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mb43

Transmission Lock-Up

32 posts in this topic

I have a 2006 WR450F, with all the free mods and have been loving it to death. I bought it as a leftover so it has very low hours. Today I was tooling along an old RR bed at about 55-60 for about 2 miles, then horror of horrors, the back wheel locked up. If I pull in the clutch I can start the engine, but if I let it out the engine quits. I was able to get it into 2nd gear and ride it for a short time, but when I tried 3rd gear the tranny locked up solid, now I can't get it to go back into any useable gear. Has anyone had any issues with the transmission on this bike? I guess I have my winter project all set. Are there any gotcha's I should look out for when rebuilding this tranny. Any help appreciated!!

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If the oil was low before the 2 mile 60mph jaunt that could have been a main reason. I know many are hesitant to dualsport a plated WRF for long stretches at speed but two miles at 60 should've been fine.

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I know many are hesitant to dualsport a plated WRF for long stretches at speed

I dont think so...Both my dad's 06 and my 06 have over 13K miles of dual sporting

Heck I just did 300 miles on my dual sported 08 this weekend...no issues :excuseme:

There are plenty of people out there who have dual sported WR that have tons and tons of miles with ZERO issues :bonk:

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Sounds to me like your transmission is acting like a pre-teen girl. Can't figure out where to fit in.

Shift forks may be bent causing pressure on individual gears allowing them to partially transition between where they are SUPPOSED to be. Time to tear it down and inspect.

I would NOT recommend attempting to ride it until you've resolved what's happening inside.

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I

There are plenty of people out there who have dual sported WR that have tons and tons of miles with ZERO issues :bonk:

Like Me!:excuseme:

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Yes, my transmission locked up too. I got a hold of the factory and they said was probebly due to a bent shift fork which typically happens when switching gears without using the clutch. They where right....

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Thank you for the reply George,

But I am of the opinion that If you shift

**properly** without the clutch it is less stressful

to the whole system than shifting with the clutch.

By the way don't you ride a KX450F? It wouldn't

surprise me that you bent your shift forks on that

pig.

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Look MB,

Check out this motorcross forum from Dirt Rider magazine. You may get a different option.

http://forums.dirtrider.com/70/7885233/yamaha-dirt-bikes/is-shifting-with-no-clutch-bad/index.html

They say this WR450 has a Constant-mesh 5-speed transmission. It sounds like you have a tangeled mesh locked up transmission. And by the way, the KX450F weighs in a few pounds lighter than that no-go your riding. It's going to be a long cold fix in the garage this winter.

Maybe some other people will weigh in on your no-clutch power shifting techique and how it effects your transmission reliability....

:excuseme:

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(Dirt Rider) say this WR450 has a Constant-mesh 5-speed transmission.

Maybe some other people will weigh in on your no-clutch power shifting techique and how it effects your transmission reliability....

Shocking news! Were you aware that your KX and every other motorcycle I can think of made in the last 50 years and longer without an auto trans has a constant mesh transmission? (I knew you weren't).

Shifting without the clutch is completely harmless when done right.

http://www.thumpertalk.com/forum/showthread.php?p=8830912#post8830912

The probable cause of the issue here is a gear seized to one of the shafts. Since it moves, or did move, in second, my money's on the second wheel gear, left end of the counter shaft.

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gstrelke,

I agree that shifting without a clutch is an advanced technique and

is not for everyone. I'd be glad to instruct you sometime if you are

interested. Till then I suggest you keep using your clutch. In fact you

should think about double clutching, it is even safer for the non-sycro

trannys of your era.

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Yes, my transmission locked up too. I got a hold of the factory and they said was probebly due to a bent shift fork which typically happens when switching gears without using the clutch. They where right....

I have a Rekluse clutch on my bike for the past three years. Every shift I make is "without" the clutch. Done properly (unload the gears during the shift) is should not damage either shift forks or gears. Many, many miles on my gearbox with no problems.

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Double clutching on a constant mesh transmission? :excuseme: And you want to find the neutral between double clutching ? Show me that when upshifting from 4th to 5th.

Roll back the throttle for a moment before you move the shiftlever and then back to full, it works like a charm.

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I have a Rekluse clutch on my bike for the past three years. Every shift I make is "without" the clutch. Done properly (unload the gears during the shift) is should not damage either shift forks or gears. Many, many miles on my gearbox with no problems.

X2!! :excuseme:

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I'll post a reply once I get it apart, but I'm pretty sure either something

came apart and was snarled into the gears or something was inadvertently left

in during assembly. Maybe I'll find that missing gold tooth Yen Wang lost in

06..

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Double clutching on a constant mesh transmission?
And why not?

The term "constant mesh" indicates only that each gear pair remains meshed at all times, regardless of which gear is engaged. "Sychromesh" is the feature that eliminates the need for double-clutching. Lots of older heavy duty trucks were both constant mesh (in the upper gears) and non-synchronized, requiring that they be double-clutched to match the gear speeds. Until recently, reverse gear was nearly always out of mesh while idle, but over the past couple of decades, an increasing number of transmissions designs have emerged with reverse gear sets that are constant mesh, and even synchronized.

In a constant mesh trans, the gear pairs are always in mesh, but one member of the pair spins freely one one of the shafts, making the pair incapable of carrying power. To engage the gear, a clutching sleeve that is splined to the shaft slides up against the free gear, locks into the side of it by means of matching "dogs", or lugs, and thereby locks the gear to the shaft.

Synchros are a friction brake device that is placed between the gear and clutching sleeve to prevent the dogs from coming into contact with each other until it has match the speed of the two elements. Without these, it falls to the driver to use timing and/or double clutching to match the speeds himself.

Motorcycle gear boxes differ from automotive ones primarily in that all their components are vastly lighter. The design normally varies in that the clutching sleeve is removed, the locking dogs placed on the sides of neighboring gears, and the gears themselves are slid along the shafts to lock a neighboring free gear into play. They are never moved far enough to take them out of mesh, however. Also, the scale of the locking lugs is increased so that there are only 3-5 per gear, rather than the large number of small teeth used in automotive designs. This allows the lugs to handle the impact of two speed-mismatched gears coming together, so synchros are also eliminated from the design, a fact made possible by the lighter components.

The thing that makes double-clutching impossible is not the design of the trans, per se, but the shift mechanism. The typical car automotive trans selector mechanism allows gears to be selected in random order, always passing the neutral position in the process of moving one to another. The rotating cam/ratchet selector in a motorcycle selects each gear in succession, with no opportunity to halt in neutral between most of them.

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And why not?

The term "constant mesh" indicates only that each gear pair remains meshed at all times, regardless of which gear is engaged. "Sychromesh" is the feature that eliminates the need for double-clutching. Lots of older heavy duty trucks were both constant mesh (in the upper gears) and non-synchronized, requiring that they be double-clutched to match the gear speeds. Until recently, reverse gear was nearly always out of mesh while idle, but over the past couple of decades, an increasing number of transmissions designs have emerged with reverse gear sets that are constant mesh, and even synchronized..

Grayracer, what an excellent description of both and automotive transmission and a bike trans and the differences between them. I couldn't have done better myself and you saved me a lot of typing. As I said in my eariler post, it's OK to shift without the clutch on bike transmissions as long as the gearsets are "unloaded" during the process. They are designed to shift with unmatched speeds. Thanks

Edited by ncampion
to fix quote

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anyone that shifts without useing their clutch is a dumb*** and deserves everything that happens to their bikes. I'm really tired of hearing that this don't hurt the bike but it's really sad to destroy a bike then pass if off to unsuspecting kids that will have to spend a forture to repair it or hurt them from locking up and hitting a tree or something worse.:bonk:Sorry thats just how I feel about it!

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anyone that shifts without useing their clutch is a dumb*** and deserves everything that happens to their bikes. I'm really tired of hearing that this don't hurt the bike but it's really sad to destroy a bike then pass if off to unsuspecting kids that will have to spend a forture to repair it or hurt them from locking up and hitting a tree or something worse.:bonk:Sorry thats just how I feel about it!

I, Dumbass-extrordinaire (let's just use that name for me instead of my real name) have been shifting gears without a clutch for decades. I've yet to damage a transmission, gear set, shift drum, etc. I DID bend a shift fork once on a street bike from abusive behavior with my left foot and the shift lever - Meaning I was trying to force the transmission to shift while still under load. The transmission is not designed to be FORCED under load. Shift forks are slender, fragile components compared to the shift drum, gear sets, etc. Weakest link of the transmission if you will. Apply force and expect them to eventually fail. They bend- causing the trans gears to be out of alignment, which can cause "lock up" as it's been described here.

If you got a bad bike, bummer. Irresponsible of any seller to pawn off a bike IF they really knew something was wrong with it. A good percentage of the people I buy bikes from know little to nothing about maintaining machinery. It's a hard reality.

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