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Blackjack

Building a Bike Based Trike

36 posts in this topic

Building a Bike Based Trike

There's two ways to do this, one is to go off and re-invent the wheel, the other is to tread the path of least resistence. If you're thinking "Yeah, re-invent the wheel, that's for me..." well the doors over there, off you go, and good luck.

Clearly there are two basic elements to a baike based trike, you got the bike, you got the axle. Starting with the obvious lthere's the bike to consider. Chain drive isn't impossible, but it does bring a lot of problems with it, though admittedly none of those are insoluble. However, there's something that a lot of people miss here. It's all very well converting an axle to chain drive and screwing around with all that, but if you have to stop and re-pack the differential with grease every 50 miles, in my book you didn't solve the fucking problem...

What I'm trying to do here is sketch out the basics for building, with minimal effort, a trike where the aim is to have the sort of usability you'd expect if it came from the factory that way. Get on it, ride it 1000 miles, only put gas in the tank, air in the tires, and check the oil. Reasonable MPG, and the ability to both climb hills and cruise at highway speeds (or better...).

First thing then is to choose the base bike carefully. I've already implied that it ought to be a shaft drive bike, but I'd lean towards either a Suzuki or a Yamaha as opposed to a Kawasaki or a Honda. Kawasaki make some fine motorcycles, but they use a weird fitting on the drive shaft of their shaft driven bikes. Not an insoluble problem, but an unecessary one. Hondas, well TBH, I plain don't like Honda's design philosophy, theyre way more concerned about showing the world what a bunch of smartasses they are than actually making usuable products. Because of that prejudice, I've never looked that closely at how they hook their drive shafts to their motors. What you're lookng for is a flange with four bolt holes in it, get a manual, look at some pictures.

Suzuki and Yamaha tend to use four bolt flanges on their shaft drive stuff. This makes them pretty easy to adapt to drive a car axle using a hydrid drive shaft. Some Yamahas have a cast knuckle on the drive shaft (V-Max for one) which is fucking horrible, but uses the same spline fitting as the flanged ones, so bolting an XJ 900 flange on there is pretty straight forward on all the ones I've ever encountered (though that's not all of 'em...). Some, if not all Yamaha flanges (dunno about Suzukis) have the same bolt pattern as some Toyotas, which makes life easy if the budget stretches to having a drive shaft built using new parts throughout.

The majority of bikes have the drive shaft on the left of the bike (though some, BMW, Gold Wing, Moto Guzzi, have it on the right), and most (though not all) car axles will have drive shafts that rotate the opposite way. That may be a factor in making a decision about a bike if you're planning on covering literally tens of thousands of miles a year on the finished trike. A bike with a drive shaft on the left, will normally mean flipping the axle, and that in turn means the hypoid cut rear axle is running backwards, this will increase the wear on the axle. Instead of lasting for 100's of thousands of miles hauling several tons of car around, it'll probably only last the 100,000 miles hauling nowhere near a ton of trike around. Yeah, fuck it was what I thought too...

OK, you picked out a bike, what's next? Well the rear wheels and tires believe it or not. Two reasons, the rear wheels and tires will affect the height the rear axle needs to be above the ground. Pretty hard to sort out the frame if you got no idea where the axle has to go...

Second thing is that the taller the rear wheel and tire combo you choose, then the further the wheel (and hence the trike) will travel for one turn of the wheels. Taller wheels, you need a taller diff ratio, so not only does the height of the wheel tire combo dictate the position of the axle, it has an effect on the choice of the final drive gearing too.

That's a major issue, as I see lots of trikes that are just plain fucking unpleasant to ride because they're screaming their tits off at 10,000 rpm at 70mph, and more rarely I see one that's a bitch to hill start because the gearing is to tall.

Either count up, or look up, the reduction of the stock final bevel on the bike. Say it's 3:1 that means that for one turn of the drive shaft, the rear wheel is turned by 1/3. The next bit is either obvious, or you just want to trust me on this, the height of the stock wheel/tire combo divided by the ratio (in this case 1/3) gives us a "magic" number. So if, in this case the stcok wheel/tire was 24", the Magic number is 24/3 or 8.

If the new wheel tire combo has a height of 28", divide that by the "magic" number and you get 3.5, which means that using those wheels and tires, you'd need a 3.5:1 final drive to keep the stock gearing.

As a rule shooting for 10% lower gearing is the safe bet, so I'd be looking for an axle with a final drive ratio of between 3.85:1 to 3.5:1.

That holds true for whatever you decide to do at the rear, IRS or rigid.

For my money, IRS (or any rear suspension) is a waste of time and effort on a trike. Rigids ride nearly as good and handle better. You know how riding bitch on a rigid bike is way more uncomfortable than actualy riding it? Well that's because the further in front of the axle line you sit the smoother the ride is. I set rigid trikes up with the center line of the axle where the rear most edge of the stock wheel used to be, and that seems to work.

This also make the wheelbase a little longer which helps with the stability quite a lot (less chance if steering wobbles) and reduces the steering effort a little. Combined with the more forgiving car tires (taller profiles make more sense here...) and the fact that if one rear wheel hits a 4" bump, then the diff only goes up 2" make the ride a LOT more comfortable than a rigid bike.

I like axles out of leaf sprung cars as the "perches" for the laef spings are easy to make mountings to suit. Bolted on using the stock locating pin and "U" bolts, if it turns out you screwed up and misaligned the axle, it's easier to fix the alignment issues.

BE ABSOLUTELY CERTAIN that when you apply drive to the rear axle, it's going to go forwards. As I said earlier, if the bike's drive shaft is on the left, then this will usually involve flipping the axle over. At this point the axle's breather will dump oil all over the floor. So you'll need to deal with that. Last one I did, I tore the breather off, cut some rubber and a piece of steel, then hoseclipped that over the hole to seal it. Popped off the pressed rear cover, drilled a 5/8" hole in that and welded in an elbow. Re-fitted the cover, an fitted a little K&N style "filter" to the elbow.

That was because, where possible I don't like to weld on the axle, because if I don't weld on it, I can't distort it.

People who are saying things like "Yeah but I've got a fucked back..." should take into account that IRS set ups fall OUT in bends and that has serious implications for the steering effort which ALL has to go through your lower back.

Moving the axle line back a little also means that the UJ's in the drive shaft are at less of an angle and will have a much easier time of it. Last one I did, I had the drive shaft custom made, and it sounded like quite a lot of money, until you looked that the cost of swapping out used UJ's for new ones if I made the shaft myself. By the time I'd factored in hunting around for parts, it was starting to look cheap...

Rear brakes, well I just use what came on the axle, most Euro stuff seems to work best with a 5/8" master cylinder and a 6;1 pedal ratio. American stuff might need a bigger bore m/cylinder, not sure, ask some Hot rod guys, or midget racers or something. Or choose cheap, generic stuff that you can swap out if you need to. :ph34r:

There are some issues with UJ phasing, flange alignment, and that sort of shit, but there's plenty of "how-to" hot rod tech articles out there that cover that stuff.

Frame, well remember that trikes experience much larger lateral loads than bikes. You got two major choices going this route, attaching the axle to a mostly stock frame to build something that's more or less going to look like a stock bike with three wheels, though is you started with something like an XVS650 Yam, that could be quite cool, or you appraoch the thing a little more full on and keep the lower half of the engine cradle from the stock frame and approach the job more like hardtailing a a stock frame to get more of a "chopper" profile.

Last word, trikes work best with WAAAY less trail the bikes, and they subject the forks to all sorts of horrible forces that forks in general aren't very good at. You want long forks and big rakes, girders or leading links is the way to go. Trail numbers between 1 1/2" and 1/2" (yeah, half of an inch) work best.

Paraplegics may NEED to have those sort of numbers to be able to steer the thing at all.

That's it I guess, hardly comprehensive, and certainly not the only way to go about it. But on the other hand it's laid out a few of the major pitfalls (ans the solutions), and if all you want is a trike, then that's about the easierst way to get there.

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Nice write up. :whistling: I like trikes...I know some don't care for them. I hope more take the info to heart and do it. :thumbsup:

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Guess I could've spiel chicked it first though. Rather a lot of typos in there....

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Forget about the typos, it's the information that counts. I plan to build a trike some day. Have you ever experimented with anything that comes with reverse? I think some of the Goldwings had it if I'm not mistaken. The only thing that doesn't apeal to me about trikes is pushing the damn thing backwards out of a parking spot.

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Forget about the typos, it's the information that counts. I plan to build a trike some day. Have you ever experimented with anything that comes with reverse? I think some of the Goldwings had it if I'm not mistaken. The only thing that doesn't apeal to me about trikes is pushing the damn thing backwards out of a parking spot.

Errr....

You got reverse on your bike?

Nah, you just use a bit of common sense when you park it up.

Which ought to work on a trike too.

About 40 secs into that, I'm turning it round, but using the hill to roll it back.

Bit later I'm paddling it back, TBH, it's probably easier than a bike, you can't drop the fucker for a start.... :ph34r:

If you got a Gold Wing with the electric reverse and triked it, I can't think of any reason why it wouldn't work.

Quaife do a reverse splitter you can fit in line between the motor and the axle that lets you switch from from forward to reverse (gives you just as many reverse gears as you got forward ones, goes just as fast backwards....) but those are nudging $2000 over here.

Getting adventurous, you could use a small four speed manual tranny from something RWD as part of the driveline from the motor to the axle, 4th gear on most four speeds is 1:1, so there you go, normal forward service. Select reverse on it though, and you got a crawler reverse gear.

Other more Heath Robinson arrangements involving sprockets/pulleys between the drive flange, starter motors out of cars, jack shafts, and dog clutches are sort of possible. You need the dog clutch so the motor doesn't get driven, generating a current and burning up the windings, when you're not using it. Apparently, you're looking at wiping a motor out every time you do 30 miles in a hit otherwise.

Cheapest, least hassle way to get reverse, build a car derived trike. B)

Doesn't have to be bad ass V8. What's a 2 liter Pinto worth? Pretty much anything with a conventional RWD set up is game. I'm probably going to be building one out of a Reliant Robin soon. Not because its a stupid ass three wheeled car, but because it's got a sweet little 750cc in line four in it, and a tranny and axle to match.

But that's car derived trikes, and another thread really... B)

Edited by Blackjack

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Just plain awesome write up Blackjack!

I intend on building a trike some day down the road as well. Figured I would gather stuff here and there.

What car rearend would be a good starting point to keep an eye out for? Is there any out there that don't have to be narrowed or altered besides flipping upside down?

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Just plain awesome write up Blackjack!

I intend on building a trike some day down the road as well. Figured I would gather stuff here and there.

What car rearend would be a good starting point to keep an eye out for? Is there any out there that don't have to be narrowed or altered besides flipping upside down?

I'd get the bike first. Then the wheels and tires (or at least some hard information on the diameter of the wheels I wanted to use) and then work out the final drive ratio I needed.

Then look for an axle with that ratio, the sort of width I wanted (if that's possible/likely), that was originally mounted on leaf springs.

Stuff with four link suspension is usually going to mean cutting all the mounts off and welding something else on there. There is no sensible way to do that without stripping the axle to a bare case and that means new seals, bearings, what have you really.

You can take an axle that strikes you as really easy to mount, clean looking, and cheap, but if it's got the wrong final drive ratio in it....

Pretty much any bike with the shaft on the left is going to need the axle flipped.

That V-Max has a bone stock Ford Capri axle in there. I believe it was sold as a Mercury in the US. That one came out of a 3 litre V6, but those came with 3 different diff ratios. I just built the frame with mounts to accept the stock leaf spring mounts and it bolts right up with four "U" bolts. The mounts on the frame have a pin sticking down that does the actual locataion, the U bolts just clamping it against the pin. I figure if it that's good enough to accelerate a heavy ass car....

Edited by Blackjack

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Got this from blacksmithbilly, I think :ph34r: don't remember for sure, flywheel and car stater motor. Reverse.

post-7756-1246300820_thumb.jpg

Forget about the typos, it's the information that counts. I plan to build a trike some day. Have you ever experimented with anything that comes with reverse? I think some of the Goldwings had it if I'm not mistaken. The only thing that doesn't apeal to me about trikes is pushing the damn thing backwards out of a parking spot.

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Got this from blacksmithbilly, I think :ph34r: don't remember for sure, flywheel and car stater motor. Reverse.

Should work.

Though the "bacon slicer" being to lowest point between the rear wheels might be a worry..... B)

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did you happen to take pictures of how you atached everything?

it looks like you was able to center the rearend with bike so did you use something to move the drive shaft over on the bike? i cant realy tell in the video. i only ask because ive got a good start on my kz1000 and i used a s10 rearend but had to move it over to keep the driveshaft strait. and now realy need to cut one side down and realy dont have the money to go threw that so just looking for more ideas. thanks.

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Thanks Blackjack, the info is much appreciated!

Regards,

Rev. D.

Edited by Reverend D

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did you happen to take pictures of how you atached everything?

it looks like you was able to center the rearend with bike so did you use something to move the drive shaft over on the bike? i cant realy tell in the video. i only ask because ive got a good start on my kz1000 and i used a s10 rearend but had to move it over to keep the driveshaft strait. and now realy need to cut one side down and realy dont have the money to go threw that so just looking for more ideas. thanks.

Ha Ha...

Got a little more than a few pictures dude.

But in the mean time.

Shaft doesn't run straight in the bike, it goes up and down. There's no need to offset the diff as long as you're not using big angles.

I like to set them back a little further than the bike wheel, keeps it from being too twitchy, gives it a better ride, and keeps the drive shaft angles sensible. If you run UJ's with no angle at all, you can beat the crap out of the needle roller bearings (look up brinelling if you want more detail on that), so you need some angle there.

Edited by Blackjack

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What's the rear suspension?

Looks like trailing A arms, but I cn't relly work out wht's going on there in the pics.

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Looks like a 3 link to me. Similar to a Suzuki Sidekick/Geo Tracker.

The 3rd link in the Zuke is a wishbone with the legs pivoting on the frame and the center on top of the pig.

I have 2 X90s and it's a neat setup. Coilovers and you're set. (and the axles are pretty narrow, I'll measure them later for future reference)

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Can we get this pinned please, some great info here and it could be hard to find later on! Thanks Blackjack, great little write up.

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ummmm...it's pinned already.

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ummmm...it's pinned already.

Whoops... :whistling:

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Maybe I'm the only one but I'm just not a big fan of a trike that looks like it was done by just removing the swingarm and bolting on an axle, as in leaving the stock rear fender and etc. just hanging in between the tires. A lot of them are done that way, I just don't care for the way it looks. JMO

"Rebel Jack" of http://www.rebelcatalog.com/html/rebelpics.html seems to have success using rear diff's from ATV's...

thoughts ?

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I tend to agree -- it looks like a budget conscious way to do it (and there's alot to be said for that), but at the same time I'm not a fan of the fiberglass "trunks" that alot of the pricier trikes have out back :unsure:

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I tend to agree -- it looks like a budget conscious way to do it (and there's alot to be said for that), but at the same time I'm not a fan of the fiberglass "trunks" that alot of the pricier trikes have out back :unsure:

all the looks aside

imo they are a bit narrow and a little light duty.... with the length of most axles in one gets bent a tiny bit there will be issues... in the dirt it will not be a problem.

cours i am a little bias towards independent suspention ...

stace

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I'm a bit bias to shortened car/truck rears myself.

post-7756-1300327497_thumb.jpg

I tend to agree -- it looks like a budget conscious way to do it (and there's alot to be said for that), but at the same time I'm not a fan of the fiberglass "trunks" that alot of the pricier trikes have out back :unsure:

all the looks aside

imo they are a bit narrow and a little light duty.... with the length of most axles in one gets bent a tiny bit there will be issues... in the dirt it will not be a problem.

cours i am a little bias towards independent suspention ...

stacepost-7756-1300327536_thumb.jpg

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I found this setup, looks like it's been adapted from an ATV...

as such, I reckon it shouldn't be taken to speeds above 45 mph ?

post-1139-1301669787_thumb.jpg

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