steering question

[Deleted]

If I want to keep a motorcycle type look to an RT, including using MC handlebars like can ams etc, would I get a decent enough turning circle using one of the small dune buggy type rack and pinnions?

[Liteway]

Hard to see how an r&p would work with handlebars. Anyway, buggy units are not recommended for street use. There is a reason they cost so little,as quality is relatively poor, at least the Empi unit I tried. Your choices are a production unit(like Mustang II) and a high quality custom (exspensive) unit. If you want handlebars, you might try to copy the CanAm set-up,though it may be complicated with its pwr assist and electronic nannies. By the way welcome to the forum.

[Deleted]

thanks for the welcome triplethreat. Thought that would be the case. Will have to dig around and see what sort of setup the can am has. Just dont want a reverse 3 wheel "car" style with a steering wheel and sitting in it rather than on it. If im going to do it, I want to sit on it like an mc holding the bars if poss. Is this a possibility?

[joeld0803]

If there is a will there is a way I assure you but it will take some studying up on it and seeing pictures of different designs will help you make a decision.

Welcome

[Liteway]

Has anybody seen pictures or diagrams of how the CanAm steering works? I'm curious about it also.

[joeld0803]

Can-Am Spyder Roadster Steering - 2008 CAN-AM SPYDER ROADSTER ...
2008 Can-Am Spyder Roadster problem with Steering. 2008 CAN-AM SPYDER ROADSTER Steering problems.
www.arfc.org/complaints/2008/can-am/spyder_roadster/...

They apparently has steering issues and recalls..

[hangonrider]

I plan to use atv type steering the type on the newer ones with power steering verry simple easy to instal

[joeld0803]

I have about 3-4 degrees of positive caster in my front wheel geometry and have noticed that I have no returnability of the steering wheel to nuetral.

I am using the mustang II front spindles and a mustang II manual steering column and the front end seems free enough and not binding up any and it steers relatively easily but doesn't return. I don't seem to have any issues with alot of in or out toe nor camber problems.

Ackerman my still be a little off but not certain what the issue is.
It handles the bumps very well and I don't feel any kind of bump steer issue.

Any suggestions?

[DaveJ98092]

Well Positive Caster is what you build in for that returnability. So you could add a bit more Positive caster. You could move the upper control arm back a bit or the lower one forward a bit. Ether one will rotate the steering knuckle's top back a bit more positive.

I take it you have put it on an alignment rack and are not quoting the "SPEC's" for the Mustang ll from the book?

How are the angles of the tie rods?

Rack and pinion steering does not like input from the rack side as much as from the pinion side. The more direct from the wheels input, the easier for it to return to center. If the angles are sharper the effect will be less.

[DaveJ98092]

Apr 23, 2012 5:09:44 GMT -5 @ronin said:

If I want to keep a motorcycle type look to an RT, including using MC handlebars like Can Am's etc, would I get a decent enough turning circle using one of the small dune buggy type rack and pinions?

You could keep the handlebars with a POWERED rack and pinion if you use a steering "2:1 Quickener" on the shaft. www.summitracing.com/search/?keyword=quickener&dds=1

It will not fix everything as you can not do a full turn with handlebars with controls as the cables or hoses will bind. A 2:1 QUICKENER will make a 3 turns lock to lock Rack a 1.5:1 But will also make the turning force much harder so a powered rack is better.

[joeld0803]

I haven't had it on a rack yet as I am still working out a few issues with the engine and chain connection.

The rack is manual and it is inn straight alignment with the spindle arms. Maybe a hair off to the front but pretty much straight dead on so the steering knuckles are not really being pulled forward nor backward.

I have a feeling my angle may be a little more positive than I originally posted closer to around 6-7 degrees and that could be the issue but if it helps with stability at higher speeds then I will rather deal with it I think. It's not like I am laboring to steer it but used to a steering wheel returning to neutral more or less.

Due to the weight of the car and being lighter than 95% of the cars out there I might want the steering to be tighter more or less to cut down on roll issues.

Thanks for the response.

[Deleted]

MC to RT is pretty straight forward. The key is caster, more = stability less = easy steering. You have to find a happy medium which is normally 5-6 degrees.

I am on my 4th RT now which is a GL1800, here is the link to a couple others www.rtrike.com

The other trick is to get the center of balance as close to the front wheels as you can and again longer wheelbase = more stability.

As far as steering head - it's simple tie rods and the steering shaft just couples to the original bikes triple trees,

[DaveJ98092]

Apr 23, 2012 5:09:44 GMT -5 @ronin said:

If I want to keep a motorcycle type look to an RT, including using MC handlebars like can ams etc, would I get a decent enough turning circle using one of the small dune buggy type rack and pinnions?

If I were to build a handle bar steering I would just make a shaft with a L bracket at the bottom with Heim joints going out to the steering knuckles. The shorter the L the less the knuckels get pushed and is slower. A longer L will make it quicker. look at the Eco-Exo kits steering.

[Liteway]

It looks like this would result in tie rods much longer than a-arms resulting in bump steer.

[joeld0803]

I would agree with Tripple on that concern.......but I think bump steer also mainly depends on the amount of up and down travel the spindle does. The more travel the worse the less travel the less bump steer.

Minimizing the cushion give by stiffening up the suspension would reduce it and the fact that the steering arm is so long it has a larger outer radius circle diameter of travel so therefore not as likely to be too aggressive. A shorter distance steer arm pivot outside of the centerline of the A arm pivot would cause far more bump steer than the long arm inside of the centerline.

My project has longer arms and they are offset to the inside of that upper and lower A arm centerline and I have very little bump steer characteristic.

I would be more concerned with oversteer concern due to the steering mechanism leverage point. From what I see it that very little movement of the steering wheel would be pretty aggressive on the spindle movement and at higher speeds could be very difficult to steer it without some sort of power assist.

Just my 2 cents worth which isn't much.......LOL!

[painter]

I too agree with JOELD0803 but after a little thought see if this makes any sense.... The centrifical force of the turning wheels tend to keep them in a straight line and with no power steering, the movement could not be as quick and dangerous. The videos of the Eco Exo seem to indicate this. My concern would be at slower speeds.... not sure I have enough 'muscle' !!! The Can Am Spyder uses power steering below 20 mph and it cuts out over that speed. Seems to work.

I very much wanted to use handlebars simply because hand controls are better and more sensitive than foot controls. Many builders stall out or rev too high to take off with foot controls. Secondly, after all, it is a 'motorcycle'!

[endeavor]

RT steering geometry really takes advantage of standard automotive steering geometry with a few extra ingredients. First you are correct with 4-6 degrees of positive caster. Too much and steering will be difficult as the trike will fight in the corners. Too little and you will experience the Burt Monro high speed wind wobble.
Camber is normally set to zero so toe should also be zero in most cases as toe merely compensates for camber. Offset is normally set by the spindles and is non-adjustable.
The other important little things are with wheel base - width vs length and placement of center of mass.
Ideally the length should be greater than the width. On a typical MC conversion the width is 60 inches and length 70 this will allow for minimal caster yet offer a 20 foot full circle turn.
In the perfect world the center of mass should be just behind the front axle so the bulk of the mass is centered over the wide area of the RT "triangle"
However one must take into account while hard braking the center of mass should be far enough back to prevent stoppies. As with all things there is a trade off.
And a firm, very firm anti-sway bar is a must. Typically I use a non-bendable arrangement and take advantage of rubber cushions on the bar ends along with vulcanized A-arm bearing mounts to allow for some flex.

There really is a science to all this as the arrangements of one component will affect the performance of other components so a balancing act is also part of the mix.
Even after 5 years and 70k + miles I am still fine tuning the perimeters.

ido-endeavor.com/why-reverse/