Grand Daddy build

[OzFab]

Don't beat yourself up over your welding; for what it is, it looks ok to me...

 

[mysteryboy28]

Sadly though, with the bigger wheels you will either need a bigger sprocket, or a jackshaft, if you want to have any decent torque. For a buggy like that you're prolly looking at wanting around a 9:1 gear ratio (with those tires).

 

[landuse]

Nice progress! Don't worry about those welds, they look good enough to me.

You can raise the motor mount by welding some tubing on top of your mount and then bolt the engine onto that.

 

[mysteryboy28]

I'd move the motor back about 6 inches too, so you don't come anywhere near hitting the back of the seats on hard bumps. Plus it'll give the swingarm a little better balance, so the weight isn't all so far forward.

 

[Mballen13]

Landuse and Fabroman,

Thanks for the encouragement on my welds.

Mysteryboy28,

I suspected I would need a taller gear ratio...not going to change until I get to test drive and approximate how much more torque I desire. I will likely end up adding a taller sprocket. I will only go through the trouble of a jackshaft it the needed sprocket is too large in diameter.

Also I had previously read that the motor didn't have enough clearance on the seat side and thus as indicated in my earlier posts I have already pushed it back 5 inches. I am hoping it will be enough and by eyeballing it it seems like it should do. I am going to keep the motor rearward when I fabricate the motor mounts.

Landuse,

Thanks for the idea for clearancing the torque converter. In the picture I posted I had the motor sitting up on 1 inch square tube. I plan to drill then weld it on. The 1 inch will make for tight tolerances, but I don't want to push it up any higher than necessary so I can keep the center of gravity as low as possible.

Thanks guys!
Matthew

 

[landuse]

Thanks for the idea for clearancing the torque converter. In the picture I posted I had the motor sitting up on 1 inch square tube. I plan to drill then weld it on. The 1 inch will make for tight tolerances, but I don't want to push it up any higher than necessary so I can keep the center of gravity as low as possible.

Thanks guys!
Matthew

I didn't catch that it was sitting on tubing already. I see what you mean...

 

[Mballen13]

Pic shows the new engine mount. Welded a piece of scrap to the 2 tubes to hold it aligned for welding onto swing arm. Time is running short but I hope to weld mount today. I will throw up a pic once done.

 

[Kentguy13]

Thanks for the updates! Looking good

 

[Mballen13]

Motor mount works nicely. Tight clearances with sprocket but I think I can get a big enough sprocket in there once all is said and done. Additional 5 inch stretch on the swing arm seems to fit the bill with clearance on the seats on big bumps.

Mount steering column, throttle cable, brake line, and install proper hardware and she'll be ready for a test drive.

Then to finish up:
Roll cage
Seat belts
Install battery box
Install head lights
Install winch
Run electrical
Paint


Let me know if you have any questions/comments!

Thanks,
Matthew

 

[mysteryboy28]

noticed a small problem. your rear bottom shock mount bracket is too wide. with a long skinny bolt like that taking the full weight of the buggy on hard bumps, you will be bending the bolt for sure. if you can make the bracket just narrow enough for the shock, then the inner sleeve of the shock will prevent the bolt from bending. i would cut off the bracket, make it just narrow enough for the shock and a washer (so that you know it will fit just the shock when you're done), then weld it back onto the buggy.

and yes, i'm calling it a buggy, cuz it's too cool and big to be called a kart. lol. i've been watching your build and progress, cuz there aren't a lot on this site that really get my attention since i "graduated" to building 80hp mini buggies. you should feel special. lol.

the only other issue i see is that you may want to find a way to throw a 3rd bearing on the rear axle by the sprocket, cuz you're going to have some axle flex when you punch the gas. same with the brakes if you don't have a bearing near the rotor.

 

[Mballen13]

Mysteryboy,

Lol. I suppose it is more of a buggy frame with a go kart engine on steroids! Would love to push the hp higher, but my wife has me on a budget for this build. And I am building this for my 5 year old to enjoy too!

As for the rear bottom shock mounts, I have fabricated some spacer to fill in the gaps from a thick piece of steel tube that I had in my scrap bin. If they don't work out I will go with your suggestion and cut them down. Why did I do it this way? Laziness I guess! I had those brackets on my shelf and just grabbed them while mocking things up.

I do have a question for you...what negative effects will I have from potential axle flex? My brake will actually mount directly next to the driver side bearing so I think I will be fine while braking. Adding a third bearing in the center of the axle wouldn't be difficult, however I would have to order it as I don't have a local supply shop.

Thanks so much for your suggestions! Fabrication flaws/changes are much easier at this stage in the game!

 

[mysteryboy28]

Tell me about it - I just completed a complete rebuild of one of my buggies. I would much rather have built from scratch! Lol.

Axle flex is bad for a few reasons. A couple i can think of: constant bending will fatigue the metal, leading to premature failure. Plus your chain will be more likely to slip, causing excessive wear on the sprockets.

 

[Mballen13]

Tell me about it - I just completed a complete rebuild of one of my buggies. I would much rather have built from scratch! Lol.

Axle flex is bad for a few reasons. A couple i can think of: constant bending will fatigue the metal, leading to premature failure. Plus your chain will be more likely to slip, causing excessive wear on the sprockets.

Stopped by BMI karts today and picked up an additional axle bearing. Bit of a drive but I was already on the road.

Also picked up the MCP cast aluminum hydraulic brake kit. Pricey, but a band brake for this kart is silly!

Will be back in the garage on Thursday.

Thanks,
Matthew

 

[MisterRoboto]

****, i wanna live near bmi.

 

[landuse]

****, i wanna live near bmi.

You and everyone else.....

 

[OzFab]

noticed a small problem. your rear bottom shock mount bracket is too wide. with a long skinny bolt like that taking the full weight of the buggy on hard bumps, you will be bending the bolt for sure. if you can make the bracket just narrow enough for the shock, then the inner sleeve of the shock will prevent the bolt from bending. i would cut off the bracket, make it just narrow enough for the shock and a washer (so that you know it will fit just the shock when you're done), then weld it back onto the buggy

Mysteryboy,

As for the rear bottom shock mounts, I have fabricated some spacer to fill in the gaps from a thick piece of steel tube that I had in my scrap bin. If they don't work out I will go with your suggestion and cut them down. Why did I do it this way? Laziness I guess! I had those brackets on my shelf and just grabbed them while mocking things up.

with Mysteryboy on this one, setting the bracket close to the eye of the shock is the way to go. Even with a spacer between the bracket & the shock, you run the risk of bending/breaking the bolts.

The easiest solution is to cut the tabs off the brackets, bolt them to the shock with a thin washer between the shock & one of the tabs (to provide a small gap to make fitting easier) & reweld them to the base plate. Tack them first then remove the shock, you don't want to melt the rubber bush...

 

[Mballen13]

I have run into a little snag mounting the master cylinder. I don't have clearance to mount where I had planned. I originally planned to use a band brake and that idea was thrown out the window and now I am left with figuring out a work around.

I have mounted the third axle bearing and the brake caliper. I will be running steel hard lines for the brakes with a section of plastic line for flexibility at the caliper.

And I suppose I will break down and fix the rear bottom shock mounts. I agree that it has potential to be problematic and haven't sacrificed anything else on this cart so I won't start now.

Don't have any updated pics at the moment but I will be back out in the garage this weekend so I will snap some pics and post in the next couple of days.

Thanks,
Matthew

 

[mysteryboy28]

where did you plan to mount the master cylinder? what i've done in the past is run a 1/4" rod from the pedal back to the master cyclinder mounted next to my seat, then ran the hose from that to the caliper. worked great. however if you're gonna have front brakes too, it gets more complicated. what kind of master cylinder are you using? pics? on my last buggy i used 2 master cylinders. one for the front 2 calipers, and one for the rear. both were connected to the single 1/4" steel rod.

here's a some pics and videos of different hookups i've done for master cyliders.

http://www.youtube.com/watch?v=o262xrY-Oi8

http://www.youtube.com/watch?v=DTe_6uw0z1Y

 

[Mballen13]

Working on shortening the rear bottom shock mounts. Thought I'd give you a picture of progress

 

[Mballen13]

This pic shows modified shock mount and caliper mounted.