Dirt bike engine swap, and more....

[icebox187]

Why not use chain and freewheel?

[Masteryota]

Could you expand on that idea?

I had thought of modifying the starter gear into a coupler, and make it engage a hub on the end of the jackshaft, but machining something like that would not be cost effective. I had also thought about a smaller chain and something like a go kart clutch, but I would lose the nose cone support bearing in the process. I am open to ideas.

[x-bird]

Originally Posted by icebox187

Why not use chain and freewheel?

interesting thought ... reverse sprocket hub/chainring on the axle with a one way roller bearing (sprag), hi-torque 12 volt electric motor with a sprocket or small centi clutch.

[Masteryota]

I don't like the idea of sprags, but the small clutch I like, due to being somewhat enclosed away from dirt and such. It wouldn't be much effort to install one either since the shaft is 1" keyed. Off to search and research......

[Masteryota]

Ok. I haven't been working on the buggy for a few weeks, and now I am looking at things a bit differently. I can't help but see all the downfalls of using a pull start no reverse engine. With the possibility of scoring some free cv axles, I have been tossing the idea around of doing an IRS, but with a different engine. Possibly bigger, but at least with reverse and electric start. I know spider box's are not the best candidates for IRS conversions, so I might stick with the swingarm rear but build one from scratch instead of patching this one back together.

Basically, I just want a thumb start and reverse....

Someone talk me out of it. Or into it.

[2SlickNick]

I say finish what you started first.
Enjoy it for a while then improve on it or start a new project.

[rocko]

reverse and electric start is a necessity not an option

[x-bird]

Yep. Once you decide to pull the trigger on that thought, Your next thing to consider will be whether a belt driven system like a polaris or a chain drive. Ditch any thoughs of swingarming a larger engine. more hassle than it's worth with no comfort/handling gain for all the work.

then suspension setup and the choice of CVs and double a arms or chain drive trailing arms. I wouldn't even think about anything under 400cc--unless you do a screamer bike engine coupled to a reverse box. I really don't think one swingarm buggy is better or worse than the next to convert to irs. there's enough builds around to follow and you've got the tools and skills to do it.

[Masteryota]

Thanks X, I would rather have an integrated engine/trans quad unit over the Polaris, based on me hating CVT's, and absolutely no 2 strokes! I would lean toward CV type IRS, it doesn't have the articulation that dual trailing arms come with, but it seems simpler for me fabricate. The only thing that concerns me about doing a +400cc engine is the rest of the frame holding together at +40hp. I am going to start looking for donors, my wife gave me 'the look' last night when I told her what I was considering, but she would rather me be happy, than kicking my self every time i take it out.

[x-bird]

That's almost where i'm at with this old quad engine. it just takes too much to keep it together and have a year in it without it running at it's full potential. one more race season and something 2000 or newer goes in. I'm pretty well set on the LTZ400, it lets me reuse some of my rear framework and only adds in the manual clutch. For smaller displacement, a ninja 250 engine or similar high revving bike engine would be pretty sweet, but you'll still need the center carrier or a box like the RPM. With or without reverse, that tends to be the pricey part of doing CV joint irs. With one of those, i don't think you'd need to reinforce the front end quite as heavily. FWIW, that set of Roketa trailing arms and axles someone posted on GN (CL ad out west) the other day is a STEAL. If you're really up for doing this, grab that setup asap--more than 50 percent done right there. with built arms, installed can be pretty simple, just don't follow the method i used LOL. Start with your own fresh mounts.

[toomanytoys2]

Master,

Any updates on your build, or what direction you are going to take?

[Masteryota]

Have not been working on the Yerf while I have the Miata in the garage. I am around 80% done with that monster, then back to the Yerf after some tweaking with the new Dazon.

As far as direction, I am looking to try a semi-independant rear swing arm set up I picked up off another site. I have a discussion open on it on BN, but had not brought the idea over here just yet.

Been mulling over the idea to hard mount the engine to the frame, and run a single chain to a floating center pivot type swingarm, but can not get past the twist effect on the chain.

The result is going to be a scratch built swing arm, since I looked the results of my patch work, and was disgusted. With this, it will allow me to build any type suspension I want, and I want some type independent rear while retaining the straight axle. Most likely the engine will still be mounted to the swing arm, and while I picked up a polaris FNR box, I am still looking for the correct sprocket, so I may wait to implement that for now.

I may not make the progress I was making, due to motivation finally kicking in to start school and GTFO of my field. Not that it is a terrible area to be an expert in, it has become a dead end and the rut keeps getting deeper. Sacrifices for the long term, at least thats what I keep telling myself.

[2SlickNick]

Do you have picks of this semi IRS on BN? The idea sounds awesome, best of both worlds.

[x-bird]

I had two IRS setups in mind with the polaris FNR. The first was pretty much what i have, trailing arms with chain drive and a pivot point jackshaft. The second uses a little more real estate lengthwise. Engine driving FNR, FNR driving a carrier hub right behind or under it with CVs. could be dual a-arm or trailing arm setup with that configuration and there are several zero-plunge builds out there to copy the a-arm geometry from.

A couple years back 3 or 4 of us on here kicked around the same idea you've been pondering and just couldn't come up with any reliable and simple way to get around the twist. It's a driveshaft type configuration ... unless you invent some spherical ball link chain.

[toomanytoys2]

"I may not make the progress I was making, due to motivation finally kicking in to start school and GTFO of my field. Not that it is a terrible area to be an expert in, it has become a dead end and the rut keeps getting deeper. Sacrifices for the long term, at least that's what I keep telling myself. "

Being an educator myself, I whole heartedly agree with what you are going through. Even though your sig, states that you have reached a relatively high level of proficiency for your field, "everyone" needs to strive to reach their highest obtainable goal. For myself, I get so frustrated when students do not realize the potential that they have and just seek the needs for now. I can not count the number of students that have dropped out of school to get a job so that they can make payments on some #@%^ car.

Hang in there. You can NEVER have too much education, unless it is in a field like Underwater basket weaving or Philosophy.

[Masteryota]

Originally Posted by toomanytoys2

"I may not make the progress I was making, due to motivation finally kicking in to start school and GTFO of my field. Not that it is a terrible area to be an expert in, it has become a dead end and the rut keeps getting deeper. Sacrifices for the long term, at least that's what I keep telling myself. "

Being an educator myself, I whole heartedly agree with what you are going through. Even though your sig, states that you have reached a relatively high level of proficiency for your field, "everyone" needs to strive to reach their highest obtainable goal. For myself, I get so frustrated when students do not realize the potential that they have and just seek the needs for now. I can not count the number of students that have dropped out of school to get a job so that they can make payments on some #@%^ car.

Hang in there. You can NEVER have too much education, unless it is in a field like Underwater basket weaving or Philosophy.

What about majoring in music appreciation, with a minor in cultural histories?? LMAO

I appreciate the sentiment, I do, but it seems to be a daunting task, and with all the press on student loan rates and such, makes me nervous. As far the top of my field, yes, I am at the top. At the age of 30 I have been told I have capped my own salary, and will never move out of the shop. Yeah, not what I was expecting either. So, with that in mind, I shall start my journey in a few weeks, and hopefully, I will have the job I have been after for several years. I can't stand to leave all the knowledge I have and start over, but if this comes through, I shall pass my know how onto others.

Do you have picks of this semi IRS on BN? The idea sounds awesome, best of both worlds.

I can link you a thread if you like. X likely knows of which design I am speaking of.

Here you go

[toomanytoys2]

Master, I really do not see an advantage to that type of suspension over a trailing arm or A-Arm type. I have been trying to visualize it for its movement, but it seems like for the work, that it would only be marginally better then just a regular swing arm. I can see how it might be better in situations like off camber, but it seems like it would still upset the whole rear end in whoops and other bumps. Do you have any more info on this type of design?

[Masteryota]

Originally Posted by toomanytoys2

Master, I really do not see an advantage to that type of suspension over a trailing arm or A-Arm type. I have been trying to visualize it for its movement, but it seems like for the work, that it would only be marginally better then just a regular swing arm. I can see how it might be better in situations like off camber, but it seems like it would still upset the whole rear end in whoops and other bumps. Do you have any more info on this type of design?

It is better in the sense that I can reuse the axle I already bought, and all the hubs and such. Plus, like you already found out, adding IRS to a Yerf frame is like putting lip stick on a battleship. Although a control arm/CV set up would be better, and a triple chain/trailing arm would be best, I also have to consider cost and labor involved in adding CV's or trailing arms, hubs and so forth.

This design seems simple, yet effective for a semi-IRS with a swing arm mounted engine. I don't want to be working on this buggy for another year without any seat time, so it's the best of both worlds, so to speak.

[Masteryota]

Ok, back on the buggy idea search while I have some time between classes and projects. I have decided to go head with an IRS conversion to the Yerf Dog. In doing so, surfing CL turned up a few new engine ideas. So tomorrow I am going to pick up a running Katana 600 for the remainder of the build. The katana puts out about 80hp, and is air cooled, which makes it a pretty simple swap, since I was going to use and air cooled engine in the first place.

The only thing I am still up in the air about is the type of IRS I want to build. I have a pair of left over axles from the miata I just finished. I know they will need to be shortened, but should hold up pretty well. I thought of using the stock miata rear spindles along with a-arms to make it easier to match the hub and bearings to the axle stubs. Still on the fence with that idea due to the offset nature of the top and bottom mounts. Using the stock knuckles would allow the use of the stock miata calipers and rotors, provided I can use 14" wheels, which I also nabbed a set of stock alloys from the miata.

I could go with dual trailing arms, but they seem to get heavy once they are properly built. Not really an issue with the new powerplant, but still a little on the tricky side to get braced properly and still leaves the axle a little under protected for my taste.

Jigs can be made for the a-arms, not a problem. A notcher will be either made or purchased before I get started. What I do need, is input on building the spool and flanges for the axles to bolt to. I was thinking of using a shortened 1" axle and pillow blocks.

I know, I have a problem, but this is too dang fun!

[2SlickNick]

Nice to see you back at it...

[SYCARMS]

Good luck and keep us posted.

[x-bird]

I think you may run into more headaches and expense with the CV's and a-arms vs the trailing arms. Martin so far has built the nicest set I've seen yet with nothing "exotic" at all in the hubs. DOM tubing can handle the torque of the axle being at the end and off to the side of the tube. The bigger the diameter, the less wall thickness you need. Reverse isn't an issue if you can come across a roketa FNR box, it mounts in line with the pivot shaft. There is one for sale on MBN.

[Masteryota]

I know the trailing arm IRS affords a lot more articulation, but here in the south, we ain't gots much hills an' rocks. lol. Someone else mentioned it before I could on the rockhound, but the top heavy-ness of it makes me uneasy of having an 80hp engine capable of more than 60mph in a 1k lb frame. The trailing arms would also afford a more straight forward approach for shock angle as well, as it basically the same as a full swing arm as far as pivot points. The '3 chain' set up I just don't like. I don't like the noise of chains, I don't like the mass and weight of chains, I don't like the maintenance and constant adjusting of chains, and also trying to design the pivot point of the arms inline with a large jackshaft under my keister also makes me uneasy. That being said, a single chain is much more do-able for me, as a tensioner can be easily made, or simply slotting the pillow block mounts for adjustments.

I am actually looking at grabbing a set of plans for the badlands st2 frame, and grafting the rear section to the frame of the Yerf. The plans are reasonable for all the measurements and planning all sorted out, and you pretty much cut and assemble.

I would like to go with something cheap and stout, like cobalt hubs, that are also easy to mount, but I need to get into spline counting and such, and spending time at the parts store down the road matching something up. I may try to off load the miata axles and recoup some funds for a set of GM matching hubs and axles to eliminate that issue. Did some checking on using VW axles, and was not expecting that sort of price tag.

Honestly, I like the trialing arm/CV axle set up, but the axle is just so exposed. I'm not sure I could drive it like it should be driven worrying about everything I drive over getting launched into the boots. At least with the a-arms, some sheet metal can be tacked on for protection.

[x-bird]

I get where your at with the chain drives, I decided to go ahead with it after following Alex's buggy build (the green one racing in europe somewhere) and seeing the end result of the durability of it. Now i get what you're saying about the axles, had me head scratching for a bit. That's also a setup i also don't like. If I were to go with a center section carrier, then i'd do the a-arms as well. As far as top-heaviness goes, that's due to the ground clearance I've created, strictly for the terrain of the race. I could've kept it to about 4-6 inches, it has good CG overall except for the droop level i run it at. I've got more clearance (13 to 15 inches under the floorpan) than all of the VW-based rails racing at the same place, both stock and modified classes. I intend to push another inch or two up at the front if i can. )))

[Masteryota]

I would ideally like to retain 12" GC at the floor pan and rear center section. Anything over that here and you are mud boggin', and I don't even want to temp myself into doing that again. right now, with the SA and blaster shocks on the rear, I was sitting at 13.5" at it's lowest point, but I might drop it a bit depending on the top speed factor of the new engine. I am going to gear it down some from the 3.35:1 ratio down closer to 4:1 for top speed reduction and increased grunt in the bottom two gears. The kan-a-tuna's were notoriously high geared, and it's top speed was in the 120's, I want to max out around 50-ish. The upside to using this engine is the parts available for just about what ever you want to do. Right now looking at getting it running and finding and 4-1 header for a bit more low end rather than using the 4-2 it has now. Also being a cable clutch makes the shifter placement a bit easier.