Restoring Optima Mid Custom

[Holdinghausen]

I did fear something like what you are saying...
Is it possible still to save the rear ones you think?

[Guccismith]

I did fear something like what you are saying...
Is it possible still to save the rear ones you think?

Of course! Just fill them with shock oil, that's a good start. Then compress and decompress multiple times and see if any oil accumulate in the spring retainer at the bottom.

As I mentioned previously you can change the o-rings and polish the shafts and they will be good as new

We are talking Kyosho quality here.

[Holdinghausen]

Thanks Guccismith!

Future looks bright
I will soon start takeing the car to pieces.
Even just cleaning every piece will be fun
I'll be back with loads of questions for sure.

Cheers!

[Holdinghausen]

Hmm...What oil should I use in my shocks?
Theres a jungle out there...

Thanks

[Coelacanth]

Hmm...What oil should I use in my shocks?

Silicone oil is what you want, and there's plenty of brands to choose from: Kyosho, Losi, Associated, Tamiya...it doesn't matter which. I would buy a few weights if you were going to work on more cars; 20W, 25W, 30W and maybe 35W. For the Optima series, depending on your choice of piston holes, somewhere between 25W and 30W seems to work great for me, when not overfilled. When the shocks are filled and rebuilt but no springs installed yet, when you compress the shock shafts, you want the shock end to resist a little and decompress on its own, not stay plunged inside the shock. If it's too hard to compress, then it's a bit overfilled. When all shocks are mounted on the car, I like the car to come back up to full shock extension when you press down on the car and let go; adjust the spring perches for this. Next, when you drop the car from a foot or so, you want to make sure there's no bounce. It should stay planted when dropped. If it bounces, the oil is too heavy or the piston holes are too small...and the springs may possibly be too hard, too. Getting all those things adjusted can be a bit of a balancing act, but very rewarding when it's done right.

[Holdinghausen]

Thank you Coelacanth!

This was a fantastic explanation! Wonderful!
I will start by checking/changing oil, before I try to take them apart... Newbie

Cheers!

[Holdinghausen]

Hi dudes and dudettes

If I am to try to restore the shocks, I guess I will have to get hold of
some certain o-rings and stuff. And hints/tips?

Cheers!

[Guccismith]

Hi dudes and dudettes

If I am to try to restore the shocks, I guess I will have to get hold of
some certain o-rings and stuff. And hints/tips?

Cheers!

Kyosho part# ORG03 are exactly the same ones that sit in those shocks (2 pcs / shock body) -> https://rc.kyosho.com/en/org03.html

Readily available.

Did you also check the health of the diaphragm in the top cap? Mine were actually OK (surprisingly).

Replacement diaphragms then I ordered the corresponding part for the Schumacher small bore shocks part# U4362 -> https://www.racing-cars.com/1-10th-touring/mi6evo/small-bore-diaphragm-pk4-u4362

Looks the same as the originals.

Enjoy!

[Holdinghausen]

That was a very helpful answer
Thank you!
I have not opened them yet, I will soon though.

Cheers!

[Holdinghausen]

Hi again.
Not much happening here, waiting for parts...
Anyone got an idea about what oil to pour into these old original shocks?
I got a feeling our modern oils are not what they need...

Cheers!

[Coelacanth]

Anyone got an idea about what oil to pour into these old original shocks?
I got a feeling our modern oils are not what they need...

I answered that already with my previous post. Silicone oil is what you want, not motor oil.

[Holdinghausen]

Sorry I forgot, AND did read somewhere that these old shocks needs
a totally different oil/weight than what is used today.
I read your answer again now. I will trust you ofcourse. Sorry.
Bought a set of six different weights from LOSI.

Cheers!

[Coelacanth]

The weight of shock oil you use depends on other factors in the suspension, not age of the car. Silicone shock oil, regardless of age or brand, is what you want because it won't degrade your O-rings and plastic internals. Any RC car shock oil is probably silicone. Your springs, pistons and your desired damping ability all play a role in how your shocks absorb bumps, along with shock oil weight. If you do a 1-foot drop test, you want your shocks to absorb the full drop without bottoming out or bouncing back up. With older cars that don't have adjustments for droop, you'll want the springs adjusted so when the car is pressed down, it springs back to nearly full uncompressed shock height.

Thicker oil increases the damping ability, as will shock pistons with smaller holes in the rings. If your car bounces when dropped, use piston rings with bigger holes and/or a thinner oil. If it bottoms out when dropped from a foot, you need thicker oil or pistons with smaller holes in the rings. If the car doesn't return to ride height after being pushed down, you need to adjust your spring collars to give the springs more tension, and if that isn't enough, you need stronger springs.

I find that 25W to 30W is near the sweet spot for Kyosho Gold shocks.

[Holdinghausen]

Thank you again Coelacanth!

When I look around it seems common among many drivers that they want a heavier oil up front, than in the rear shocks.
Guess I will have to try
The buggy-bug seems to have bitten me HARD
Ended up buying also a Xray XB4 to have something modern along with the vintage car.
What have I done Lol
I will start with restoring this old Koyosho for sure...

Cheers!