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Question 1983 IT 250 Rear shock bushing and dampening adjuster

  • SWB
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Three issues I'm having.
First issue: The rear shock top bushing is shot. It is nearly impossible to remove the old one and where can I find a new one?? ( Yamaha says not available but maybe available throughout eBay?) I did order a ALL BALLS top shock bearing for the YZ250 because it looked to be the same exact shock but I'm thinking now that it will not fit so hence I"m on the hunt for a NOS bushing.
Second issue: The dampening adjuster looks to have been over turned and now it won't move at all. Anyone know how these come apart to be reset if that is possible??
Third issue:  Any suggestions on how I can get the shock shaft apart to install the new shock seal?? It looks as though the mounting head will screw off the shaft but I'LL bet that won't be an easy task!  ( ALL BALLS has the proper one again for the YZ 250 model but this is the correct fit for the IT model Thankfully!!)

Thanks for any advice from the members..  Great bunch of people on here always looking to help.
10 Dec 2021 16:10 #1

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Your best bet is to send it to Sage Suspension or Racetech and have them rebuild it. There are snap rings that hold the seal head in, and from memory one is below the head and one above. The damping adjuster controls the rebound and there is a long rod inside the hollow shaft that gets stuck from corrosion and won't slide like it should. It all comes apart once you get the seal head and guts out. 

I did one years ago. If you don't have the proper tools or a way to recharge it, send it out.
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10 Dec 2021 19:02 #2

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Before you attempt any dismantling let the gas pressure off from the end valve in the reservoir first. If original it'll require a hypodermic syringe needle with a drip of oil on it & down the hole & have to push it through solid rubber. Only about 6mm diameter rubber but solid all the same. You'll soon know when its through as 200lbs of nitrogen will shoot out--slowly through the needle. If the adjuster is stuck its possible [i've seen it] that someone has turned it right down then forced it one more. So could 'gently' try to wind it back. You'll know within two clicks if you're heading back away. Trouble 'is' bottoming it down hard can jam the damper needle in the seat. I've had luck once at work backing it away then banging the end on an alloy block. That popped it back with gas pressure then taking over. Second one i tried i D shaped the rubber-steel bush from smacking it down but still worked. Center mount hole was ok though. Specialist job to be honest. Reservoir has a small philips head screw stopping you getting the needle in there.
Everything Scootern29 said above.
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11 Dec 2021 02:48 #3

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A quick update: I was able to bleed off the nitrogen and tear down the shock. Everything seems to be in good condition and I have installed a new Seal head ( ALL BALLS ). I'm still concerned about the stuck pushrod so I'll try tapping on the end of the shaft to see if that frees it up but if not I guess I'll take it apart again and deal with the pushrod now rather than complete the assembly and find that it doesn't work. My plan right now is to recharge it with my air compressor to test that everything function properly and then I will bleed off that air and take it to a local shop for the nitrogen fill. I had thought of retro fitting a Shrader valve in place of the rubber plug and needle set up but I might just leave well enough alone and stick with the needle filler...    Thanks for all the great advice so far. 
11 Dec 2021 18:53 #4

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The pushrod is a tapered needle that controls the damping. If it doesn't slide easily or is froze it doesn't work. I ended up getting the rod out and polishing it. I forget what it took to get the metering rod out.
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11 Dec 2021 19:32 #5

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Ok, read if ya like & ignore if doesn't make sense or you're way ahead of me. Just my thoughts.

The needle should be separate from the rod & doesn't come out but moves within a small range to change the damping. So what i'd do--or have done a lifetime ago-- is push on the end of the needle. Problem 'is' though, if its stuck from being force seated by over adjusting then that's an easy release--but if the long rod is corroded in--bigger problem!!. Rod is made out of some trick alloy by memory. But not trick enough to stop corrosion. If the end is still screwed on you'll need to remove it to get at the rod that hopefully will move up pushing the needle its against, then try to work it. Maybe push it down then push the needle to bring it back a few times until you feel it will pull out to clean & grease it. I have some genuine alloy blocks to clamp the shaft in the vice but need to use a strip of emery in each block or it'll slip as they are tight tight. Adjuster is just a pin like a crank roller crossways covered by rubber covers on the adjuster ring. Got a feeling you're way ahead of me!!. But anyway--piston in the reservoir has to be set to a measurement. without knowing the measurement i'd probably set the bottom edge [not bottom center as i'm thinking it'll be stepped], bottom edge about 1/3 up from the bottom of its travel. Trouble 'is' you'll need to remove the valve assembly to measure it.

Maybe i'm getting carried away & if the end is out of the reservoir & gas piston looks about safe then fill that up then pour some in the shock body & fit the reservoir hose while oil is running out. Then fit the main rod/piston assembly slowly & i'd push it to the bottom then cap it with the top bush & let the gas push it back up. I've gassed up any mono's in my junk bike stable with the compressor which in theory goes to about 120psi, about half recommended i'm guessing but all worked great.

That reminds me. I've got an IT shock that looked pretty sad & hose had burst or caused by damage. I just screwed a valve somehow into the hose fitting thread of the main body & gassed it up. That was years ago & give it a push just to see when passing it in the farm shed & still holding pressure. Is gas oil mix of course like that, so end up with a Nothing area at top or bottom depending which way the shock runs. Nothing area for rod displacement without the reservoir. Just thought i might use it oneday on something if i'm desperate.
11 Dec 2021 23:36 #6

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All good information here guys. Thanks very much. My plan now is take it back apart and make sure the pushrod works freely. 
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12 Dec 2021 07:04 #7

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So I finally got back to the rear shock rebuild and just as I suspected there is a problem with the tapered end of the dampening meter rod. I did get the long dampening rod out after some trial and error. But it seems as though the tapered end of the rod is and was stuck for some time. It looks as though someone has tried to use a punch to drive it back up into the shaft and it may be flared on the end and stuck very solidly in the shaft. I'm assuming that the shaft and the rod are tapered to regulate the dampening. Not sure how or if I can get the damaged rod out and if it has damaged the tapering inside the shaft?? Looks like I might be in the market for a different shock if this is beyond repair.  Anyone ever had to deal with this situation??  
12 Jan 2022 15:22 #8

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