Poly Chain, which is their latest design synchronous belt design, a properly applied set up can be 99% efficient. That is well worth considering.

Ceramic bearings and hybrid bearing using ceramic balls are additional ways to reduce parasitic losses, although they are pretty spendy and going along with what fredvance said about seals I would try to design a setup which allowed you to use them without seals. Also good lubrication is important and there are some very good high speed greases available today that should be used, I have used Kluber brand before with great results on high speed spindles at over 10,000 rpm.

As I am also planning to be building a car that will have limited horse power and be chain driven and I am planning to incorporate both synchronous belt and ceramic bearing technology to reduce parasitic losses.

Rex
Title: Re: Resistance Forces Other Than Aero
Post by: Tman on November 18, 2011, 02:50:33 PM
Some of you know that I also play with Mountainbikes and other forms of pedal power. We have been seeing ceramic bearings being used for many years. I still have some wheels set up with ballbearings that were lapped in with polishing compound, coast like a dream.

Also, I remember a tale of a friend that ran in fairy fast karting circles told. He had some guy that hated him for how good and fast the karts he tuned went. Swore my pal was cheating until one day he got tired of the jealousy and told the guy he would show him his secret. He went over and gave the guys kart a shove and it went a few feet. Did the same to his kart and it rolled all the way across the pits! Things need to track and not bind, the other guys kart was all bound up with the four corners fighting themselves.
Title: Re: Resistance Forces Other Than Aero
Post by: Koncretekid on November 19, 2011, 04:37:17 PM
Thanks for the response.

I currently use 20W50 Amsoil full synthetic in my motor, transmission, and primary chain case.  I might be able to get away with lighter oil, but keep in mind that this is an air cooled motor that runs hotter than a water cooler.  My rod bearing lasted thru about 14 runs at Bonneville over a 2 year period, and 5 runs at Loring.  It was ready to go, but didn't.

I don't plan to use ceramic bearings in the near future, but I will probably pop the seals out for the last couple of runs.

Lapping the bearings with polishing compound sounds interesting.  How do you do that and what do you use?

Also, wheel balancing will get more attention for next year.  Vibration at the handlebars last year was so bad that I got blisters on my hands.  I got the motor rebalanced for next year, but some of the vibration could have come from wheel balance issues. Tire issues (radial vs. bias ply) and size (when is bigger better?),  other than pressure did not get mentioned, but I know this is important as well.

And lastly, I read up on the Gates GT Polychain and it sounds quite amazing.  Unfortunately, their charts only go to 5500 RPM, but they do say that max belt velocity is 6500 ft/min or so, which is doable on both the primary and drive.  Changing over would be costly, so it won't get done yet.  I have no doubt that for low horsepower vehicles, this is the way to go. Converting both primary and secondary drives over to belts could free up 10% more horsepower.

Tom



Title: Re: Resistance Forces Other Than Aero
Post by: Tman on November 19, 2011, 05:01:25 PM
The old bike mechanis trick was something like pear drops tooth paste followed by a SHORT spin. I have used VERY FINE polishing compound then cleaned them out real well and pack with a slick grease. The track guys used oil.
Title: Re: Resistance Forces Other Than Aero
Post by: mtkawboy on November 19, 2011, 09:13:19 PM
I dont know if this would work or not in landspeed racing but at motorcycle dyno shootouts Ive seen +10hp from spraying the chain with WD40 before a dyno run compared to a run without it
Title: Re: Resistance Forces Other Than Aero
Post by: wobblywalrus on November 20, 2011, 12:50:26 AM
The Triumph uses Mobil 1 Racing 4T 10W-40.  It has additives for tranny gears and the ones in the bike look good during the teardowns.  This is lighter weight than 20W-50.  It might help to reduce drag in the trans and primary.

Sometimes a person wants to keep the seals.  One trick is to replace the double lipped ones with single lip seals.  Also, taking the spring out of the seal can help to reduce friction.  Do not do this with engine seals.  They are designed to withstand crankcase pressure and they can leak during racing use if they are modified.

What sort of ignition and charging system are you using?   
Title: Re: Resistance Forces Other Than Aero
Post by: Koncretekid on November 20, 2011, 06:20:52 AM
I dont know if this would work or not in landspeed racing but at motorcycle dyno shootouts Ive seen +10hp from spraying the chain with WD40 before a dyno run compared to a run without it
Methinks the chain in question might have needed a good cleaning and WD-40 is probably a good choice.  It's very light, and might be good for one run, but would probably have to be re-sprayed before each run.

Bo,
If 10w-40 is a good choice for the transmission and the primary, maybe straight 10w or the above mentioned ATF would be even better.   Has anyone tried ATF with a wet clutch? In high gear on the BSA, the mainshaft is locked to the sleeve gear, so theoretically, the only load is on the bearings which are ball at each end of the mainshaft, the rest of the gears are rotating but with no load.  Another problem I have is a third bearing on the mainshaft known as an outboard bearing, which replaces the seal holder behind the clutch.  Seemed like a good idea at the time, to mitigate flexing of the mainshaft, but in hindsight, it is practically impossible to have all three bearings perfectly aligned without some friction.  For sure I could pop the seals on this bearing, as very little oil from the primary would escape, and then only onto the chain.

I run total loss ignition with a Boyer.  BTW, the seals on the wheel bearings don't have springs.  I'm thinking that they could be removed, sanded on the inside to give a few thousandths of clearance, and replaced to keep out the majority of the salt and dirt.  I still would, of course, want to replace before the next event.

But on the subject of bearings, I know there are different classes, the better ones have tighter tolerances.  Would the lower tolerance ones be more likely to self align and therefore be more frictionless?

Tom

Title: Re: Resistance Forces Other Than Aero
Post by: Milwaukee Midget on November 20, 2011, 10:33:37 AM
Tom,

Recognizing that you don't have a lot of space to run this type of thing, and ignorant to the rules of the class (special construction, isn't it?), is an oil cooler or reservoir a possibility?  An extra quart would fill the cooler, and probably let you go lighter on the oil viscosity.

It's always a worry - British castings and what not.
Title: Re: Resistance Forces Other Than Aero
Post by: johnneilson on November 20, 2011, 11:42:12 AM
Tom,

running ATF in the trans is possible, the issue will probably come down to "shear stability" in the oil. It will break down and make shifting difficult. For short duration it should be fine (not over the road).

Another consideration would be to narrow the gears in the trans to minimize gear meshing/parasitic losses.
Ceramic hybrid bearings can help. Full compliment has more contact and depending on the load can be very efficient.

Something about chain efficiency, more it is consistancy, if the chain has short or long links along the length it will create heat and absorb HP. Also, if the chain is stretching this indicates either the wrong size, incorrect center distance or wrong material/construction of chain. I found using very small chain, high quality with CNC machined sprockets on karts the chains stopped heating up. Search up RK chain, I hear it is made for bikes now.

John
Title: Re: Resistance Forces Other Than Aero
Post by: SPARKY on November 20, 2011, 12:30:07 PM
on bikes  it takes a while to get the chain sides to not drag on the sprockets
Title: Re: Resistance Forces Other Than Aero
Post by: wobblywalrus on November 20, 2011, 10:56:13 PM
Tom, vibration has been a problem on that bike.  Lots of people like to use motocross bikes for desert racing.  Usually the MX bikes have a magnetic rotor on the crank end and it spins inside of the coils.  This provides little flywheel inertia.  This results in some engine vibration and it is no big deal for MX bikes.  The races are short, unlike desert races.  We put external flywheels on a lot of desert racers.  The coils were inside of the rotor.  The bikes vibrated less and were easier to ride.  The total loss system has no coils and where the coils used to be would be a great place for a flywheel.  The flywheel mass might reduce engine vibration.  Just an idea.

 
Title: Re: Resistance Forces Other Than Aero
Post by: bak189 on November 21, 2011, 10:41:14 AM
Using ATF in the primary chain case works just fine....it works great with a wet clutch....we used that type of oil in our Vintage dirt track bikes (BSA, TRI, NORTON, HARLEY)....workes even better when using a Barnett clutch...........
Also works in the trans. of the above noted bikes.......................................
Use the grease in the wheel bearings that the bicycle racers use..................
If possible change the size`of the rear sprockets....larger Dia....less chain
"wrap around"
In over 35 years of racing solo bikes and sidecars at LSR events......Used nothing more then WD-40 on the rear chain.......have had no chain problems
Title: Re: Resistance Forces Other Than Aero
Post by: bearingburner on November 21, 2011, 05:28:20 PM
I owner a 1978 Chrysler  Le Baron with a 4 speed manual transmission and the recomended transmission oil was ATF
Title: Re: Resistance Forces Other Than Aero
Post by: Old Scrambler on November 27, 2011, 03:02:14 PM
On my Triumph Cub I changed my duplex primary chain to a single and run ATF at only 1/2 of the recommended amount of oil. No problems but I made sure my clutch plates were lubed on assembly.  I run DID 420 drive chain that was cleaned and then sprayed with WD40.  Tranny oil is ATF and only half-full. Motor oil is 10-40 synthetic at only 1-qt. capacity. I run Honda 21-inch dual-sport wheels with original bearings but looking for advice about shaving the tires....old school Avon on front and modern HD front on rear.

After tech teardown we put a plastic bag over the open motor and used a large rubber band to secure it around the barrel. We had the tranny in 4th to rotate the crank to measure the displacement. When we started to push the bike back to the pits, Drew noticed the bag was "puffing".  The bike rolled so easily in gear that may builder, Dave, was amazed.  And yes..........both wheels will spin on the bench for 8 or more minutes.

We have a home-made ignition running off of the cam...........plan to change that to run off the crank.  At the dyno end of the crank we mounted a thin aluminum rotor with a degree-wheel decal on center. I don't know if it helps to balance the motor..........but it sure is smooth!

Thanks to all for posting this helpful info.............Dennis in Wisconsin
Title: Re: Resistance Forces Other Than Aero
Post by: Rex Schimmer on November 27, 2011, 05:19:27 PM
Another "parasite" that has not been mentioned is brake drag. Both drum and disc brakes can and will drag. Making sure that the pads are back away from the disc or that the shoes are well away from the drum can make a noticeable difference in speed and if you are looking for that last mph to break a record it may be worth it.

Rex
Title: Re: Resistance Forces Other Than Aero
Post by: Koncretekid on November 27, 2011, 07:59:39 PM
Dennis,
I believe your transmission is virtually identical to the B50.  Does your rear wheel spin for 8 minutes with the chain installed?  If so, I like to know how you did!
Tom
Title: Re: Resistance Forces Other Than Aero
Post by: Old Scrambler on November 27, 2011, 10:57:50 PM
No chain for the test spin.....................I need to take Wobbly's advice about cleaning and oiling the chain after you run on the salt............With only WD40 for lube the chain rusted so badly in a few days that it is now recycled.
Title: Re: Resistance Forces Other Than Aero
Post by: Koncretekid on November 28, 2011, 06:51:56 AM
Thanks, Dennis, for that bit of info.  I tried rotating my back wheel with the chain installed and got 5 seconds of rotation!  The 428 chain is a good idea and with new chain technology it will probably handle a lot of horsepower, especially when used with largest sprockets possible.

Rex,
Your point about the brakes is important.  I'm using a Honda rear wheel and it is easy to get zero drag, unless you forget to adjust it after installing a smaller rear sprocket which moves the rear wheel back.  Disc brakes do not have sprung retract mechanism, so I've heard you should use a very small screwdriver to ensure the pads are backed off before each run.

Tom
Title: Re: Resistance Forces Other Than Aero
Post by: Peter Jack on November 28, 2011, 07:51:13 AM
WD40 isn't a particularly good lubricant and besides which it attracts or combines with water which is why it works to fix a wet ignition. I'd be more tempted to try a variety of light lubricants which may offer better results and will help prevent the corrosion caused by the salt rather than encouraging it.

There, that should cause some controversy! :evil: :evil: :evil:

I'd be very tempted to experiment with what I've just said before rejecting it out of hand. :-D

Pete
Title: Re: Resistance Forces Other Than Aero
Post by: Milwaukee Midget on November 28, 2011, 08:13:07 AM
WD40 isn't a particularly good lubricant and besides which it attracts or combines with water which is why it works to fix a wet ignition. I'd be more tempted to try a variety of light lubricants which may offer better results and will help prevent the corrosion caused by the salt rather than encouraging it.

There, that should cause some controversy! :evil: :evil: :evil:



Pete

What has the world come to?  Next thing you know, he'll be dissing duct tape.   :lol:
Title: Re: Resistance Forces Other Than Aero
Post by: Peter Jack on November 28, 2011, 08:15:24 AM
The good American made duct tape is the only kind. Watch out for foreign imitations.

Don't you be causing trouble MM. :-D :-D :-D

Pete
Title: Re: Resistance Forces Other Than Aero
Post by: 38flattie on November 28, 2011, 08:57:18 AM
Being that these runs are fairly short, had anyone experimented with a dry lubricant, like graphite?

Title: Re: Resistance Forces Other Than Aero
Post by: WOODY@DDLLC on November 28, 2011, 09:45:25 AM
Chains don't stretch - they wear! A new chain has variation just from the tolerances on all the pins, links and holes. All the little high and dry spots accumulate their wear and you have your "stretch'! The pins have high pressure contact and the chordal action of the links around the smaller counter shaft sprocket is very ugly motion. Think about the geometry, change of direction and accel/decel involved. Chains are amazing that they last at all when you start pumping HP into them and make them turn sharp corners!  :cheers:

You have to do your test rotation with a repeatable applied load not by hand spinning. Attach a weight on a small peg taped to the tire so the weight falls off at the same point each time. Average at least 3X!

No o-rings, Dri-Slide (moly-based) to penetrate inside all the clearances - first time let the carrier fluid evaporate overnight - clean, blow dry and re-lube after each run at B'ville! I first bought Dri-Slide when the guy was selling it out of the trunk of his car! It would free up clutch and brake cables that were rusted fast!  :-o

Works very well in your weapons, too!  :-D
Title: Re: Resistance Forces Other Than Aero
Post by: Old Scrambler on November 28, 2011, 10:40:46 AM
+1 to Woody...............I have been using Dupont Teflon Dry Wax spray for several years with good success. I also use Graphite spray from my gun case on cables.  The WD40 got on my chain because my crew grabbed what they thought was best while I was at the rider's meeting.  I tend to use WD40 just before I wash my bikes as it seems to help remove collective oil film.

Speaking of slippery lubricants.........Pam spray on a clean frame and inner fender sure helps to remove salt...........do not put it on the motor or exhaust as it is causes excessive smoke...........the lady with the exotic electric streamliner put it on her front disks and had to exit her start because of smoke in the cockpit!

Regarding the weighted wheel spin..........I'll give it a try.
Title: Re: Resistance Forces Other Than Aero
Post by: Koncretekid on November 28, 2011, 11:32:43 AM
......the lady with the exotic electric streamliner put it on her front disks and had to exit her start because of smoke in the cockpit!


I guess when you're hot, you're hot!
Title: Re: Resistance Forces Other Than Aero
Post by: wobblywalrus on November 28, 2011, 09:48:04 PM
The WD-40 was developed by my father's cousin's husband.  Our family had some familiarity with the product.  The WD stands for Water Dispersant and it took 40 tries to get the product developed, hence the 40 in the name.

My father always used a quality lubricant made for the purpose such as Hoppe's oil for a shotgun or Lubriplate grease for a fishing reel.  The WD-40 would be used if the item got wet and its purpose was to displace the water to keep it from rusting.  The item was dried, cleaned, and regreased or reoiled as soon as practical.  WD-40 was not developed to be a great or long term lubricant, it is an OK lube whose primary purpose is to displace moisture, I was told.

That is all I know and my father is no longer here.  The last time I used the stuff was 30 years ago.  There are some teflon and silicon water dispersant sprays that work better.     
Title: Re: Resistance Forces Other Than Aero
Post by: Tman on November 29, 2011, 11:19:54 AM
Tri-Flow works great on chains. Light lube smells sorta like bananas
Title: Re: Resistance Forces Other Than Aero
Post by: johnneilson on November 29, 2011, 12:14:29 PM
Transmission can be treated, REM process current, in the past used SuperTech treatment.
If nothing else, you can narrow up the gears (within reason) or groove them to reduce the pumping action.
Ceramic bearings can reduce drag also. Be carefull of application, I have destroyed full compliment units due to shifting (engine speed accel/decel).

John
Title: Re: Resistance Forces Other Than Aero
Post by: Jack Gifford on November 30, 2011, 02:23:21 AM
This may not be useful to anyone here, but link-plate-chains (aka "silent" chains) have a surprising attribute- they inherently display near-zero internal friction! The Morse website has a very clear illustration of how the design (using Morse Hy-Vo as an example) utilizes a "rolling" action rather than the pivoting action of a roller chain. I don't know, however, how typical chain-to-sprocket friction values compare with roller chain.
[Anybody remember the monster-sized engine-to-transmission link chain of the FWD Olds Toronado?!]
Title: Re: Resistance Forces Other Than Aero
Post by: SPARKY on November 30, 2011, 05:56:03 AM
We had those trannies in the GMC motorhomes