shock oil

[Nails]

I changed the shock oil once before, and it was only a moderate hassle. But this time I can't get the fork oil either out or in. I'm trying to follow the manual procedure to fill the shocks with oil and then pour out the "air space volume".

I hung the shocks upside down for a couple days, but they didn't seem to drain right. (I was draining them into a pan that already had some oil in it, so couldn't tell how much really drained.) With minor percussion, they drained a few more drops of oil.

Then I could only get a little oil back in. I tried pumping the shocks, but just a little (don't want to knock it off the centerstand). The photo has just one shock on the swingarm (rag around it because I'm making a mess) with no air lines attached. I pumped that 2X4 to move the swingarm about 1/2"; and then left it partially compressed (the concrete bricks), but still could only add a ml or less of oil at a time.

Now I'm trying to drain the "air space" oil back out (upside down again), but it's coming out just a drop at a time.

I think, to do this right, I'll need to compress the shocks a lot, and then add oil as I extend them. I have spring compressors for struts (yes, I hate using them), but I bet I could put a long bolt through each shock eye and then put a compressor on each end of the bolts. (Yes, I'd wrap a safety chain, somehow.)

Right now, I have no idea how much oil is really in there. Suggestions?

[edit: I've slept a few times since the last time I did this. But I think they drained right because the oil was like water; and I got oil back in using a blunt needle that fit through that little hole in the air line fitting.]

[cushman eagle]

Nail,when I changed my shock oil,I removed them,and made a devise to pump them upside down on my workbench .After I could get no more oil out,I was able to get the right amount of oil back in.
It was a couple years after that,the left one started leaking,so I put Progressive 416s on,but they are too stiff ,and unless we are loaded for a trip ride too hard.I wished I could have gotten the originals rebuilt.

[HMB Don]

Nails
You have to remove the shocks. The shock with the two openings drains fast, the other takes time, so lots of patience. I use Amsoil for forks, mixed 5w % 10w trying to get a 7 1/2 w oil.

235 cc is what each of my shocks held when I drained from my shocks. That is the amount I filled them with.

[Nails]

so lots of patience.

Thanks. That worked for me last time, but I've waited two days already -- still waiting, actually. They aren't draining at all, even after I put some oil in. But I'm having trouble this time getting the oil back in, too. I'll visit with a vet friend to see about getting a syringe and needle. And start building a "device".

I wish I never messed with it. Last time, I old oil was just disgusting, but this time it came back looking great. I guess I got all that pus-like substance out last time. I had used ATF to clean it out.

I'm trying to put Motul 10wt in, just because I already have it on the shelf.

[SgtSlag]

HMB Don,

Dexron 6 ATF is 8 weight, stable viscosity across its operating temperature range, highly detergent, fully synthetic, available everywhere, and reasonably priced. 7.5 or 8.0 -- negligible difference in viscosity. Cheers!

[GrandpaDenny]

Fork oil specified is 10W-20 (unobtainable). Being in a hot climate, Nails may want to consider going with 20wt. or mixing to 15w. Fork oils do not contain detergents, and AFAIK one is not supposed to run a detergent-containing oil in forks (or shocks, for that matter).

Just my unscientific opinion.

Now, as to my own front forks... I'm running 10 weight, and what pass for regular bumps around here kick the handlebars up something fierce. NOTHING like they did before I put in the Progressive springs, however. What I wonder is would I want to go with a heavier or lighter fork oil to smooth out the ride?

[HMB Don]

Lighter, and play with the amount of oil in the fork legs. I have 5 weight in both 1200 and 1700. On the 1700 I filled the fork legs to factory specs, they were to stiff. So I took out 5 mm of oil in each leg, and it softened the ride.

[Nails]

I hesitate to call this a success, but here's the weirdness I went through to get the shock oil out. It took me a couple hours to design and build this abortion ... and then just a couple minutes to pump all the oil out of both shocks.

After about four days, most of the oil had drained out by gravity -- maybe 20-30 ml was still stuck in there. The problem was that I just didn't know. With pumping, I got a satisfying wheeze that all really was out.

This thing also holds the shock right-side up for filling.

The manual calls for 230mls of oil, which should leave a 160ml headspace. Tomorrow, I'll swing by that friend's vet clinic -- she was pretty sure she could find a syringe with a needle that'll fit in the tiny hole in the air fitting. Last time, I squirted in that 230 ml, which seemed to work accurately. I just had to refill the syringe a bunch of times.

The ATF did a great job cleaning out the skanky oil that was in there; and I'm not screwing with this again anytime soon.

[cushman eagle]

I hesitate to call this a success, but here's the weirdness I went through to get the shock oil out. It took me a couple hours to design and build this abortion ... and then just a couple minutes to pump all the oil out of both shocks.

empty shock.jpg

After about four days, most of the oil had drained out by gravity -- maybe 20-30 ml was still stuck in there. The problem was that I just didn't know. With pumping, I got a satisfying wheeze that all really was out.

This thing also holds the shock right-side up for filling.

fill shock.jpg

The manual calls for 230mls of oil, which should leave a 160ml headspace. Tomorrow, I'll swing by that friend's vet clinic -- she was pretty sure she could find a syringe with a needle that'll fit in the tiny hole in the air fitting. Last time, I squirted in that 230 ml, which seemed to work accurately. I just had to refill the syringe a bunch of times.

The ATF did a great job cleaning out the skanky oil that was in there; and I'm not screwing with this again anytime soon.

Nails,your "shock pumper" looks a little more professional than mine

[cranky]

.. just lazy... waiting forum to die and put new ones on....
at my age, I just might win!!! GBG

[SgtSlag]

Dexron ATF is a an old mechanic's trick for dissolving deposits within an engine (alternative to using SeaFoam); note that Ford Type F, and other brands/types of ATF, do not have the same properties, and they were not used by bike factories (see below). Dexron ATF was added to the crankcase, by auto mechanics, for minutes, or a few hundred miles, before an oil change, to clean the engine, internally.

Dexron ATF is not the same as detergent engine oil. Detergent engine oils work by suspending particulates within the oil, once the oil reaches 180 F, or higher; these particulates are then captured by the filter media. Until the oil reaches 180 F, the particulates sink to the bottom of the engine chambers.

The Dexron ATF detergent basically acts as a solvent, liquifying varnish deposits within the engine, or the fork tubes. With Dexron ATF as fork oil, there is no need to use mineral spirits, or other solvents, to remove deposits within the fork assemblies. That is why I like using it, and because it is 8 Weight (most Fork Oils come in the 5-15 range, so 8 is about in the middle), and many bike factories used and recommended it to owners, as fork oil. It has multiple OEM stamps of approval, dating back to the 1970's. Cheers!

[Nails]

Okay, S came through with a 60ml syringe and a 5.5" urinary catheter for cats. Seriously.

It fits in the tiny hole in the shock air fitting (loose enough for air to come out around it), so I should be able to inject oil directly into the shock. But I just brought the oil into the house and it's still a little below freezing -- I couldn't draw much oil into the syringe like that. I'm hoping I'll be able to get oil through the catheter once it's warmed a bit. And I can cut it in half or shorter to limit the length of that super small-diameter tubing. (S says she can get bloody body-temp pisss through it just fine.)

I'll leave you with that visual.

[Nails]

I got the shocks reinstalled. The catheter worked pretty good, but honestly this was a PITA. I have no idea why because last time I just drained and refilled the shocks without any drama, just like the manual says. But this time, the oil wouldn't drain out, and it would drain in either. I used my pump gizmo both ways, and still spilled oil that I needed to account for.

The oil from my first change a couple years ago was super skanky (looked like pus), so I used ATF to clean it up. (The ATF performed well, as Sarg has said.) This time, I wanted to get all the AFT and whatever dissolved into it back out. (I didn't see any pus this time, at least.) I wanted to start with totally empty shocks, as opposed to the manual which starts with totally full shocks.

I think the process described in the manual is good except you'll probably end up with a fair amount of old oil carrying over -- hard to know just how much. I'd recommend measuring how much drains out, as Don did. (He got back 5ml more than was supposed to be in there in the first place; and I bet there was more than that stuck in there -- who knows?) But if you fill the shocks and then drain back out the headspace, as described in the manual, you should end up with about the right total amount of oil left in each shock. But it also can be hard to know whether the shocks got totally full (I couldn't tell), so you might end up with way too little oil left in there. I recommend being careful ... and patient, just like Don said.

Anyway, I ended up with dang close to 230ml of totally fresh oil in each shock, and I'm not messing with this again for a long time.

I think all this hassle is better than having shocks that don't even allow changing the oil, because the oil is what wears out first -- like forks. And the stock XII shocks perform really well -- until they leak. God forbid.