Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: Rex Schimmer on March 17, 2009, 11:10:46 AM
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Pretty good article in this months RaceCar Engineering regarding chain drives. Good explanation on selecting sprocket diameter, and chain loads specifically when used for racing. When used for "normal" industrial applications where the chain is going much slower than a racing application the sprockets need to be large to be most efficient but when you get to the speeds that happen in racing the chain is trying to "centrifuge" off of the sprockets and this adds an additional load to the chain that increases wear and reduces efficiency.
One point that I find very interesting is that chain drives are only about 90-91% efficient, so chains can get hot which accelerates wear and reduces life. This also might be a reason not to use an intermediate jack shaft, as then the overall efficiency of the chain drive could be as low as 80%. They also do not see a good reason to use "O" ring chain as it increases friction and the chain cannot be lubricated properly especially when most of the small sports racers that use chain drive put on a new chain every race, sounds like Bonneville!
They comment that it might be more efficient to run a smaller pitch double chain than a larger pitch single chain but they did not have any data to prove their thinking.
At 90% efficiency it really make me think about going with a cog belt (efficiency ???) or turning the motor sideways and running a drive shaft to a small rear end.
Rex
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in the checkout line on sunday, i saw Aliens landed again, they came for Obama..!.... don't believe everything you read.... non "O" ring chains wont make it to the 5 mile... the "O" rings help space the link plates apart and reduce the contact rubbing friction and the "O" rings hold the lube inside the rollers..... when i ran non "O" ring, the chains use to turn purple and snap... picked alot of em up off the salt..... just speaking from my experience...
Kent
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I was just musing over the article in Race Car Engineering, if the writer really tapped the correct source for up to date infomation on a chain driven race car. Rick Yacoucci has the record of 352+ mph in a car and I think the exit speed was over 360 or close to it, with less than 122 cubic inches,all chain driven. I believe that car to be the fastest all time car in a cubic inch to speed attained ratio. Not too bad for a couple of guys, Jack & Rick, who work out of small shops, small funding and build everthing themselves. Amazing! I would also like to add the red car was the "Quickest" streamliner I ever timed at El Mirage. No! I am NOT a Official timer, but I do like to time certain cars and trucks that exhibit good aero chararteristics, because you can observe the dirt movement the car produces, Kinda like a Jr. G-man wind tunnel. The Red car and the Orange car hardly disturb the dirt at all.
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Rick uses an "O" ring chain.... So does ACK, Dennis, and Sam....
Kent
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I posted the other day in LSR GENERAL CHAT a visit with jack costella. No one has looked at it , maybe i posted in the wrong area.
Sheri Buchta
sorry glen i changed it
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Nothing today in LSR general chat, I read the one the other day. Are you sure you posted today?
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I saw the post.
DW
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Kent,
Pretty obvious that they should have talked to some Bonneville people regarding the O ring chain. Nothing teaches better than experience! How many runs can you get from an O ring chain?
Pookie,
I am in complete agreement with you regarding the Yacoucci car, it probably is putting the most horse power thru a chain of anything on the salt (Noonan is probably right there also) It would be interesting to know what kind of chain life they are seeing.
If chain drive efficiency is really around 90% then something like Rick's engine which must be making at least 600+ hps would be putting 60 hps into heat in the chain. It has got to be hot when they complete a run.
Rex
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Optimisation of the chain drive system on sports motorcycles
http://endless-sphere.com/forums/download/file.php?id=16750&sid=1270fb1a93e1447e4d8040136d55d2e8 (http://endless-sphere.com/forums/download/file.php?id=16750&sid=1270fb1a93e1447e4d8040136d55d2e8)
If you are going to run a pre-lubricated chain like Kent then you need an o-ring chain.
I have said it before and still say that you need a non o-ring chain that is lubricated while running. The chain needs continuous lubrication just like the gears in a gearbox.
Seems to me that the efficiency at high speeds may be significantly lower than 80 percent for a chain that is not lubricated while running.
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Interesting file, but the author has embarked on research that assumes use of sprockets below the minimum tooth count recommended by manufacturers, on the basis that they were stock on a motorcycle.
His tests are limited to 13, 14, 15 and 16 tooth.
Smallest size (i.e., "this is the smallest sprocket you should use for a power train unless there is no alternative"): 17.
Smaller sprockets eat chains and shaft bearings (Honda 750 K is the poster child here), and have huge cyclic pitch changes due to the polygonal effect he mentions.
This is a strong argument for dual row: you have too few teeth on the minor sprocket in your load and ratio choice, and don't have enough load capacity in a single row.
There are also cases where the diameter is simply too big for convenience, and reducing the pitch with dual or triple saves you.
There may be some useful conclusions in his data, but not as much as if sizes chosen by engineers were used instead of what his bike had.
I certainly agree that by whatever method the chain must be wet throughout the run, not only for lube but to carry away heat, or it will simply de-harden and be chewed away like a chocolate bar.
Many industrial apps use an enclosed bath, and the chain industry is very happy to tell you exactly what oil, grease etc. you need for your speed/load/temp.
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sheri and i run a 35 tooth engine sprocket 56 tooth clutch basket ( triple row ) 23 tooth countershaft sprocket and from 46 to 52 tooth (single row number 530 ) rear wheel --we can run all year on one rear chain (non o ring ) with racing and testing is about 70 miles although after bonneville we usually put on new chains our speeds range from 100 mph to 141 mph ---on the same rear chain i can get about 40000 miles on a street bike --i buy the cheapest motorcycle chain i can 37 dollars each --the harley shop uses 520 chain on all of there flat track bikes some chain just narrower and lighter --i think if you cook your chain in hot oil (non o ring ) after each race and use a good chain lube your chain will last much longer ----at higher speeds than we are going you might want to consider a chain cooler and oiler ....many times ive seen chain problems because of alignment more than any other thats the fastest way to kill a chain just some thoughts-------willie buchta
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Rex
with both motors I am putting a little over 800 to my chains and ACK has up to 1000hp to use. My car is at 2200 lbs and ACK and Rick I'm guessing are around 1600lbs... power, speed and weight are a big factor in chain life... a 100hp chain running 100mph will last a life time as Willie can prove.... i have not snapped an "O" ring chain yet because i made other changes that have helped life... i have found for high HP that 23tooth is the smallest you can run for tooth engagement so the stretched chain wont crawl up the face of the tooth.... i also made 3 passes at Bville and 2 passes at Elmo just to pre stretch chains for speedweek... we should be ready to lay down some speed this year but the chains remain our weakest link
Kent
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kent --- good info--- what size chains are you running --are you spraying them with anything willie buchta
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Mrs. Sheri, I also saw and read your post on you folks' visit to Jacks' place. Mike R.
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Interesting topic. I have always wondered how the guys running long chains do it - I used to race sports racers where we used o-ringed 530's but really short to what you guys are used to, 78 links short... Here's an interesting video of a bike powered formula car on a dyno you should check out - http://www.vimeo.com/1131103
Now imagine what the chains go through on a liner... lots of chain slinging in those machines!
Josh
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Interesting video, looked like the chain was a little loose... or the drive sprocket is a little small, didn't notice a number... we run 530 X-ring, about 120 pins on the lakester, and a chain tensioner on the slack side, mostly because the suspension pivot and the front sprocket are about 10 inches apart. I would think a chain is more efficient than a geared differential but what do I know...
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Stainless,
As it was described to by me the chain was not as loose as it looks to be in the video. Not sure if they ever figured out what was going on. Sprocket setups typically 16/48 in such a machine, nothing like what you guys are used to. That's probably why the article in question only covers the small front sprockets - race car engineering would gear such an article towards bike powered formula cars and sports racers.
Josh
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I posted the other day in LSR GENERAL CHAT a visit with jack costella. No one has looked at it , maybe i posted in the wrong area.
Sheri Buchta
sorry glen i changed it
You be wrong, Sheri.....I checked it....I liked to see my old friend Jack and how wide his smile is after all last year......and I'm glad to see his smile so wide as it was long time not.... :-D
Thanks for sharing the picture
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To Rick and the NT2.
Some year ago Rick had some trouble with his chain - after half of the run the chain was stretched. Terry brought one of the chain we use in our streamliner to the salt.
There was no effect on this chain - but the sprocket out of the transmission was gone. When I checked the sprocket axle I found out that the axle had a crack before and it was more than one run which let them break.
Also we found out, that the chain drive was not aligned properly, the chain went "around" a vertical tube from the frame.
Rick rebuilt the transmission and used a stronger chain from his brand, also the chain drive was aligned properly - after that he never had a problem again.
To the 360 mph run - he run a 92 cu engine - he told me that 800 hp would be possible - but he used in the measured mile around 600 hp - at the first mile after the start he has to run a very low boost, due the rough salt in this mile and the lack of a suspension. In the second mile he increased than the boost to the level he run in the timed mile.
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I would think a chain is more efficient than a geared differential
X2
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The pitch diameter change (going over the center of a link) which causes the damage is about 1.7% for 17 tooth, doubles with 12 tooth to 3.4%, drops to 1% with a 22, to .75% with a 26, to .5% with a 31. I have an Excel for this if interested.
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I've heard the question asked and answered a bunch of times -- about why my touring bike has shaft drive instead of chain. Besides easier maintenance and less oil slinging -- I've been told that a shaft drive has about half the loss that a chain drive has. I have no data -- just hearsay, but I've been glad to pass it on over the years.
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Chains on racing bikes have always been a problem.........but the "old timers" knew and understood the problem.........look at the large sprockets on some of our Vintage roadrace bikes
(Norton Manx....AJS 7R....enc.) more wrap around
slower chain speed....................................................
Back in the 1960's when we ran our Norton on Axtells chassis dyno, we put a strobe light on the rear chain while under full load.......it was downright scary what we saw....................................
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Can someone pleae help me get a copy of said Racecar Engineerig article? I was trying to get it on Racecar Engineering's website with no prevail.
Thank you in advance
Michael Werner
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The 90 or so % efficiency of a chain drive is about as good as it gets for any drive system. I dont know the efficiency percentages of MC shaft drives but I do know that they are lower. I think between 75-80% The maintenance schedule is the biggest draw to those systems. Cleanliness and reliability are generally good too, but not always. I have no opinion ether way towards belts.
I did however find a secret chain lube that is fantastic. While on a 7100mile sport touring ride, my 30k old chain started wearing VERY rapidly. 2k from home and a holiday weekend I couldn't find a chain, so I picked up some bar and chain oil for a chainsaw liberally doused the chain every 50-100 miles. The chain wear almost halted the rest of the trip home. This was on an O-ring 525 chain but many of the O-rings were chewed and no longer sealed properly. Since then, I lightly coat the sprocket side of the chain with bar and chain oil using a rag. The sling off is much less that any other non-wax lube I have ever tried and I am not a fan of wax lubes.
That being said, I am planning to use a shaft drive if I ever build a liner.