a-arms need help

[keepitpinned]

i was looking at a-arms and some say that they move the a-arms forward like 1 or 2 inches sometimes. what does this do? is it better?

[zephead400ex]

Wider arms = more stability

[TC426EX]

What you have to understand about forward is this... That has nothing to do with how wide it is. When you move the arms forward you keep the front end on the ground more and help with cornering. Sometimes this is good, sometimes it isnt. On a bike like the 400ex, the front to back weight ratio is pretty good. If you throw the +1 or 2 forward a arms ( most are just +1) then you screw it up. IF you add an extended swingarm (+1.25" is the most popular) then it is advantageous since you get the ratio right again. Somertimes you need to pop the front end up like in whoops and what not, and the +1 forward will make it a bit more difficult. Keeping the ratio right will keep you nice and even when sailing though the air on jumps also instead of being seemingly front or rear heavy. Granted, you could probably SURVIVE with the forward arms and a stock swingarm, your bike definitely wont be handling at its best. Rule of thumb is if you extend one end do the other!

[mxgirl]

Yep, I agree with the previous post.

[Shocka400ex]

Actually, extending the front a-arms forward makes the front end lighter and easier to lift wheelies. That is why you compensate by an extended swing arm. Most shops don't make plus one forward a-arms for the 400ex because the front ends are already light. 250R's on the other hand are very popular with the plus 1 arms

[redrunner]

Originally posted by Shocka400ex
Actually, extending the front a-arms forward makes the front end lighter and easier to lift wheelies.

Is that true? I thought going +2 +1 on my 300 would help keep it down! :confused:

[ghak99]

Originally posted by Shocka400ex
Actually, extending the front a-arms forward makes the front end lighter and easier to lift wheelies. That is why you compensate by an extended swing arm. Most shops don't make plus one forward a-arms for the 400ex because the front ends are already light. 250R's on the other hand are very popular with the plus 1 arms

OK.... I am going to have to ask you to explain how +1 forward A arms makes the front end lighter? By moving the weight of the tires, brakes, wheels, and spindles forward it stands to reason that it would be harder to pull the front end up.

[Narly R]

I really like the +1's on my r. It seemed to make the steering better, but I also switched to a +3 at the same time so maybe that helped too...:blah:

I dont think you would need a +2 forward.:confused:

[batgeek]

Originally posted by ghak99
OK.... I am going to have to ask you to explain how +1 forward A arms makes the front end lighter? By moving the weight of the tires, brakes, wheels, and spindles forward it stands to reason that it would be harder to pull the front end up.

look at your quad as a fulcrum:

- - - - X - - - -

with X as the center of weight bias.

if you add length to the front:

- - - - - X - - - -

you move your center of weight bias toward the back. with more weight to the rear, upon acceleration the rear is weighted down even more, allowing the front to come up easier.

now if you add length to the rear:

- - - - X - - - - -

you shift your center of weight bias toward the front. thus keeping the front end down even during acceleration.

:)

this isn't an explaination for you ghak99, you understand this already. :cool:

[Ball]

Originally posted by Shocka400ex
Actually, extending the front a-arms forward makes the front end lighter and easier to lift wheelies.

I am afraid that you are mistaken. It is the reverse of what you said. It will make the front harder to pull up.

[redrunner]

I thought I was a fairly smart guy but now I am confused. Batgeek it looks like it make sense on paper but aren't you offsetting the bias by extending the wheelbase? The fulcrum would be moved also as ghak said. As if the front end of this didn't come up easy enough on climbs. I do understand where stability come from extending the swinger, that makes sense obviously. So I ahve heard not to go more than 1" on the swingwer for a 300 in trails, is that correct? does anyone else have a good handling tip for me?

[300exOH]

By adding length to the front you effectively add weight which would move the fulcrum toward the front of the quad. That added weight will keep the front end down. By adding to the swingarm you bring that weight back to the rear.

I was told by the Quadshop that +3/4" was recommended for the swingarm with +1 forward a arms to balance out the quad.

I have +2+1 a arms on my 300ex with a stock swingarm and it is much more difficult to pull the front wheels than before.

[Shocka400ex]

Batgeek explained it simply put. If you still don't understand, try and buy a +3+1 a-arm set up for your 400ex from a major dealer. Lone star, roll design, Houser etc. They'll tell you it's not recomended for 400ex because they are already front light. The 450R is the same way too. They usually recomend a +1 swing arm the keep the front end down more. Hopefully you all can except this and not argue about it anymore!

[redrunner]

But let's take a top fuel car for example, the weight is all in the back with a wing to create down force to apply pressure to the wheels The front end, well is real long right + 20' a arms. I don't know!!!

Wheres wilkins when you need him!:grr:

[wilkin250r]

When riding whoops, cornering, and other maneuvers in which all four wheels are on the ground at the same time, you want a certain amount of weight on the rear, and a certain amount on the front. This will keep your quad properly balanced in relation to your suspension.

By going with +1 foward a-arms, you change the wieght distribution while all four wheels are on the ground. It actually decreases the weight on the front wheels, but all those effects dissapear when the front wheels come off the ground under hard acceleration (wheelie).

When the front end comes up, the rear wheels become the pivot point, and the rest of the quad is a lever arm acting on that pivot point. There are two ways to increase the leverage acting on that pivot point. Either increase the length of the lever arm, or increase the weight. +1 foward A-arms wiegh the same as normal a-arms, so you obviously did not increase the wieght.

If you increase the lever arm using and extended swingarm, you move ALL the wieght, the quad (350lbs) AND the rider (150lbs) foward, for a total of 500lbs foward away from the pivot point. This creates a HUGE increase in leverage acting against the pivot point of the rear wheels. An extended swingarm is very effective to keep the front wheels down.

Yes, by moving the front wheels foward, you are increasing the lever arm, but how much are we really talking about? Wheels, hubs, spindles, maybe 20lbs total? One little inch forward? This is a far cry from the 500lbs that we moved with the extended swingarm. Yes, there is some small advantage, but it's really insignificant compared to the weight of the rest of the entire quad. So yes, there is a tiny advantage, but I doubt you'd even feel it.

The purpose of +1 foward A-arms is to adjust your weight distribution while all four wheels are on the ground. It's really ineffective as a tool to keep the front wheels down. If anti-wheelie is your goal, go with an extended swingarm, it has easily ten times the impact.

[300exOH]

Finally a good explanation. Good post wilkin:D

[redrunner]

OK so as my goal is to keep the front end planted i should have just gotten +2+0 arms! So a +.75 or 1" swinger is in the works.:D

[wilkin250r]

Originally posted by 300exOH
Finally a good explanation. Good post wilkin:D

That's what I'm here for ;)

[Tommy 17]

wilkin are u a engineer????

[wilkin250r]

Originally posted by redrunner
OK so as my goal is to keep the front end planted i should have just gotten +2+0 arms! So a +.75 or 1" swinger is in the works.:D

If you're goal is to keep the front end planted, the +1 foward arms aren't going to do it for you. The extended swinger will do the trick. As for the benifits of +2+1 vs +2+0, I'm can't really tell you, I'm not sure of all the benifits and drawbacks of the foward arms, other than weight distribution. I'm not sure how that affects the rider in terrain. Hmm, maybe I'll research that this afternoon. :cool:

[redrunner]

Originally posted by wilkin250r
That's what I'm here for ;)

[redrunner]

Originally posted by redrunner


with all due respect to batgeek, his explaination was very similar;)

[wilkin250r]

Originally posted by Tommy 17
wilkin are u a engineer????

Yes, electrical, but I have a strong mechanical background, and a bit of metallurgical as well.

A good rear SSD shock will help keep the front end on the ground...:cool:

[boogiechile]

the main reason for changing the a arms forward or rearward for that matter is to effect the handling as to pushing or loose and to help with straight line stability. Like Wilkin said moving the a arms forward will shift the weight bias to the rear when all wheels are on the ground. This can effect how the quad handles. As a general rule more frt bias will tighten up the quad(cause pushing). Since moving the a arms forward would lessen the frt bias the effect would be to loosen the quad. So if you have a problem with pushing, + forward may help out a little. But remember the rear has to be taken in to acount. If you add a +1 1/4 swinger, a +1 a arm will have less effect than on a stock length swing arm.

Lengthening the quad will help keep it straight and it will not try to swap ends in the whoops so easy. But length will make it not turn as quick on the other hand. Most things are a trade off.

If all you are concerned about is wheelie problems than take Wilkins advice and go to the swing arm. The frt will be a waist of time and money. A longer swing arm will add to pushing though, but sometimes that is needed too.

[Tommy 17]

Originally posted by Rico
A good rear SSD shock will help keep the front end on the ground...:cool:


thats for sure... its hard to pull wheelies with a SSD shock... i know its alot harder on mine then on my friends stk shock 400

[redrunner]

Lengthening the quad will help keep it straight and it will not try to swap ends in the whoops so easy. But length will make it not turn as quick on the other hand. Most things are a trade off.

If all you are concerned about is wheelie problems than take Wilkins advice and go to the swing arm. The frt will be a waist of time and money. A longer swing arm will add to pushing though, but sometimes that is needed too. [/B][/QUOTE]

OK but I already have +2+1 arms so a + swinger will just kinda bring it back to stock handling? But will help me keep it "planted"?
This is on a 300 with a rappy rear and 400 spring.

[boogiechile]

Originally posted by redrunner
OK but I already have +2+1 arms so a + swinger will just kinda bring it back to stock handling? But will help me keep it "planted"?
This is on a 300 with a rappy rear and 400 spring.


yes that is right. Both the a arms and swing arm will help it stay planted, mostly the swingarm. Ask around to see what 300ex gurus think about the right swing arm length. i would think a +2 would be about right, but I am just making my best guess.

Greenestreak Racing Projects (http://www.picturetrail.com/mojaveaddict)

[redrunner]

OK it will be off to Bradley and Jeff world for some more answers!;)

[boogiechile]

for what its worth LSR recomends a +2 swing arm for MX on the 300ex. That is probably considering no forward on the a arms so more than +2 may be better with your +1 forward a arms. I like to put bathroom scales under all four wheels and take readings with the rider on. Then you can better determine which way and how much you need to go.

[redrunner]

Originally posted by boogiechile
for what its worth LSR recomends a +2 swing arm for MX on the 300ex. That is probably considering no forward on the a arms so more than +2 may be better with your +1 forward a arms. I like to put bathroom scales under all four wheels and take readings with the rider on. Then you can better determine which way and how much you need to go.

Interesting concept with the scales, the objective being as close as possible to equal weight on all 4 corners?

[wilkin250r]

Originally posted by redrunner
Interesting concept with the scales, the objective being as close as possible to equal weight on all 4 corners?

Hmm, this would be an interesting question to pose to a suspension or racing expert, because they will know the positive and negative effects of changing your wieght bias.

My spider senses tell me it would probably be better to have a little more rear wieght bias, but not so much that it affects the quad's characteristics in the air. A little more weight in the rear will give you better traction for hook-up coming out of a corner, and keep your rear tires planted and headed straight rather than letting them spin and turn you sideways through the corner.

So in that respect, your +1 forward a-arms are just the ticket. I bet they would significantly improve your lap times on a flattrack.

[bradley300]

IMO, on a 300ex for xc racing/trail riding i wouldnt go more thana plus 1.25 mine is a 1 inch ext. lonestar and with a 309 kit, i could tell the loss in traction, more so w/ my 350 but not too bad. the one inch was a night and day difference thru the whoops tho. plus 2 would prolly be alright, i just wouldnt try it my self b/c a big advantage of a 300ex in xc racing is there small size.

as for the a-arms, last time i looked, most of the bigger copanys only made 300ex a-arms in a plus forward-IMO, there must be a reason for this. not to mention, once you have a ext. swinger, i would want to even out the wieght distrubution closer to the stock bias (wich is actualy pretty good)