Swingarm Replacement

[blsnelling]

I need a longer swingarm on my 300EX. I've read several threads on using either a 350X or 450R swingarm. First of all, it needs to be at least 2" longer. Do either of these fit the bill. Also, I already have a good Raptor rear shock and would like to use it. Will that be possible with any of these swingarms? What about brakes? Let me break it down like this. I'll list want I know and perhaps you guys can help me fill in the blanks.

350X swinger
Requires washers to correctly space between frame rails.
Does this swinger use linkage, requiring tabs on the frame?
Length + 1 3/4"??
?? shock (can Raptor shock be used)
?? brakes
??Bearing Carrier

450R swinger
Needs tabs welded on frame for mounting of linkage. Any other mods required to install?
How much longer?
250R shock (any other options?)
?? brakes
??Bearing Carrier

Other swinger Options?

[TWISTED DINLI]

just get a JB +2 300ex swinger.

[honda300EXtreme]

350X swinger
Requires washers to correctly space between frame rails.
Does this swinger use linkage, requiring tabs on the frame?---yes
Length + 1 3/4"?? ------- i think so...
?? shock (can Raptor shock be used) ---no
?? brakes-- longer rear brakeline required
??Bearing Carrier---- im pretty sure you have to use the 350x carrier

450R swinger
Needs tabs welded on frame for mounting of linkage. Any other mods required to install?---no
How much longer?----- around 3''
(any other options?)--- 250R shock
?? brakes ------450r
??Bearing Carrier--- 450r carrier required

Other swinger Options? --250r


if budget allows just get a +2 300 swinger.. its alot less trouble...
and you can keep your raptor shock...

burgard makes a nice one...


hopefully that helped

[TWISTED DINLI]

yea the JB swinger is $600.

[blsnelling]

Originally posted by TWISTED DINLI
yea the JB swinger is $600.

Woah. I'm trying to this on the cheap:eek:

I need more info on the brakes. Will the 300EX caliper mount on both the 350X and 450R swingers? What about the stop that keeps the caliper from spinning once applied?

I didn't think a 450R shock could be used because the sideways mounted reservoir hits the frame. Any issues with the 400EX shock and does is have a reservoir?

[honda300EXtreme]

if i recall the 350x swinger needs a new caliper bracket..

and the 300 rear caliper will work on 450r swinger.. not sure whether or not you need the bracket...


personally i used the 400ex swinger.. but i made backets that attach to the shock mount moving it in about 1.75,,, it seems to work good.. but havent tested it yet... so dont say i told ya to do it cuse i dont wanna see ya get hurt

[blsnelling]

OK. Lets see a complete parts and mod list to do the 450R setup.

Parts
450R Swinger
450R Carrier
450R Linkage
450R Axle??
Will me 300EX sprocket and brake hubs work?
Will my 300EX hubs work?
250R/450R/400EX Shock. Which one is best? I like to jump.

Mods
Weld tabs onto the frame to secure the linkage.
What about pivot mounting width?
What about linkage, frame, and shock bolt/pin sizes?

Anything missed?

[honda300EXtreme]

ok...

i would find a 450r axle cheap to widen it up a bit..

sprocket will work, brake hub should work.

300ex hubs should work,, not positive on the spline count.

i would get the 250r rear shock


yes weld tabs on frame for linkage....

it will line up.. you can use your pivot bolt...

use 450r linkage/250r,, and im not sure on the bolt sizes.. but you could probably find out on service honda.

i know theres a guy on here who did the 450 rear end.. if you do a bit of searching you could probably find it...

[jay80]

I just did 450r swinger. Bought the whole rear end, axle, brake system, linkage. I used a 250r shock. Also need a longer chain. In all with cost of new chain, new brake pads, 450r rear end, 250r shock it was around $450. Sprocket and hubs fit fine. You need to open up the top shock mount on the frame for the 250r shock to fit.

[2muchquad]

the 350x swinger DOES NOT require tabs for linkae.It will be the easiest and most economical for you.The 350x axle is also wider than even a 450r axle.use the caliper mount from your 300 ex.

[honda300EXtreme]

are your sure... im positive, the 350x uses a linkage

[blsnelling]

Well, I'm going with a 450R swinger. I've bought nearly everything I need for the conversion. I got the quad taken apart tonight. Both front and rear. I'm installing 400EX a-arms and YFZ450 shocks as well.

A couple questions.
1. Is a longer rear brake line required? If so, will one from a 450R bolt to my rear master cylinder.
2. Do my 300EX hubs have the same spline count as the 450R axle?
3. Will the 450R shock be mounted with the reseroir above or below it? It sure does look like the intake frame tube will be in the way. No?

[honda300EXtreme]

yea you will need a longer brakeline....

a 450 brakeline will work,,,

the 300ex hubs will work im not positive on the spline count but ill find out....

your front end should be a good set-up also,,, just remember you need the relocator bracket...

[blsnelling]

Originally posted by honda300EXtreme
your front end should be a good set-up also,,, just remember you need the relocator bracket...

Got that covered:) Thanks.

[blsnelling]

You call this progress? :eek2: :D

http://tweaker.smugmug.com/photos/181972102-M.jpg

http://tweaker.smugmug.com/photos/181972123-M.jpg

I'm still waiting on a lot of parts. I did get the front shocks today.

[honda300EXtreme]

yup i say you've made some progress,,, keep us posted,,

i know that front should kick @ss, it will be like a whole different quad once you get it back together...


so you decided on the complete 450 rear?

[blsnelling]

I built the front shock relocation bracket and installed some 400E shocks, using all stock 300EX suspension parts. That left the lower shock mount in way too close, making already springy 400EX shocks even springier. Enough of that. So out with the new and in with the newer:) This was a complete and rideable quad about 6 PM yesterday and it looked like this before I went to bed.

Yes, I bought a complete '04 450R rear end. Talk about a hybrid setup here. 300EX, 400EX, 450R, and YFZ450. Gotta luv it! Now I've got a bunch of 300EX parts to sell. EBay, here I come!

[blsnelling]

I got quite a few of my parts today and took some measurements to compare the length of 300EX parts to the new ones.

400EX a-arms are each 1 1/2" longer than those of a 300EX, for a total width gain of 3".

At 29 1/4", the 450R axle is 2 7/8" longer that of a 300EX.

At 18 1/2" center-to-center, the 450R swingarm is 3" longer than that of a 300EX.

Now, I was told that the 450R shock will bolt right up. Take a look at this and tell me how. No one mentioned having to cut the frame up. I'm not sure I'm ready to do that.

The reservoir is clearly hitting.
http://tweaker.smugmug.com/photos/182225334-M.jpg

Coming down from the top.
http://tweaker.smugmug.com/photos/182225346-M.jpg

Upside down.
http://tweaker.smugmug.com/photos/182225344-M.jpg

[honda300EXtreme]

looks like the shock should fit the way you have it in the third pic,,, if i recall correctly thats the way it should go anyway...


if worse comes to worse you might have to cut off that tube,, but it serves no structual purpose,, but you will have to seal the hole in the airbox

[blsnelling]

I stopped by the dealer on the way home today to check. The reservoir is supposed to be on the bottom. I doubt it really matters though. I'm going to go take another look, and perhaps another pic, but I don't think it's even close to fitting either way. I'm sure this is why others have recommended a 250R shock.

[honda300EXtreme]

i dont know, ive never seen any body experience this problem, i read the build up with the guy who used the 450r rear end and i dont recall him having any problems.... :ermm: :confused:

[blsnelling]

Someone please show me where I'm wrong, but I don't think this shock can be used at all. There's interference with too many things. Even cutting off the intake tubes don't look to get the job done. Furthermore, cutting off the intake tubes would leave the front of the air box totally unsupported and would not likely stay connected to the plastic intake tube. What you need to picture is where the intake tubes are below the shock mount. Cutting them off behind the mount still leaves them under the mount and in the way of the reservoir. You can't remove the tubes under the shock mount because that's an integral part of the frame.

http://tweaker.smugmug.com/photos/182237665-M.jpg

http://tweaker.smugmug.com/photos/182237702-M.jpg

http://tweaker.smugmug.com/photos/182237670-M.jpg

[blsnelling]

I've been doing a little research and it looks like everyone else is using a 250R shock. That sucks. I just bought this thing. Oh well. Just something else I have to sell.

Now comes the question of linkage compatability with a 250R shock. Is the lower mount of the 250R shock the same width as my 450R linkage? What about bolt size?

[2muchquad]

Yeah the 450r shock wont work,i have tried it myself.Hence the 250r shock i use instead.I think the 250r lower mount may be a tad wider but it will work on the linkage.Im not sure if the bolts are the same though,i m pretty sure the 85 and 86 250r 3 wheeler uses a bigger bolt than the ones on the 86 to 89 250r shock mounts or vice versa..I did mine a while ago so i forgot what i used.

[honda300EXtreme]

dam, that sucks,

i could of sworn i have seen it used before (guess not)

it wont be bad you can sell that thing for enough to buy a 250 rear shock

[SET THE STAGE]

88-89 250r swingarms work

i didn't do mine myself, but i did a little research and people were doing it to their 300's about 3 years or so ago and all that needed to be done was you needed to grind down the top mount on the 250r shock and create a linkage mount on the frame.
here's mine:
http://i14.tinypic.com/68bj4p3.jpg
http://i10.tinypic.com/6h52oon.jpg

sorry i don't have better pics of it

[blsnelling]

Hey. What can I say? You're doing your best to help me out. I appreciate that. I'm sure we both learned a little lesson here.

Anyone ever try using the '01 Raptor shock with the Raptor linkage? I'm guessing it doesn't work.

So, what linkage do I need? 450R, 250R, 400EX.....

What shock works best? Is there any difference in the different years of the TRX250R? I believe the ATC250R shock is less desireable since it's longer.

Keep the info coming guys. I appreciate it.

[jay80]

Heres what I did. I used TRX250r shock, reason being the res. line is longer than the ATC line so it makes it easier to mount the res. To make the 250r top fit you need to grind a bit to the frame mounts and grind a bit on the top shock mount. For the bottom I used 450r linakge. The bottom of the 250r shock is wider than the linkage and the bolt hole on the shock is larger. I ended up using collars from one of my old a-arms to slid into the shock, big part on the inside, smaller threw shock hole. I did have to trim them a bit but it worked out nice because they made up the difference between the hole sizes. For the frame tabs I had some L brackets laying around so I cut them to size and drilled holes threw them. Then welded onto frame.

[blsnelling]

Here's the deal. The upper shock mount in the frame is 12mm. On the 250R shock it's 10mm. I'm hoping I can just drill out the shock bushing. The ears on the bottom of the shock are 12mm but the 450R linkage is 10mm. I should be able to drill that out for 12mm as well and then use a washer on each side to make up the width difference. I do really like the creative idea of using the a-arm bushings. See any problem with my plan?

Anyone have a good TRX250R rear shock for sale? There's not much on eBay right now.

[jay80]

Your right about the top, forgot about that. I did drill the top of the shock bigger, but I use a collar to protect the shock bushing.. The bottom I didnt because I used the a-arm collars and the holes were so close to the same size.

[SET THE STAGE]

i have a pretty good looking atc250r shock i'm trying to sell for 50 shipped off an 86

[blsnelling]

What's the length of the 250R shock vs the ATC shock?

[SET THE STAGE]

about a quarter inch long, i believe. it's the same length as the 86 trx250r shock, too. it shared the same shock minus the length of the res. hose

the atc res. hose is short the trx is decently long and allows for easier mounting. i'm sure there would be some place to mount the atc one, though

[blsnelling]

So there's only about 1/4" difference in the length of ATC250R shocks and TRX250R shocks?

[SET THE STAGE]

i believe so. something around there. there should be some information on the length differences on here if you search.

and i think there's stuff on 3wheelerworldforums.com that should help

[blsnelling]

A little update here. The a-arms are painted and installed. I'm still waiting on the 400EX spindles. Meanwhile, the hubs are disassembled and sporting a new coat of red paint while waiting on new bearings/seals. I also ordered a set of stainless braided brake lines to finish off the front. For the rear I went with a 450R brake line. The 300EX pivot sleeve was a little narrower than the 450R swinger. The sleeve needs to be a hair longer so that when tightened down, the swinger moves freely. So I removed the steel insets and took about 1/8" off both sides of the swinger. I had to take the same amount off the steel inserts before reinstalling. I'm waiting on a new pivot bolt in order to install it. The 450R bearing carrier needed new bearings. The old bearings are out and the carriers cleaned up waiting on new bearings. The rear hubs are also sporting a new coat of red paint. The only real kink I've run into is the width of the upper shock mount on the YFZ450 shocks. 400EX shocks are a hair less than 3/4" wide where as the YFZ450 shocks are a full 1 1/4" wide. I didn't want to hack that much on my shocks, so out came the sawzall to modify the relocation bracket I had just made for the 400EX shocks. I hope to get that done tomorrow night. I'll post more pics later.

[cjpoole1]

Originally posted by SET THE STAGE
88-89 250r swingarms work

i didn't do mine myself, but i did a little research and people were doing it to their 300's about 3 years or so ago and all that needed to be done was you needed to grind down the top mount on the 250r shock and create a linkage mount on the frame.
here's mine:
http://i14.tinypic.com/68bj4p3.jpg
http://i10.tinypic.com/6h52oon.jpg

sorry i don't have better pics of it
does anyone know if a 250R no link swingarm will work without any modification?

[blsnelling]

I got my spindles today. After a little polishing, they're installed along with the tie-rods. The bump steer is a little better with the 400EX spindle than the 300EX one. There's hardly any at all until the last 2-3" of travel as the quad bottoms out. I'm still waiting for hub bearings in order to complete the front.

Help me decide on a shock. I can get a TCS dual rate in very good condition for about $215.
Or, I can get a OEM rebuilt and revalved with zero preload by ELKA for $165 shipped. It's dual rate as well. It's only been used once since being gone through.
Then there's an OEM I can get for $50.

Here's a couple pics from tonight.
http://tweaker.smugmug.com/photos/183705231-M.jpg

http://tweaker.smugmug.com/photos/183705269-M.jpg

http://tweaker.smugmug.com/photos/183705205-M.jpg

The swingarm's just barely hanging there. I'm waiting for a new pivot bolt.
http://tweaker.smugmug.com/photos/183705247-M.jpg

[honda300EXtreme]

i would go with the tcs dual rate..... they make very good shocks


looks like your making some progress

[SET THE STAGE]

Originally posted by cjpoole1
does anyone know if a 250R no link swingarm will work without any modification?

i would imagine it would work as long as you have a no link shock and an 88-89 style swinger

[blsnelling]

The front end is basically finished. New bearings and seals are installed in the hubs. The calipers are mounted with new braided stainless lines, and bled. The shock bracket is modified to accept the 1/2" wider FYZ450 shocks, and the shocks are installed.

I'm really happy with the ride height. I built the bracket with the 300EX a-arms and 400EX shocks and it sat too high. With the 400EX a-arm lower shock mount being farther out and the YFZ450 shocks being shorter, it lowered it significantly. Yet the shocks still bottom out 2-3" before the frame hits the ground. It's going to be much more stable. Significantly lower and 3" wider make for a huge improvement. Not to mention loosing those crazy springy 400EX shocks.

I also bought my rear shock this evening. I ended up going with the Elka. The TCS was no longer available. The Elka has one ride on it since being gone through and is actually set up for my weight and riding style. It is dual-rate with zero preload. This is going to let the rear ride a lot lower in addition to being 3" wider and longer. This should end up being an awesome handling machine!

http://tweaker.smugmug.com/photos/184070876-M.jpg

http://tweaker.smugmug.com/photos/184070921-M.jpg

http://tweaker.smugmug.com/photos/184070863-M.jpg

http://tweaker.smugmug.com/photos/184070913-M.jpg

http://tweaker.smugmug.com/photos/184070900-M.jpg

[SET THE STAGE]

wow that thing is SO clean

question about the spindles, though. did you use 400ex hubs and calipers? i want to get 400ex spindles for mine because they look a lot better, i've heard they perform better for the 400 setup, and they go pretty cheap on ebay.

[blsnelling]

Originally posted by SET THE STAGE
wow that thing is SO clean

It wasn't when I got it earlier this summer! If you haven't followed it's progress, it was a basket case when I got it. It's come a long ways.

I'm using the 400EX spindles with the original 300EX hubs and calipers. Everything bolts right up. The 400EX spindles have a little less bumb-steer, although the 300EX spindles are useable. The 300EX are steel whereas the 400EX are aluminum. I have a polishing wheel on a bench grinder and shined mine up before installing them.

[blsnelling]

I finally got my pivot bolt and carrier bearings. Tomorrow night I'll be welding up the linkage mounting brackets. I learned that my 300EX rear master cylinder can't be used with the 450R bracket and disc. If I hadn't already sold and shipped my old disc, I might have been able to use all the old brake components. But since I don't have them all, I bought a 450R caliper off eBay tonight. Just something else to hold me up. I'm a little concerned about sprocket alignment. If I put a straight edge on the rear sprocket, it appears to be about 1/4" to the right of the front sprocket. If I lay the chain in the the chain slide on the swingarm, it's obvious. If I just pull the chain tight from the front to the back sprocket, you can't really tell. Not much I could do about it anyway. What do you think?

Chain pulled tight.
http://tweaker.smugmug.com/photos/184428727-M.jpg

Chain laying in slide.
http://tweaker.smugmug.com/photos/184428732-M.jpg

Getting there. You can tell it's 3" longer.
http://tweaker.smugmug.com/photos/184428674-M.jpg

http://tweaker.smugmug.com/photos/184428712-M.jpg

http://tweaker.smugmug.com/photos/184428716-M.jpg

I've got to weld me up some brackets tomorrow night. I hope to have my shock by Friday.
http://tweaker.smugmug.com/photos/184428721-M.jpg

[SET THE STAGE]

is there any way to put a spacer behind the front sprocket to make it sit out a little more? that may fix it

[honda300EXtreme]

i wouldnt try to shim the front sprocket over... you may have to grind the swingarm a little so you can put a few washers in there to line it up,

i know when i put the 400ex swinger on mine, i had to grind the piss out of it so i could get it shimmed over far enough

[blsnelling]

Take a look at the first picture in my last post. Do really think I have anything to worry about?

[SET THE STAGE]

Originally posted by blsnelling
Take a look at the first picture in my last post. Do really think I have anything to worry about?

it doesn't look too bad in the first pic but better safe than sorry

try maybe grinding down the right side of the front so you can move it over a bit, then put a few washers on the other side

[2muchquad]

when i had my 450r setup,i didnt have to do any grinding on the swingarm.I have never had problems with it.As long as your chain is tight you should be fine.You may be able to put a washer to move it over if you have to.

[blsnelling]

The linkage mount is all welded up and painted. The swingarm is permanently installed and the linkage bolted up. I'm using a 2x4 in place of the shock. Tonight was the first time it had rolled since the process began. The rear brake pedal is installed on the pivot bolt. I'm supposed to get my shock tomorrow. I'm still waiting on the rear brake caliper.

I was able to make an adjustment on the sproket allignment. I had previously made a then spacer for my axle nut from one of the old carrier bearings. Instead of putting it right behind the nut, I pulled the axle from the carrier and put the shim on the other side between the sprocket hub and bearing. The shim is only 1/8"-3/16" thick, so the seal is still on the hub. I went ahead and installed my EK x-ring chain. I need to count the links for future reference.

No pics tonight. I'm not about to show you guys detailed shots of my welding.:eek2: I'm not worried about it holding, but it isn't pretty. That's some difficult angles and tight spaces for a rookie welder to be working at.

[blsnelling]

I've got the shock and have a couple issues. The 250R lower shock mount uses a 12mm bolt. The holes in the shock are considerably larger than that though. Probably 14mm or better. I'm thinking the collars in the 250R link must go through the shock mount as well. So I've got a holes in the lower shock mount that are probably 14mm and mounts with a 12mm bolt. What to do?

The 250R upper mount uses a 10mm bolt. The 300EX frame uses a 12mm frame. The collar in the shock is too hard to drill. What to do here?

[blsnelling]

It looks like I got a bad shock. Neither the compression nor the rebound adjuster do anything to change the function of the shock. This thing was supposedly rebuilt last year, yet the bump stop is dry rotted and falling apart.

How much travel is typical for the rear end, measuring at the grab bar? Full compression to full droop.

[SET THE STAGE]

the 250r bottom mount SHOULD be a 14mm (mine always have been) and the top should be 12mm with the sleeve in but when its out its a 14mm.

[2muchquad]

The shock for a 250r 3 wheeler and 250r quad use different size bottom bolts.

[SET THE STAGE]

yeah but they're less than a millimeter different i believe.

[blsnelling]

The 250R shock takes a 10mm on the top mount. Check out the microfiche at hondapartsworld.com. As far as the lower mount, I think the shock is sandwiched between the inner and outer linkage and there's a collar there. These holes are not wallered out and are closer to 14mm.

[SET THE STAGE]

maybe it is a 10mm with the sleeve in, but i know for a fact if you take the sleeve out it becomes a 14mm. i had to do it to my blaster to make it fit because it uses a 14mm in the top

[blsnelling]

14mm sounds about right with the sleeve out.

[blsnelling]

Even thought the rear shock is defective, I was finally able to ride it yesterday. Man what a difference! It's so much more stable it's not funny. Power sliding and donuts on pavement are simple to do now. Pulling the front end up requires a LOT more. With the stock swingarm I could probably pull the front end up in 4th, 3rd for sure. Now it requires a fair amount of effort to pull it up in second. I can get it up whenever I want to, but it takes a lot more. Once up, it's still very easy to ride. I've yet to get any air with it. I'll save that for when I get the rear shock sorted out. I'm very pleased.

[SET THE STAGE]

good to hear it's all running. so is the shock blown or what? pep can rebuild for 90 like i said. maybe keep that in mind

[blsnelling]

It has about 125 psi of nitrogen in it. I don't know what supposed to be in it. The problem is that the compression and rebound adjuster do nothing. They click but don't affect the shock at all. What is this a symptom of? The seller has agreed to give me a refund. Once again, I'm looking for a 250R shock.

[SET THE STAGE]

well i always still have mine.

[blsnelling]

It's mine now:D I just sent you payment for it.

[2muchquad]

They click but don't affect the shock at all. What is this a symptom of?

Either the shock oil has seeped out due to a bad seal or if it was supposed to be rebuilt,there is air in the system.;)

[blsnelling]

No signs of oil anywhere. Oh well. It's boxed up and going back to the seller tomorrow. In its place I bought a 250R ATC shock for $50 shipped. If it works, fine. I got a great deal. If not, I have it rebuilt for $90-$100 and add a longer stainless line and I'll know what I have. I should have done this in the first place but didn't want to mess with having it rebuilt should it need it.

[pitcrew14]

any more updates. going to put same setup on my sons quad this winter wanting as much info as possible

[blsnelling]

I finally got to ride the quad this past weekend. Not much air time but a little. WOT down the country road followed by my bro-in-law showed 62 MPH. I'm going to try to sum everything up here for everyone.


400EX or a-arms bolt right up with no mods.
400EX tie-rods will be required. You can reuse your 300EX tie-rod ends.
Either 400EX or 300EX spindles will work. 300EX are steel and 400EX are aluminum. 400EX have a little less bump-steer. Not a must have though.
300EX hubs and calipers bolt right up to the 400EX spindles.
I installed new 400EX braided SS brakes lines, so I don't know if the 300EX lines will work or not.
A shock relocation bracket will be required to mount the new shocks.
Any of the following shocks can be used: 400EX, 450R, YFZ450, and maybe others. 400EX shocks bolt right up with no other mods but are very springy and not a good choice. They are also not adjustable. 450R and YFZ450 shocks are fully adjustable and are a much better choice. I think the 450R shocks will bolt right up. The YFZ450 shocks are 1/2" wider at the top than your bracket will be made for. I modded my bracket to accept them. Others have narrowed the shocks themselves. I like the YFZ450 shocks since they have progressive springs. They have worked out well.
Either a 350X ATC or a 450R swingarm can be used. I went with a 450R since they're new and are aluminum. The 450R swinger is exactly 3" longer than the 300EX swinger. I could not pull a holeshot with the stock swinger. The front end would fly off the ground every time, even in dirt. It's now not a problem even doing a 2nd gear holeshot in the dirt. It does take a lot more to wheelie now. I could probably pull the front end up in 4th gear before. Now it takes effort in 2nd and is nearly impossible in 3rd. Don't get me wrong. It still wheelies nicely, but it takes a lot more to get it up.
Some have reported just bolting the 450R swinger right up with no modding. I chose to remove the metal end caps and remove about 1/8" off each side. By doing this, the 300EX pivot tube/spacer is just barely wider than the swinger. You want this so that the swinger can swing freely when tightened down.
Notice I did say you will be using the 300EX pivot tube. It's the same OD as the 450R pieces. However the 450R uses the engine to fill part of the gap between the two sides of the swinger mount. This is solved by using the 300EX tube. You will be using the 300EX pivot bolt as well.
Either swingarm will require a linkage mount to be fabricated and welded to the frame. On a new 450R the center of the linkage bolt hole is 1" straight out from the frame. The 450R linkage takes a 10mm diameter bolt.
You will need a ATC 250R or preferably a TRX250R shock. There's only about 1/4" difference in the length of the two but the reservoir hose is much longer on the quad shock. A 450R will not and cannot work here. Don't even try it. Cutting of the intake tubes from the frame will not help. The side mounted reservoir is big time in the way.
The trickiest part for me was matching up the hole sizes of the frame, shock, and shock linkage. The bottom of the 250R shock has about 15mm holes in it. I think a bushing in the 250R linkage originally went into the lower shock mount. The 450R linkage takes a 10mm bolt. Don't even think about drilling the linkage bushing out to match the shock. It's WAY too hard to drill! I made bushings from 10mm nuts to reduce the shock holes down to 10mm to match the linkage bushing. Someone else wisely suggested using the little collars that go in the front a-arm grease seals. I HIGHLY recommend ordering these. These will be installed on the inside of the shock mount so that the flange of the collar is on the inside of the shock mount and reduces its width. This is needed since the shock mount is wider than the linkage. This will let it all fit nicely together and bolt together with a 10mm bolt.
The top of the 250R shock takes a 10mm bolt but the 300EX frame takes a 12mm bolt. Again, don't even try to drill out the shock bushing. It's WAY too hard! This 10mm ID shock bushing can be removed leaving about a 14mm hole, maybe bigger. I didn't care to try drilling my frame out. Once again I made bushings to reduce the frame to 10mm. Another option would be to have a machinist make a new bushing for the shock that is 12mm ID. Again the a-arm grease seal collars may work here to reduce the frame holes down to 10mm.
The other catch to fitting the top of the shock is that the bushings must be ground down to the width of the shock body. They stich way out past the body of the shock. The frame opening is almost exactly the same width as the shock body. I actually narrowed the shock body a tiny bit so that it fit loose in the frame and then ground the removable bushing until it fit tight. That way when the bolt is tightened down, it tightens on the bushing and not the shock body. The shock body needs to be loose.
You will need a longer rear brake line. I ordered a new one for a 450R.
Buy the axle from the same model as your swinger. Again, I went with a 450R axle and carrier. The 300EX carrier will not work with the 450R axle. I think the 300EX carrier may work on the 350X axle. You better double check though.
I think you can reuse your 300EX sprocket hub. I chose to sell mine and buy a complete 450R axle to be safe.
I ran into a problem with my rear brake. If you use the 450R brake stay and disc, you MUST use a 450R caliper. You MIGHT be able to use the 300EX caliper IF you use the 300EX brake stay and disc. I couldn't try this since I had already sold my parts when I found out the 300EX caliper wouldn't work for me. The 450R disc is much smaller in diameter.
Obviously you'll need a much longer chain now. I just bought a full length chain and cut it to fit. I have not counted the # of links.
If you get a 450R swinger that does not have the stock skid plate, you will need to buy an aftermarket chain guide. The factory chain guide is built into the 450R skid plate. I didn't want a skid plate so I bought a guide. Don't run without one though. That is unless you're wanting to replace your engine cases from a thrown chain.
The only other mod I made was to add a billet case saver that works with a 14 tooth front sprocket. The stock piece will not work with a 14. I bought this piece off eBay for something like $30-$35.


Now go out and enjoy a quad that is WAY more stable and can be ridden much harder while still maintaining full control.

This is not a simple one night mod. I'm 39 years old have tried to learn a little patience over the years. Take your time and make it right. After all, getting something wrong with the suspension of your quad could cause you some serious injury. It definately worth the time to do this and the costs are not that great since nearly everything is factory take off parts.

Let me know what I've left out and I'll modify this.

[SET THE STAGE]

so how was the shock? not blown, i hope..

[blsnelling]

Nope. I took the spring off and cleaned it all up. It only had about 50 PSI of Nitrogen. So I took it down to Tire Discounters and filled it up to about 140-150 PSI. That's all the pressure they had. This shock seems stiff for this setup though. It works fine but would probably benefir from being sprung and valved for this application.

[SET THE STAGE]

yeah, that's bound to happen when you switch a shock from one bike to another

now you that mention it, mine is kind of stiff on mine, too lol

[D-7#61-450r]

Excellent info. I would love to see some pics. I have not seen this swingarm and linkage combo in a pic of were I would actually think of doing it. The pics I have seen look like the linkage geometry is way out of wack. I own 2 450r's and have the parts, but if the linkage does not come close to what it looks like on them then I will not try this on my 300.
Please post pics or email them to me at atvmafia61@hotmail.com

[2muchquad]

The pics I have seen look like the linkage geometry is way out of wack


Looks can be deceiving.Just because it may not mimic stock doesnt mean it doesnt work.Lots of quads come stock with shotty suspension that looks good but doesnt work.Just ask any polaris owner:D

[D-7#61-450r]

Say what you will about the geometry but this is supposed to be a better rear not a cooler looking rear and bragging rights. I don't care about how pretty your welds are or how everything still needs cleaned up or painted. I would just like to see pics of this done. I have seen one pic and was not very convinced it would work. I hear alot of how to info but noone seems to supply proof of this swap being done and working. I would just like to see this swap turn out and be a great thing to do to a 300ex/250x.

[blsnelling]

Give me a couple days and I'll get you some pics. Exactly what angles/parts are you looking to see?

[D-7#61-450r]

The one pic I have seen the linkage almost looked straight across sitting on level ground supporting the wieght of the quad. on a 450r from the rear point the linkage goes down at an angle an connects to the front link, which is slightly angled back to the front mount.
Thanks for the reply I will be looking forward to some pics.

your shock info is great along with the whole parts list.