Project "4 wheel Street Bike"

[RoosterBooster]

with winter approaching (and earlier darkness)
it is time for me to get back to "thinkering" with this project

i`m working on the concept of a ultra lightweight, street bike powered "canyon carver"
(aka BEC; bike engine car)

i grew up around street bikes and miss the thrill (and sound) of them.
but at 46 years old i kinda feel like its time for something with a little more wheels.

dumped the first idea of a "Morgan" style reverse trike like this rather quickly;

a 3 wheeler just cant generate the handling & lateral G`s that i`m looking for

so when i stumbled over pics of an 1930 "Austin 7 Special"...

... i was in love with its shape & layout

last winter i worked on a CAD of a "retro-modern" interpretation of it
here are some screen shots;

however, after working on some of the details i kinda feel somewhat limited with the long retro teardrop shape

so lately i find myself daydreaming about changing direction to a more modern styled BEC,
that is also capable of performing on rougher roads as well as off the road

when surfing the net for inspiration i seem to always land back on an old favorite ;
the Bowler Raptor concept;

typical for "designer cars" it is way over the top and would not work well in the real world,
but there are several details that are very inspiring to me.

i started a new CAD based on the clever "off-set" drivetrain layout of the Austin 7S...

..but this time with a shorter WB and a wider & shorter body/hood

more in my next post

 

[hackwelder]

Very cool! and FWIW the Austin 7 specials are what inspired Colin Chapman of Lotus fame. You might already be aware but there is a fairly big following for scratch built Lotus 7's (known as "Locosts") and some of them are bike engined. I got about half way through a Locost myself....anyway there are a bunch of Locost websites plus a group on Yahoo, would be worth checking out even if you want to stick to something closer to a Austin 7. Don't know if you have settled on an engine yet but would strongly recommend a big Triumph Triple, torque like a twin but winds up like a four and the sound is quite soul stirring...have owned many MC's over the years and my Tiger 955i had the best engine by far and that engine would be highly appropriate in a car inspired by a British design ;-)

 

[RoosterBooster]

Hackwelder
thank you for the suggestions

yes, i`m already a member of the LocostUSA.com forum and also like to visit the UK Locost branch for ideas

but to be honest a Lotus 7-ish kinda car is just not working for me
the design/look is not really pushing my buttons and the layout is too much "smooth street/track" oriented

on top of that i feel that it is important to keep this a single seater;
it absolutely has to be as compact & light as possible to not lug down the low torque street bike engine

yeah, i agree that the TT would be a awesome BEC engine ...
i dont really have a engine in mind (i guess i have to see whats available when i finally start building),
but it definitely has to be a rather large displacement/high hp engine
i have a soft spot for Yamaha (my last bike was a FJ1200 and i toured all over Europa with it)
a R1 is the lowest displacement engine i would consider for this

in my drawings i use a 1400 cc Hayabusa mainly because i found the exact dimensions online

the key feature of the Austin7S layout is the "off center" driveline;
it allows the driver to sit next to the driveshaft instead of on top of it,
what results in a very low profile (and center of gravity)
this works also perfectly together with the offset transmission output shaft of bike engines
here is a screenshot of the bare driveline layout;

click here for a higher definition pic; http://www.supermotors.net/getfile/1036158/original/spectre1.jpg

high res; http://www.supermotors.net/getfile/1036160/original/spectre3.jpg

high res; http://www.supermotors.net/getfile/1036159/original/spectre2.jpg

WB is ~ 86" with no overhangs and all the mass centrally located
weight distribution should be close to 50:50 front to rear
target weight is (hopefully) under 1000 lbs

i`m surrounded by excellent mountain/canyon roads (southern Utah)
but most of them are rather rough/bumpy and somewhat isolated,
so i think it is essential that i can carry a full size spare, at least 10 gallon of fuel and have at least 12" suspension travel
....

any comments and suggestions are very welcome

 

[NASTYZEN]

Perhaps rear engined? The grandfather of F-1 the Cooper.
This is the nicest one I've ever seen and the man races it to the limit. Quite beautiful to watch.





That 3 wheeled Morgan is just bad *** looking.
My ********* is to build myself a Harley powered one one day.

There's also the T-Rex 3 wheel design. They can lap faster than cars can at the Icar circuit here.
They have major grip.....when it's dry.

 

[Stuart in MN]

Some other websites for inspiration:

There's a 200 page long thread on the HAMB about cyclecars that is pretty interesting and fits the single seat with vintage looks idea: http://www.jalopyjournal.com/forum/threads/lets-talk-cyclecars.226791/

This guy designed a single seat, all wheel drive, Hayabusa powered track car: http://www.dpcars.net/ Look in his "PAST" section for the DP1. It's pretty modern and not very suitable for a street car but may provide some good ideas.

This guy built a mid-engine interpretation of a Lotus 7 that's pretty cool: http://www.midlana.com/index.html

 

[gus1962]

That's pretty interesting.

 

[hackwelder]

A few more things in favor of a Triumph Triple are the excellent low RPM torque, on my Tiger it would pull smoothly well below 2000 rpm (but would still wind up FAST and shriek above 5000)...also if you need to do any tuning (very likely if you modify the intake or exhaust plumbing) it only requires a $20 cable and free Tune ECU software if the engine has a Sagem ECU, there are lots of maps out on the web or you can freely modify your own, no screwing around with piggyback solutions required. Anyway, it would definitely be worthwhile to test drive a Triumph triple before making a decision..
Agree that plenty of suspension travel would be a good idea, I had a Birkin S3/Lotus 7 and eventually sold it partly because it was lousy on rough roads...like you I have hundreds of miles of twisty roads nearby (Calif. wine country) but many are rough...lack of ground clearance was a serious issue too.

 

[Jagmandave]

How will you handle reverse? Or is that what that little box is in the middle of the driveshaft?

On the Morgan three wheelers, they attach the bike motor to a Miata gearbox....

I was also working on a three wheeled BEC, I was going to use the Hayabusa also, but I was going to drive the front wheels so I wouldn't have any driveshaft to deal with in the car.

 

[GMBracing]

look at 600 ledgends race cars for inspiration or check out a modlite style car on racing junk .com

 

[nine4gmc]

Cool Project!

 

[iagsxr]

Yeah I was going to ask about reverse as well.

I'd use a 'Busa motor just because anything that's ever been done has been done to a 'Busa. The are many out there with turbos making huge power reliably.

If not 'Busa I'd look at a touring bike engine. Some have reverse and actually make good power. More importantly big torque.

 

[AgentZ]

'Busa V8? I dare you!!! I was going to link to dpcars but see someone has already done that!

 

[bullnerd]

You can see the revese box about half way down the drive shaft.

I gotta say Mr B., I was really looking forward to the original design. But you know I'm a big fan and I'm sure whatever you come up with will be sweet! Cant wait.

 

[RoosterBooster]

thank you all for the links and all the suggestions

yeah, the reverse could be done with a FNR box (forward/ neutral/ reverse)
the one in the drawing is actually a RFalcon FOR (additional overdrive) ;
https://sales.powergearperformance.com/RFalcon.pdf
at ~ $1000-1200 it is maybe a little too much for me ...
i rather spend that money for a LSD/E-locker combo diff and just watch where i park
... or get out and push

i`m fairly set on a front/midship engine
imho i never liked rear engine handling (all that junk in the trunk )
mid engine is problematic for the reason that i want to avoid a chain
(i prefer axle & driveshaft)
midi seat position is also too far forward for my taste (and virtually no frontal protection is bothering me as well)

another factor is cooling;
i definitely want a nose mounted radiator that is exposed to direct slipstream and connected to the engine with short coolant lines.
in my personal experience with building sand/desert cars i learned to avoid rear or forced air radiators

talking about sand/desert cars;
this was my old Buggy (i actually called it "Muggy" for its mustang drivetrain )

handling and weight distribution was just about perfect
the car was a blast in the sand, the desert and on the street ... i miss that thing

what i try to say is that i did the V8 thing already (even with 1000+ hp engines),
so this time i want something a lot lighter, smaller and cheaper

the great simplicity of Legends race cars has been very inspiring for me ...
but i do want a little more travel and independent rear suspension instead of the solid axle.

that brings me to the IRS i plan to use;
it is actually a Dana "super 30" IFS axle (2002+ Ford Explorer) turned around
initially i was going to use a Dana 35 (pre 2002 Exploder) but dumped that idea for its short halfshafts (limited travel)
and lack of available LSD diff
here is a comparison of the two axles with halfshafts;

the D30 housing is aluminum and surprisingly lightweight
Dana/ Ford did not use reverse cut gears on the D30 ,
so if used as an IRS it is actually running on the correct side of the gears

best thing is that there is a very interesting LSD/E-locker available;

Auburn Gear ECTED Positraction Locker
http://www.ringpinion.com/b2c/Produ...Front Diff - 4WD&DiffId=121&Source=DiffWizard

default LSD with the capability to lock 100% with the push of a button
...unfortunately not cheap at $1000+

 

[RoosterBooster]

I gotta say Mr B., I was really looking forward to the original design. But you know I'm a big fan and I'm sure whatever you come up with will be sweet! Cant wait.

Bull
thanks for the compliment

yeah, i liked the look of the A7S as well
but as i mentioned i just did not like the restrictions of that narrow teardrop body shape
it would wrap the engine too tightly ...
making any kind of future power upgrades like a turbo & charge cooler next to impossible

i just found a RC model that also seems to be inspired by the Bowler Raptor concept;
the Kyosho "Rage":

i`m thinking about a body/spaceframe of similar shape
however, obviously it needs to be tweaked for the real world
(that impossible low roof/high hood would not work )

i used Yamaha R1 headlights already on another street legal buggy project for their compact size and DOT numbers,
but i may shape the nose around Honda 1000RR headlights this time;
(cut in the middle and spread out wider)
i like the angry eye look .... and there are a lot of cool upgrades available like LED DRL, devil eyes, etc ;

... just thinking out loud

 

[bullnerd]

ETA for you first CAD model?

 

[hackwelder]

DeDion rear suspension might be a viable option too, works really well on 7's and unsprung weight is relatively low.
http://en.wikipedia.org/wiki/De_Dion_tube

 

[EdT]

Something to consider is when it's all done, will you be able to register it or is it going to be a trailered to the location kind of thing. The hassle of registering a homebuilt varies state to state and it may be dead simple where you live. Not so much where I live.

 

[rmmiller]

I have been in love with this one since I first saw it on the HD Forums!

 

[RoosterBooster]

hackwelder

thank you for the suggestion ... i appreciate different ideas

but i think on this project i`m going to stick to what i`m experienced with;
basically a "light" variation of the I- and H-arm IRS that i used on several other projects already.
i got it already drawn with all the pivot points established

high resolution; http://www.supermotors.net/getfile/1036467/original/rearsusp2.jpg

i prefer the I&H arm over a traditional double A-arm for "packaging" reasons
it is also a low CofG design with the beefy H-arm low to the ground and only a slim upper link

i used the same design on several cars , like on this front engine buggy i build over 10 years ago;

iirc i should be able to get about 11" of travel out of the stock Explorer axle shafts ...
custom axles would net more travel
but i try to stick to stock "off the shelf" parts as much as possible fore ease of replacement and to keep the $$ down

that is also the reason why i plan on using mass produced unit-bearings and brake discs.
only the brake calipers will be (aluminum) aftermarket ones

 

[nine4gmc]

Do you plan on using custom knuckles or will those be over the counter parts?

 

[theoldwizard1]

that brings me to the IRS i plan to use;
it is actually a Dana "super 30" IFS axle (2002+ Ford Explorer) turned around

That stupid stub tube will cause handling problems especially on hard pavement. Cut it off and figure out how to mount another half shaft.

 

[theoldwizard1]

but i think on this project i`m going to stick to what i`m experienced with;
basically a "light" variation of the I- and H-arm IRS that i used on several other projects already.

That is a good, simple design. Its biggest negative is camber change through the total travel of the suspension. The longer the arms, the worse the chamber change. Not a really big issue on IRS.

About the only IRS that has perfect chamber is a Watts Link on each side. COMPLICATED !

I would use Heim Joints or thread rod ends for the inboard pivot points for simple toe-in adjustments.

 

[RoosterBooster]

Something to consider is when it's all done, will you be able to register it or is it going to be a trailered to the location kind of thing. The hassle of registering a homebuilt varies state to state and it may be dead simple where you live. Not so much where I live.

EdT
getting it registered as "street legal" is not a big problem where i`m at
in rural UT & AZ you can register just about anything for the street as long as it has the minimal requirements like lights etc.
this rig will be under 1500 lbs so it does not need any fenders

Do you plan on using custom knuckles or will those be over the counter parts?

i could not find any uprights (or knuckles) that matched my needs,
so they will need to be fabricated

in the rear i`m planing on using the stock Explorer unit-bearings;

but probably drilled/machined to remove some excessive material/weight
kinda similar to this one;

at the front i`m thinking to use this Nissan Rogue 2wd front unit-bearing

it is already very lightweight and matches the rear bolt circle (5 on 4.25")

i considered machining the uprights out of aluminum bar stock,
but when i moved i sold my large mill and the midi mill i still have is just not up to it
so i probably just fab them out of waterjet cut plate
here are two screenshots of the front one with the Nissan bearing;

 

[-Brent-]

There are a couple electric reverse options. Some trikes use starter motors.

 

[creativecars]

Subscribed...

I started a much lower tech project before I moved and it still has not made it to the todo list.
How large will this project be? Do you have street/track/fun events in mind with this?

 

[bullnerd]

"The longer the arms, the worse the chamber change. "

Whaaa? Can you explain how the length of the "arm" changes camber gain?


I was sitting behind a Hyundai sedan in traffic the other day that had tail lights that would be a nice compliment to those angry eye headlights, looked just like them.

 

[theoldwizard1]

"The longer the arms, the worse the chamber change. "

Whaaa? Can you explain how the length of the "arm" changes camber gain?

Probably poor choice of words on my part. When I said "longer arms" I was implying further up and down (bounce/jounce) travel of the suspension.

 

[theoldwizard1]

EdT
i could not find any uprights (or knuckles) that matched my needs,
so they will need to be fabricated
.
.
.
i considered machining the uprights out of aluminum bar stock,
but when i moved i sold my large mill and the midi mill i still have is just not up to it

There are folks here who have the equipment. They don't advertise, so you may get a PM.

so i probably just fab them out of waterjet cut plate
here are two screenshots of the front one with the Nissan bearing;

Should I assume that the red and blue parts are 2 separate pieces ? Are you going to use a press brake to fold them and then weld them together ?

I probably don't need to say this but, make jigs to verify critical location points. I would at least cut out 2 of each.

 

[RoosterBooster]

Probably poor choice of words on my part. When I said "longer arms" I was implying further up and down (bounce/jounce) travel of the suspension.

like Bullnerd i have trouble to understand you there as well

IMHO the beauty of an unequal length, non-parallel A- (or I&H-) arm suspension is that you can set it up to get the exact chamber change you desire.
for example i may post a screenshot from when i set up the rear suspension layout;

i set the ride height at a slight negative (inward) chamber
the full compression (red) is set with lots of chamber gain to fight "wheel scrub" (track dimension change)
it also helps me to keep the tire vertical to the ground in a high G turn
(when the body leans into the turn)
i added also a lot of chamber gain for full drop (green)
again, mostly to fight wheel scrub on very rough roads

the green chamber gain is usually putting the outer CV joints to the limit of its travel,
but the nice thing on the explorer front "steering" axles is that the outer CV is a non plunging one (it allows a high degree of angle for tight turning)
my suspension travel limiting factor is actually the upper tripod joint...

very similar chamber changes are also designed into the front axle;

again, mostly to fight scrub (however, i had to compromise on the full drop due to balljoint & heim travel limitations)

 

[creativecars]

What wheel base and track width are you looking at?

 

[bullnerd]

"my suspension travel limiting factor is actually the upper tripod joint..."

Whats a tripod joint? I know what a tripod drive joint is ,but upper?

Looks great Mr.B

 

[theoldwizard1]

IMHO the beauty of an unequal length, non-parallel A- (or I&H-) arm suspension is that you can set it up to get the exact chamber change you desire.

But would you not agree that ZERO chamber change throughout the total travel of an IRS is optimal, at least for a car that has to make left and right hand turns ?

Hence my previous comment

About the only IRS that has perfect chamber (I should have said zero chamber change throughout the total suspension travel) is a Watts Link on each side.

"English is an imprecise means of communicating ideas."

 

[bullnerd]

"But would you not agree that ZERO chamber change throughout the total travel of an IRS is optimal, at least for a car that has to make left and right hand turns ?"

No...Mr.B explained why a few posts back.

 

[RoosterBooster]

Subscribed...

I started a much lower tech project before I moved and it still has not made it to the todo list.
How large will this project be? Do you have street/track/fun events in mind with this?

What wheel base and track width are you looking at?

sorry for not answering quicker ... i`m a slow typer
(English is not my native language )

things may still change, but as of right now i`m at 86" WB
Track is 60" front and rear (dictated by the stock Explorer axle parts)
outside tire to outside tire is 70" (with lightweight 17" FWD "deep backspace" rims)
overall length is 112" (no front and only very minimal rear overhang)
tires are ~ 26" tall (no radical low profile for a better "rough road" ability)
probably going to run a 225-235/50 ZR17 ultra high performance all season tire
(all season due to the altitude that i`m at)
fuel cell is a 10 gallon cross linked poly (24x9x12")that i plan to fully enclose

i`m making slowly progress with the frame drawing
here is a preview:
(still missing a lot of details ... and things still change from day to day )

high res; http://www.supermotors.net/getfile/1036534/original/spectre4.jpg

high res; http://www.supermotors.net/getfile/1036536/original/spectre5.jpg

high res; http://www.supermotors.net/getfile/1036538/original/spectre6.jpg

track day is definitely a possibility
but main target is just a fun canyon carver that is very rough road "forgiving"
(no need to back off the throttle for cattle guards etc )

 

[MillerMav]

Very cool build. I like the idea of the offset drive shaft to lower COG.

 

[buu]

Awesome.
If you need some help with parts design, I would be glad to help you

 

[RoosterBooster]

"The longer the arms, the worse the chamber change. "

Whaaa? Can you explain how the length of the "arm" changes camber gain?


I was sitting behind a Hyundai sedan in traffic the other day that had tail lights that would be a nice compliment to those angry eye headlights, looked just like them.

unfortunately car head/tail lights are probably too large for this little buggy
so i guess i have to use smaller MC lights front and rear

something that is "leaning over" would look good tucked under the rear tubing
so i`m thinking to probably use two LED ZX6R lights with amber turn signal function:

anything but regular round or oval

 

[bullnerd]

I hear ya, the modern car housings are huge!

 

[petawawarace]

For reverse, mount a ring gear between the driveshaft and diff yolk. Then use a starter to drive it backwards. You can even get real lightweight starters to keep things light.

Looks like a cool project. I really like the look of that RC car. Like a modern George Barris.