TOPIC:

I seem to be getting through quite a few recently (rebuilding shocks), so does anyone know what size the Tamiya shock o-rings are? I'm hoping to buy some in bulk

You mean the black and red ones that are in the bottom part of the damper?

these are the most common ones that are used with the'older' damper

red - Tamiya - 50597 id 3 od 6
black - Tamiya - 84195 id 3 od 6

in my opinion the red are a little softer

then there is the TRF versions (id 3 od 6)
o ring blue Tamiya - 42137
x ring for mineral oil Tamiya - 42215
x ring for silicon oil Tamiya - 42214

and then your shaft guides (not sure if they fit HiCap damper)
TRF id 3 od 6,5 th 2 - Tamiya - 84292

I would suggest using the red o-rings instead of the black ones if you can, in my experience the black ones have more resistance to suspension movement and stick to the inner shock shaft when left for a while. What do people think of the blue TRF o-rings?

ah, this is why I was asking - I was finding contradictory information & wanted a bit of a "sanity check" with what I'd found ...

As far as I can work out, they are 3mm ID, 2mm section - so 7mm OD - but the gaps they fit into in the shocks are 6mm.

I agree that the red o-rings are softer/less grabby - but I wonder about durability. On a lot of dampers there's space for two, so I have been putting a black one on the outside & a red one on the inside in the hope that I'm getting the best blend of sealing & durability ...

Now I've run out & was looking to save a few quid on Tamiya prices - I found a seller on eBay offering 50 packs of 2mm section, 3mm ID, 7mm OD black nitrile rubber O-rings for 2.71 GBP, posted

7 od will be a tight fit, the shaft is 3, so with a id of 6 on the damper you would have to compress the ring section diam .5, if it runs dry that will sure cause some friction, so i would advice using some lubrication on your shaft(s)o-rings.

quote 'It ensures a smooth sliding action'

waterbok wrote:

...

quote 'It ensures a smooth sliding action'

Kind of like a Barry White CD then ?

A trick I picked up from Lars (I think it was in his 959 build) is to lubricate the damper shaft before you put it through the O-rings as well so there's less chance of damaging them. Mostly meant as a general remark...

Edou wrote:

A trick I picked up from Lars (I think it was in his 959 build) is to lubricate the damper shaft before you put it through the O-rings as well so there's less chance of damaging them. Mostly meant as a general remark...

Thanks

That tip is actually in some Tamiya manuals ... but I couldn't tell you which ones, or whether it came in at a particular point, or whether it comes & goes ...

The lubrication of the shaft before fitting O-rings is to get lube in there in the first place, as once it's all together & the O-rings are doing their job, no lube will be able to get between them to where it's needed (Making easier to fit or preventing damage is just a useful side-effect).
If you're planning to use industrial O-rings (That's what they'll most likely be if they're on ebay & cheap, in bulk), be aware that they're likely to be either EPDM or FPM/viton, & will be relatively hard, whereas I'm pretty sure the soft red Tamiya ones are silicone rubber. You also have to watch O-ring material type with oil type - they'll be ok with silicone oil, but mineral oil will go for 1-type of O-ring, & I can't remember which.... (Read up on red fluid vs green LHM in Citroen DSs, & the agro it caused - LHM is similar to motor oil, red fluid is similar to brake fluid & the fluids/seals aren't compatible).
Also bear in mind that EPDM or FPM are going to be harder than silicone, & will most likely give you sealing troubles, or maybe be too tight & cause friction.
Of course, it may also go in your favour, but bear it in mind....

The ones I bought were described as "70 shore nitrile" ... I'm not sure how hard the red or black Tamiya O-rings are.