Brakecaliper Orings problem, need advise please

[kiteman]

Following the post I put up in feb 2012 about doing a brake caliper refurb, see below.
http://www.clubvr4.com/forum/showthr...ghlight=brakes

Back then I couldn't get the Oring seals from the Irish K-sport agent, so I emailed K-sport UK. They didn't even bother to reply to my email request, so I sourced Orings from a seals supplier in Dublin. I brought the pistons and calipers with me, when I made the purchase so as to get the correct size and ensure they were suitable for use with brake fluid.
After reassembly I noticed the brake pedal always felt ever so slightly spongey. After a couple of weeks I took off the calipers and noted all the pistons were weeping brake fluid..
Anyhow, today I removed the new Orings I'd fitted and noticed they appeared to be squared in shape instead of the original circular shape.
Now comes the dilemma, I have an assorted box of metric Orings, the type you could buy for about €25 or so. It has the size required to replace the ones I fitted last feb. So I did replaced them with the cheap and cheerful ones, and now have a good solid brake pedal.
Now for the advice I'm after, Considering the Orings fitted today are the cheap and cheerful kind, can anyone give advice on what effect the brake fluid will have on them in the long term.
Thanks for reading.

[adaxo]

Put one oring in a jar with brake fluid and observe what's happen for few days/weeks, if it stay 'strong' you the winner.

[kiteman]

Put one oring in a jar with brake fluid and observe what's happen for few days/weeks, if it stay 'strong' you the winner.

Now theres something I didn't think of doing. I just popped one into ajar of brake fluid now, and will watch it with interest, to say the least.
Thanks Adam

[alan]

adaxo is right, the rubber industry refer to this as a soak test,or dip test cheap o rings may appear to be sealing but in reality they could be swelling,they will work for a while then fail very quickly.like most things you pay for what you get, cheap commercial o rings contain more fillers than the rubber compounds while a better quality one contains fewer fillers,it could be that yr supplyer looked to see that compound x worked with brake fluid but supplied a really cheap version of it which often happens with these guys im afraid to say.its the rubber that gives the resilience you need,( im using rubber as a generic term to cover all the compounds).

[kiteman]

adaxo is right, the rubber industry refer to this as a soak test,or dip test cheap o rings may appear to be sealing but in reality they could be swelling,they will work for a while then fail very quickly.like most things you pay for what you get, cheap commercial o rings contain more fillers than the rubber compounds while a better quality one contains fewer fillers,it could be that yr supplyer looked to see that compound x worked with brake fluid but supplied a really cheap version of it which often happens with these guys im afraid to say.its the rubber that gives the resilience you need,( im using rubber as a generic term to cover all the compounds).

Thanks for the advice Alan, and I understand what you're saying.
However I paid a lot of money (nearly €100) to the the seal company for 56 Orings in total.
I was advised at the time they were the best available, and the quality far exceeded that required for use with brake fluid.
No doubt I'll be paying them a visit next monday.

[CANDEE]

Tommy, do you have a local AP Racing supplier?

They should be able to supply them, as the AP's are compatible with the K-Sports/D2's(same thing).

[alan]

what brake fluid do you have dot3 / 4 a common mistake is to use viton in these aplications they contain alcohol and alcohol attacks flurocarbons (viton ) non petrolium based is useually best suited by an ethelene propolene compound ( e p )it depends on yr brake fluid really , if you do a search on here http://www.efunda.com/DesignStandard...ke%20Fluid#mat
you will see a fluid compatability guide, also dupont kalrez has a brilliant compatability guide though you may have to register to view

[kiteman]

Tommy, do you have a local AP Racing supplier?

They should be able to supply them, as the AP's are compatible with the K-Sports/D2's(same thing).

Jeremy, see the attached link showing we dont have an AP agent in Ireland. There are a few distributors who will sell complete brake kits, but for seals they will direct me to the company i bought the Orings from previously.
Thanks for the suggestion just the same.
Tommie

[kiteman]

Put one oring in a jar with brake fluid and observe what's happen for few days/weeks, if it stay 'strong' you the winner.
__________________________________________________ _____________________________________________

I just removed the cheapo Oring from the jar of brake fluid and its as solid as when I put it there a week ago.
Thanks again Adam.
__________________________________________________ _____________________________________

Alan, your link to the various Orings and their compatability was very interesting indeed.

I use 5.1 fully synthetic brake fluid, castrol SRF actually.

So one week after fitting the cheap and cheerfuln Orings, I still have a rock solid brake pedal.
Thanks again guys.
Tommie

[alan]

glad to have been of service tommie

[kiteman]

Rep sent all round guys, thanks again.

[adaxo]

Rep sent all round guys, thanks again.

hmmm