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liv4drt
07-01-2012, 07:00 PM
Kinda new to the site. A lot of good info on here. I am going to be starting a kids buggy ( mini utv) and was wondering if the harbor freight 420cc motor is any good. Going to be running 18" rear tires and weight hopefully around 325 to 375 pounds

Martinm210
07-01-2012, 10:33 PM
I have the "Duromax" flavor on my kids buggy plus a Comet 500 clutch. It doesn't do too bad even with me in there I can climb pretty steep hills and still get up to around 32mph or so. Gearing I used the Comet 500 to a jackshaft and went 10/60 sprockets to the solid axel with 18" rear tires. Seems like a pretty good ratio to have hill climbing plus some speeds without over stressing the clutch/belt.

The Duromax is pretty lean and restricted on the intake and exhaust. I still need to build a custom exhaust and rejet, should help it do a little better.

It's not as much power as I had hoped, but plenty for the kids.

liv4drt
07-02-2012, 02:03 PM
What about a direct chain drive clutch

Snoopy
07-02-2012, 08:18 PM
those don't have as good of a direct take off. The torque converters are a little better in the bigger karts.

liv4drt
07-02-2012, 09:12 PM
Cool thank. Might have just scored a Polaris 500 quad so might use that as my drive and rear suspension. It has f n r so we will see if not go comet then. Have front suspension already. Will start frame when I find out.

Martinm210
07-03-2012, 12:06 AM
Nice, the polaris will make a great engine for a buggy. With a clutch you might even be able to run the belt forward to the secondary which helps in certain setups.

Yeah, the direct chain clutches are pretty limited on the industrial motors. I had one on my kids buggy when I had a 6.5HP motor in it, when I geared it down to climb hills it would top out at 15mph. I think engagement is around 1200 and govenor is 3600, so you only have about a 3x RPM ratio for 5-15mph or 10-30mph, etc. Works fine for flat track or street track type racing, but not enough ratio for off course leisure stuff with hills and variable terrain.

The polaris has a clutch and FNR, so you'd be all set there.:D

liv4drt
07-03-2012, 07:04 PM
Ya it's the whole quad so basically turn it into a buggy for the kids might even incorporate the 4x4 dont have final idea yet on frame still drawing it out in my head. I just wounder if rear cv's can be extended to the width I want.

Snoopy
07-08-2012, 11:00 PM
With a center spool o think you'll be around 55 to 60 to the outer tire edge. , if you use vw cvs that is. I'm sure others will have different type cvs.

Wheels
09-15-2012, 02:46 PM
have you started the build yet liv4? post some pics, if so... i'll be building a buggy for my son in a couple of years and always like to see other kids' buggies.

liv4drt
10-29-2012, 05:42 PM
Sorry it's been awhile, work and traveling. Ditch the Polaris idea, got new plan so hope to have a basic idea fro new frame in a couple weeks keep you guys posted.

liv4drt
11-05-2012, 07:10 PM
If I am using a 11" rack how far should my bottom a-arms mount be?

liv4drt
11-06-2012, 07:56 PM
Looking for a reverse gear box that changes direction of rotation not a FNR???
Chain driven like RF1 Mod Karts use. Thanks

ironknot
11-07-2012, 01:59 AM
Hi, liv4drt hope these help, I find a couple of different articles usually helps me with new ideas. I gather from your first question you may need to know the dimensions of your spindle to use these articles but you will have a start.



http://www.longacreracing.com/articles/art.asp?ARTID=13 (http://www.longacreracing.com/articles/art.asp?ARTID=13)

 
 
http://www.circletrack.com/chassistech/ctrp_1001_bump_steer_explained/viewall.html (http://www.circletrack.com/chassistech/ctrp_1001_bump_steer_explained/viewall.html)

 
 
http://suite101.com/article/race-car-suspension-bumpsteer-a146600 (http://suite101.com/article/race-car-suspension-bumpsteer-a146600)




Not sure what change of direction means, as I understand it alll FNR's change direction, but the Jeffco I think uses a chain? Tompro also has this type of FNR as does Yoshi from Sinister Sand Cars.

liv4drt
11-07-2012, 05:17 PM
Hey thanks for that steering info.

Ya I am looking for gear box that with change the rotation of my motor, so my motor is turning counter clockwise I can run it to the gearbox that will change it to clockwise not a FNR gear box.

ironknot
11-07-2012, 09:04 PM
ATVs often have reverse, there's a 400z Suzuki quad that has reverse and i think the Yamy 660 has also a lot of Polaris CTV drives have but a lot are shaft drive, could be handy if you run the rear diff for irs.

Martinm210
11-11-2012, 06:55 PM
Also keep in mind many of the articles/diagrams assume your ackerman setup doesn't give you an offset tie rod.

http://www.longacreracing.com/articles/text/bsdrawing.jpg

If your spindle is setup for good ackerman, you actually end up with an offset tie rod setup similar to this:
http://image.circletrack.com/f/26716693+w750+st0/ctrp_1001_03_z+bump_steer_explained+tie_rod.jpg

At first I tried to line up the inner points, but ended up with significant bump and had to shorten the rack. This is what I ended up with:
http://martinsliquidlab.files.wordpress.com/2012/08/bigbuggy71.jpg
I would probably lower the upper inner arm points if I was going to do it over again to allow some roll with the bod roll, but it's pretty close now.