MTD Columbia build issues Please help

[WillyBoy4343]

Hey guys I’ve just got into the older mini bikes scene and decided to pick up an old MTD Columbia bike, don’t know too much about it but I have some questions. So in the first picture is the top I’m assuming of one of the front fork arms and I can’t quite figure out what that bent piece on the end is. There’s two other pieces as seen in the second picture that look like they go on top of the arms but that bent piece is in the way. Also how do these arms attach to the steering assembly. Last question is how do the rear shocks attach to the fram (last picture) because there is a lot of space and I’m obviously doing something wrong there

 

[WillyBoy4343]

I would appreciate any help

 

[Moderator]

Haven't messed with one of those in years but the rear shocks are wrong for the bike. Should have a bushing eye on the end instead of that clevis end. You could probably make those work by installing a spacer on each side to keep the clevis centered. Slide those fork lowers up inside the upper tree and rotate them to lock the spring into the cup and see what it looks like. Not sure what that other piece of tubing is with the cross hole in it ?

You can get some idea of what the bike should look like from this thread...look for the models with the same front end as yours with the short trees.

https://oldminibikes.com/forum/index.php?threads/the-official-mtd-mini-bike-thread.60858/post-503160

 

[WillyBoy4343]

Haven't messed with one of those in years but the rear shocks are wrong for the bike. Should have a bushing eye on the end instead of that clevis end. You could probably make those work by installing a spacer on each side to keep the clevis centered. Slide those fork lowers up inside the upper tree and rotate them to lock the spring into the cup and see what it looks like. Not sure what that other piece of tubing is with the cross hole in it ?

You can get some idea of what the bike should look like from this thread...look for the models with the same front end as yours with the short trees.

https://oldminibikes.com/forum/index.php?threads/the-official-mtd-mini-bike-thread.60858/post-503160

Thanks for the tip, do you know if there’s any aftermarket fork arms being made that would fit because it’s hard to source parts and I’m doing this project for a fun rip around and not a restoration. I’m pretty sure Baja warrior arms work as they have the same 1” diameter but those are hard to come by

 

[Moderator]

Notice in this close up the nut where the yellow arrow is pointing. On the top of that weird bracket ( 2nd pic red arrow) is/was a threaded stud that must protrude out the top of the tree and takes that nut. This prevents the forks from falling out when you jump the fountains at Caesars Palace. That bracket must flex or telescope internally to allow the front suspension to function. Never had one like that but that's my theory from looking at it.
(The extra piece of pipe with the hole is to throw at people who call the bike ugly.)

 

[WillyBoy4343]

Notice in this close up the nut where the yellow arrow is pointing. On the top of that weird bracket ( 2nd pic red arrow) is/was a threaded stud that must protrude out the top of the tree and takes that nut. This prevents the forks from falling out when you jump the fountains at Caesars Palace. That bracket must flex or telescope internally to allow the front suspension to function. Never had one like that but that's my theory from looking at it.
(The extra piece of pipe with the hole is to throw at people who call the bike ugly.)


View attachment 243130

View attachment 243131

I figured that, I did some smithing and got that straight and just the top bent at a 90 but unfortunately there isn’t enough thread to reach through the top of the fork assembly and take a nut so that’s why I’m looking into “making an upgrade”

 

[WillyBoy4343]

There’s barely any thread at all for some reason, definitely not enough to reach

 

[Moderator]

Somebody probably snapped them off when they removed the rusted nuts. You could cut those old studs off and install new bolts in their place. tack weld or braze the heads to the bracket to keep them in place.

 

[WillyBoy4343]

Somebody probably snapped them off when they removed the rusted nuts. You could cut those old studs off and install new bolts in their place. tack weld or braze the heads to the bracket to keep them in place.

It seems as though that or sourcing discontinued Baja arms are gonna have to be the road to take..

 

[Havasu Dave]

If I am seeing the photos right, Cat (HPE Muskin) used a similar front fork mounting method where a 3/8 bolt was welded to the top of the tube, and protruded through the top of the tree. There was a piece of rubber snubber withing the tube where it butted to.

 

[Moderator]

If I am seeing the photos right, Cat (HPE Muskin) used a similar front fork mounting method where a 3/8 bolt was welded to the top of the tube, and protruded through the top of the tree. There was a piece of rubber snubber withing the tube where it butted to.

Yep. The difference I see here Dave is the MTD design will not allow it to telescope in and out of the top hole of the tree like the CAT. That's a weird design but it must have the ability to flex downward.

 

[WillyBoy4343]

Yep. The difference I see here Dave is the MTD design will not allow it to telescope in and out of the top hole of the tree like the CAT. That's a weird design but it must have the ability to flex downward.

Pulled a piece of steel off a shelf might try a little fabrication and see if I can replicate that piece and if that doesn’t work then I’m gonna find some real suspension for this puppy