Caliper Piston sizes
Stellar HDF Member
Joined: Feb 2013
Posts: 3,072
Likes: 1,726
From: Dallas, Texas
WHY? It does not matter what size the caliper pistons are. Ya can't bore it out and get oversized pistons cause nobody makes them. It HOW MANY PISTONS in the caliper that count. Needing more stopping power???? Get better BRAKE PADS and ditch the OEM crap.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
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Road Master
Joined: Jul 2009
Posts: 849
Likes: 13
From: Santo Domingo, Dominican Republic
WHY? It does not matter what size the caliper pistons are. Ya can't bore it out and get oversized pistons cause nobody makes them. It HOW MANY PISTONS in the caliper that count. Needing more stopping power???? Get better BRAKE PADS and ditch the OEM crap.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
If anyone else knows this info please share.
Stellar HDF Member
Joined: Feb 2013
Posts: 3,072
Likes: 1,726
From: Dallas, Texas
Sorry, but I was only attempting to be of some help. Didn't quite understand the question and gave a response to give you information. Obviously, that was the wrong thing to do since it's gotten ya all riled up. So here's a FOOLPROOF METHOD to get the correct information you are seeking. Remove the front (easier than the rear) caliper and measure it. THEN stick it up yea ***. Ya know, I really don't give a damn if ya wanna tell me off. In parting, all I can say is Bye, Bye and F++k oFF.
Seasoned HDF Member
Joined: Dec 2005
Posts: 19,830
Likes: 7,968
From: poway
WHY? It does not matter what size the caliper pistons are. Ya can't bore it out and get oversized pistons cause nobody makes them. It HOW MANY PISTONS in the caliper that count. Needing more stopping power???? Get better BRAKE PADS and ditch the OEM crap.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
I don't find any problems is someone wants to change the lever to brake pad force ratio..
Cruiser
Joined: Mar 2017
Posts: 152
Likes: 41
From: Surrey, UK.
WHY? It does not matter what size the caliper pistons are. Ya can't bore it out and get oversized pistons cause nobody makes them. It HOW MANY PISTONS in the caliper that count. Needing more stopping power???? Get better BRAKE PADS and ditch the OEM crap.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
A little FYI - Pre Brembo Touring calipers were also used on the Dyna & Softail.
Simply swapping components based on e.g. looks, or what works (in isolation) on other bikes and worst of all, the name of the manufacturer is a recipe for making your brakes worse. If you don't understand how they work, maybe you shouldn't be messing with your brakes in the first place, but if truly ignorant about all this, DEFINITELY don't give out incorrect advice on a public forum.
I am also searching for this information, i.e. the diameters of the pistons/bores in the main caliper types H-D have used. From single piston sliding caliper type on '80s/'90s models, to the 4 piston Nissins on I think mainly later Touring models and the latest Brembos. I cannot find this information anywhere, so if anyone can help, it would be much appreciated, certainly by me and probably the OP as well.
Cruiser
Joined: Aug 2019
Posts: 109
Likes: 16
From: karlstad
As i rememberd, stock front cal.was 40mm x4 . I changed to 30 mm x6 pistons so the combined area of pistons were smaller, I preferd to use a smaller mc. (1/2")
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Cruiser
Joined: Mar 2017
Posts: 152
Likes: 41
From: Surrey, UK.
Are you sure about size? Seems unlikely to me as 40mm would be extremely large for a 2 piston sliding or 4 piston fixed caliper design. Never come across such large pistons in that configuration.
I have since found that the 4 piston Brembos are 4 x 32mm. Prior to that they were 4 piston Nissins and Hayes even before that and I've no idea who makes the single piston caliper used on Evo models, nor its piston dia. - but I can measure that.
So piston dia. for pre Brembo 4 piston calipers is still unknown.
Why do manufacturers try to hide this information. It's not secret as anyone could measure it if they really needed to for business purposes. Just makes life difficult for us customers/users. Drives me nuts.
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