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I've bought myself some platinum shocks for an optima mid I plan on bringing back from the dead and have refilled them using some 40wt oil. I'm finding that they feel like they are sticking a bit, is the 40wt too thick or is it a common issue with these shocks. I'm waiting on some parts for the optima but will post some pics when I get started if any one is interested. Cheers in advance.

mrfoski wrote:I've bought myself some platinum shocks for an optima mid I plan on bringing back from the dead and have refilled them using some 40wt oil. I'm finding that they feel like they are sticking a bit, is the 40wt too thick or is it a common issue with these shocks. I'm waiting on some parts for the optima but will post some pics when I get started if any one is interested. Cheers in advance.

Sticking -> have you try new o-rings?

Paul

I don't think I'd go higher than 35-weight, I use 30 or 35 in my Gold shocks, which are essentially the same. I'm assuming you're using RC car shock oil and not 1:1 car motor oil.

Are the shocks sticking only after you put the oil in? Then it's most likely the oil. If they're sticking when empty, it's something with the shock parts themselves.

oil doesn't create stiction... if it sticks, then it's mechanical what the above info says is that they were "refilled" only... 20 y.o. o-rings sure stick

Paul

Platinum shocks are rather complicated and employ an internal dampening adjustment; so there are lots of places for things to gum up over 20+ years . See the attached pics for a (somewhat fuzzy) exploded view and shock adjustment instructions. I would recommend completely disassembling, cleaning and replacing the two larger shaft seal o-rings (if possible). Take great care with the two tiny o-rings that seal the inner to outer shaft; they are almost impossible to replace.

40wt oil should not be too thick, but the internal adjustment may be set too high which could effectively make the dampening quite hard.

Lonestar wrote:oil doesn't create stiction... if it sticks, then it's mechanical what the above info says is that they were "refilled" only... 20 y.o. o-rings sure stick

My troubleshooting advice is to help determine which direction to look for a problem. Obviously one wouldn't expect oil to cause something to stick, but I also wouldn't expect loose, worn out O-rings to stick--if anything, they'd leak. Lots of mechanical things can cause sticking, including scratched or abraded piston shafts or slightly bent shafts, and I would agree that hardened O-rings would too. I should mention also that as long as shocks haven't been stored completely dry, I've had 20-year-old shocks still have nice, pliable O-rings still working perfectly--as they're constantly lubed by the presence of oil in the shocks.

I'm going to go with bent shafts. That or flashing on the piston.

Coelacanth wrote:

Lonestar wrote:oil doesn't create stiction... if it sticks, then it's mechanical what the above info says is that they were "refilled" only... 20 y.o. o-rings sure stick

My troubleshooting advice is to help determine which direction to look for a problem. Obviously one wouldn't expect oil to cause something to stick, but I also wouldn't expect loose, worn out O-rings to stick--if anything, they'd leak. Lots of mechanical things can cause sticking, including scratched or abraded piston shafts or slightly bent shafts, and I would agree that hardened O-rings would too. I should mention also that as long as shocks haven't been stored completely dry, I've had 20-year-old shocks still have nice, pliable O-rings still working perfectly--as they're constantly lubed by the presence of oil in the shocks.

Silicon o-rings swell in silicon oil... stiction

Paul

So you're saying they're doing what they're intended to do to prevent leaking?

P.S. You previously said oil doesn't create stiction... Anyway, nobody really knows what the problem is, we're just giving ideas to help his troubleshooting.

I've had mine since the late 80's, ('bought Turbo Ultima new in '88) and I've always thought they were a bit stiff compared to the golds or any other brand I've seen.

I think the're OK on a heavier car with a slightly lighter shock oil or spring swap. I've never rebuilt mine, nor have I had any obvious problems either.

Thanks for all of the suggestions, they are all very helpful.
I've 'now' pulled the shocks apart and checked the shafts and the inside of the shocks and they look brand new. The "O" rings look to be soft and intact (better than some of my other cars). In general, the shocks look excellent. The oil is Associated shock oil so i'm assuming it's not the type of oil, but they don't seem to stick when they are empty.
I should probably clarify that when I say 'sticking' I meen that there is some resistance at the start of the compression no matter what possition they started in. There is no resistance on the way back out.
It may be the swelling of the O ring like Lonestar mentioned, but what can be done to stop that?

maybe not the right amount of oil? I don't remember if there is a bleeding procedure, I think I may have the original instructions, either for an option house set I bought a long time ago, or as part of the instructions for a Turbo Mid SE, or both.

Sounds like o-ring swell to me. There really isnt anything you can do to curb it either. There is the possibillity that you can rearange or substitute some of the spacers in the o-ring pack to reduce the compression on o-rings themselves. One thing I always recommend when building shocks is to also use a o-ring lube such as AE Green Slime, or any other reputable motocross shock o-ring lube. Makes a huge difference, and does help to protect the o-rings from the shock oil a little. On my race buggies, I rebuild/replace o-rings on a consistant basis because they swell quite easily. I would say get a new set (if you can find them) and check the sizes side by side to see if there is a noticeable difference. -Jeff

When filling the shocks with oil, be sure not to fill them too much, and also to push in the piston a little bit before tightening the top down. I've overfilled the shocks by a drop or two too much, and the pistons fully extended out, and once the top was screwed down tight, they wouldn't even push into the shock bodies.

EDIT: If you roll the shafts on a table, do they roll smoothly, or do they have a wobble? Just to confirm the shafts are fine.

mugenbulldog wrote:maybe not the right amount of oil? I don't remember if there is a bleeding procedure, I think I may have the original instructions, either for an option house set I bought a long time ago, or as part of the instructions for a Turbo Mid SE, or both.

With Gold shocks, you insert little rubber diaphrams into the tops of the shock bodies, with the round ends facing down--towards the oil & shock bodies. The round end pushes out excess oil before you screw on the caps. That's all there is to it, and you won't find many shocks that perform better than Goldies, when dialed in right. Smooth as silk!