Geometry Alterations with 450r A-Arms??

[trailrider894]

I've really been looking into creating a complete custom rolling chassis, just for fun, before i leave for my first deployment, and i was wondering if changing mounts on the 400ex frame to cater to aftermarket 450r a-arms would significantly change the geometry of the bike. Do you think it would make it better?? or worse?? Stay the same?? TO me, i don't see it changing anything, EXCEPT i wonder about LT Shock and A-Arm setups?? I guess you would have to search and find a custom length shock, because the distance between the shock mount and the the mount on the -a-arm might be different... I just wish i had a 450r to measure off of...

[Baileygunns]

450r shocks are an inch taller and the arms are an inch wider... Nothing you couldn't over come.

The only issue I would see arm placement if you are moving the frame mounts. You want the spindles in the correct location... Not to far forward not to far back

[honda400ex2003]

if you use the fronts in the same place you wont change the geometry at all. the mounts for the back are just further back. you wouldnt gain anything unless you got a forward addition on the 450r arms.

steve

[trailrider894]

Originally posted by honda400ex2003
if you use the fronts in the same place you wont change the geometry at all. the mounts for the back are just further back. you wouldnt gain anything unless you got a forward addition on the 450r arms.

steve

I'm just thinking that there are more setups available for the 450r that are more custom than the 400ex.

[honda400ex2003]

ah nice i thought you were talking about modding a frame to keep it as close as possible and not change the geometry. if you really want to go custom you could make different lengths, different space between arms, and different spindle heights to make a great setup.

im not sure on any different setups that would make it any better or worse.

the best of both worlds would be to try to make it a 250r front end setup using 450r arms and such.

im not sure on how to do it off hand but keeping the arms parallel and keeping the spindle straight up and down while traveling is key.

check out as much info on 4 bar linkages as you can. http://en.wikipedia.org/wiki/Four-bar_linkage

each part is a linkage and has a factor in the model. if you can create a linkage using the arms that keeps the spindle straight up and down you can incorporate it into the frame and make a great geometry for arms.

not sure if that will help at all but i guess that is where i would start out when looking into a custom setup for a frame.

the next thing to look at is how far from center of the axle to center of the front spindle is. this will make it handle a certain way also.

i wish i could get some info from roll and such on how they create custom frames.
steve

[trailrider894]

Well, I am thinking about trying to make the best handling MX quad that i can based around the 400ex Frame... so It should be interesting. You guys keep posting up ideas, and maybe some concepts. I'd love to get some input!!

[honda400ex2003]

later this week i will sit down and draw something up and see how it comes out.

lol

steve

[fearlessfred]

if you dont plan on moving the frame mounts ,than i dont see any gains to be had over what you can allready buy for a 400ex.the thing steve was saying about keeping it were the spindle stays straight up and down isnt exactly what you want. slight gains in camber the closer you get to full bump would be better,but that cant be changed from stock without changing mounting points for the aarms. the two key things to make sure is correct ,is lower shock mount location and your tierod balljoint height ( you dont want to add any bump steer that thay dont allready have )

[honda400ex2003]

good to know, thanks for the info. I cant guarantee anything from my side. I am going to be very busy this week working on stuff for senior design. lol

steve

[trailrider894]

I am ideally, lookin to create the perfect 400ex as far as geometry and handling goes.. Just a little sneak peak, is that it WILL be a Hybrid, this is all part of a little trick i'm trying to pull... but I can't say much!! HE HE :devil:

[chronicsmoke]

How about trying to run LT-R spindles and hubs, like the pros are doing to the 450s? Or maybe a +1.5 swinger, lt link/shock, or fabbing up an no link rear end.. That would be a sweet ride

[Muzzgit]

the front of the frame of a 250r rakes up more than 400ex or 450r which is part of the reason they handle so well.

[trailrider894]

Originally posted by Muzzgit
the front of the frame of a 250r rakes up more than 400ex or 450r which is part of the reason they handle so well.

Okay, then lets discuss the differences between the 400ex frame and the 250r frame that make the 250r better???


Anybody have any links to an link setup on a 400ex???

[CJM]

I cant speak much from experience, but I feel the 400ex handles better than the 450r. The R wants to lean to much imho and also wants to kick the back up much easier than the EX (by kick the back up, I mean in tight turns the back wants to lift).

A 250r is said to be the best geometry around. If I was gonna build something up it'd be a CRF or TRX450R engine on a 250r chassis.

[chronicsmoke]

You guys need to ride a modded 450, they are night and day difference than what you probably have experience with... It sits low and never bicycles around corners.

Stock they are ****, but who that rides that hard keeps their bike stock? With a different linkage/shock (GTT is what I'm running for now) the rear end feels probably 3" lower than stock (I'm just estimating here). With no buck or any ill-handling tendancies, its awesome. Plus you can also lower the subframe for a lower COG.

The 250r is a beast, it feels like you're sitting on the swingarm because youre down so low. I don't think its possible to flip these things, COG is so low. I find it also tires you out if you ride aggressive because you have to "pull yourself out of the quad" in order to stand up!

My perefereance for MX/playing around goes 450,250,400

I wouldn't use a stock 250r chassis to build a hybrid.. Aftermarket is where it's at.. there have been a few frame/rearshock/swinger setups selling for like $700 in the 250r classifieds.. That's a damn good start. A hybrid is also worth way more if it has an aftermarket frame.. JMO

[trailrider894]

Well the point for me, is that i have a spare 400ex frame, sitting around, a cutting torch, welder, etc... so i have all the equipment to make a custom setup. I plan on using a CRF motor, with a custom suspension setup, by a secret company..

[chronicsmoke]

Originally posted by trailrider894
Well the point for me, is that i have a spare 400ex frame, sitting around, a cutting torch, welder, etc... so i have all the equipment to make a custom setup. I plan on using a CRF motor, with a custom suspension setup, by a secret company..

That's a conversion that I'd think about doing if my 426ex motor goes sour.. There was a really good write up on putting a CRF engine in a EX frame.. The member that did the write up was anal, but it turned out sick.

What I really want is a KTM 300 2-t engine in the EX frame :cool:

You should try and use the LT-R Spindles though, I dont think anyone has tried to run them on the 400 yet..

[Muzzgit]

The 250r geometry is similar to the Bombardier DS650 in that the front rakes up. The front suspension goes up AND back as it compresses.

Most other quads the suspension is almost square to the frame, creating a more jarring effect when you hit a big bump.

The 450r rear end geometry is not right because it has to make way for such a big airbox. GT thunder does a linkage to help sort this out without having to spend too much.

[trailrider894]

So whats the plan on getting the 250r A-arm setup on the 400ex frame?? I'm searching for a slow motion Go Pro video of the 250r front end taking a hit, so i can see how it works.

[trailrider894]

So, its like the front a-arms are just tilted backwards a little?? does anybody know how many degree's they are tilted backwards?

So it would more than likely involve, angling the a-arm mounts, along with changing their location... Changing the angle of the upper shock mount, and possibly having to move it back??? Since the shock is angled now?? or would it be easier to just angle the shock mount, and move the a-arms forward on the bike???

[Muzzgit]

I really can't help with the technical stuff. I learnt this stuff when I was looking for a bigger bike to replace the 400ex.

I kept asking the local quad mechanic what he knew about the different models and the pro's and con's of each.

I always wondered why, when riding a DS650 it could hit big stuff harder than most quads. Sure it has extra weight to carry it through and make the front shocks work harder, but the front geometry is also a big factor.

[CJM]

Thats why the DS650 is the perfect setup to throw a very large engine into. 2 locals here have them for that. One has a 600cc engine from a streetbike and the other guy has a busa motor in it.

[250x_kyle]

Originally posted by trailrider894
So, its like the front a-arms are just tilted backwards a little?? does anybody know how many degree's they are tilted backwards?

So it would more than likely involve, angling the a-arm mounts, along with changing their location... Changing the angle of the upper shock mount, and possibly having to move it back??? Since the shock is angled now?? or would it be easier to just angle the shock mount, and move the a-arms forward on the bike???

in order to to these kinds of alterations to the frame a frame jig would be a must to make sure it was done symetricaly . on a side note the only way to get this kind of information is to have both frames side by side pulling measurements and crunching numbers.

[CJM]

imho it is possible to cut the front of the frame and simply change the angles-but that doesnt mean its gonna be right or exact. But thats honestly what has to be done, compare the 2 frames and try and transfer the better angles to the 400ex frame.

[250x_kyle]

no argument with you there cjm. basically to change it to get the geometry you want you might as well just try to build your own frame or buy and aftermarket one. on a side note i have been in the search for a ktm300 motor for my spare 400ex frame.

[CJM]

I think changing the orientation of the front tubes to rake up slightly could work. Id want a 250r to look at before I did it tho.

Honestly I find it easier to buy a used walsh or such frame to make a hybrid. Hard works already been done.

FWIW even with 450r shocks on the front and 6 ply razr2's I dont have an issue with the EX. But I dont do insane jumps either, for MX Im sure theres room for improvement, for your standard trail rider or GNCC it would be fine with some good shocks and arms.

[trailrider894]

Originally posted by CJM
I think changing the orientation of the front tubes to rake up slightly could work. Id want a 250r to look at before I did it tho.

Honestly I find it easier to buy a used walsh or such frame to make a hybrid. Hard works already been done.

FWIW even with 450r shocks on the front and 6 ply razr2's I dont have an issue with the EX. But I dont do insane jumps either, for MX Im sure theres room for improvement, for your standard trail rider or GNCC it would be fine with some good shocks and arms.

Well i'm your EXTREME MX'er... Looking for something better... and I don't really want to spend 700 bucks on a walsh frame... its just too expensive... I have all the machinery and know how to make the frame my self for probably 100 bucks total...

[250x_kyle]

Originally posted by trailrider894
Well i'm your EXTREME MX'er... Looking for something better... and I don't really want to spend 700 bucks on a walsh frame... its just too expensive... I have all the machinery and know how to make the frame my self for probably 100 bucks total...

the bigger question here is where are you finding walsh frames for 700 bucks lol.

it can be done just take your time. i would really recomend building a frame jig. and dont buy cheap tubing. use dom tube of erw. and if your using 1020 steel i would used something around .120 wall.

[CJM]

Then id suggest trying to find a frame to copy somehow. The 250r frame would be best imho to take measurements off of.

[QuadOwner]

Originally posted by Muzzgit
The 250r geometry is similar to the Bombardier DS650 in that the front rakes up. The front suspension goes up AND back as it compresses.

Most other quads the suspension is almost square to the frame, creating a more jarring effect when you hit a big bump.

The 450r rear end geometry is not right because it has to make way for such a big airbox. GT thunder does a linkage to help sort this out without having to spend too much.

im aware of the age of the thread, but im pretty sure a 400ex has rake in its geometry as well (infact i know it does). still reguarded as one of the best handling quads ever made. i had a 450r and i agree the rear end sucked and i found out the hard way