The real title of this thread is "Rebuilding a shock with aand pliers", or possibly "How not to rebuild a shock". I have titled it "Rebuilding a shock" for ease of reference if someone wants to look for information on rebuilding shocks in the future. I decided to rebuild the Showa shock from my 1984 ATC480R myself, and what I ended up figuring out is it can be tricky to find diagrams or exploded views of these shocks to aid in servicing and rebuilding. I was pretty much on my own for this, but I ended up getting a lot of advice from Doug Ironchop. I started out by referencing his thread where he is rebuilding an 86 ATC250R shock, which is very similar, but not the same as my 84 shock. To the best of my knowledge, the 83 and 84 shock are different, and the 85-86 shock is a bit different as well, so I think the 83 and 84 shocks are both one year only shocks. The rebuild kit from Schmidty covers 83-86 ATC250R shocks, all of them, but the shocks are slightly different inside.
I began by referencing Doug's thread as I said, then we started texting, then a full blown phone call was necessary. We both agree there is very little information out there to guide you through this process. This is a very loose guide to show how I did this, not how it should be done. I was a brute and you will see claw marks and the
What I'm attempting to share are pointers, things I've learned, and mistakes I made, because I went into this essentially blind. If you can learn from my mistakes, you might be able to rebuild your shock without piercing your finger. This will make a lot more sense if you have a shock apart in front of you.
Taking most of the shock apart seemed elementary to me. Remove the shock spring, I'm not going to tell you how to do that. That's the easiest part of this so if you can't figure that out don't try the rest. Release the nitrogen, drain the oil. On the body of the shock you will see a cap which is the obvious next part that needs to come off. It has small holes in it likely for a spanner, or if you're me, you grab it with Channel-locks. Don't be like me, get a spanner. I turned the cap in the direction you would expect to thread it out, but it's not threaded. It backed out just the same as if it were threaded, but it's not. It's just an interference fit. Removal of this cap will expose the seal head, but you will not be able to remove the retaining circlip just yet. You must first push the seal head gently down into the shock body away from the retainer clip in order to expose the clip so you can pry it out. Don't let it boing across the shop.
Then you'll remove the shaft side by pulling it out of the body, taking the whole seal head out with it. Now your seal head will be exposed for you to see and you will see the nut which holds it in place at the end of the shaft. If the nut has an obvious factory stake staking it to the shaft, you'll know it's factory and has never been rebuilt. If the shaft has been previously ground and the staking looks more like it was done by a guy with a punch or has no staking at all, then you know your shock has been apart before. If the nut is staked, simply grind the staking off until you have a clear path for the nut to be backed off. Once the nut is off, you can start removing the stacks of washers and the valve block looking thing that's on there.
REMEMBER- These shocks have stacks of washers which are a bunch of different sizes and they go in a VERY SPECIFIC ORDER. Doug had a zip tie ready to line them up just as they came off. I'm wicked smaht so I laid everything out on a rag as I removed it. Well what you don't want to be is wicked smaht like me, because I didn't take into account that even though I had everything lined up the way I had removed it, I did not reference which direction each stack of washers was facing when I removed them. I didn't take note of which way the valve looking thing went either. I THINK I got it all right putting it back together, but LEARN from my mistakes, and have a zip tie handy to keep everything in order as it comes off.
After you get the nut, washers, and valve thing off, you're left with a UFO on the shaft, at least on the 84. This UFO is threaded on with the finest threads I have ever seen. I was turning it around and around trying to back it off and it was working, but I couldn't tell at first because it moves so slowly due to the threads being so fine. I then put a puller on it and it didn't budge, so I went back to spinning it and eventually I was able to see that yes, it was indeed backing off. It just takes forever. Yes, these are threads!
After the UFO comes off, you can get the seal head off the shaft. This is where things get cruddy. This farking snap ring is in the seal head so friggin tight, it's unnecessary and ridiculous. There is no way to get behind it on the 84 seal head. Doug's 86 seal head has a relief cut in it so you can get a pick in behind the circlip. I had every pick in my shop on deck, I tried snaking feeler gauges in there, a razor, sewing pins... Nothing could pull this clip away from the walls of the seal head. There is a hole in the head which one would assume goes behind the pin in order to aid in removal, but your assumption would be wrong. The hole is there to aid in removal of the washer that the circlip retains, which is pointless because that washer falls right out as soon as the circlip is removed. This is where things got difficult for me and I was at a loss. It was time for power tools (the Schmidty kit comes with a new circlip).
So I broke out the dremel and directly across from where the break in the circlip is I cut the stupid circlip in half. Even having cut the circlip in half, it still wouldn't come out! I continued with the dremel until I went right through the seal head itself (oops), which I was pretty bent about at first. Then I realized I could use this hole to push the clip out, which worked and was necessary. Both pieces of the clip sprung out under tension even though it had been cut in half. I had to remove one piece then slide the other piece over to the hole I made to push that one out. I looked at how the shock itself works to see what effect this new hole might have on how the shock works, and as far as I can tell it might have a fraction of an effect on bottoming, as in it might bottom slightly easier, but by an unmeasurable amount. Just a tiny, tiny bit.
Here's the hole I made.
This is the existing hole.
This is the carnage from wrastling that stupid circlip.
Once that awful clip is out of the way, the interior seal falls right out. I didn't bother explaining replacement of the seal on the outside of the seal head because that's quite obvious.
While you're reassembling, you will be wrastling some of the circlips. Some go in easy with just your fingers, others are more of a battle. When dealing with circlips, picks, and tiny, sharp screwdrivers, always be aware of which direction you are pointing the tool and how much pressure you have on it. Otherwise you'll end up sticking the screwdriver straight through your finger, like in one side and out the other. Don't do that.
When you're reassembling the shock, it should all be obvious how it goes together after you just took it apart. Another couple tips from experience- Fill the shock itself with shock oil laying it on it's side with the hose removed as well as the hole on the shock body oriented to release any air that might be trying to escape the shock as you fill it. Also, make sure you install the big spring retainer spanner hardware BEFORE you assemble the shock so you don't have to pull your shock apart a second time like I did because I forgot to put those on. The second time I put the shock together, I didn't remove the hose from the shock body and fill the shock body itself back up with oil, I decided to try and just fill it using the reservoir and leaving it attached to the shock. If you fill the shock before you attach the hose and reservoir, it will prime almost immediately. If you try to fill the shock with the reservoir attached, it will work, however it will take far longer to prime. A lot longer, but it works.
I rigged the reservoir to the spring to use as a little pedestal to aid me in filling and bleeding the shock. You are trying to remove air, so hold the shock upright below the reservoir. If you don't understand this part, you shouldn't be trying this. Of course the first time I rigged the the reservoir to the spring it worked perfect, and I could move the reservoir around the bench or to the edge of the bench so I could hold the shock below it for priming. Unfortunately on my second attempt, since I had to take mine apart twice, I couldn't get the stupid spring/reservoir deal to stay upright anymore. Learn from my mistakes, strap your reservoir once and if it works don't frig with it! The second time I had to involve vise grips.
I only have two questions before I get this shock charged tomorrow, and hopefully someone here might be able to help. I have to do some research and see if I can figure this first one out. I installed the bladder back into the reservoir and if you've ever seen these bladders, you know they maintain their "expanded" shape, or rather the shape of the reservoir itself. What I don't know is, do I install the bladder scrunched down with as little air inside of it as possible, or do I just install it as it looks? Doug suggested it should probably be scrunched down in order to be more nitrogen then anything else once filled, which makes sense in my mind, but I just don't know.
Also, this adjustment is frozen. It doesn't want to move in either direction and I don't know what to do about it.
So it's all together right now, I just might have to take it apart to scrunch the bladder if it turns out I'm supposed to do that. As it feels in my hands, it has plenty of resistance on compression, it feels right, but the rebound goes back much easier. I don't know if I did something wrong, I don't think so. I've never done this so that could be completely normal. We'll have to see once it's completed and charged.
Anyhoo thanks for looking and thank you to Doug for all the guidance. I hope this can help people in the future.
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Originally Posted by fabiodriven
