ATC 250r suspension tech

[loganm]

Not that I was just waiting to be unbanned, but airfoolers doesn't get much traffic and I need more input on this...

Started with this:
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Used every clamp I could find and an old jig table to keep it as straight as possible:

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It's +10". So 24 1/4" ish. It is LONG, but, I effectively doubled my suspension travel with the stock shock, effectively putting it at ~9+" Someone on another forum told me that 1.5 .120 wall HREW would bend if I jumped at all, so the 1" flat bar on the top and bottom should help prevent that a bit.

I hanmered the carrier out cutting it off and welding it on and installing the new bearings, so I reinforced it a bit. BEFORE the new bearings were installed.

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This is full compression.

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I also modified the chain tensioner. I'm not sure if this design will hold up, I'll just have to run it and see how it works.

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As for the front suspension, seeing as every pair of 85 forks on ebay seem to be bent, I'm going with inverted forks. Either a Honda VTX triple clamp, or I'm seeing if my friend can make me a set. I like the rake on the stock design, some of the inverted fork trikes I found on google seem to have the forks too vertical for my liking. Hitting a tall square edge bump would put a lot of stress on the fork tubes instead of the springs absorbing the hit. I'm 6'1, 225+ in full riding gear, I think USD forks would be a good investment.

I still need to find an extended brake line. 40" is what I measured for the entire length of the line. Seeing as the parking brake didn't previously work I'm not too worried about keeping it. My hubs are also hammered. I think I want a smaller more modern atv tire and definitely a bit wider rear end.

Feel free to point out any glaring flaws in the design I overlooked.

[barnett468]

It's +10". So 24 1/4" ish. Someone on another forum told me that 1.5 .120 wall HREW would bend if I jumped at all, so the 1" flat bar on the top and bottom should help prevent that a bit.

I hanmered the carrier out cutting it off and welding it on and installing the new bearings, so I reinforced it a bit. BEFORE the new bearings were installed.

I'm 6'1, 225+ in full riding gear,

Feel free to point out any glaring flaws in the design I overlooked.

You would have been far better off using rectangular tubing.

Your swingarm will flex like a rubber band in a hard turn or whenever a high enough force is applied more to one wheel than it is to the other.

I would add more reinforcement braces/gussets.

Your flat plates will do very little to increase resistance to bending . They would have made it more resistant to bending if you would have stood them on their edge as shown on the arm below.

Just lay the same size piece of flat metal on the floor with a 2 x 4 on each end and stand on it, then place it on its edge with a vice holding each end and stand on it . Obviously it will be a little stronger because it is welded to the swingwarm but not be very much.

http://straightupcycleparts.com/img/1108/110879_07_xl.jpg

[loganm]

When the swingarm bends, the bottom piece SHOULD be under tension and the top under compression forces. But I'm not an engineer, so I don't know all the technical details. I will see how this one works, if I build another I'm planning on having a new carrier machined and building out of DOM tubing, which is almost twice the strength of HREW. The stock swingarm by comparison is made out of thin gauge steel, but it is very short.

[El Camexican]

I like the rake on the stock design, some of the inverted fork trikes I found on google seem to have the forks too vertical for my liking. Hitting a tall square edge bump would put a lot of stress on the fork tubes instead of the springs absorbing the hit. I'm 6'1, 225+ in full riding gear, I think USD forks would be a good investment.

The longer you make the swing-arm the tall the rear of the trike will be. That will decrease the rake of the front and make the forks "more vertical". If you use USD forks that are longer than the stockers you may be able to get the angle back to what it was, but the trike will be taller. Don't worry about the stress on the USD forks, anything 43mm or larger will out last your frame if it comes to one or the other bending. You'll want a stiffer rear spring for that longer swinger as well if you plan to jump it.


I still need to find an extended brake line. 40" is what I measured for the entire length of the line.

Spiegler. Call them, give them the length, banjo size and angle and tell them what color you want. The banjos are adjustable which makes things a lot easier when building something.


definitely a bit wider rear end.

The wider you go the more leverage you'll be putting on that swing-arm which (don't take this the wrong way) I'm glad you'll be testing it and not me:beer

[loganm]

I can jump on the rear grab bar and bottom out the suspension... But I fully expected that. Even with the preload maxed out. Now, I'm running chinese 22" ballon tires. They were brand new when I bought the trike, but I've wanted to go down to 20s or 18s, which will lower the rear 1-2"

I'm shooting for about the same stance as stock with me sitting on it. As it is right now it leans forward quite a bit under its own weight. I did some rough measureing today and with USD forks and a stock size front tire I should be at the ideal ride height front and rear. Maybe a little tall for my liking. But smaller tires and some suspension tuning should help with that.

[barnett468]

When the swingarm bends, the bottom piece SHOULD be under tension and the top under compression forces. But I'm not an engineer, so I don't know all the technical details. I will see how this one works, if I build another I'm planning on having a new carrier machined and building out of DOM tubing, which is almost twice the strength of HREW. The stock swingarm by comparison is made out of thin gauge steel, but it is very short.

Again, rectangular stock will be far better.

Your swingarm will be just as flexy if you build the carrier out of DOM.

The thickness of the stock swingarm is irrelevant since you are making yours 10" longer AND using wider tire spacing, however, the stock swingarm can be thinner because it has a massive box section reinforcing it.

You said you are not an engineer and asked for help so that's what I'm trying to do.

http://i.ebayimg.com/09/!BmW3yGwBmk~$%28KGrHqMH-CsEtrjEoZm1BLf%28fJn+mQ~~_1.JPG?set_id=880000500F

[loganm]

If I remember correctly the ticket said it was A513 1.5"x11 gauge HREW tubing.

I agree that mine could use more triangulation between the tubes, but, the real question I have is how hard of a hit will it take before the swingarm actually BENDS, not just flexes.

Also, if you notice on the stock swingarm, the shock mounts are actually welded to the carrier, so VERY unlikely that it will bend. You would be snapping axles off before that swingarm breaks. Mine however has a lot more leverage acting on the tubing itself due to the design.

[El Camexican]

Pre-load has no effect on bottoming out and DOM is not necessarily stronger than ERW tube. The strength depends on the grade of steel and shape either is made of.

This A513 11ga. (.108 - .120") you mention is typically grade B (55KSI) and close to .118" thick if made in the USA and .110" thick and grade A if imported. If from Mexico, or South America the KSI will be at least 44, if Turkey, or China 36 on a good day.

The grade is what's important, but few if any mills use grade C coil to make ERW tube thinner than 3/16". When you get into DOM then you start finding higher strengths in smaller sizes, usually rounds only. Once you're set on a design you may want to use 4130. It comes in a wide variety of sizes that would be perfect for you, plus its very strong. Unfortunately it's not cheap and MIG welding it isn't recommended.

[barnett468]

..the real question I have is how hard of a hit will it take before the swingarm actually BENDS, not just flexes.


Well, my guesstimate is that the first time you land on a hard flat surface off a 5 foot or higher jump, it will turn it into scrap metal.

[loganm]

It's a moot point. If it breaks I'll build another one, stronger. Build it and break it until everything is stronger than my riding abilities.


Pre-load has no effect on bottoming out and DOM is not necessarily stronger than ERW tube. The strength depends on the grade of steel and shape either is made of.

This A513 11ga. (.108 - .120") you mention is typically grade B (55KSI) and close to .118" thick if made in the USA and .110" thick and grade A if imported. If from Mexico, or South America the KSI will be at least 44, if Turkey, or China 36 on a good day.

The grade is what's important, but few if any mills use grade C coil to make ERW tube thinner than 3/16". When you get into DOM then you start finding higher strengths in smaller sizes, usually rounds only. Once you're set on a design you may want to use 4130. It comes in a wide variety of sizes that would be perfect for you, plus its very strong. Unfortunately it's not cheap and MIG welding it isn't recommended.

I don't want to use chromoly for cost reasons. And because of heat-treating. It is far more work than I am capable of. I think with 1" 1020 DOM and a truss-style swingarm it would be far stronger than anything I'm capable of breaking.

[barnett468]

It's a moot point. If it breaks I'll build another one, stronger. Build it and break it until everything is stronger than my riding abilities.

If you break it or bend it bad enough off a big enough jump, you won't have any riding abilities because both your legs will be broken or the cartilage will be shredded.

The intelligent thing would have been to ask for help designing it BEFORE you built it instead of building it and then asking for people to "point out the glaring flaws" in your "design" and then not listening to them and telling them their suggestions are "moot points". :rolleyes:

[onformula1]

Since the swingarm has be commented on, I think you next concern would be-

The rear shocks compression & rebound damping, spring rate.
The frame flexing, flexing of the adjustable swingarm pivot bolt.
Chain derailing and tension.
Overall handing on the trike.

Plus 3" is about max on a first gen, unless you only dirt/sand drag.

[loganm]

Since the swingarm has be commented on, I think you next concern would be-

The rear shocks compression & rebound damping, spring rate.
The frame flexing, flexing of the adjustable swingarm pivot bolt.
Chain derailing and tension.
Overall handing on the trike.

Plus 3" is about max on a first gen, unless you only dirt/sand drag.

Mine is a plus 10. See how I more than tripled your "about max". I'm setting records.

Jokes aside, my options for shocks are limited. Most everything nowadays has a rising rate linkage. This does not, the spring is progressive rate. Is the stock shock worth rebuilding or would I be better off finding a more modern dirtbike/atv shock on ebay and using a progressive rate spring?

Overall handling is a complete shot in the dark at this point, which is why this swingarm is a rough prototype and not a show quality master of engineering... It will take a lot of time and work to dial it all in.

How do you see the swingarm bolt flexing to the point it becomes a problem? Frame flex could be an issue, no way of telling until I ride it. As for chain tension I will have to get it into riding condition before I decide if a roller/spring tensioner and chain guide are necessary.


If you break it or bend it bad enough off a big enough jump, you won't have any riding abilities because both your legs will be broken or the cartilage will be shredded.

The intelligent thing would have been to ask for help designing it BEFORE you built it instead of building it and then asking for people to "point out the glaring flaws" in your "design" and then not listening to them and telling them their suggestions are "moot points". :rolleyes:

So you've done this before then? Can I see your swingarm, I would like to take some "design features" as notes. If you don't have anything constructive to say, or if you're just mad that I have no reservations about hacking up vintage 3 wheelers... :beer: :rolleyes: :welcome:

[loganm]

Here are some more facts. The rear grab bar will in fact bend and break well before 1400lbs. Ask me how I know, or wait for pics... I would say at most I had 1000 lbs on the rear end. The swingarm was just starting to bow. I do agree with barnett that it may be too flexy especially with an uneven landing

And with the preload maxed out the spring bottoms before the shock. Backed it off a bit and netted me another inch of travel. Maybe the stock shock will work with a rebuild and stiffer spring.

[DohcBikes]

Adds 10+ swingarm, touts the gain in suspension travel.

Because, um, long swingarms are great for jumping.

Cmon guys, this dude is a pro fabricator, there's not a single thing you could teach him.

[loganm]

https://www.ebay.com/ulk/itm/361505003022

No report on quality yet, but it's less than 1/3 the price of a custom line, didn't have any trouble bleeding it either. Recommend using the stock banjo bolts.

[barnett468]

https://www.ebay.com/ulk/itm/361505003022

No report on quality yet, but it's less than 1/3 the price of a custom line, didn't have any trouble bleeding it either. Recommend using the stock banjo bolts.

No its not . A standard length line from Galfer is $26.00 and they may extend it to the correct length for only 5 or 10 bucks . The line you bought is 2" too long.

http://www.pipe-city.com/brake-lines-c-929_8656_34902/braided-stainless-steel-rear-brake-line-p-314100.html

http://www.galferusa.com/brake-lines-for-street-sport-racing-motorcycles/

They also have different colors.

http://www.galferusa.com/wp-content/uploads/2012/01/custom-brake-lines.jpg

[loganm]

That would've been nice to know about before hand. Spiegler was the only company mentioned and shits expensive

[barnett468]

That would've been nice to know about before hand. Spiegler was the only company mentioned and shits expensive

Well you could have known before you bought the other one if you had simply asked . That's the whole purpose of this particular forum.

[loganm]

I did ask. 4 dollars is nothing to fret about though ��

[barnett468]

I did ask. 4 dollars is nothing to fret about though ��

Nobody saw it then . If you want answers, it is helpful to make clear specific questions that are not combined with a lot of other info where it can be lost and you will get them.

No, the price difference isn't a big deal but its sometimes hard to find a place tor 2 extra inches of brake line . plus you could have goren a colored one if you wanted.

contrary to what you have inferred at times, there really isn't anything that someone doesn't know on this site and they are all very happy to help people that are courteous to them.
.

[El Camexican]

That would've been nice to know about before hand. Spiegler was the only company mentioned and shits expensive

Spiegler offers custom lengths, colors (fittings and lines) banjo angles add the banjo fittings can be rotated 360 degrees for a perfect fit. They are also DOT and TUV approved and guaranteed for life.

That shits expensive

[loganm]

I'm fitting the chain up right now I'll post a pic with the tensioner tight and see if you guys think I need an idler or chain guide

[kaymo]

buncha haters up in here lol.

[loganm]

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I think the chain slap is going to be bad...

Now, if this swingarm bends, or if I just decide to build a better one, would I be better off designing one from say 1" .120 wall DOM and incorporating a truss into my design, or just use 1.5 .188-.25 wall DOM, with the same general design used here, and a new carrier made. I know this design is easier to make and I could knock it out in a couple hours. The other option I thought about is designing and fabricating one out of plate steel.

[loganm]

First impression; well I can actually slide the damn thing now. Wheel spacers and some ITP hole shots and it should be pretty fun to ride

[loganm]

Second swingarm, thinking I'm going down in length to a +6, which should put me ~20", or the length of a modern trx450r.

Does anyone think it would be worth my time modifying the frame for a 450r linkage? Only downside I can see without measuring would be that the chain tension is adjusted via the front pivots, which would move the shock angle a few degrees when adjusting the chain.

I have (very) basic drawings for a swinger made out of flat plate, either cut by me with a plasma or sourced out. I still have to find a shop to make me pivots and a new carrier (any takers?).

I think if I buy a set of inverted forks + triples on eBay, I can take them to a competent machine shop and have them build billet triples at the width I want out of aluminum, shouldn't be crazy expensive aluminum is not as time consuming to mill. Or I will contact Jason hall to see if he's going to be building more any time soon. Idk what most people run but I think I can get a 200x hub and brake setup to work.

[loganm]

I`ve been running this +6 with all stock linkage for over 10 yrs ..... longer brake line and banshee slider thats it .

That thing is slick? What is the swingarm made out of? First gens didn't have a linkage, I think modifying one to work would be less work than spring and valving changes on a shock that isn't even adjustable.

[loganm]

Is there anyone with a 450r linkage setup that can take some measurements for me? I picked up a 450r shock on ebay for $35 total, couldn't pass it up. Judging from pictures I thought it was a lot shorter, nope just beef.

I have very basic drawings for v2 atm. Tried CAD but I didn't have the best of luck with it. Going to make it out of 3/16" flat plate, cut with a plasma. Carrier machined out of DOM. Should be pretty beef.

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[loganm]

Does anyone happen to know the inside width of the carrier bearings? Need to have a carrier machined to build this swingarm, before I put these holeshots on.

[oldskool83]

you gues need to learn to look up stuff on partzilla.com it tells you bolt sizes and bearing ID/OD/width...

[loganm]

I need to know the width BETWEEN the bearings.

[oldskool83]

yeah man...its there. Its called the sleeve..........same one used on a 86-87 200x.

[RubberSalt]

After reviewing the design of the swing arm, the flat bar isn't going to last. My recommendations for a cheap fast fix, some angle iron. It will provide the necessary vertical support to the full length, easy to weld on, and will provide strength somewhat close to square tubing while being combined with your set up.

Another option would be to add curved supports. I'd give an interesting look and much strength.

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Are you close to Wichita, Loganm? The yard store has everything you could dream of as far as materials go. They are typically scrap aviation parts/materials. Very high quality and sold by the pound typically. All kinds of tubing, plates, pipes, etc.

[loganm]

I'm scrapping the current design. Still not 100% on the flat plate design though. Need to sort out my plasma if I'm doing that.

[loganm]

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They're a little heavier than the balloons, not by much though. Bearings are at the machine shop, once those are done I can put this swinger together.

[briano]

All the extra weight is going to make it harder to push it home when you blow it up, AGAIN.

[oldskool83]

dont jump or flip much they tiny axle will bend at the mass point of extended hub. you just need to put a good rear shock on there and call it day and make it nice. are those 20's or 19's. I wont run bigger then 18's on a 3wheeler, no real need.

[loganm]

dont jump or flip much they tiny axle will bend at the mass point of extended hub. you just need to put a good rear shock on there and call it day and make it nice. are those 20's or 19's. I wont run bigger then 18's on a 3wheeler, no real need.

They're 20s. I think 20s were cheaper, I don't remember. It topped out at 60 with the 22s so I may add a tooth in the front or minus 2 in the rear. I'm planning on a durablue axle at some point, I don't expect this one to last. I don't plan on winning any pro level ATV races, just want to have some fun on the track.

I have a set of 2000 cr125 forks with triples on the way, and a complete 200x hub, rim, disc. Going to taper bearings in the head tube if it doesn't have them already, and maybe some extra reinforcement in that area.

[loganm]

Forks in. Straight, light visible scratches that I can't feel and some mild discoloration on one tube. Should be perfectly usable after a rebuild. Now to figure out triples, I think if I'll get some design ideas off the Google and take the forks into a machine shop and see if they'll build me some clamps. Also will need to have an axle made, I need the front hub first so I can figure out width and such.

If anyone wants my complete front end speak up, everything but the bars can go. Forks are straight, need seals. Front disc works, hub is good.

[loganm]

Triples in. Bottom clamp gonna need bored ~<1mm, top is too large, gonna need a sleeve or something. Pulling my front end off this weekend. Gonna get measurements for a new steering stem, and a front axle. I'll post up a parts list and total cost for the front end when I'm done. Hoping to be ~$600, could be cheaper if I already had a front hub and tire, and if forks and hub didn't need rebuilt.

[RubberSalt]

If your looking into rear axles, why not find the machine with a wide tough axle, the build your swing arm to bolt to the carrier?

That or find a machine that has cheap after market axles and adapt to that machine?

[loganm]

I honestly don't know. There's 1000 different directions I could go with this and honestly I'm just winging it at this point, there is some thought that goes into it but in 10 years airfooler parts will probably be hard to come by and I'm looking less from a parts availability longetivity standpoint and more of what can I build that will work okay. Plus right side drive makes it hard to find any parts.

[RubberSalt]

Oh yeah, right side drive.

I've got this figured out. Flip the carrier upside down! Polaris has a swing arm/carrier set up that could be flipped around without a problem. They are also tough, those machines were heavy. On top of that, the parts ran for ever without much change. The trail blazer, xplorer, trail boss, 330 400l, 350l, ect, All had the same frame. Even the scrambler and the sportsman.

Pretty much any Polaris from the 90s and early 2000s. Look for this swing arm and the carrier to match. It's also a chain tentioner by design.
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[loganm]

Well, I measured something wrong... More like found the wrong measurement online, I can't even find where I found it. So I spent $50 on a useless piece of metal. Now is there a more accessible axle I can run? 400ex stuff?

Machine shop is boring my bottom clamp and making sleeves for the top. I'm gonna pull the front end off tonight, get measurements for a steering stem. When I get my triples back I can get measurements for an axle etc. like actual physical measurements, not "measurements" I find online.

Also, why not taper bearings for the rear axle? Seems like a much better fit, and would eliminate having that pesky collar.

[Mr. Clean]

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They're a little heavier than the balloons, not by much though. Bearings are at the machine shop, once those are done I can put this swinger together.

I dont have much to offer, but whats up with that dude who is laying on the ground, he might need some help getting up or at least a nice cool refreshing drink!!

[loganm]

I dont have much to offer, but whats up with that dude who is laying on the ground, he might need some help getting up or at least a nice cool refreshing drink!!

I told him I would do that radiator since I already know what not to do, but he's like no I'll do it. Then it leaks, because you have to unbolt the fan clutch wire holder thing to get the rad in without tearing it up.

[loganm]

Alright here's a bit of info on this swap, note that this might not be significantly cheaper than custom triples.

2000-2007 cr125 forks
~2002 vtx 1800 triples
200x front hub
All balls taper bearing conversion for the head tube

Alright so you will need to press the steering stem out of the clamps. Take the clamps and forks to a machine shop, the bottom clamp will need to be bored ~1 mm over, best to have the forks with you for a good fit. This is where it stops being cheap; the top clamp is too large, I had them machine me a couple sleeves out of aluminum, with a small flange so they won't fall through. You will have to grind the steering stop down significantly, but you can use the stock steering stop on the frame.

You will have to have the steering stem turned down. The top bearing surface has to be brought down on the shaft ~1 5/8". The bottom surface will have to be turned down to fit the bottom bearing. The bottom bearing is slightly larger ID than the top. MAKE SURE THEY DO NOT TURN DOWN THE STEM WHERE IT PRESSES INTO THE TRIPLE. I still need to work out a shim stack. I'll get pics when I actually have the triples on the bike.

Center to center the forks will be ~10.5 inches. Front hub is a TIGHT fit, you will have to get rid of the studs on the rotor and run countersunk Allen head bolts, or regular bolts with slight grinding on the head. You CANNOT run an 8" front tire, it will not fit between the forks.

This is as far as I have made it. I'm not sure but I THINK the stock rim will fit, not sure if brakes are even possible. I wouldn't recommend doing this, at least until I finish mine, just in case it's not viable to make this setup work.

[loganm]

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That's the approximate ride height with a 23.5" front. Stock clamps have a few degrees of rake built in, these have zero. Looks like it will turn out to be pretty good as is. Steering stop can be ground down a bit on the end for more turning.

Yes I used a bunch of 1" washers for shims, no I don't care about your opinion. The bottom spanner with the dust shield was ground out, instructions said to use a nut with a dust shield, and since the vtx 1800 stem is longer, I ground the threads out to use the nut as a washer so I would have the dust shield. The washers will get replaced with collars cut to length for the final. Sorry about my iPhone turning the pictures sideways.