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Discussion Starter #1
been digging on some parts websites and i think i figured out how to make the newer 400s have low range when in reverse. i printed out and cross-referenced both shifter assemblies (trans and the subtrans) and the transmissions and subtrans themselves, and 98% of the parts are the exact same, and guess what the difference is.... the reverse shift shaft for the subtrans is the same, but some parts have been rearranged or removed in the subtrans shifter assembly. this is comparing the 02-03 400Ms to the 04+ 400Ms.

below i'm referencing extremepowersports.com parts pages

if you look on the subtrans shifter assembly (called "gear shifting 2") sheet for a 2002 or 2003 400m, then one for a 2004-and-up 400m, you'll notice that on the 04+ reverse shift shaft, there is a "spacer" (as it was described) that looks like a wide collar. well, on the 02-03 there is a washer and a spring where this collar is... and on the other end of this same shaft, there is a "shift cam lock plate" (also as described) just before the reverse shift cam that looks to have been just omitted for the newer 400s. i'm betting that this is the reason you can't access low range while in reverse in the newer 400s... it needs that spring and the cam lock plate to keep the low range drive gear engaged when you stick it in reverse. without that lock plate, it must default to the high range drive gear. this is just a guess though, but i can't imagine how it would work any other way.

the only other difference i could find on the parts sheets is that in the subtrans ("transmission 2"), on the shaft where the high and low range drive gears are located, they moved 1 washer (part# 8) from one end of the shaft to the other... i'm assuming they had to do this to make everything line up after they removed the washer, spring, and cam lock plate from the reverse shift shaft.
 

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Discussion Starter #3
Ok, threw this together in paint real fast... the other diagrams aren't worth showing since they're pretty much the exact same (the transmissions are the same, the trans shifter assembly is the same except the foot shifter is a little different).

here's the 2002 Subtrans shifter assembly, showing the parts that are missing:
[attachment=87878:02_400_S...Modified.JPG]

here's the 2002 subtrans showing the washer that was moved:
[attachment=87879:02_400_T...modified.JPG]

here's the 2006 subtrans shifter assembly, showing the collar that replaced the washer and spring, and where the lock plate is now missing:
[attachment=87880:06_400_S...modified.JPG]

and finally, the 2006 subtrans showing the washer that was moved from one end of the shaft to the other:
[attachment=87882:06_400_T...Modified.JPG]

i guess the next step is to verify that all the part numbers are the same.... if they are i'm willing to bet this will be a cheap fix, but you will have to pull down one side of the bottom end of the engine to get to these parts. i've looked through the 2006 service manual at the chapters where they're pulling down the trans, subtrans, and shifter assemblies, and it doesn't seem too awful hard. they have some good pictures of it all too.
 

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Wish i had the mechanical skills to try this on my ride. i could have used it this last weekend right before i got stuck in deep, hard-pack snow !
 

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Discussion Starter #5
i figured i'll put it here first... i hate to say this after all this work so far, but there was something i didn't see before. that's actually good and bad. but we ARE making forward progress and i think this is the final solution. in the end, the only bad thing is that there will be some welding and cutting on one little piece to make it work. read on...

i snagged these screen shots while studying the 06 service manual.

first: notice that you DO NOT have to split the cases to get to these gears as they're right behind the clutch [EDIT- not the clutch, behind the flywheel/recoil in the left side engine cover]. it looks like if you can put in a clutch kit, with the right tools and a little more effort, you can gain easy access the subtrans gears:

[attachment=88300:06_400M_...ns_Pic_1.JPG]


but the simple gear swap won't work. the black gear in the picture below, which is the low range driven gear (part# 2), is what turns the gear and shaft that's attached to the bevel gear. so we can't swap these because the high range gear set won't mesh with that larger gear. also in the picture below, notice something? the shift fork is engaging the low range driven gear (part# 2)... look at that shift cam and how it has the shift fork and dog gear situated during this time... the grooves in the collar (shift cam) are what move the shift fork to the left or right as the shift cam rotates (when you move the shift lever back and forth from L to R).

[attachment=88309:06_400M_BAD_PART.JPG]


i can see some simple welding and a little milling on that shift cam pushing that shift fork/dog gear back onto the low reduction gears when you shift into reverse. just repeat the pattern for low range on the other side of the "high range part" of the shift cam and voila, you've just gained yourself low range reverse. the "shift fork groove" in the shift cam would have to be modified to look like a symmetrical Vee... if you catch my drift... with the shifter in "L", the fork rides in the shift cam groove and pushes the dog gear to the left, locking onto the low range reduction set. with the shifter in "H", the fork ride in the shift cam groove in the other direction and pushes the dog gear to the right, locking onto the high range reduction set. now to get low range reverse, the pattern on the shift cam has to go back the other way as you rotate it so that it engages the low range reduction gear set. making a Vee pattern.

that shift cam (part #8 on the 06 subtrans shifting assembly diagram) isn't an expensive part, $35 at mr cycles. this is where it's going to take a guinea pig to buy this piece, modify it, and install it. i played the guinea pig on the tachometer and spent $70, and it worked out for me. now someone will have to give the "shift cam mod" a try. if (WHEN) it works, that's what it's going to be called. :D
 

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Discussion Starter #6
wanted to update this thread... might be the last time

the top picture is what the stock shift cam looks like. the bottom picture is just a mirrored version of the top, so use your imagination that the shaft and bearings are oriented like the top, except now the channel on the shift cam is laid out how it needs to be to get low range reverse. and the shifter pattern will be flipped from L-H-R to H-L-R. i'm sure a lathe, or better yet, a milling machine would do this pretty quickly. just weld up the old channels, or weld in some pieces of scrap in the crossovers with the old channel (recommended, it's easier), to make a straight transition from one side to the other. remember all you have to do is move that shift fork to where it needs to be.

[attachment=88514:06_400M_Cam_Mod.JPG]


the shift cam is only $35, pretty cheap price at trying this mod. people spend thousands on mods and lifts... this is a drop in the bucket. and it's hard to beat having good gearing in forward AND reverse.
 

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well i really wish someone would figure this out cause i bought 2 400s in november i and the reverse is killing me. it really sucks i beleive i can hold the damn thing still when in 4x4 and reverse. my dealer is willing to trade me but we havent done it yet due to im not ready to lose my ass in only 2 months. i like the 400 as far as the looks but this reverse has made me stop riding all my friends mud rid and im always stuck due to this reverse makes me keep going forward when i should be backing up. im really sick at my stomach about the hole damn think thought i might drive them to the artic cat plant and bog it down on their grass and ask them to back it up it wont back out its own tracks. 10 years ive waited to get a arctic cat and ill i got was arctic crap. i sure wich arctic cat would address this issue . i think im gonna put a video on you tube to show how weak this reverse is. maybe that wioll get some attention.
 

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Discussion Starter #8
i've figured it out... just need to modify that shift cam.

i know there's people on here capable of doing this. i don't own a 400 so i can't go barking up someone else's tree to do it.
 

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well i wish u could explain this to my dealer he is a friend of mine i sure dont mind him using my ass a test monkey i went riding today pulled down in a ditch went to back out couldnt it was embarassing but what can u do i just got off and pushed .
 

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Discussion Starter #10
You can print out and show this thread to them if you wish. The only thing they really need to see is this post.

if they have a milling machine or some other way to mirror the shift cam channel to look like the bottom photo of the picture below, it'll work. it's cat part # 3423-525. the top photo is of the stock subtrans shift cam, and i've pointed out what parts of the channel coincide with either high or low range. if the channel is re-cut (or milled) and welded so that it looks like the bottom photo (simply mirroring the stock channel), then you will have low range reverse. and your shifter pattern will go from L-H-R, to H-L-R (looking from front to back).

[attachment=90478:06_400M_Cam_Mod.JPG]

just have to remove the left side cover and pull the subtrans shift cam out (pretty easy to get to). machine/cut in the new channel, weld up the old one, and put it back together... that's it. the picture below shows how easy it is to get to the subtrans shift cam:

[attachment=90479:AC400M_S...Location.JPG]

if one of your dealer's techs were to look at it, they should know exactly what i'm talking about doing (if they have even the slightest clue about the cat's trans). all that shift cam does, is move the shift fork left or right to engage the particular high or low range driven gear. we're just mirroring what the factory (stupidly) did on the shift cam. it will be a worth while fix since you will then get about the lowest reverse gear in the industry, instead of having the highest.

if you show this to them, let us know what they say.
 

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Can you remove that shift cam, notch the low range channel for reverse, and then possibly weld the high range channel where it is not needed?
 

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Discussion Starter #12
Not quite sure I'm following you Jake... that little "finger" on top of the shift fork is always engaged into that S/T shift cam channel. anytime you move the lever the shift cam rotates, and the little "finger" on the shift fork just follows the channel (as the cam rotates) to the left or right to engage the high or low range driven gear. does this answer your question, or can you clarify a little more?

and do y'all have a milling machine? I would try the channel mod myself with the drill press at our shop, but I'd trust doing it the other way more.
 

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Whooops, what I was TRYING to say is, remove the shift drum, notch the low range, weld the unused part of high range, and INSTALL BACKWARDS. or install it in the other direction, flip it over? Would that do the same thing as having a mirror image machined? Just an Idea.
 

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Discussion Starter #14
oh ok... yea i thought about that before, but found out that the gates for each range are not evenly spaced. Low range is off to itself, while high range and reverse are very close together and there doesn't look like there would be enough space for the transition. this is why i think it will require a complete relocation/mirroring of the channel.

here is the backside of the shift cam, where the spring-loaded pin "locks" each range and reverse as you move the shift lever:

[attachment=91548:AC400M_shift_cam_b.JPG]



what are your thoughts about this? think you could whittle this thing out? the 400M's reverse would be insane with low range.
 

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The part is in and at the dealership. I will pick it up this friday. Maybe by next weekend I will have it ready to test out. I have a friend that has a 2003 AC 400 5 speed. I'll be testing it on his. The first prototype will be rough, but you have to start somewhere.
 

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Texas A&M Mechanical Engineering Dept. will be aiding me in this project. I am told to do this job a 5 axis milling machine is required. Keep your fingers crossed.
 
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