Building an IRS type suspension for your trike

[BIBS]

Hello all!! I'm a newb here...and I really like what I see in this great Site!!
I have an Idea to make my own IRS rear for a lighter weight trike such as mine.
My scoot weighs in at about 700lbs.
It would have spider gears in an enclosed pumpkin, with short drive shafts,a disc brake on either side with about a 9" rotor...utilize wilwood brakes and have a set of Airshocks...one per side.
I have rough sketches on the drawing pad...but they arent presentable to post.

When I price out these rears,I see price tags of 7 grand plus!!!
I'm a poor boy living on a disability pension from the VA.(disabled Vet)
I'm a pretty fair welder,have access to a machine shop,have some machine tools myself and I love a challenge!!!

Eventually I'd like to fit up the rear for my own trike and perhaps offer detailed plans for anyone interested in doin one themself.anybody have an Idea or three?

 

[1550vt]

The most difficult part will be the suspension and drive components. If you are going to do this from scratch...I would start cruising the junk-yards for small British/European vehicle components. Maybe the suspension components/axles, etc. either off the rear, or front could possible be "married" to what you are trying to do. You will have to figure out how to get a chain-drive in there if you want to go that route and my have to purchase that "chunk" from one of the kit suppliers.

Lehman uses Ford components married to parts from as far away as Argentina, many of which local auto dealerships can even identify....if they can do it, you can too.

 

[Nauga Mok]

Check "Skip20's" posts. He put a Mazda IRS on one of the older Wings. He did a great job of documenting with pix. He also rebuild a crunched body for it. Came out NICE! He build a spare body patterned of the one he repaired & might still have it.

NM

 

[BIBS]

Hey skip20...you out there?

I found his thread on the goldwing....that what your talkin about?
http://rides.webshots.com/album/574919979juLqDQ

He's really talented!!!!!
what I would like to do though is make up something dedicated to chain drive with out too many angles,changes in drive direction if that makes any sense.
Ideally...if I had an exploded view of the DNA rear I have.....I could almost take it from there myself.
If anyone has access to it/one...please let me know,I would go as far as to call DNA on monday to ask if they'd sell components of the rear they distribute....the pumpkin is half the battle with the spider gears in it.

 

[BIBS]

Here's a thread I came across from a fellow over on chopperweb.net
>>chain driven diff !!!!!! - 100% Biker & Trike Magazine Forums

If ya scroll down about 2/3rds of the first page you can see some detail as to the "pumpkin" that retains the spider gear arrangement.
I question the logic of 1 disc brake rotor though................I think that each wheel would have to have it's own rotor.

 

[Terry Trikedude]

OK Bibs... I read all of the threads from the link you posted and was quite impressed as to how many people in that thread seamed to know a lot about difs. For the most part they all have made good some what correct statements about difs how ever not a single one of them understand how a single inboard brake works with a true dif. With a true dif. you have a planetary gear setup... which means that the housing of the dif. is turned by the drive sprocket, pulley or drive-shaft ring-gear from the drive train of the trike. The housing is turning which is driving two beveled gears around two independent half axles which intern turns the half axles which are attached to the wheels thru CV joints and hubs, thus the wheels turn. Now this is what they call limited slip drive...and that is what allows the trike to go into a turn WITHOUT the inside wheel skipping. Now with that said that means an inboard brake attached to the dif housing will brake both half axles together thus stopping both wheels. Now it is true that having a brake on both wheels has more stopping power than the inboard brake because... there is more surface area in two brakes than there is in one brake. Also I saw one comment about when the inside wheel lifts off the ground and you are in a braking situation that the other wheel will not brake....'NOT TRUE' well in the first place we are talking an IRS here NOT a fixed axle... IRS's do not lift the inside wheel period.

 

[Terry Trikedude]

I didn't mean to write a novel but I needed to make sure you understood how a dif worked. Also all I have used is inboard brakes on all of the trikes that I have built and they all stop well.

 

[BIBS]

Terry...your explanation makes sense to me!!
What I'm hoping to find is SOMEONE that has either done what I'd like to do or perhaps someone that would care to participate as far as Ideas,parts sources(on-line or otherwise).
I'm reasonably certain I can do all the fabrication but Pictures of different IRS rears would be helpful along with parts sources.

 

[1550vt]

Terry is exactly correct. The belt, chain, or shaft turns the ring gear in some fashion. If you slow-down, or stop the ring gear....you slow-down or stop it all.

The only drawback I see is additional wear on the pads and rotor of a single-disc set up, but there are lots of them running around out there and they work. Terry seems to have built a few of these and I am sure the pads, calipers and rotors are designed to last. I wish I could get a single inboard brake on my Lehman belt-drive setup, but I would have to completely rebuild the diffy housing to do so.

The small differentials that I have been into are very strong. Lehman uses one of "unknown origin" that no local auto dealership, or mechanic can identify around here. I think it came from some un-imported foreign compact vehicle.

 

[BIBS]

Terry is exactly correct. The belt, chain, or shaft turns the ring gear in some fashion. If you slow-down, or stop the ring gear....you slow-down or stop it all.

The only drawback I see is additional wear on the pads and rotor of a single-disc set up, but there are lots of them running around out there and they work. Terry seems to have built a few of these and I am sure the pads, calipers and rotors are designed to last. I wish I could get a single inboard brake on my Lehman belt-drive setup, but I would have to completely rebuild the diffy housing to do so.

The small differentials that I have been into are very strong. Lehman uses one of "unknown origin" that no local auto dealership, or mechanic can identify around here. I think it came from some un-imported foreign compact vehicle.

Roger...does lehman utilize a straight axel concept?

If so,I may be getting a case of "cold feet".
I'm looking for a project for the late fall early winter months.....Now I'm reading that straight axel trikes hold the road better on curves than do IRS type Rears.
Whats the story?

 

[1550vt]

As far as I know of at this moment, all Lehman kits are straight axle designs.

This is not a "knock" on the trikes with IRS and most people say they handle very well in the corners. But....it takes a bunch of additional components to make an IRS do that as opposed to a straight axle design. There can be no doubt that the IRS design is a more comfortable ride than a straight axle going down the interstate, but with suspension improvements (as opposed to just simple shocks) you can get a comfortable ride with a straight axle and one must never forget to consider that tires are also an important part of the suspension system. Just a few pounds one-way-or-another can make a huge difference.

 

[BIBS]

YEAH.....um thinkin here that I got over my head on this Idea about an IRS suspension,but by the same token I'm surprised more people havent posted something to the effect of expressing an interest in delving into the project.

Oh well.

I'm going back to my trike table and chain adjuster starting tommorrow(teusday october 26)

 

[Terry Trikedude]

Originally Posted by BIBS

Now I'm reading that straight axel trikes hold the road better on curves than do IRS type Rears.
Whats the story?

BIBS... I will write another novel tonight about this comment. I don't know where you got that info but where ever it was forget about taking any advise from that source.
To be continued.

 

[BIBS]

Terry....My e-mail is harleyguy1953@comcast.net....I'd like to hear from you,Thanks Dude!!

 

[Terry Trikedude]

Base-Cone Illustration

http://www.triketalk.com/forum/attachment.php?attachmentid=2531&stc=1&d=1288076732

 

[Terry Trikedude]

The drawing in the previous post I have shown a base-cone illustration of a trike. Note the location of the center-of-gravity (cg) should be low and near the side-by-side wheels as shown in this trike. A trike’s margin of safety against rollover is determined by its L/H ratio, or the half-tread (L) in relation to the cg height (H). The trike’s half-tread is determined by the relationship between the actual tread (distance between the side-by-side wheels) and the longitudinal location of the cg, which translates into an "effective" half-tread. The effective half-tread can be increased by placing the side-by-side wheels farther apart, by locating the cg closer to the side-by-side wheels, and or to a lesser degree by increasing the wheelbase. Rollover resistance increases when the effective half-tread is increased and when the cg is lowered, both of which increase the L/H ratio.
A trike’s margin of safety against rollover is displayed by constructing a base cone using the cg height, its location along the wheelbase, and the effective half-tread of the trike. Maximum lateral g-loads are determined by the tire's friction coefficient. Projecting the maximum turn-force resultant toward the ground forms the base of the cone. A one-g load is all any tire can withstand so using a one-g load acting across the trike’s cg, would result in a 45 degree projection toward the ground plane. If the base of the cone falls outside the effective half-tread, the trike will overturn before it skids. If it falls inside the effective half-tread, the trike will skid before it overturns.

 

[Terry Trikedude]

Roll Center

http://www.triketalk.com/forum/attachment.php?attachmentid=2532&stc=1&d=1288078010

 

[Terry Trikedude]

The drawing in the previous post I have shown a trike that uses a double wishbone suspension IRS, which can clearly be seen by a pair of (upper and lower) control arms.
The roll center for this double wishbone suspension, is illustrated by the lines extending from each control arm past the center of the trike and off into space. At the point, those lines intersect is the instantaneous center, and there will be one instantaneous center on each side of the trike (on the left side for the right suspension, and on the right side for the left suspension). The intersection of a line from each instantaneous center to the center of the tire's contact patch is your roll center. The important variable here is the height of the roll center from the ground.

 

[Terry Trikedude]

Now what does all this mean??

To be continued.... its late.

 

[BIBS]

Terry your expertise on the matter appears to be typical fare from an engineers point of view....I appreciate your input.
I've been pricing out the components needed for assembly of an IRS type rear....way out of my price range for a disabled Vet living on a disability pension.
Unless I walk into a deal that wont break the bank,I'll have to be content with my DNA rear for now.
I HAVE figured out how to fabricate a straight style rear for several hundred dollars though....I may give it a try this winter to give me something to do.

I went to your site....I like the frames your producing!!! Really sharp lookin "outlaw" style!!
Thats something I could do!!