Yerfdog spiderbox frame dimensions

[md95]

Hello all, new here! I'm in the chassis planning stages for my 2 seater, custom buggy project, and from what i'm wanting to do, the yerfdog spiderbox looks to be the size i'm after. I may make it slightly wider, and maybe slightly lower, but if anyone can give me approx measurements of the bottom main frame assembly, that would be much appreciated. Basically I need width at front of frame(foot area behind front end), mid frame, and rear of frame(not the swing arm, but behind the seats). Also, width of front tires, from outside edge of each front tires, and each rear tires, and approx wheelbase. If anyone can take a few moments and measure these out, it would really help. I plan to use this simple main frame design, but change it up some. I'd like to keep total width just enough to fit a pickup truck..plan on using a trailer, but just in case. Thanks!

[metalstudman1]

I've got your dimensions but when I scanned my sketch the file was too big to upload-I'll PM it to you. Just so you'll know- the front clip you've found for $150 won't be brand new- it will be take-off's from karts during the re-call. (I bought one for spare parts a couple of years ago) I know you want to fab your own chassis- the science to this design was it's weight and tubing size. For $250. + freight from Virgina you can get just the frame part you want. I couldn't build it for that and have it powder-coated too, just a suggestion.

[md95]

Wow, thanks for doing that, that's more than I expected. Yeah, I had found exactly what you describe for the whole frame assembly..I thought about it, but I really want to build my own, make some adjustments here and there, you know, make it mine. For me, building the frame is fun and very rewarding. I figure i'll have around 250-300 in steel, which to have that new frame shipped, would be at least 300. I want it powder coated, but if funds dont permit, i'll have to spray it. As for the front end, ************* offer all new parts, at least that's what it says. Here is the link: http://www.*************/shop/?shop=1&cat=127

Scroll down a little bit and you will see it. Farther down you will see a complete used setup for 100. I plan to *maybe* extend the centerbox where the control arms mount, to give the front end a bit more width. I'll use heim joints instead of ball joints, and i'll probably fabricate my own knuckles/spindles. This way I can make it tough from the start. I may even extend the upper shock mounts for longer shocks, but that may wait until later on after some fun with it.

I also want to make a nice strong swing arm assembly too. I will find some good control arm bushings from an automotive application and steel tubing to press them into. I plan on using 3 mounts to the main chassis. I still haven't decided if I want to mount the engine to the chassis or to the swing arm..not much room to work with, if I want to keep wheelbase from being too long. I'll be obtaining a 340cc 2 stroke, 2 cylinder yamaha sled engine for 50 bucks(actually the whole sled!) so that should be plenty of power. I'll gear it low for good pulling and climbing power. Once the ball gets rolling on the project, i'lll be sure to start a thread with updates. Responding to your pm, thanks!

[roysheepdog]

if you want the front wider,i would make the aarms longer.this will give you more travel.with the 340 it will be to fast for the swing arm,the swing arm will beat you like a dog.even with good shocks it will be to ruff to go very fast.
it sounds like a good build but some thing that fast needs irs.

[md95]

Originally Posted by roysheepdog

if you want the front wider,i would make the aarms longer.this will give you more travel.with the 340 it will be to fast for the swing arm,the swing arm will beat you like a dog.even with good shocks it will be to ruff to go very fast.
it sounds like a good build but some thing that fast needs irs.

Hmmm..I don't see why a properly designed swing arm wont handle good. I'll have to look into it more, thanks for the info(after all, motorcycles, ATV's, ect, all have swing arms). That's why I was thinking to have the engine mounted solid to the chassis, and just have a more natural axle like swing arm. Basically like a motorcycle/ATV. I really wanted independent rear, but I'm trying to keep it simple, and on a tight budget. I had even thought of doing a dual rear swing arm, using a longer jackshaft and dual sproket setups. I'm not wanting to go 70mph in the thing either. I figure 40-45 would be plenty. It's going to see grass, dirt, and some sand dunes. This engine will have plenty of power, which is why i want to gear it lower for more grunt than speed. I'll be using the sled's CVT clutches as well, then from that to a jackshaft setup. Maybe a 9 or 10 tooth on the JS, and a 60-70 tooth sprocket on the axle. Keep in mind this will be considerably heavier than a stock yerf too. I plan to use 1.5" square tube for the main bottom frame, and 1.25" square for the upper and rollcage. Yeah i know, no round tube..not as pretty, but gets the job done! Any info or ideas is greatly appreciated guys!

[roysheepdog]

we are building one now.it was a carter 150 that i cut everything off but the floor frame.its has long travel front aarms(15'' travel)and a swing arm in back.when you hit a bump in the frount you cant feel it but when the back hits it the hole buggy moves.it will have irs and a new motor but for now it still has the 150.
at first i thought i would run the swing arm,but when i seen how much better the frount was than the back its got to have irs.
its not hard to put it together if you can do the frount you can do the back.it will cost a little more but when its done you will have a better buggy.
you can go back later and make it irs but i would not put the motor on the swing arm.
from driving this one i dont think you like 45 on a swing arm.

[md95]

I've never ridden in a rear swing arm buggy, so I will have to take your word for it My easiest IRS solution was to do a dual swing arm setup. Longer jackshaft, with dual drive sprockets, one per wheel. Might look a bit odd/different, but I think it would work. This forces me to put the engine on the chassis, which is what I really want anyway. Unless I can find a halfshaft/u-joint setup on the cheap, I think its the only real option. I know I haven't seen anything like it..i'm sure i'm not the first to try it lol..

[md95]

Ahh yes, like this:

The blade 250xt. One thing that I didn't think about though, was making tight turns. Thats going to put a ton of abuse on the chains and sprockets without the use of a differential of some sort on the jack shaft.

[metalstudman1]

Your sled motor and CVT should already be geared low enough for your buggy build.If you can find a cheap used Polaris ATV you can use the gear box to get reverse. A cheap 1/2 shaft solution if you can one find is old Baja65 like I found (whole buggy for $50 bucks!)They were sold at Pep Boys back in early to mid 2000. That's what I'm experimenting with on my Frankenbuggy now. I haven't found a cheap CV set-up yet either,used or otherwise. My opinion on swing arms is that location of the shock in relationship to the frame and length of swing arm makes a world of difference on the ride.Also the position of the rear tires in relationship to your butt contributes heavily to stability and comfort as well. Buggynuts/Krusekontrol ( http://buggymasters.com/forum/showthread.php?t=282) UFB builds shows that and Bigkid's (http://buggymasters.com/forum/showthread.php?t=1083) sled motor on his Coolster is a good example of another swingarm set-up.Square tubing is FINE!! it's certainly is easier to fab-

[md95]

Is bigkid's trans assembly there from a sled? The sled i'm getting is a bit vintage- 1976 Yamaha GS340. I've never dug into a sled before, but i know its the CVT setup. I'll be picking up this thing later today, so i'll have the weekend to take it apart and get some ideas.

I'm thinking if I can find a rear diff from an AWD car/small SUV, that may work wonderful. Just connect the driven pulley of the CVT to the diff, then use the oem halfshafts. I'm into Mitsubishi eclipses/talons(AWD turbo cars) and i know the rear diff on those cars are viscous coupled LSD, and the wheel side of the halfshafts are bolt on cups..easy to make an adapter plate/hub to go to a 1" or 1.25" wheel axle shaft. The diff's are pretty heavy, way overkill for a smaller buggy, but it would work. Just looking at the rear diff on my Honda CRV, it would work perfect. Smaller diff, lsd, smaller halfshafts..lol cant rip that out though..

I'm just going to have to do some searching and see what I can come up with. Luckily, I have enough connections with people into sleds, ATV's and motorcycles..

Thanks for your diagram, it was very helpful!

[metalstudman1]

NO-the trans is from a polaris ATV with the driven unit being a match for your sled set-up,(you get F-N-R using that trans).Your sled is also going to have shocks that may work for you. The issue for me with car CV's is the huge/heavy wheel hubs. It's your build and we all love inovation. Using a differential will make your buggy turn really well but you lose that fun of sliding and spinning the rear tires! I also have a vintage 1976 engine (440 liquifire) that I'm coupling to a polaris trans after my current build.

[md95]

Picked up the sled. She runs good! Needs some plugs and some going over, some leaks here and there, but nothing too bad. Clutch on the engine works, and the sled actually moves ok. The entire engine and clutch setup is a bit bigger than I had imagined, but it will fit just fine.

I'm still uncertain of the rear end/drivetrain. I can get a rear diff with limited slip from a early 90's Mitsu talon/eclipse for 25 bucks from a buddy..These diff's used a viscous coupling limited slip unit, but allows slip in turns. I'd have to source some halfshafts and shorten them(not a big deal there). The cool thing with these axles is the outer CV joints are bolt on cup style. I could make an adapter plate/hub to connect to lets say a 1" or 1.25" standard keyed axle shaft, then just use standard 4 on 4 hubs. The drawbacks would be size and weight of the diff(they are pretty heavy and bulky), and unsure if the diff's gear ratio would work out-supposed to be 3.54:1.

I'm still leaning to doing a dual swing arm setup and just see how it works out without any differential action. Tight turns will really work the chains, but good sized chain and good drive geometry may work out. If not, then I can always go back to the drawing board..after all, it can always be changed.

[metalstudman1]

Looks good for a sled engine that old.Glad that it runs and the clutch is still good.I forgot that the brakes were on the driven unit! I may be out of place but I think you're over-thinking the gear ratio issue and the need for some other gearing beyond the CVT.The beauty of the CVT is the range of torque thru final top speed-that sled probably went 60+

[md95]

Haha yeah, I tend to over think things! That gets in the way sometimes from the day job(fixing cars).. But if I do end up doing a dual swing arm, i'll have to run a jackshaft off of the secondary clutch and need 2 sets of gears for each drive wheel. Not sure what tooth counts I would need on the Jack shaft, then on the drive wheels..this is where gear ratio's get confusing, esp when going first through a CVT setup..For example, I know a 10 tooth driver, and a 60 tooth driven is a 6:1 ratio, and I know smaller driven means faster, and larger means slower and more torque.

[metalstudman1]

Gear ratio's can get complicated!There so many varibales to deal with. You need to have an idea of your tire size to even have a clue about where to start calculating. You spoke about ground clearance and that has lots to do with tire size. Unless you have a machine shop availibilty of chain size to sprocket choices will effect your decisions. You're on the right path! You have basic wants from your buggy- now you have the power plant and a potential transmission with the CVT. Now it's all about "how MUCH are you willing to spend" on your hobby?

[md95]

Another question, what size diameter tubing does the yerf use? I'm thinking i will build the bottom frame section from 1.5" square, then maybe use round for the upper frame and rollcage. I found some DIY plans to build your own hydraulic tube bender, can build with one size die for maybe 200 bucks...I want to try to keep the weight down as much as possible.

Got the sled motor yanked out today, just a few more pics. I'll prob have to rebuild the carb with new diaphragms, and it kind of looks like the head gaskets are leaking, but it may be from the spark plug gaskets, not sure. Re-wire it and clean it all up. Maybe paint it.

[metalstudman1]

Wow that motor has a small foot print. Easily wedged into a tight space. The tubing on a Spiderbox is 1-1/4".Die's get expensive quick- I have one of the Northern $130. benders, it's slow but it works! It won't bend 18 gauge tubing like on the Spiderbox without filling the pipe with sand.What's the HP/torque rating on that 340?

[md95]

The engine was larger than i thought really..pics dont do it justice. With the full exhaust and the secondary clutch, it's going to take more room than I thought. But still easily done, so no problem there. With many hours searching on the internet today, I found a few specs on the engine. It's 338cc displacement, with 25bhp @ 5500 rpm. Magneto ignition, fan cooled. Its not the 40hp I was told(i thought that figure was a bit generous haha), but still that's plenty of power.

I'd really like to use round tube, but I haven't decided yet. Worst case i'll use all square. The bender i'm talking about is like this one:
http://www.speedwaymotors.com/3rd-Ge...ign=GoogleBase

You can buy a certain size die with roller for 150. I can build the frame of that bender quite easily out of 1" square stock. Go to HF for a cheap bottle jack, maybe 25 bucks. Downside to that style bender is only 90 degree bends max.

[metalstudman1]

I saw several youtube vid's on a home built benders that looks alot like that one from Speedway. Sorry the motor isn't as strong as you were led to believe- 25hp is still a good powerplant.Sure seems like that 2-stroke would turn a good bit more than 5500 rpm. With square tube you're not spending anything extra to fab your buggy right now that you may need on the tailend for something important to complete it. Sounds like your young enough you could wait on a bender!