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3/4 scale Mini Crawler

VintageSmoke

Active member
Joined
Sep 2, 2020
Member Number
2804
Messages
38
Starting a build thread on a project i'm starting. I was planning on building a "kids buggy" for my son, but I wanna drive it too and he grows so fast that he'll probably outgrow it by time I finish it. Tube frame, 90-95" wheelbase, lightweight 35" sticky SXS tires, 400cc Polaris ATV motor/trans, Samurai axles. I'm in the process of gathering up parts and hope to start mock up in the next week or so...
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And a bunch of tubing....LOL.
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Cool idea, I've thought about a mini buggy many times.

W.E. Rock has a children's class that looks pretty interesting and is right along the line of what you are talking about building if you have any interest.
13.4.1: Child Buggy: class is designed for children with a minimum age of 5 prior to
their first competition, to a maximum age of 8, maximum 35” tire, single seat or 2 seats,
no axles larger than 9” ring gear (un-cut), maximum engine size of 650cc, NO forced
induction, NO rear steer, No portal axles.
Click to expand...
 
'84 Bronco II said:
Cool idea, I've thought about a mini buggy many times.

W.E. Rock has a children's class that looks pretty interesting and is right along the line of what you are talking about building if you have any interest.
Click to expand...
I'm really going for lightweight as well as smaller size. I'm trying to stay as close to 1,000 lbs as possible so hopefully the lightweight axles will live. The Sammy axles are stupid light and I don't plan on running a transfer case. The polaris has forward, reverse, hi/low range, so I may just use a chain driven jackshaft with a flange on each end for the driveshafts.
As to the kids class, it would have been awesome, but he's 11. Do they have a teen class?
 
VintageSmoke said:
As to the kids class, it would have been awesome, but he's 11. Do they have a teen class?
Click to expand...

Sort of. They have a Youth class, but he's getting close to the age cut off for that one. Seems crazy that they expect 13-16 to compete in the regular classes.

13.4.2: Youth Buggy: class is designed for children with a minimum age of 9 prior to
their first competition, to a maximum age of 12, maximum 37” tire, single seat or 2 seat,
no axles larger than 9” ring gear (un-cut), rear steer allowed, maximum engine size of
900cc, NO forced induction, NO portal axles.
Click to expand...
 
VintageSmoke said:
I'm really going for lightweight as well as smaller size. I'm trying to stay as close to 1,000 lbs as possible so hopefully the lightweight axles will live. The Sammy axles are stupid light and I don't plan on running a transfer case. The polaris has forward, reverse, hi/low range, so I may just use a chain driven jackshaft with a flange on each end for the driveshafts.
As to the kids class, it would have been awesome, but he's 11. Do they have a teen class?
Click to expand...

RCV makes birfs for the Sami axles. That's all i have done to the axles under my little samurai and it probably sees more stress under a full body samurai.


They were like $400 for inner and outters :laughing:
 
I'm seeing full front axle sets for $650 on the RCV site. Were you able to get just the Birfs?
Shit...even $650 isn't bad. For that price I might use one of the extra front axle assemblies I have and go rear steer!! LOL I have a plie of front and rear Suzuki axles.
 
Neo said:
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Here’s my kids buggy, Goatbuilt kids chassis, 1.6 8v, tracker 3 spd auto, Sammy transfer case, Toyota axles, 37” treps
Click to expand...
That's badass. Are you able to fit in it?
 
Any reason behind the 2 stroke/cvt vs a bigger 4 stroke and 5 speed?
 
So...do you need that old polaris shifter?
 
VintageSmoke said:
I'm seeing full front axle sets for $650 on the RCV site. Were you able to get just the Birfs?
Shit...even $650 isn't bad. For that price I might use one of the extra front axle assemblies I have and go rear steer!! LOL I have a plie of front and rear Suzuki axles.
Click to expand...

Well, I think that was pre Biden dollar. :homer:

I also got them through the parts counter on here.
 
what year is your Polaris Xplorer? I have a 1996 and might be interested in some of the parts you won't be using...send me a PM if interested.

thanks!
 
Looking forward to this build. I would like to build a small buggy for my kids and I that will legally fit sideways on a trailer even if I have to put small roller tires on to trailer it. I have a Chevette Diesel engine and auto trans that would be nice for it. When I am ready I will find a Sammy tcase and I have a bunch of toyota axles already.
 
AK_F250 said:
Any reason behind the 2 stroke/cvt vs a bigger 4 stroke and 5 speed?
Click to expand...
Honestly I found it cheap cruising Facebook marketplace. It's a 400 and makes 40hp stock which should be more than enough for the weight I am shooting for. If not, I build/port 2 stroke motors so I can wake it up if I have to. Once I get the CVT tuned right it should be an added bonus. I've been kicking around the idea of a mini buggy with a motorcycle motor since I picked up a stash of Sammy axles in 2004 ish. The challenge for me was finding a way to get reverse in a small/cheap package. The real attraction to this ATV (besides the price) was the trans since it has hi/low range and reverse. My current plan is to run a chain from the trans output sprocket to a jack shaft running front to rear with a flange on each end going to the front/rear driveshafts....so no transfer case needed. I should be able to get a perfectly flat belly with a low COG and plenty of ground clearance.
 
D_JEEPER said:
So...do you need that old polaris shifter?
Click to expand...
Sorry. For now I plan on using it. IIRC it's a cable shifter so re-using it should simplify mounting in the buggy. If I change my mind i'll let you know.
 
KungFooMASTA said:
Looking forward to this build. I would like to build a small buggy for my kids and I that will legally fit sideways on a trailer even if I have to put small roller tires on to trailer it. I have a Chevette Diesel engine and auto trans that would be nice for it. When I am ready I will find a Sammy tcase and I have a bunch of toyota axles already.
Click to expand...
That's awesome!! I really wanted to do a small diesel. I was thinking a small Kubota diesel with yotas for the next project.
 
jeepnmatt said:
what year is your Polaris Xplorer? I have a 1996 and might be interested in some of the parts you won't be using...send me a PM if interested.

thanks!
Click to expand...
Once I strip it down of everything I need I will be selling everything that is left over as a whole. I am in NJ though.
 
KungFooMASTA said:
Because 4 stroke is for gays.
Click to expand...
2 strokes are actually bisexual. They run in both directions. :lmao:
I am a 2 stroke fan though. I build/port RD350/400 motors and manufacture a small line of parts for them. I also have a 2008 250 Ninja with a hot rodded, reverse cylinder, Banshee motor in it. 68hp (with small carbs and stock ignition) and 257 pounds. It's a handfull to ride. I have a programmable ignition and a set of big carbs sitting on the shelf for when I grow a set of balls.
 
VintageSmoke said:
Sorry. For now I plan on using it. IIRC it's a cable shifter so re-using it should simplify mounting in the buggy. If I change my mind i'll let you know.
Click to expand...
It is a linkage, unless something changed between years haha.

Keep me in mind! I have that 4 wheeler and woud be interested in some scraps haha :beer:
 
Small update. I have an old motorcycle lift that I converted into a frame table of sorts. It's very heavy duty and made for longer term motorcycle builds (not up and down service work). But...it's flat, square, rolls around very easily, and was free since I already own it. I made cradles to hold the front and rear axles that are adjustable for wheelbase in 1" increments as well as width. I decided to build at ride height and set the axle height off the table surface at what I approximated (guessed?) the SLR of the Roxxillas would be. This is with the wheelbase set at 95".
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BTW...I am heavily leaning towards rear steer with 2 front Samurai axles. Considering how reasonably priced RCV axle kits are for a Samurai (about $650 retail) I might just take a chance that the shafts and birfs will live in such a light weight/low power buggy. I had planned on dragging a couple of front axles out of storage today to start mock up, but rain and a looming "honey do" list put a damper on things.
 
VintageSmoke said:
BTW...I am heavily leaning towards rear steer with 2 front Samurai axles. Considering how reasonably priced RCV axle kits are for a Samurai (about $650 retail) I might just take a chance that the shafts and birfs will live in such a light weight/low power buggy. I had planned on dragging a couple of front axles out of storage today to start mock up, but rain and a looming "honey do" list put a damper on things.
Click to expand...

I'm betting you'll be just fine with that little engine. If not, Toyota axles would be an easy upgrade down the road.
 
You also might consider a Sami tcase. They're crazy light. 25 lbs iirc? Then you get tons of options for low range to dial in your speed if you want to.

Stock ~2.3:1, 4.16:1, 4.9:1, 5.14:1(used to be, don't seem to pop up now though) 6.4:1 and 6.5:1.
 
YotaAtieToo said:
You also might consider a Sami tcase. They're crazy light. 25 lbs iirc? Then you get tons of options for low range to dial in your speed if you want to.

Stock ~2.3:1, 4.16:1, 4.9:1, 5.14:1(used to be, don't seem to pop up now though) 6.4:1 and 6.5:1.
Click to expand...
I have one stashed away, but the Polaris trans has F, R, N, and also LOW range. Between the trans and the CVT (which varies from between approximately 4:1 and 1:1) I should be low enough. I will also be able to "fine tune" the final gearing with sprocket size and HOPEFULLY wind up with a combo that lets me cruise comfortably at about 25-30mph so it's not too painful (or boring) going trail to trail, but still have plenty of low gear for tight sections.
Please keep the suggestions coming!! Anything that sparks thoughts or ideas and keeps me from over complicating things or having to build anything twice is appreciated!!
 
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