RallyHarry
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 posted on 18/11/04 at 02:21 PM |
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Chain length
If I put my engine in the back, driving the rear wheels by chain, I might aswell drive the front ones too.
What will the problems be concering this ?, is the length of the chain going to be a problem ?
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JoelP
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| posted on 18/11/04 at 03:01 PM |
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what type/style of chassis are you thinking of? i assume you mean a bike engine. a chain that long would vibrate a lot. is it really necessary, having
4wd? the extra weight of chains, diffs and half shafts might have more affect on conering than the extra grip would provide.
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adampage
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 posted on 18/11/04 at 03:05 PM |
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Have a look at...
www.dpcars.net
The guy on there has designed a one-off car with a mid mounted hayabusa engine, central diff, and 4wd.
He originally wanted traditional prop & diffs, but went for chain.
Not only a good analysis of your specific idea, but also a damn interesting exercise overall.
Warning - his lifestyle of designing & driving sportscars and flyling round the world may prompt jealousy!
Adam.
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RallyHarry
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| posted on 19/11/04 at 07:26 PM |
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yeah, I've been following Dennis project since his first sketch, however he has the engine in the middle of a really small car. I'm going
to have the engine in the back of a "normal" sized small car, that's why I need the help with figuring out if the chain length would
be "too long" to be feasable ?
Why 4wd ? - that's easy, SNOW
It'll be my lightweight rally car :-)
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andkilde
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| posted on 19/11/04 at 08:19 PM |
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I'm looking at the idea myself as well -- seeing the pics of the MK Mini has got the gears turning in my head.
I don't know enough about long chain runs to say anything particularly useful.
It would probably be a good idea to connect up with some rallycross or hillclimb specialists as they seem to perform crazy, chain driven, engine swaps
all the time.
You might also look up industrial power transmission firms or bearing houses -- they sell chain drive systems for factories and whatnot and often deal
with funky chain setups -- don't be tempted to use their chain though, they usually don't have access to the "good stuff" as
used on bikes.
At the FSAE competition in Detroit this year there was a nicely crafted 4wd bike powered machine from Guelph Uni. I'll dig out some pix when I
get a moment. Their car used a chain driven center diff (fancy computer controlled unit) with shaft driven conventional diffs front and rear.
I was thinking you could go a little simpler using a viscous LSD for the center. They're plentiful in the scrapyards, come in plenty of Nissans
and Mitsus, and the internals are already sealed up so you don't have to futz about with sleeves and whatnot to keep the gear oil in.
Cheers, Ted
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Rorty
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| posted on 20/11/04 at 04:02 AM |
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A friend here in Australia runs a Busa powered hillclimb special which is 4WD. I think he holds (or did hold) a record for the Race to The Clouds in
New Zealand.
Anyway, he runs the chain down the inside of some square tube. His cars are extremely agricultural to be kind, but they get the job done.
I would look at an industrial T drive or bevel drive and run a prop to the front.
You could attach the T drive directly onto the engine's output shaft and one side of the T directly onto the rear diff. Then run a prop shaft
forwards from the other leg of the T.
You can pick them up second hand and in various ratios from 1:1 to odd sides etc.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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andkilde
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| posted on 20/11/04 at 03:28 PM |
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Photos of the Guelph University 4x4 FSAE car are in my photo archive -- it's tricky to see the whole drive system as it's quite busy at
the back, but it should give some idea.
Cheers, Ted
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Aloupol
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| posted on 20/11/04 at 04:48 PM |
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quote:
Originally posted by Rorty
He runs the chain down the inside of some square tube.
This is the first thing I tought about seeing the tread for the first time. The biggest problem a long chain would bring is whiping if not supported
longwise.
This sorted I think it has to work...
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MrFluffy
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| posted on 20/11/04 at 06:08 PM |
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Long chains
Little to add, except experiences on bikes with overlength arms and large power outputs.
On a long chain run its kinder to run nylon chain guides at the point of maximum deflection as they whip around when you change the loading on the
drive/shift gear etc and you can treat these as sacraficial along with a nylon roller on the chain tensioner mechanism. Chains in fully enclosed
guides last a LOT longer than something exposed to the airflow too..
The best type of chain to run is O ringed, as they seem to last much longer than regular stuff but you do have to lube them with special o ring
lube.
The big worry is that if that chain snaps one day, your are going to want to position it where its not going to come up and chain whip you, which
wasnt pleasant when it happened to me..
Im not sure I should tell you when I had a chain snap and shower onlookers with bits of broken side plates and link remains when doing a burnout,
fortunatly (miraculosly) nobody got hurt though....
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Rorty
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| posted on 20/11/04 at 08:32 PM |
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I've been toying with the idea of building a light weight bike-powered 4WD off-road racer for years and the drive layout has always been the
stumbling block in the design.
Sourcing suitable light weight diffs and axles is quite simple, its the transfer of power from the centrally (or rear) located engine to the diffs
that's the problem.
I've entertained chain drive and prop shafts in various guises, but they both create as many problems as they solve.
My Holy Grail is to find a light weight, compact enough hydraulic system that will also not rob the engine of too much power.
Sacrificing up to 30% of a turbo Busa's power in an off-road car isn't too bad, but not ideal for on-road use.
The weight of the hydraulic pump, hoses, motors (one for each of the front and rear diffs), fluid tank, filter etc is not insignificant. Even
"portable" hydraulics (BobCats etc) are quite bulky and heavy. Aviation hydraulic components are much more compact, efficient and weigh a
lot less, but the price would almost put an international airline out of business.
Yamaha, in conjunction with Ohlins, developed lightweight hydraulics for their current 2WD dirt bike. Although everything has been miniturised and
they seem to have dispensed with a bulky reservoir, the parts are bike-specific and again, would cost the earth. So, the technology is there.
Hydraulics has to be the way to do it; by connecting the pump to the bike engine, and attaching a hydraulic motor to the front and rear diffs, the
system would be very flexible. The diffs could be rotated so their noses pointed vertically, thereby "shortening" them and saving space.
In a road car, they could also be off-set to distribute weight more appropriately without having to worry about prop and UJ angles.
Reverse "gear" would be as simple as throwing a lever to reverse the flow of oil to the diffs.
Front to rear split would also be simplified with the use of valving.
Maybe if an aircraft carrying a shipment of Yamaha 2WD bikes crashes in my back yard, I could strip the lot of any useful components and build my 4WD.
Until then, I'll keep scheming and planning. 
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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MrFluffy
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| posted on 20/11/04 at 10:22 PM |
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hydraulic drives
S'funny you should bring them up rorty, Im part way into constructing a blower drive for one of the bikes driven from a crankshaft mounted
hydraulic pump motor (from a ride on lawnmower) with a matching unit on the blower, mostly from packaging and lubrication difficulties. There is a
huge power loss penalty though (20%, but given the limits of my rear tyre its no bad thing probally). However there has been a huge leap recently in
ultra efficient hydraulic drives, that are even more efficient than belts or chains, theres much talk of them being used in wind farms so the
generators can be mounted at the base etc. Thats probally the same design as in the new yamaha awd stuff..
Now when THOSE type become generally availible in a range of sizes, bye bye drive chains 
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Rorty
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| posted on 20/11/04 at 11:12 PM |
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Interesting. Efficiency isn't the problem (just look at automotive torque converters and viscous diffs etc.) it's miniaturisation and
cooling/reservoirs (and to an extent, price) that are standing in our way.
With better materials for seals and motor vanes, the tolerances and pressures are much higher, leading to greater efficiency.
The Yamaha hoses are not much larger in diameter than the brake hoses!
How the hell do you keep a supply of cool clean oil available though without a heavy bulky recirculating tank. When I looked into hydraulic drives
initially, I would have needed a 30-40 litre tank. That's 30-40 extra kilos on board before I turned a wheel. 
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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MrFluffy
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| posted on 20/11/04 at 11:20 PM |
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In my case, the drive is only for the supercharger, so heat generated isnt huge amounts and is taken care of by a oil cooler mounted in the airflow,
and a small resivoir. If it works properly is another thing entirely
With hydro final drive, heating does become a significant issue..
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kb58
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| posted on 21/11/04 at 02:01 AM |
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In case you didn't know, this exact thing has been done before. I used to work with the inventor.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Rorty
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| posted on 21/11/04 at 02:24 AM |
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quote:
Originally posted by kb58
In case you didn't know, this exact thing has been done before. I used to work with the inventor.
And....?
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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kb58
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| posted on 21/11/04 at 04:44 PM |
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No ands... I'm just saying a patent search might show some helpful stuff... or not. Last I heard he was trying to sell the design. Like was
posted above, it's main advantage is packaging.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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RallyHarry
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| posted on 22/11/04 at 01:10 PM |
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you lost me, do you mean driving the supercharger or the diff's ? (patent)
How expencive is expencive when it comes do the yamaha/ohlins version ?
Is there a final product or just prototypes ?
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RallyHarry
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| posted on 22/11/04 at 01:24 PM |
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quote:
Originally posted by andkilde
Photos of the Guelph University 4x4 FSAE car are in my photo archive -- it's tricky to see the whole drive system as it's quite busy at
the back, but it should give some idea.
Cheers, Ted
Thanks a lot, looks like Haldex was involved, not cheap to retorofit one of those ...
It would be really interesting to know where they got the front diff from ? ( unless it runs the "wrong way"
So the solution is Swedish I guess Haldex or Ohlins ...
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andkilde
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| posted on 22/11/04 at 04:53 PM |
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quote:
Thanks a lot, looks like Haldex was involved, not cheap to retorofit one of those ...
It would be really interesting to know where they got the front diff from ? ( unless it runs the "wrong way"
So the solution is Swedish I guess Haldex or Ohlins ...
It looks like the Guelph car takes the rear drive directly off the crank and runs the Haldex off a chain -- the Haldex system is computer controlled
and quite spendy, and from the looks of the way they've configured it can only send a maximum of 50% of the torque to the front wheels. I
believe their front and rear diffs are from "quads", those little offroad utility cycles that hunters and campers are fond of.
I was thinking of something a little more conventional out of junkyard bits.
Center diff would be chain driven, bike engine, all tucked inside an old Mini shell -- please excuse the wrong hand drive .
Anyone have any thoughts?
[Edited on 22/11/04 by andkilde]
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RallyHarry
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| posted on 22/11/04 at 05:23 PM |
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I've been researching ATV/Quads front diff's but I havn't come across one that can handle the output from an R1 etc ...
Does anyone have an idea on that one ?
andkilde:
Why would you want more than 50% torque at the front wheels ?
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RallyHarry
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| posted on 22/11/04 at 05:34 PM |
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Dreaming ...
So ....
If I buy 4 Ohlins 2wd systems, and hook them upp to a single pump or 4 smaller pumps (original), computer control them in an ESP mode, one for each
wheel ...
But they can only handle 25Kw each x4 = 100Kw/134Hp
2x600CC + 2x2wd systems handling 100Hp each ... sound like a plan, all we need is Ohlins cooperation and a lottery ticket.
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Rorty
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| posted on 22/11/04 at 08:43 PM |
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quote:
Originally posted by RallyHarry
How expencive is expencive when it comes do the yamaha/ohlins version ?
Is there a final product or just prototypes ?
Yamaha put their WR 450F 2-Trac into production in about '98 and it has since won some high profile events including the Shamrock Rally and the
Paris-Dakar.
I'm not sure if you'll find one at your local Yamaha dealership, but they are becoming more plentiful. Not sure of price.
As I mentioned, the hydraulics are mostly bike-specific, though the chain-drive pump above the crankcase may be a universal item.
It would be interesting to price one at a Yamaha spares counter. Yamaha own Ohlins, so it's not going to be any cheaper through Ohlins.
Quad diffs aren't really suitable for car use. The FSAEs can get away with them because the cars weigh not much more than a go-kart and run low
torque engines.
The typical 4WD quads that run independant diffs produce around 30-45 hp (even the latest 700cc V-twin models), so split that across two diffs and
you'll see the problem.
For higher torque rating diffs, have a look at garden, lawn, golf and maintenance vehicles. They start to get heavy again though.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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RallyHarry
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| posted on 23/11/04 at 10:03 AM |
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Yes, but in true FSEA tradition you could gut the internals and make your own alu casing to save weight.
I talked to a hydraulic guy yesterday evening, and he said that you could calculate with 5% "transmission loss" in a hydraulic motor and
that they easily runs 100 000 RPM, which means that if you run the calculation 80 000 RPM @ 80 ft/lbs you get 100 Hp.
I'm still chasing the 2x600cc + 2 hydraulic motors, but there will be a weight penalty unless its bike gear ...
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Rorty
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| posted on 23/11/04 at 12:40 PM |
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I did a lot of foot work on hydraulic drive about 4 or 5 years ago and put it in the "too hard" basket due to bulk, weight and price.
Things may have changed but I can't believe the changes will be too significant.
Let me know when you get it sorted and I'll listen.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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CooperLight
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| posted on 23/11/04 at 10:37 PM |
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Yeah, what you need is a high speed,low torque hydraulic motor that's lightweight ... where do you find that ?
If you do, tell us ! it's a perfect addition to a rearwheel drive unit, when the rear spinns, it will automaticly move torque to the front
wheels, and you could use an ordinary diff, spinning the "right way"
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