Custom swingarm (a little more than just extended!)

[89custom]

Yo so, i got a nice stock swingarm from mr305, thanks again. What i want to do here is redesign the sucker. would be some good experience for me and i have accsess to a good welder that can do it for me but i need to design it and mach it all up to be welded.

What im thinking is, +3 extended at most, want to raise the rear end up atleast 1"-2". and make it long travel.

if you laughed and said just buy one, don't because this is a good chance to go wild and try to learn a little something.

now the issue is, how do i make it sit higher, yet have more travel? i know i need a new shock, its just, what do i get? should i try to find a long travel blaster rear shock or find something like a 400ex long travel shock. i cant spend to much on the shock, thats my only setback.

Now i just stumbled on this, i had the idea in my head, ive even got a sketch from earlier. what does this bend angle give me instead of it being straight?

(btw the pics not even a blaster, totaly stumbled apon it)

i was thinking(in my sketch) i had that angle, not as steep, as well as the shock mount lower, mounted like phragles custom swingarm he made.

i don't know anything about suspension geometry, but im a fast learner.

Hit me.

oh and moving the mount on the frame, i dont think thats going to happen. MAYBE if it makes things easier, possible, but i would like to leave it alone.

thanks.I:I

 

[245stroker]

Just by going to a longer swingarm, its going to give you more travel. If you look around at all the different aftermarket companies that are making blaster swingarms, there is one thing in common with all of them, they pretty much look the same. I'd just extend a stock one and not try to do anything fancy

 

[phragle]

all the bend does is allow you to run a differnt shock (longer) shock without the bike sitting as high. it also increases the chances of running into chain torque issues, there is a point (which varies by shock stiffness, swingarm angle and length) at which the bike no longer wanys to 'squat' in the back, while lifting the front end. what happens is that under too much angle, the wheels want to drive under the bike, eliminating any sag, making the back end jump up under power

 

[Paulie B]

A swinger bend like the one you posted will give you a lower rear height.

 

[phragle]

Just by going to a longer swingarm, its going to give you more travel. If you look around at all the different aftermarket companies that are making blaster swingarms, there is one thing in common with all of them, they pretty much look the same. I'd just extend a stock one and not try to do anything fancy

the reason they all look the same, is that nobody out there is using any creativity in modifying the geometry, same goes for most of the aftermaket a-arms.. simply build a jig around the exisisting factory part, then stretch the jig. no R&D, no thought.... if a company was to develope a shock/swingarm package like I had, or develope extended a-arms optimizing balljoint angles and shock location, there parts would be far superior than 99% of the stuff out there. the problem is it takes considerable R&D time and expense. Couple that with the fact that blasters are cheap, and there riders are usually young with very little disposable income. Who would design and make truly well designed engineered and built parts (which would be expensive) when the target market would rather buy a $200 + 3 stock geomtry and poorly designed swingarm (that will eventually twist) off ebay. I defy any of you to take one of those ebay , place the pivot bolt on V-blocks and measure. it will not be straight. I have straightened and braced over 20 of them and have yet to find a straight one.

 

[89custom]

thanks phragle. your the guy i was lookin forward to chatting with. what would you say if i wanted to design a linkage system? even posible for a blaster?

 

[phragle]

Just by going to a longer swingarm, its going to give you more travel. If you look around at all the different aftermarket companies that are making blaster swingarms, there is one thing in common with all of them, they pretty much look the same. I'd just extend a stock one and not try to do anything fancy

TRue, but no where near what you are thinking. since don't have a blaster sitting next to me to measure, I took a theorhetical length of 18" (if someone wants to post the actial length from the pivot bolt to the axle I will recalculate) and +3 swingarm (theorhetical 21" long) the stock shock actually only provides about 5" of travel (no where near the 7.1" yamaha claims) the +3 swingarm did incrase wheel travel, but only by 0.75 inches (3/4)

 

[phragle]

thanks phragle. your the guy i was lookin forward to chatting with. what would you say if i wanted to design a linkage system? even posible for a blaster?

a linkage would be simple to design and put on an aftermarket swingarm, getting it dialed in would be another story. IMO the best thing you can do for a quad is toss the linkage in the trash and mount direct. linkage werent put on dirtbikes to revolutionize suspension geometry, they were added to centralize mass but advertised as a revolution. there is noting you can do on a quad with linkage that you cant accomplish thit a properly valed and sprung shock

 

[Unstock240]

To raise the rear I would cut the shock tabs off and weld in longer ones. When I Measured for my riser block 1/2" will bring up the rear more like 2". Making shock tabs 1/2" to 1" wouldnt run into any chain problems or anything either. 1 inch of rise at the shock was too much to me jacking the back up about 4 inches. Felt like i was sitting on a ski slope.

 

[89custom]

so no linkage. ok.

so whats a good shock i could use? i need a shock to work with to go by that length to work out the geometry.

 

[b_russell_82]

I would try a yfz 450 rear shock.. From the looks of ppl that have them they make your rear sit up pretty high

 

[phragle]

a I used an 87-88-89 250r, valving should be good though you will need to crank the preload way up, should be good up to a 200lb rider setup for 12" of travel. if your going to be doing major launches with hard landings, I would search cycle salvage etc, for a little heavier spring and may up the valving by 5~10%, but I have had people from 120 to 210 ride it and like the action. you don't need to go longer than +2 either, long travel soft suspension will help keep the front end down.

 

[89custom]

awsome.

so are you talking a long travel aftermarket shock for a 250r or a std length? got a length on that? how do i figure out where to make the shock mount? i was almost going to go +2 anyway so now im set on it. i dont want it to long. 12" of travel sounds awsome. and yeah im about 200lbs and it will be being jumped. mostly trails, mx, and just jumping.

if say, depending on shock length, i drop the mount like that one you made(could you post that pic again please?) and the ass sits to high, should i be angling it instead of leaving it straight? i know theres that certain angle the shocks gota be at and im not famliar with suspension setups so not sure how i should approch it.

thanks.

 

[phragle]

stock 250r shock, it will be high extended but it will only be extended when in the air, you set it up wit 5 or 6 inches of sag when you sit on it just follow the posted instructions..when you have questions..ask, when you get serious and actually get started I will pm you my number

 

[phragle]

Suspension Geometry 101 - Yamaha Blaster Forum

 

[89custom]

awsome man. ill let you know when i get to it.

thanks a ton.