WR tranny in YZ? - revisited

[shaunusmaximus]

Hi, Ive read so many posts on this subject and havent been able to get any real info. I have an 01 yz426 and would like to install the WR 5th gear. I've read about people doing this conversion. Is it a matter of just buying the 5th gear out of a WR from a yamaha dealer or is there a lot more involved?

Some posts state that 1st and 3rd also need to be changed. Anyone of you that can give me some accurate info would be really appreciated. I have to mail order the parts from another country as there isnt one here. Exact part names would be nice so I can look on web for part numbers.

cheers. ?

[Tau]

`2006 yz can be fitted with wr gearbox. it has been done in RSA by Shimwells yamaha. Our national champ Clayton Enslin rides one and the runner-up in last years national oofroad championship Gray Dick. They are the best bikes money can buy. They are so good it is like cheating

[yzf450jack]

Hi, Ive read so many posts on this subject and havent been able to get any real info. I have an 01 yz426 and would like to install the WR 5th gear. I've read about people doing this conversion. Is it a matter of just buying the 5th gear out of a WR from a yamaha dealer or is there a lot more involved?

Some posts state that 1st and 3rd also need to be changed. Anyone of you that can give me some accurate info would be really appreciated. I have to mail order the parts from another country as there isnt one here. Exact part names would be nice so I can look on web for part numbers.

cheers. ?

Right down every part number in the YZ gear box and then right down the part number in the WR gear box and see what numbers are the same

[steve lemley]

didnt read throught the thread, just throwing in my 2 cents, I went to look at a 99 yz 400 a year ago that had the wr tranny. The owner said that to do it correctly, he had to machine the you know what out of the case. Dont know if he was lying or what but he said it was a hoar on the 99 yz400. Hope it helps and correct me if Im wrong please!!! How about but the WR motor and do the yz mods to it and save the headache???

[grayracer513]

That's why you should read through the thread first. The subject in the first place was the use of the 5 speed from a WR450 in place of the 4 speed in a YZ450, which IS a direct, drop-in modification requiring no machine work of any kind. Swaps involving 426's or 400's are interesting, but off-topic.

[steve lemley]

excuse me???????? Feel free to remove my comment ?

[steve lemley]

actually the original topic askes about what Rob Tuluie was doing and that was with a yz 426,just reinterating that if you want the closer ratio of the 426 in a 03 it does take machining, thats the post I replied to? How is that off topic ? ?????????????????????? ?

[grayracer513]

The OP asked specifically about a WR450/YZ450 trans swap. His post indicated there was some confusion between Mr. Tulie's YZ426 5 speed conversion and the process of installing a WR450 trans in a YZ450:

several weeks ago, ... it was suggested that i just put a WR tranny in the YZ motor. i looked up all the parts and was planning on doing so.

now, it was brought to my attention that the 03 may need extensive machining to accept the WR tranny.

After that was straightened out, there was the request to assemble a parts list and sticky it:

Guys;

If you get the parts list together (especially for the 03) can you please, please, please post it and maybe sticky it for us to use as an upgrade. Maybe you guys who are master mechanics can conspire to write up a quick how to also?

Seeing that so many people drop 500+ bones on some silly exhaust pipes it would seem to me that this would be a far better upgrade.

So, that was the original subject. Since then, there's been questions about WR426/YZ426 swaps, and now whether parts from a 400 can be intermixed. Both these subjects, while they are, as I said, interesting, seem off the original point to me. But don't let that bother you too much, OK?

Since the question of the '06 came up, when the '06 YZ450 5 speed is assembled into an earlier YZ450, the cases fail to close by roughly .125", so the trans is wider, and it will not interchange. The people who were playing with this say they aren't done trying yet, but it seems it would be even more involved than the 426/450 swap was.

[bryant40]

How does the '06 WR tranny compare to the '06 YZ's? Since both are 5 speed this year, I'm guessing that the also 5 speed WR just has wider ratios. If you wanted wider gears on the 06 YZ, couldn't you just do some sprocket swaps? ?

[grayracer513]

The '06 WR450 transmission is essentially identical to last year's, meaning that it's the same bearing-to-bearing width as the '03/'05 4 speed was. The '06 YZ450 5 speed is about 12mm wider, which is why it will not interchange.

On the sprocket question, yes, gearing an '06 YZ450 higher will make the ratios feel as if they are wider spaced, just as it will on any bike, and it adds to the top speed in high gear more than it takes away from the grunt in 1st, which is usually uselessly low on the track. The first one I rode had a 14 on the front, and was a lot less "shifty" than the stock gearing.

[Spadman450]

Tau...

If the 2006 YZ can be fitted with the WR tranny, it is not a given that the reverse could be done. I assume some spacers or wider bearings might be required to make the swap you describe work knowing that the new YZ box is slightly longer at the shafts. Any details you could provide might fill some squares and greatly appreciated.

I know special gear boxes were made for the 2003-2005 YZ's that had the same ratios as the 2006 gearbox does. It may have been done using some or many parts from the YZ250P boxes which also have the same ratios above except for 2nd gear.

Those of us using WR's in SuperKarting would kill for the 2006 YZ gearbox for long course/long straight away tracks. The spacing from 4th to 5th is just too tall in the current WR's.

Thanks to all for the info provided so far in this thread.

Don E

[Tau]

I HAVE A 06 YZ450 THAT HAS A WR GEARBOX,KINDOF. hERE IN THE GOOD RSA WE HAVE A BIKE SHOP CALLED SHIMWELLS YAMAHA AND THE NATIONAL CHAMP RACES FOR THEM AND THE NO 2 AND 8 AND 13 SO THEY KNOW WHAT THEY ARE DOING. THEY HAVE CUSTOM MADE MY YZ450 A WR GEARBOX. IT STILL HAS FIVE GEARS, HOWEVER THEY ARE CUT TO SIZE (ALL VERY SECRETLY ABOUT THIS THOUGH). THE BIKE IS BEAUTIFUL TO RIDE THE ONLY DOWNSIDE IS THAT THE TOLERANCES IS SO CLOSE THAT THE CLUTCH NEEDS TO BE PULLED IN WHEN THE BIKE IS REVVED DUE TO THE BIKE JUMPING INTO GEAR. THERE IS PLENTY OF THESE BIKES RUNNING AROUND RSA AND THEY ARE VERY RELIABLE.

[stk0308]

If you do desert or high speed applications, this is an excellent swap.

If you do not do any type of riding over 75+mph(SX&MX riding) than this is not a big deal. Honestly and personally I LOVE the 4spd, but I run out of gear in the desert, so I made the swap.

This is confusing me a bit. Not only would you get higher speeds out of the WR box, but wouldn't you get a lower 1st gear? That would benefit trail riders who do a variety of riding, wouldn't it? Seems to be alot of focus on this as nothing more than a top speed mod.

[dave03yz]

Yeah of course a lower 1st is benificial in the tight technical tuff. I suppose I was generally speaking of the riding I do. When I do get in to single track and nasty little rocky uphills I swear by that first gear. Also when I posted that I think I had the trans in for about a week or 2 and hadn't really had a chance to explore all the goodness the wr trans has. Still an excellent swap IMO but, like I said if all you ride is mx, stay w/ the 4spd.

[grayracer513]

...THE ONLY DOWNSIDE IS THAT THE TOLERANCES IS SO CLOSE THAT THE CLUTCH NEEDS TO BE PULLED IN WHEN THE BIKE IS REVVED DUE TO THE BIKE JUMPING INTO GEAR.

Sounds like high quality work, alright.

Don't type in all caps.

This is confusing me a bit. Not only would you get higher speeds out of the WR box, but wouldn't you get a lower 1st gear? That would benefit trail riders who do a variety of riding, wouldn't it? Seems to be alot of focus on this as nothing more than a top speed mod.

You're right, but that's part of the trade-off. It's a wider ratio transmission from top to bottom. The spacing of the middle 3 in the WR is pretty close to that of the top 3 on the 4 speed, but there's a fairly hefty jump from second to first. How this works out for you depends on what kind of riding you do.

[MotoGoalie]

I've been on trails that my XR will just idle up, but the YZ must be slipped clutch, off the seat and bulldogged up.

If I can get the wifey to sign off on the 7 bills +....gray what do you charge for tranny work?

[Spadman450]

I would be very careful to knock the knowledge and work that is being done at Shimwells. Do to the the leads I picked up on this forum, I was able to contact Braham in SA with a series of emails and he was extremely helpful. I am in the process of building two complete transmissions that will interchange between any 2003-2005 YZ and 2003-2006 WR 450's. The beauty is the choice of "digger" first gear with a close ratio 4 speed to follow or a close ratio 5 speed. For my use (SuperKart) the decision of what to use will generally depend on whether or not the race has a rolling or standing start. The over drive 5th gear in the WR is not the hot ticket in my racing (especially on long tracks like Elkhart Lake), but I wanted the electric start and charging system.

Now for the best part. All the parts are off the shelf Yamaha. I was fairly certain that it could be done, but it took Braham to guide me through without tons of new parts to end up on ebay. The combinations will work with my slipper clutches and output gears (sprockets).

As I indicated, they are not in my cases yet...but, I am certain they will work. The folks at Shimwells have a ton of combinations in play including 4 speed 2006 YZ's and various internal ratio changes. While we have all been speculating and querying, they have been out there building, racing, and selling.

Nuff said.

Don E

[grayracer513]

I would be very careful to knock the knowledge and work that is being done at Shimwells.

I think it's great that they're spending all the time and money on doing all that pioneering, and that we can reap the benefits of both their successes and their failures, but a gear box that drops into gear on its own is one of the latter. It's one thing if the trans just doesn't index neutral very well, but if it's able to do that without the shift cam moving it runs a clear risk of a double engagement. Having been on board a 427 Corvette that went into first and third simultaneously, I can tell you that to say it was catastrophic would be a masterpiece of understatement, and also that I don't want to be within 100 feet of the next one that does that, thanks.

[chris 426f]

i have an 02 yz426f and i an having problems with forth gear it wont engage can you help me

[censured]

OK................................Hopefully this should be the last post on this stickicky!!!

YES, you can put a WR(04-05) 5spd trans in a '03-'05 YZ450F.(WITH NO MODIFCATIONS TO ANYTHING)

If anyone ever has any questions about this mod please ask, I am more than happy to help you out. It is really not that hard to do!!!

This is EXACTLY what I was hoping for. I have an 03' and I really enjoy the bigger tracks. I am currently running 16/38 on my four speed and it still isnt enough. I am riding Mid-Ohio again tomorrow and even though it is a blast I desperatly need more top end speed. Beaverun was a bit better because the back and front straights are not quite aslong but it is way to slow even with extra tall gearing. This WR swap may just be the ticket! PM sent!

Tony