Damaged shock body 2008 YZ450f


35 replies to this topic
  • Wes Woodin

Posted January 22, 2009 - 06:25 PM

#1

My bike is an immaculate 2008 YZ450F. It has 13 hours on it. It has been perfectly maintained. I purchased a Factory Connection spring and went to replace it on my bike. I loosened the loch ring as anyone would do, however it seemed to not want to go. I tightened the spring more to relieve the pressure on the lock ring, then tightened the lock ring back down, only to find exposed stripped (flattened) threads. I tried to clean out the threads, however no luck. Question #1. Has this happened to anyone else?
Question #2. What are my options?
The shock body has damaged threads, and sits where the proper sag would be set. I have been a mechanic for 20 years and have raced for 15 years. I have never seen anything like this. I am so pissed.:banana: :lol: :lol: :lol: :p
Thoughts?

  • davcon

Posted January 22, 2009 - 06:51 PM

#2

Thats scary! I have an 08 also. My sag is ok so I've never touched it. It sounds like your lock ring and tension ring were fused and when you went to relieve the pressure you accidentally forced the lock ring to cross thread the body. Sounds like an unfortunate lesson that may help the rest of us. Sounds like a new shock or try to reassemble with the good threads you have.

  • Phil Hannah

Posted January 22, 2009 - 06:55 PM

#3

My 08 KXF 450 was the same way. Patience and a thread file with care can repair it.

  • Wes Woodin

Posted January 22, 2009 - 06:57 PM

#4

Thats scary! I have an 08 also. My sag is ok so I've never touched it. It sounds like your lock ring and tension ring were fused and when you went to relieve the pressure you accidentally forced the lock ring to cross thread the body. Sounds like an unfortunate lesson that may help the rest of us. Sounds like a new shock or try to reassemble with the good threads you have.

It is unfortunate! It's one of the things that you will never know, and can't predict. What pisses me off is that the bike only has 13 hours. It not like I ragged the bike out.

  • KJ790

Posted January 22, 2009 - 07:30 PM

#5

I had this happen once when I went to adjust my sag, the threads stripped. I cut the ring off, used a thread cutting file to clean up the threads, and bought a new ring. It worked fine for me.

  • Chevelle70SS

Posted January 22, 2009 - 07:39 PM

#6

I had the same thing happen to my brand new 06 YZ250. I needed to back off on the preload alittle to get the correct sag for my wiehgt. I could add more but the rings wouldn't back off. I took the shock off and took it to the dealership and they got it loose and used a thread file to clean it up. It's been fine since then.

Chevelle

  • Wiz636

Posted January 22, 2009 - 07:57 PM

#7

Similar thing happened with my 08 shock. While adjusting the sag everything bound up and that was all she wrote but it was where I needed it so I didn't worry about it. Later on when I sent my shock to DaveJ for service he said he had a hell of a time getting the rings off and had to work on the threads.

  • Kasjok

Posted January 22, 2009 - 11:21 PM

#8

Maybe you could use some giant washers or something like that to put under the pre-load ring, so that the ring can get into threads somewhere higher. Just a thought.

  • Wes Woodin

Posted January 23, 2009 - 05:23 AM

#9

Well, I have to tell you that this whole thing made me sick! I was able to get the rings off by tightening the spring pre load and the lock ring to expose the damaged threads. I went to Home Depot and got a Nicholson 1/2 inch special purpose hobby file set. I used the triangle file and did my best to clean up the threads. With the file, however I had to use the tip of the file where is was more fine, to avoid flattening the threads, due to the angle of the file wasn't as steep as the threads on the shock body. I worked with patience for about an hour and low and behold I could unscrew the rings and got them off:cheers: :banana: WHAT A LEARNING EXPERIENCE! I will say, anyone who tries to replace you spring and the lock ring doesn't spin freely, STOP! and tighten the preload and ring to expose the threads. I kept going and messed up about three threads. If I would have stopped I could have avoided more damage. I hope this thread helps someone else!

  • dvn

Posted January 23, 2009 - 06:06 AM

#10

I have a friend with a very low hour 08 YZ450F that had the same issue. Sounds like a mfg. defect. :banana:

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  • SXP

Posted January 23, 2009 - 07:12 AM

#11

Well, I have to tell you that this whole thing made me sick! I was able to get the rings off by tightening the spring pre load and the lock ring to expose the damaged threads. I went to Home Depot and got a Nicholson 1/2 inch special purpose hobby file set. I used the triangle file and did my best to clean up the threads. With the file, however I had to use the tip of the file where is was more fine, to avoid flattening the threads, due to the angle of the file wasn't as steep as the threads on the shock body. I worked with patience for about an hour and low and behold I could unscrew the rings and got them off:cheers: :banana: WHAT A LEARNING EXPERIENCE! I will say, anyone who tries to replace you spring and the lock ring doesn't spin freely, STOP! and tighten the preload and ring to expose the threads. I kept going and messed up about three threads. If I would have stopped I could have avoided more damage. I hope this thread helps someone else!



I always spray the rings/threads with PB Blaster (or similar) and let it soak for about 30 minutes before attempting to break the locking ring free. Seems to have worked for me.

  • grayracer513

Posted January 23, 2009 - 07:43 AM

#12

Sounds like a mfg. defect. :banana:

Handling error, more likely.

I always spray the rings/threads with PB Blaster (or similar) and let it soak for about 30 minutes before attempting to break the locking ring free. Seems to have worked for me.

This is a good point on two levels. The first is that the threads need to be clean when they are used. Such thread damage is often the result of dirt or rust working in between the two threaded parts and galling the threads when the rotating element is turned. The second is that they will work better, even if damaged or dirty, when they are lubed. Wash the lube away after you finish setting the shock to avoid gathering dust.

  • Wes Woodin

Posted January 23, 2009 - 08:47 AM

#13

Handling error, more likely.

This is a good point on two levels. The first is that the threads need to be clean when they are used. Such thread damage is often the result of dirt or rust working in between the two threaded parts and galling the threads when the rotating element is turned. The second is that they will work better, even if damaged or dirty, when they are lubed. Wash the lube away after you finish setting the shock to avoid gathering dust.

Definitely not a handling error, in all due respect.

  • grayracer513

Posted January 23, 2009 - 09:25 AM

#14

Definitely not a handling error, in all due respect.

So the threads damaged themselves, with no human intervention? It's almost impossible that the threads were cut improperly, or that the designed manufacturing process failed. The threads were either mishandled at some point, or were damaged by foreign material when the ring was turned. Even if this occurred during the original assembly at the plant, it's more an assembly/handling error than a manufacturing defect. I never pointed to you in particular, but since you've had the bike a while, it does seem unlikely that this would be the first time you have adjusted the sag.

  • dvn

Posted January 24, 2009 - 05:47 AM

#15

Handling error, more likely.


Oh, that's right; Yamaha couldn't possibly have a problem! This was a brand new leftover bike that was ridden indoors twice. No dirt or rust on the threads. I have never had a problem with shock body threads. So, you're at the track and you want to adjust your sag. You say to wash and lube the threads first??? Not gonna happen. Give people a little credit, will ya............ Not everyone is a dummy and Yamaha is not perfect.:banana:

  • Beaz

Posted January 24, 2009 - 07:42 AM

#16

My shock is the sameway on my 08 stripped threads
I havent fixed it My sag is ok now

  • Wes Woodin

Posted January 24, 2009 - 06:59 PM

#17

I have been thinking about why the threads could have been damaged on the shock body and the only thing I came up with is this. The lock ring is steel and the preload ring is aluminum. I believe that if the lock ring is overtightened, it would put a lot of pressure on the aluminum ring. With all of the pounding it wallows out the threads, thus creating the problem. Grey, care to comment. There must be a safe torque.

  • grayracer513

Posted January 24, 2009 - 07:23 PM

#18

The spring pressure is, or at least should be, borne by the steel lock ring almost entirely.

Threads have clearance, so when the lock ring is loosened, the spring pushes the adjuster ring up against the lower surface of each thread. In order for the lock ring to "jam" the rings together, it must push the adjuster ring down against the upper thread surfaces, so that the two rings push against each other. Once that's done, the spring pushes up on the adjuster ring, which is no longer bearing on the lower thread surfaces, but against the lock ring, and the lock ring bears the spring load against the bottom of the threads.

If the lock ring were not tight enough, the pair of rings could chuckle up and down as a set, but the spring load would have to come almost completely off the rings, so it doesn't seem likely.

The fact that the lower ring is aluminum makes it more likely to gall the thread surfaces. Be sure to turn the adjuster only when the suspension is fully extended in order to reduce that tendency.

  • Beaz

Posted January 25, 2009 - 05:58 AM

#19

On my old hondas and my friends new 450 as long as his bike was on the stand you could turn the spring with your hands thus turning the collars and
adjusting your sag my yamaha i couldnt do it from the get go when the bike was brand new Also where do i purchase this file for the shock?

  • AZ Thumpdaddy

Posted January 25, 2009 - 06:02 AM

#20

I use the Enzo Tehnica Preload ring instead of the top lock ring. Works great, easy to get to for quick changes.
http://www.enzoracing.com/parts.html





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