Reverse Trike Suspension?

[unclejemima]

Calesta, I know you don't like PM tech questions, and I figure this is the most related place I could post this...you have no idea how hard it is to find tech questions on building a reverse trike ;-)

I built this...

2008 Honda CRF230L with a 400ex front end, 700xx sway bar, Houser 450R +6" A-arms, TW200 rear rim spoked to CRF hub, TRX450R shocks, extended swingarm and much more.

I built mine to drive in winter (I live in Northern Canada) as I get PMS for 6 month of the year (parked motorbike syndrome ). I've got a 145/80R14 bridgestone winterforce tire on the way from the UK for the rear, so ignore the current tire. There is only room for a 145 tire in the back but there is PHYSICALLY no 145 wide tires for 14" rim that I could find in North America. Plus this is uni-directional and a winter tire

Anyway, long story, but the issue I'm having is stability. Its VERY twitchy at anything over 30mph. I've installed a 700xx sway bar to the front that helps a little, but its VERY sensitive to the smallest steering input. I think the shocks may be to soft and causing the problem.

Any tips on this? I wonder how yours is so stable?

Thanks kindly!

 

[unclejemima]

PS...
I tried the leaning thing as well. Not as easy as it looks. (see youtube vid Honda CRF230L Leaning Trike - YouTube )

It may work good standing still, but when you drive it may not work very good at all, as it was in my case. At least I tried!

If you want, I did more research after I attempted this and found an engineer who built a working 3 wheel leaning trike and he gave me lots of tips. I can post them if you like.

 

[JoeDaddy]

Need to let me have a crack at the fabrication of the front nose and fenders. lol, nice trike

 

[unclejemima]

Here is a short of the front end. Parked with my brothers bikes. I still need to fabricate the front bumper. I tied to use off the shelf parts as my time is very limited.

That YouTube vid was just a working photo

 

[unclejemima]

The fenders are attached to the front spindle so it moves with the tires as it turns and the suspension moves ala bombardier ds650. Works pretty good

 

[vtecsir1]

you should of just started a new thread, cal would have seen it.

 

[phunky.buddha]

I'll split the thread later- replying so I know to reply to it later. Gotta go to bed for now- been a long week.

 

[phunky.buddha]

Now that I've read through and watched the video- Wow, very nice! I like it a LOT. You honestly have a lot more proper engineering in yours than is in "mine." I didn't design it- just threw in a few pointers before it went together. I would have done it quite a bit differently if I had designed and built it myself. In fact, I'm planning one on my own that's a little uh... heavier.



I honestly couldn't tell you why ours was more stable- more likely because there was a lot of weight in the front end that made it understeer more. The front end was a complete ATV front suspension setup that was grafted into position. Depending on how you built your front suspension, you'll want to really check your alignment settings- caster and toe make a HUGE difference.

Your weight distribution vs spring/shock setup might be way off too- see what your trike weighs at each wheel with you on it, then calculate motion ratios for each wheel and factor in your springs to see what the wheel rates are. Ideally you'd be at 33% per wheel (betting you have closer to 50% rear), and then you could balance the springs/shocks to match.

Your leaning setup might also be affecting your high speed balance- try locking out the lean function and see how it feels... but don't turn too much with it. Start isolating factors and see what helps.

All these are just suggestions- fabricating an entire chassis/suspension from scratch (what you've essentially done) can be pretty damn difficult.

 

[unclejemima]

Thanks for the reply. I appreciate the info.

The leaning mechanism was scrapped as I found it did not work that well. I had to convert it back to a fixed trike (aka can-am spyder)

I have a 1/4" toe in. Perhaps I should reduce to 1/8" or even slight toe out?

Any suggestions for negative or positive camber? They are fully camber adjustable a-arms with sli-cast (quick adjust camber).

I'll check the shock/spring setup as well. Good tips.

Thanks,

 

[unclejemima]

oops, I mean sli-cast is caster adjust. The camber is adjustable as well, but with a different system. I have a lot of negative camber setup right now. Perhaps I'll try to lessen that. I got the idea from the Milliken camber car. (check wiki, very neat!)
Should I try positive camber?

 

[phunky.buddha]

Toe out will only make you less stable, although closer to zero might make your more stable if your tires are skipping... maybe? Same with positive camber- stay negative, but not an extreme amount- just enough to bring the outer wheel upright (or just before) when you're in an extreme corner.

The main thing I'd look at now after you get your alignment set (or before) is your weight distribution and the springs/shocks. You might also want to check the angle of your control arms' pivots- do you have a dive/squat prone setup? Usually it's a good thing to have the upper control arms angled slightly back compared to the lower control arms- more stability under braking.

Of course, this is all just based on my limited knowledge of suspension... we got lucky with the Ruckus Trike and it just worked without any weird handling issues.

 

[unclejemima]

Good tips. Thanks again.

What make/model front end did you use out of curiosity?

Thanks,

 

[phunky.buddha]

Welcome. Go hunt up information from a guy that built the "Shrike" and read up some on reversetrike.com. There's a ton of junk to sift through, but the Shrike guy has some good information.

Honestly, I think part of your instability is in how you keep your shocks level while tilting the trike. I'm working to solve that problem myself.

And as far as the front end, I'm really not sure where it came from. I'll ask Phillip, but he might not even remember.