Does this swing-arm look bent to you?

[MiniBikeDan1980]

I have a 1971-1972 Steens Taco - Super Trail 100 Mini Bike & the swing-arm looks bent to me to the left. Are the side sections of the swing-arm supposed to be straight or are they curved in slightly? Also how should I go about straightening it, use heat & bend it back true again or just pound it out cold straight again? If anyone can take a few pictures of there 1971-1972 Steens Taco - Super Trail 100 Mini Bike swing-arm from a few different angles & take some measurements of there swing-arm I would greatly appreciate the help.

 

[MiniBikeDan1980]

These Steens Taco - Super Trail 100 Mini Bikes must be far more rare than I expected being no one has chimed in yet.

 

[DaddyJohn]

I'd just check your front/rear wheel alignment and see if there's any issues where the rubber hits the road (so to speak).

 

[MiniBikeDan1980]

Good idea I never thought of that, thanks for the help DaddyJohn.

 

[minibikin']

My T100 is straight....

 

[Havasu Dave]

Yes, the right side (photo two) shows a slightly bent swing arm. It probably has no effect on the bike outside of visual. If the spacer for the axle on the RH side was too short, and then the axle nut torqued down, it would bend that way after time. Or if it were loose and the bike was ridden, or wrecked, a lot of things could cause that.

I would use a press and cold bend it straight, but if that is not possible, heating it up with a propane torch and easing it straight in a vice will work, but probably give you some "teeth" marks. I am not a fan of hammering things that are welded like that, but it would also work, and probably give you some hammer divots.

I don't know where you are in this project, but I would definitely have the rear brake installed, axle and spacers, and then as Daddy John says above, check alignment. But put it all together first, because their is a chance that something in the axle installation caused the swing arm to bend, or the hardware or engineering required to get the rear assembled requires that bend, or some significant work. Like maybe the guy who welded in 1970-something was having a bad day and set it wrong in the jig before welding.

 

[MiniBikeDan1980]

Thanks for all the information Havasu Dave. The swing-arm on my Super Trail 100 did not have any spacers on the axle to space up the rear wheel & I had no clue it used any. That might be half of my problems to start with. I have been trying to get pictures of what the back end looks like on another Super Trail 100 Mini Bike for a good reference but no one has provided any yet. Maybe someone will post some pictures & measurements soon so I can get a better idea of what it is supposed to be like from the factory. I am still new to this model & learning as I go.

 

[MiniBikeDan1980]

My T100 is straight....

Yeah the Taco - T100 Mini Bike had a swing-arm that has its side plates welded all the way out to the edges with no offsets. The Taco - T102 & Super Trail 100 models had swing-arms that had different offsets on the left & the right sides of the pivot mounting point where it bolted onto the chassis. That is why I have been trying to figure out if it was actually bent or not because it is a weird sett-up.

 

[Havasu Dave]

The swing-arm on my Super Trail 100 did not have any spacers on the axle to space up the rear wheel & I had no clue it used any. That might be half of my problems to start with. I have been trying to get pictures of what the back end looks like on another Super Trail 100 Mini Bike for a good reference but no one has provided any yet. Maybe someone will post some pictures & measurements soon so I can get a better idea of what it is supposed to be like from the factory. I am still new to this model & learning as I go.

There are two considerations because you have a jack shaft and can work around chain alignment: Rear Brake engagement with the anti-rotation lug, and how the rear brake fits within the brake hub. Once that is established, you go back and see what spacing it takes on both sides of the axle to center the rear wheel/tire in the frame while allowing proper engagement of the anti-rotation aspects of the brake.

If you are waiting for hard and fast instructions, parts, part numbers and photographs, you're probably not going to find them. The best bet is to sweet talk someone you know who has this model and beg them to take photos. Even then, your requirements will be different. These bikes were never made to precision specifications. There were variances not only between like items, but between advertisements in brochures and actual production. (as an overall rule in the mini bike world)

Here is a link to a 2015 Build Off (build) on a T100 by a very talented member. I recommend going through it to get some ideas and looking around the threads here. In this case, Pat built a swing arm set because his were bent. https://www.oldminibikes.com/forum/...ldminibikes-build-off-entry-taco-t100.106288/

 

[MiniBikeDan1980]

You have been such great help Havasu Dave & appreciate all your helpful information. I'll take a look in the media section to see who has a Super Trail 100 model mini bike & see if they can help me out further. But your recommendations are exactly what I am going to try first & measure out things to see where the center of my rear wheel is at compared to the center of the front tire that member DaddyJohn also recommended doing. Then I will have a better idea of what corrections need to be made to line up my jackshaft sprockets compared to where the rear wheel needs to be. Thanks again for the extremely helpful information.

 

[jeep2003]

It looks to me they bent it on purpose to get the alignment to work. If you bend it straight its going to be where the front chain is and the clutch cant go any more inboard.

 

[MiniBikeDan1980]

Thanks for this important information jeep2003, you called it. I took a good look at things again from a bunch of different angles & you are totally right. The swing-arm is bent that way on purpose. If I straightened the swing-arm sides it would not allow the rear wheel to even fit then, so that was a dead give away & the clutch & 1st jackshaft sprocket & 2nd jackshaft sprocket to rear sprocket would not line up properly & interfere with each other like you also mentioned. What is actually bent is my rear fender mount bracket & the shock bushings are going on the upper right shock once I was looked at things a little more thoroughly. That is what must caused me to think the swing-arm was bent, looking at it from the back side & seeing the right shock at a slight angle created an illusion along with the rear fender mount bracket being bent. I took measurements to see if the front & rear wheels where correctly inline with each other once I found the center of my chassis & it was only off by just a tick less than an 1/8" so that seems plenty dang good & straight to me for a nearly 50 year old mini bike. Thanks again for reaching out & helping me figure this all out, I highly appreciate the help & your expertise.