Deal alert - Brembo 4P-30/34 40mm calipers
Close
Login to Your Account
Honda Grom Forum

Deal alert - Brembo 4P-30/34 40mm calipers

This is a discussion on Deal alert - Brembo 4P-30/34 40mm calipers within the Grom Performance forums, part of the Honda Grom Garage category; I've got no interest in this company, but found a deal I couldn't pass up last night - Carpimoto (Italy) is selling Brembo 4P-30/34 40mm ...

Page 1 of 2 1 2 LastLast
Results 1 to 10 of 20
Like Tree5Likes

Thread: Deal alert - Brembo 4P-30/34 40mm calipers

  1. #1
    Member
    This user has no status.
     

    Member #
    31676
    Join Date
    May 2019
    Posts
    70

    Deal alert - Brembo 4P-30/34 40mm calipers

    I've got no interest in this company, but found a deal I couldn't pass up last night - Carpimoto (Italy) is selling Brembo 4P-30/34 40mm calipers for 55% off right now and the shipping price to the USA is VERY fair:

    https://www.carpimoto.com/en-US/4240...embo-P4-30.htm - Titanium/Red
    https://www.carpimoto.com/en-US/4292...embo-P4-30.htm - Gold/Silver

    You'll need an adapter bracket, but these are available from about a dozen different companies on WeBike. For what it's worth, the price on these right now is better than the 2P calipers normally retail for!

  2. #2
    Banned
    This user has no status.
     

    Member #
    7708
    Join Date
    Jun 2016
    Posts
    714
    that is a very good deal. thought i'd suggest a change in master when doubling the number of pistons in the caliper.
    50-50 likes this.

  3. #3
    Member
    This user has no status.
     

    Member #
    31676
    Join Date
    May 2019
    Posts
    70
    Gonna try it with stock before I change it out. Given the fact that Takegawa sell 4P/2P bracket kits and don't suggest a Brembo radial master, I suspect it will be decent as-is. Worst case, I swap the stocker back until I get a radial.

  4. Remove Advertisements
    HondaGrom.net
    Advertisements
     

  5. #4
    Banned
    This user has no status.
     

    Member #
    7708
    Join Date
    Jun 2016
    Posts
    714
    You'll get a longer travel and softer lever, but lots more power.

    here's something to consider


    the two pistons in the stock caliper are 25.3mm, this gives you a total cross sectional area of 1005 mm^2
    the four pistons in the p4 30x34 are obviously 2 x 30 and 2 x 34 which gives you a total cross sectional area of 3227 mm^2



    put simply, this means you'll have 3 times the lever travel but 3 times the braking pressure.


    this is far from ideal, and will likely produce a poorly performing system.
    Last edited by Wibbly; 07-17-2019 at 02:57 PM.
    nd4spdbh likes this.

  6. #5
    Banned
    This user has no status.
     

    Member #
    7708
    Join Date
    Jun 2016
    Posts
    714
    for reference, i have this exact caliper matched with a brembo 16x16 master. i wouldn't want the brakes to be any touchier. with the stock grom 12.7mm master i suspect they may be a little too crazy.

  7. #6
    Member
    This user has no status.
     

    Member #
    31676
    Join Date
    May 2019
    Posts
    70
    I did the math on it - as you mentioned, stock master is 1/2". Front pistons (2) are effectively 1" each.

    Using the upper limits:

    Front piston area = ~1010 mm^2
    Master piston area = ~126 mm^2

    Roughly 8:1 ratio - this is why the stock front on the Grom feels firm at the lever, not very grabby at the rotor, then suddenly locks as you increase pressure. Part of this is the garbage uF of the stock pads, too.

    You can't exactly compare opposed piston calipers to the stock calipers like that, either. Opposed piston calipers work well with a much higher ratio (roughly double), generally speaking. This means you can get away with a smaller master.

    The Brembo has a front piston area = ~3230 mm^2

    This produces a ratio of 25.6:1. I had a target of 24-25:1 so I'm pretty happy with the initial math. The lever ratio isn't exactly wonderful on the stock bike, however - I'll report back once it's all mounted up.

    Your ratio using the 16 mm master is 16:1 which should be more-or-less identical to the stock brake feel (though the lever ratio is probably different). In your last post, you have it backwards in that by using the stock master, you'll be making it less 'touchy' by giving the rider more travel/feel to the lever.

  8. #7
    Banned
    This user has no status.
     

    Member #
    7708
    Join Date
    Jun 2016
    Posts
    714
    It'll be more touchy because you get more braking for less effort.

    This is just a matter of semantics.


    Keep in mind as well the Grom weighs half what most bikes do. So while 25:1 is a nice number on a 1000cc superbike, it is less desirable on a 220lb scooter.

    As I said with all considerations I'd be concerned about a 1/2" bore master on a large caliper like that. But it's your bike not mine.

  9. #8
    Member
    This user has no status.
     

    Member #
    31676
    Join Date
    May 2019
    Posts
    70
    Fair enough - it'll all be clear in a few laps around the block afterwards if I've got more money I need to spend.

    Quote Originally Posted by Wibbly View Post
    It'll be more touchy because you get more braking for less effort.

    This is just a matter of semantics.


    Keep in mind as well the Grom weighs half what most bikes do. So while 25:1 is a nice number on a 1000cc superbike, it is less desirable on a 220lb scooter.

    As I said with all considerations I'd be concerned about a 1/2" bore master on a large caliper like that. But it's your bike not mine.

  10. #9
    Banned
    This user has no status.
     

    Member #
    7708
    Join Date
    Jun 2016
    Posts
    714
    make sure you report your findings. brakes aren't discussed in detail nearly enough. especially when it comes to pairing masters and calipers appropriately.
    nd4spdbh likes this.

  11. #10
    Member
    This user has no status.
     

    Member #
    31676
    Join Date
    May 2019
    Posts
    70
    Yeah this should stop a 200 lb bike just fine...

    CDN Grom likes this.

Page 1 of 2 1 2 LastLast

Sponsored Links

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •