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 Post subject: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Wed Sep 13, 2017 10:29 pm 
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I'm sure this will boil down to application, but what material would be rated best for brake caliper pistons?
Aluminum has the weight advantage, but stainless conducts less than ten times the amount of heat. That means cooler brake fluid. Stainless is also more corrosion resistant, expands less, and wears better. Does the weight advantage trump all the pros of stainless?
Regards....
Flattop


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Fri Sep 15, 2017 3:38 am 
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Joined: Fri Jun 24, 2016 2:38 am
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Location: New Zealand
So ideally you want the light weight of aluminium but not the inherent thermal conductivity.

What you really want then is Titanium, one of the poorest conducting metals.
Issues are: Low volume production costs, and machinability in terms of ultimate surface finish. Coating them with a PVD of TiN will bring a ground finish down to a mirror finish.

I could do a run if we could get say orders for 10 sets of P08s together.

**May not be legal in many racing classes**


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Fri Sep 15, 2017 9:45 am 
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Hey nick...
Agreed, titanium would be King. I was just wondering if less brake fade would be more beneficial than less weight(SS vs Ally) during long distance racing or heavy braking short tracks. I did entertain the idea of making some Ti's, but for the four piston calipers. Then I found out there is more to it (coating) than just spinning up some pucks in the lathe. The thought of doing P08 pistons never really crossed my mind, but it's an interesting idea. Any ball park costs?
Regards...
Flattop


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Fri Sep 15, 2017 2:01 pm 
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Joined: Fri Oct 15, 2010 12:20 pm
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Location: Vermont, USA
Hi Flattop, are you getting fluid heat fade with a premium race type fluid like Brembo's? How are your pads and rotors?
Bill
http://moto.brembo.com/en/media/product/brake_fluid_brembo_racing


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Fri Sep 15, 2017 3:21 pm 
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Hey pantah good...
While on the hunt for 40mm 4 piston calipers, I found they are available with either stainless or aluminium pistons. That's when I began to question which one is a better option. I will admit that all of the anti-aluminium info I read came from car sites, mainly Corvette. They seem to prefer the SS and Ti because of lower heat transfer. I did not know about the Brembo high performance fluids. Could be all that's needed.
Regards...
Flattop


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Fri Sep 15, 2017 6:58 pm 
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Joined: Fri Oct 15, 2010 12:20 pm
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Location: Vermont, USA
I'm still curious if you're dealing with over heating brake fluid? If you're running F05's, I'll guess they would get hotter than a better braking 4-piston caliper would. But I'm thinking a Pantah based racer would be hard pressed to over heat fresh normal brake fluid, unless there was some component miss-match. When my buddy Robbie Nigl won the 2006 AHRMA BOT3 championship on my front end modified Harris TT against modern SV650's, he had to brake very hard, and brake fade was never a problem. The bike ran the better than average 4-piston calipers with aluminum pistons, Brembo radial master, good Braketech iron rotors, fresh Ferodo organic pads (we actually ran Platinum's at the time), and fresh everyday Castrol LMA brake fluid. You'd be hard pressed to convince me not to use aluminum pistons.


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Sat Sep 16, 2017 7:09 pm 
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Joined: Thu Oct 14, 2010 7:30 am
Posts: 139
There are many hi temp fluids available in the car racing world. Check Pegasus racing.com their catalog lists a bunch of different fluids with their dry and wet boiling points. Prices vary and you can certainly spend a bunch on fluid. Beware, the catalog is as dangerous as the one from Aircraft Spruce. Good reading and lots of stuff that gets your imagination running.


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Sun Sep 17, 2017 9:54 am 
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Hey pantah good...
It's pretty hard to argue with success. There are many reasons why a bike wears a #1 on its fairing and a superior brake set-up has to be one of them. Aluminium pistons and quality fluid wins the day. The picture of the radial master takes care of another question I was going to post. It's on the buy list now, but I'm going to have to settle for the not so $better than average$ calipers.
By the way... that is one nasty race bike.

Thank you for the info and pics...
Flattop

wdietz186....
Checked out Pegasus, and yes could spend a few to many dollars there. One thing they carry is the elusive 8mmx1 banjo bolt.


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Sun Sep 17, 2017 1:52 pm 
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Just to be sure Flattop, at that time that bike was set up to run in an AHRMA non-vintage race class and I don't think a radial master would pass muster in a Pantah era vintage class in too many vintage groups. We then reverted back to the vintage legal and very good Brembo linear "916 style" master working on the old school 4 piston GP Mk.1 calipers.
Bill


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 Post subject: Re: Caliper pistons.... Stainless steel vs aluminum
PostPosted: Mon Sep 18, 2017 8:05 am 
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Joined: Fri Jun 24, 2016 2:38 am
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Location: New Zealand
Yes, its probably all a bit academic really.
What little I know about pantah based racers, with F05s or F08s, overheating has not been a problem, but Glyn, Roy, and numerous other would be able to confirm.

It seems the Goldline calipers are simply regular calipers with the dust cover lips machined off, and aluminium pistons over the chromed steel ones of the standard road versions.
Don't get your hopes up about magnesium, despite being various shades of gold, and Mg would be an awful material choice for a brake caliper anyway. IMO it is simply anodising over an alloy that didn't take up the dye too well.


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