Caster, camber etc for Mx with Walsh a-arms

Message

m_mcgranahan · #1 Post by **m_mcgranahan** » Sun Feb 15, 2009 2:01 am

Hi,

I am switching over to my set of Walsh a-arms and I am looking for advice for setting them up for motocross racing. I am guessing I want the wheels close to perpendicular to the ground at ride height, but what do I want to shoot for?

Also the set came with spacers for +1 forward but I noticed that it changed the deflection of the outside tire when turning, which I did not like. I found that by making some new spacers I centered the heim joints so they are probably +1/2 forward now It did help make both wheel track better as I turn the bars. Is it better to just keep them at +1 and deal with the lack of deflection on the outer tire, or is it worth it to keep them +1/2?

Thanks

God bless...

Mark

2mike18 · #2 Post by **2mike18** » Sun Feb 15, 2009 2:27 am

I found this in an old post and the info looks good has specs for all types of racing:

go to www.lsracing.com then go to tips then to front end alignment and it spells it all out for you

cannondale27 · #3 Post by **cannondale27** » Sun Feb 15, 2009 2:29 am

When you say deflection do you mean bumpsteer?In other words when wheels go up and down they go in and out?Less is better for sure.

3-5deg caster
0-2deg neg camber

thedeatons · #4 Post by **thedeatons** » Sun Feb 15, 2009 2:38 am

Ditto on the LSRRacing.com setup manual in .pdf format. Priceless...

MX Quad Dad · #5 Post by **MX Quad Dad** » Sun Feb 15, 2009 2:56 am

it is mostly rider preferance. My son perfred +4.5 on the caster and -4.5 on the camber when he raced the Banshee. the Moto A-arms didn't allow caster adj and not enough negitive camber. I modified the camber adjustments and believe I was able to get -4 which he liked a lot better than the stock settings. his riding style was to run inside on tight turns and I think this may have help. I gave him as much caster as I could by changing the washers on the inner pivots. more positive caster gives it more stabilty on high speed straits but takes away some of the nimbleness. If he would have kept racing we were going to get some aftermarket arms and play with the adjustments to more extreme measures. I know a + foward moves the center of gravity foward, It may also help on the high speed stuff but I think that would take away some of the nimbleness also. He didn't weigh much so the shorter wheelbase may have been an advantage for traction.

One thing I allway mention when people change A-arms. after you get them adjusted with the quads on a stand remove the shocks and run each front wheel up and down to check for binding, with the steering turned in all directions. you really only need to check within the shocks travel pluss a little more to alllow for compression of the rubber stop. this is how I found out the tie rods were snagging the frame on the earlier steering stems, which I believe was only a problem with the Motos LT.

jacobw · #6 Post by **jacobw** » Sun Feb 15, 2009 3:50 am

steve you trying to kill the guy the standard for mx is 5-6 degrees of caster and same for camber 3-5 anything much less and you will be real twitchy

QUOTE (cannondale27 @ Feb 14 2009, 08:29 PM) <{POST_SNAPBACK}>

When you say deflection do you mean bumpsteer?In other words when wheels go up and down they go in and out?Less is better for sure.

3-5deg caster
0-2deg neg camber

m_mcgranahan · #7 Post by **m_mcgranahan** » Sun Feb 15, 2009 5:51 am

Hey Steve,

It has a little bump steer, but I mean that when the bar is turned all the way, the outer tire will be at say 35 deg from the frame and the inner tire will be at about 45deg or some thing like that. The issue is that the further forward you push the pivot point of the spindles in realtion to the steering stem, the worse this gets. Just wondering how much difference it makes.

God bless...

mark

Dachshund · #8 Post by **Dachshund** » Sun Feb 15, 2009 8:03 am

Mark, my nephew has the Walsh arms at the +1 and is the same way. I find no problem with it. Your not going to be moving very fast at full lock and I would assume it would be just a little tire scrub. The inside tire needs to turn sharper than the outside tire anyway.

cannondale27 · #9 Post by **cannondale27** » Sun Feb 15, 2009 1:40 pm

QUOTE (jacobw @ Feb 14 2009, 09:50 PM) <{POST_SNAPBACK}>

steve you trying to kill the guy the standard for mx is 5-6 degrees of caster and same for camber 3-5 anything much less and you will be real twitchy

If the Walshes are +3 at 3-5camber he will probably be over 50" the camber thing seems to come and go like a fad.Right now most run less than 3.Caster is a preference thing.I believe moto was under 5deg.Most Hondas are 5 deg.

Mark I never experimented with that.(Ackerman effect)Other than at the steering stem.At stem the further back from stem the rodends are the more smooth and slow the front feels.Just like the early-vs-late stems on cannondales.Not sure how it will feel in your case.But a little bit makes a big difference in feel.Really most of it is controlled by how far apart the holes in stem are.Adjust your toe in at same time you move it forward or back and difference will be much less.

m_mcgranahan · #10 Post by **m_mcgranahan** » Tue Feb 17, 2009 4:49 am

Hey Steve
I remember playing with this on my RC-10 radio control car and I found that the closer to parellel the tie rods are when straight, the worse it gets. It seems the ideal is to have the steering stem 15-20 degrees forward of the spindle pivot point to get the least ackerman effect on the steering. That messing around is what led me to make the new bushings for the arms and they seem to work well so far.

Thanks

God bless...

Mark

QUOTE (cannondale27 @ Feb 15 2009, 01:40 PM) <{POST_SNAPBACK}>

If the Walshes are +3 at 3-5camber he will probably be over 50" the camber thing seems to come and go like a fad.Right now most run less than 3.Caster is a preference thing.I believe moto was under 5deg.Most Hondas are 5 deg.

Mark I never experimented with that.(Ackerman effect)Other than at the steering stem.At stem the further back from stem the rodends are the more smooth and slow the front feels.Just like the early-vs-late stems on cannondales.Not sure how it will feel in your case.But a little bit makes a big difference in feel.Really most of it is controlled by how far apart the holes in stem are.Adjust your toe in at same time you move it forward or back and difference will be much less.