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3/4 scale Mini Crawler

VintageSmoke said:
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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I guess it depends on what you're trying to do, more of a capable little go cart or a real crawler. For a real deal rock crawler, I'd think you want at least a 4:1 tcase. Might be nice to be able to shift to high every now and then. I'm not sure 4 wheelers really have a great low gear.

But maybe you're on to something if you can basically cut the current over all gearing in half, it might work out.

Fwiw, Sami axles are all 3.73s. 4.57s and 5.38s are available aftermarket. You can also get 4.30s, 4.62s, 4.88s, and 5.12s from the front of trackers, sidekicks and vitaras, but those are getting harder and harder to find.
 
Some small updates...
I've been working alot lately as well as working on putting a motor in my son's Schwinn OCC chopper bike so not a ton of progress on the buggy.
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I got in 1 set of RCV's to run in the "rear" front axle. I just have to pick them up from my buddies shop. RCVs for a Sammy are getting harder to find as fewer distributors are stocking them and RCV is MONTHS out from doing a run of Samurai axles. It was a toss up between RCVs and the Longfields from TT, but since an extra $100 for the RCVs brings a lifetime warranty, the RCVs won out.

I had an extra stripped down front housing laying around and am working on an alignment bar. I figutre I might as well astart with a straight housing. I had a 5 foot length of 1" OD hardened and ground shaft laying around with less than .005" runout. I also had some 1.5"OD X 1"ID aluminum tubing which is almost perfect for the end pucks since the seal OD is 38mm or 1.496". The aluminum is a perfect slip fit on the shaft and only needs a few thou taken off the OD to fit in the housing. That should save me some work machining the end pucks!! :beer:. I still need to make pucks for the carrier bearing saddles.
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Next steps:
I need to machine up some carrier pucks.
I need to figure out the if/how/which/why of flipping the "rear" front axle over for left side/right side driveshaft location to match the "front" front axle as well as flipping the third member over for proper rotation. This all gives me a headache even trying to picture it in my head so i'll try it out real time with a couple of axles on the bench.
I will be cutting and turning the knuckle balls for proper caster/pinion angle.
This all leads me to a couple of questions. I did some searching, but the Jeep JK Facebook groups were no help....:stirthepot:
Since I have multiple front and rear axles laying around to steal parts from...what are the differences between the front and rear third members and are they interchangeable? If so is there any benefit to one over the other? Besides keeping proper driveshaft location and pinion rotation, Im wondering if mixing and matching carriers might allow me to go high pinion front and rear?
What about the carriers? I know some are 2 pin and some are 4. Are the front and rear carriers interchangeable? Are all the rear carriers 4 pin?
I do know about the spline difference between the side gears and have a few extra sets of rear side gears to enable installing the RCVs.
Any recommendation for caster angle on a rear steer axle where i'm not worried about automatic return to center?
I did spend about 45 minutes searching old Pirate threads to find answers, but nothing I found specifically touches on interchangeability between front and rear axle parts. If any of you know the answers off the top of your head I would appreciate the help!!
 
Only difference between the front and rear 3rds is the 22 spline side gears in the front and 26 spline in the rear. You will need the 26s for the rcv's anyway. Or some lunchbox lockers have to option to include side gears.

High or low pinion will depend on which way you spin the driveshafts. They're both low pinion, so you'd have to spin them backwards to get high pinion. I'd imagine with that tiny engine, it would be easy enough to mount it to spin them backwards.
 
I’m digging your build seems like great setup that Nina sounds like a riot also.
 
KrustyTJ said:
I’m digging your build seems like great setup that Nina sounds like a riot also.
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It's an absolute riot. Dead below 6K RPM and then it explodes. 1st, 2nd, and 3rd gear its near impossible to keep the front end on the ground making it a little difficult to ride at low speeds. In traffic I have to keep it in a higher gear and lug it otherwise it wants to take off when it comes on the pipe. I've taken it to Tail of the Dragon a few times and you should see the looks on the squids faces when I roll past them in a corner because it's so small and light letting me carry a lot more corner speed. And LOUD. It's ear splitting to anyone behind me. Not to mention the constant splatter of 2 stroke oil out the tail having the exhaust up under the seat and running a rich oil mixture.
 
I got a little more done.

I machined up some alignment bar pucks and pressed them into an axtra carrier I had. This carrier will now be a dedicated "set up and alignment" carrier.
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Then a set for the housing ends. They index off of the seal surfce as well as the machined I.D. of the knuckle ball. I made the larger diameter for the seal surface a loose fit for getting it "close" and the smaller diameter that goes into the I.D. of the knuckle ball a closer fit for fine adjustments and holding everything square when I cut and turn the balls. 2 pucks in one...just flip it over.
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The short side lined up perfect:
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The long side not so much. It's not too far off though. A little heating/quenching should fix it.
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The alignment bar/pucks will also let me keep things straight and square when I cut&turn the knuckle balls to set the caster for the rear steer axle.
 
BTW...thanks to anyone who posted comments or suggestions. It's all appreciated!!! :beer:
 
VintageSmoke said:
Any recommendation for caster angle on a rear steer axle where i'm not worried about automatic return to center?
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Jesse Haines does 5° (top pivot forward) for rear steer. He says it offsets how much the tires are steering into the ground on steep climbs. I think I've seen others post up ~6°.
 
So...me being me, I can't leave some things alone. Originally, I made the center alignment pucks to press into the bore where the shafts go through into the differential. This saved me a bit of machining as well as having to source 3.25" aluminum bar stock to actually go in place of the carrier bearings.
Once the pucks were done, I suspected the bores I pressed them into might not be 100% concentric and when I cut the "cover" off of the housing and was able to rotate the carrier, the alignment bar wobbled ever so slightly confirming it. So I picked up some 3.25" OD X 1" thick discs and machined up some proper pucks for the carrier and re-did the center pucks.
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VintageSmoke said:
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.
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I've dreamed of doing a banshee powered 250 class streetbike for years, that's so damn cool.
 
redneckK20s said:
I've dreamed of doing a banshee powered 250 class streetbike for years, that's so damn cool.
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Thanks! It's an evil little turd and far from finished. Most of the mechanical is sorted enough to ride, test, and abuse. The plan was to get it all sorted, tear it all down, and then make it functional AND pretty. That hasn't happened yet....LOL
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KrustyTJ said:
So what is it
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Sorry..I wasn't going for the dramatic effect. LOL The video didn't upload.
Please stand by. We are experiencing technical difficulties and will be back to our regularly scheduled programming shortly...
 
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