I don't think that 400 arms will work w/o the 400 spindles.
The top a-arm is shorter on a 300ex. You can turn the ball joints to get it close but it still isn't safe to me.

 

I'm using the complete 400ex upper and lower A-arms and tie rod! The only thing thats stock 300ex is the spindles; which I confirmed through my local shop will work! They all bolted up fine! It's just the shocks that will need to be moded a bit! The upper bushing housing is wider on the shock so, I'll have to thin it out a bit! Was hoping to get it done today but, ran short of time! I'll post once its all complete to tell how it went!

 

Well your local shop was half right,..300EX spindles WILL work..but not as well as the 400EX spindles.
First of all,..your tires are going to be angled in about a little over a 1/4" per side at the top.
Secondly,..your 300EX spindle will hit the lower 400EX a arm when your quad is in the air.

Using 400EX spindles will eliminate the grinding on the arm obviously because they are 400EX a arms. The 400EX spindle will still have some negative camber issues on a 300EX frame but not as bad as using 300EX spindles.

 

AH!!! Well guess I'm now in need of a set of 400ex spindles! Hey thanx for the info! Doing mods on a budget can get tricky! Getting good intel can be a challenge to get sometimes! Anyone have a set for sale? If so please e-mail me @ woody_003@hotmail.com!

 

Yeah, it can get tricky.
The issue that causes the negative camber is the frame of the 300EX verus the frame on the 400EX.
A 300EX frame has both the upper a arm mounting rail and lower mounting rail the same width.
The 400EXs upper rail is a bit closer to the wheel than the bottom rail....so when you put the 400EX arms on the 300EX, the lower arm is longer than the upper arm.

Using 400EX spindles make it a little better than using 300EX spindles but the issue is still there. It's not going to be a huge problem where handling is concerned however.

If you are seeking geometry closer to what the original 300EX was, and to stay on a low budget, you can use 250R upper a arms with the adjustable ball joints. It has enough adjustment to correct the negative camber problem.
But either way, you really are much better off going with the 400EX spindles.

 

Well I got the 400ex spindles! I modded and bolted everything on last night and I can see what you mean about the pitch of the tire being off a bit! They lean in up top a bit! So, will this cause riding issues for me on the trails? I'd hate to have done all of this only to have issues! Looks bad *** and the suspension is night and day differance but, again I'd hate to have any issues once I'm out on a trail! I know its not gonna be dead nuts on with having several differant bike parts now bolted on the 300ex frame but, really don't need to break down on a ride either!

 

One other thing...I just REALLY looked at my new set up and found that the wheels actually pitch in more up top now with the 400ex spindles then they did with the 300ex spindles!? At this point I'm thinking either once the rain stops today or tomorrow I'm gonna put the 300ex ones back one to confirm if they make my wheels straighter or not cause the way they are now isn't right! The 400 ones might be better or stronger or whatever but the way they now make my wheels pitch just isn't safe looking or riding! My steering control has been comprimised! I'd never take it out on a trail ride like this! So, if anyone has any other suggestions please let me know! Thanx again all for the help with my mod!

Woody

 

Well my bikes all done and running like a champ! Just an FYI...the 300ex spindles put me exactly where i needed to be! Attached is what it all looks like! Thanx again for all the help!

Woody


Just added:
400ex A-arms
400ex tie rods
stock Banshee front shocks

Already on was:
HMF slip on pipe
stage 2 dyno kit
brought the main jet up to a 40mil from a 38mil
Raptor 660 rear stock shock
Pro Taper fatty bars
Cush grips
custom red/black gripper seat cover
DG nerf bars
six pack rack

 

Well my bikes all done and running like a champ! Just an FYI...the 300ex spindles put me exactly where i needed to be! Attached is what it all looks like! Thanx again for all the help!

Woody


Just added:
400ex A-arms
400ex tie rods
stock Banshee front shocks
brushed aluminum bumper

Already on was:
HMF slip on pipe
stage 2 dyno kit
brought the main jet up to a 40mil from a 38mil
Raptor 660 rear stock shock
Pro Taper fatty bars
Cush grips
custom red/black gripper seat cover
DG nerf bars
six pack rack

 

Getting ready to do this on my sons 300EX. Do I need the 400ex spindles or not? I've read in other posts that the 400ex spindles work best for the camber issues. But now after reading this post, Woody003 had better results with the 300ex spindles. I already have shocks bought from an 09' 400ex and watching a couple 400ex a-arm auctions with spindles. A-arms without the spindles are cheaper. Anyone else done this mod please speak up.