My ST3 Winter Project

[Diesel62]

This is what ive been working on, I think it looks good.
I will be using a Honda 929 to power this thing. Just tacked welded so far. Almost to time to buy some shocks. Maybe Santa will leave them under the tree for me.

[rowycoracing]

Nice!

[Island Buggy]

I have steel coming tommorow to start a ST3 myself. Are you following the plans exactly or making some changes. Any tips on what you've done so far?

[Diesel62]

For the Frame yes I followed the Plans. I will be changing the size of the tubing on the front end control arms.
Also will I will be using automotive type CV axles rather then follow there plans.
As far as tips, measure 3 make that 4 times then cut. measure more and weld and take your time.
Cutting tack welds sucks. Oh and order your plate kits well before you need them. I had mine cut by a buddy who has a waterjet so they turned out very nice.
Bushings for these. I found that a toyota truck leaf spring bushing with a teflon trailer insert in the bushing fits a 9/16 bolt nicely. plans call for 1/2 and i figured 1 size bigger for the control arm bolt couldnt hurt.

[ttginc]

I too am working on an ST3 right now. I am using 930 CVs and 19.25 inch axles instead of the u-joints. I also am using 1.25 OD .109 tubing for the frame instead of the 1" black pipe the plans call for. I have a CB750 engine I am pulling out of my old mini buggy for power. I was a little disappointed with the ST3 plans as they left out some dimensions and didn't even include a bill of materials. How much steel did you use for the frame. I already bought 260 feet of tubing and I think that should be enough for the fram and chassis. I modified the suspension a great deal to move the pivot points closer to the center of the chassis for an arm length of about 20 inches. I am also going to put some miata rotors on the front wheels for more breaking as I intend to ride mostly on desert/trails with it. How much room do you have for the engine? The plans for the engine box are somewhat smaller that my older buggy but I don't want to extend the frame past 10 feet. Are you going to mount the engine on top of the rear carrier? I am going to do that but need to get an offset sprocket in order to do so with the CB750F engine. Good luck on your build. There aren't many ST3 builders on here so keep posting. As soon as I finish finals I should be able to put the frame together after christmas break.

[Diesel62]

Wow 260 ft of tubing, I had 200 ft and i have about 40 ft left.
Yup the Plans leave a lot to be desired,a lot of it is very unclear and a few dimimensons just arent there. I worked around those problems. a few less hairs now. But with common sense and a good eyeball on the tape measure the frame came out fine.

I made the backend of mine 6 inchs longer so I can mount the 929 above and ahead of the drive plates. I wanted to keep center of gravity as low as possable, So the omissions in the plans didnt matter as a bit of it was my own design anyways. time will tell if it works or not.

[Island Buggy]

Take lots of pics of your drivetrain, they'll be very helpful. My bosses brother owns a lazer cutter so I'm going to try that route. As far as bushings and that goes I think I'll turn those at work on the CNC lathe.

Keep us updated for sure, doesn't seem like many ST3's are being built.

[Diesel62]

I think the rear is still the same as in the plans. been a few days and i cant remember what it is exactully. would have to measure it again to confirm.

Front Control arms for those interested.

[wyattboche]

Hello,
I'm going to start the ST3 project here shortly.I'm going to make mine four wheel drive as I live in the colder climate.Kind of going with the UTV style and look.Going to be putting a Honda 500 Rubicon motor and drivetrain in with the option of having two and 4wheel drive. Would like to keep the overall width under 4 foot to keep it legal for wis state trails.Only thing I haven't fiqured out is how I'm going to run the front hubs.

[Island Buggy]

As far as the hubs go, look at getting a set of rubicon knuckles off ebay and modifying your suspension to fit.

I have a pair of ST3's in progress but getting yours under four feet will be tough. The buggy frame itself is 48 inches wide. I wouldn't think you would be able to get much suspension travel without moving all your mounting points farther inside the buggy.