Swingarms and A-Arms

[royalt67]

Ok, Guys. Will someone please explain all the reasons I might want to put extended a-arms and a swingarm on my son's 03 Blaster? He is racing in Blaster class mx this year on a bike thats slightly more than stock. (pipe, reeds, filter, works shocks with res) I see these things for sale but I'm a car guy. Why are they necessary? Can I get away with spacers?

 

[mr_3_0_5]

handling.. spacers are harder on your ball joints.. extended swing arm will keep him from flipping it back on the line..

 

[ruthless_one3k]

As mr 3 0 5 said the wider stance makes it less tippy and the longer swinger will make it easier to get a hole shot without flipping backwards. It may also make it slide with a little more control depending on his riding style.

 

[cwright#26]

Necessary? No, but its a good idea to have them. I wouldn't go with spacers personally, I'd end up breaking them off in a heartbeat. Better handling all around, handling makes up half of the quad equation.

 

[ruthless_one3k]

Necessary? No, but its a good idea to have them. I wouldn't go with spacers personally, I'd end up breaking them off in a heartbeat. Better handling all around, handling makes up half of the quad equation.

With out a doubt! There is no use in having speed if it rides like a mechanical bull.

 

[92blaster]

long travel. so you wont bottom out on the big jumps.. phrangle to the rescue explain why

 

[Blasterdude27]

Don't forget about shocks. A/m a-arms mean nothing without good shocks.

 

[royalt67]

Ok, I get it. But what is a good rule of thumb for swingarm length? Obviously you could add 12 inches of wheelbase and be set for straight line accel, but this has to corner. Blasters are nimble in stock form, where are the diminishing returns on length?

And yeah I can see where A-Arms are a big plus for cornering stablity. I see most are +2 width, +1 forward (length). Is that the way to go or is that just a start? I suppose at some point I should be talking rear axel width too.

So, what is the sweet setup for MX?

 

[royalt67]

Don't forget about shocks. A/m a-arms mean nothing without good shocks.

With Works up front and in back (w/remote res), I think that's covered for now. They're not ELKA's but at least they are a step above stock.

What are you guys running for tire pressure? Bear in mind non-beadlock wheels and plenty of jumping.

 

[245stroker]

I'm running +4+1 long travel a-arms with a +3 swingarm. I'm also running a durablue eliminator axle thats +4 in the rear. For mx racing try to find some +3+1 a-arms and a +3 swingarm. It'll widen and lengthen out the quad yet it'll still be quick in the corners.

 

[royalt67]

Thanks Guys, I appreciate the info

 

[blasterkid114]

and to add one more thing with the stock rear shock on the jumping will also through him around so that is another big point thought you may want to know

 

[phragle]

especially on the front... ball joints only have so much angle to them, the longer the arm, the bigger the arc = more travel, even better if the a-arm builder maximized the ball joint angles. +1 foreward also does more than add an inch of wheelbase. it changes the weight (front to rear) weight bias. going say +4 in the rear will make the front "heavier" and the back lighter. thats why you can actually loose traction if you go too long on the swing arm. the truth about what you see advertised as "long travel" is that it's not really long travel. when was the last time you actually saw anyone post wheel travel numbers in their adds? what the industry claims as long travel is usually a longer shock. a longer shock travels further than a shorter shock with trhe same amount of whhel travel. since the shock has longer stroke it can be valvedsofter and much more progressivly, giving much better suspension action.

 

[cwright#26]

long travel. so you wont bottom out on the big jumps.. phrangle to the rescue explain why

Actually... A good rule of thumb for standard or long travel is you want to bottom out on the biggest jump, not hard, but enough to let you know that you are using all of the available suspension travel.