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GT LTS Custom suspension arms

2012 Views 7 Replies 8 Participants Last post by  kavisiegel
Would you guys consider it a bad idea to make custom suspension arms?

I made these, (image attached) and I don't really know if I want to trust them. They're beefier than the stock ones, but this is different aluminum, and no ridges (I don't know if they were structural.

I didn't even know, until now, that they make FOX shocks that fit in there. I feel like an idiot, I searched way too much, and only discovered that now. Regardless, I already bought this shock and made these arms.

What do you guys think?

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cvxdes said:
Would you guys consider it a bad idea to make custom suspension arms?

I made these, (image attached) and I don't really know if I want to trust them. They're beefier than the stock ones, but this is different aluminum, and no ridges (I don't know if they were structural.

I didn't even know, until now, that they make FOX shocks that fit in there. I feel like an idiot, I searched way too much, and only discovered that now. Regardless, I already bought this shock and made these arms.

What do you guys think?
DIYed? cool man. :thumbsup:
what grade of aluminum and have they been heat treated?
The main thing I would be worried about is the change in the effective angle that the suspension activates the shock.
Interesting. What I want is something bolt-on like this that allows me to change from the trunion shock to a two-eyelet shock without any other changes to the bike geometry.
Nice work on those arms dude. I'd be more worried about the heat treatment like GM123 said. The process hardens the aluminum so you may want to get that done. On another note. Did you get those bushings (on the main pivot) or did you make them? I've never seen white bushings. Where did you get them if you did get them from some place. I've been looking at buying bushings for my LTS but ben's cycles sells the whole kit and all I need is the bushings. I can't see spending over $100 bucks when I should be able to find the bushings for less than that.
What is the stroke length? And what if any change is there to the effective rear end travel?
In general I'm wondering how this may effect the lateral stiffness too.
Ha! Here I am, 7 years after this post, searching to see if anyone else in the history of GT LTS has attempted to alter the suspension geometry.. only to find out that OP of this post is.... myself. Below is another photo of that same day.

I was in high school when I made this post originally. That suspension has never been used, I'm bringing the project back now that I understand there's more to it.

Does anyone have advice on what things I should take into consideration making the next iteration? I already know it should be 6061-T6 aluminum as the original GT part was. I know that I need to figure out the proper geometry, but I'm not sure how I should do that. I know that I need to spend more time selecting a more appropriate shock this time around too. As others have mentioned above, I should look into heat treatment and design in some lateral stiffness too. I also want to make the top shock mount holes stronger and tapered inward to the width of the shock, rather than having that 4" spread between the sides.

I originally wanted to have more suspension travel, which should be easy to accomplish by making the length of this adapter longer and the mounting location of the shock more forward in relation to the back pivot. Doing that might alter the head tube angle though and I'm not sure what's acceptable there. Maybe a new fork is in order - I have a 4" travel fork that's a bit longer than the original somewhere in my attic. I'm not sure what software to use to draw this out. My plan is/was to draw a hundred different things in Autocad and hope one geometry works in a compressed and uncompressed state of the shock, then following up to make sure that wheel travel distance is relational to shock travel. I haven't used Autodesk Inventor in years, but maybe I can break that back out, or maybe learn Solidworks. (The local hackerspace has all of the above for use)

When I bought this bike in high school, I drove 4 hours and spent my entire savings on it. I wanted to make a full suspension moped with it (mopeds were cool back then :p ) Staying true to that original commitment, I think I want to make this an electric bike, so I don't know if that adds any factors. I'm probably going to also design an aluminum weld-on to serve as a torque arm and a rear disc brake adapter.

I also destroyed all the original bushings. I can turn some new ones on a lathe but have no idea what material to make those out of. I think I made some out of nylon in high school, they're somewhere around here.

Unlike high school, I actually have a budget on this project. I think all-in to make this what I would have been proud of when I conceived of this project, I'd spend $1500. I want to put some good hydraulic brakes on, nicer wheels, shifters and better gearing. I have no idea what I'm doing though. There's so much to research. What kind of bike expert can I hire for a few hours to answer these questions? (I ask that half in jest as an avid DIYer and one who loves to read about new things all night... but kinda wish it wasn't so time consuming)

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