Success with a smaller than recommended 14mm front brake master cylinder!

From basic novice to the hard core cutomizing. Sharing tips, tricks and knowledge. Feel
free to ask question or give us your "2 cents".

Moderators: sunnbobb, Neil, Forum Moderators

Post Reply
BigSherm
Cast Iron Member
Cast Iron Member
Posts: 62
Joined: Sun Oct 23, 2016 4:15 am

Success with a smaller than recommended 14mm front brake master cylinder!

#1

Post by BigSherm »

Hi everyone,

Hauling through endless miles of twisties here in SoCal paradise, my brake hand was getting tired!

I read the recommendations of Randakk and others about upgrading the front brakes on my '77. The consensus seems to be that along with stainless brake lines, a smaller than stock 15mm or 5/8" bore will give the best feel and performance.

I couldn't find a decently priced unit in that size that looked like it belongs on my 40 year old beast, though, so I took a chance with this new but vintage-looking $66 Kawasaki Z1 reproduction unit from EBay:
IMG_0971.PNG
IMG_0971.PNG (806.17 KiB) Viewed 301 times
It's a 14mm bore, and the few experiences I've read made me worry the lever travel would just be too far, and the lever might even come back to the bar, but the price made me give it a gamble.

I was encouraged to try this when I replaced my brake lines with some stainless lines from Shaun at Slingshot Cycles and got such a solid, air-free lever feel after bleeding the brakes. I was hoping that with the perfect brake bleed, I could keep the lever travel down and the 14mm master cylinder would give me even better leverage and lower effort at the brake lever,
IMG_0296.JPG
IMG_0296.JPG (222.95 KiB) Viewed 302 times
IMG_0298.JPG
IMG_0298.JPG (216.72 KiB) Viewed 302 times
It seems to have worked!

That second picture is a hard squeeze, and that's as far as it comes back! Success!

I reused the Honda reservoir cap out of respect for Mr. Honda's masterpiece.

Unfortunately, the rain storm of the year is upon us in SoCal all day today, so no test rides.

I'll report back when I do. I'm stoked to try it!

Scott
Ride like you mean it.
BigSherm
Cast Iron Member
Cast Iron Member
Posts: 62
Joined: Sun Oct 23, 2016 4:15 am

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#2

Post by BigSherm »

Success indeed!

Finally had a break in the storms of the year in SoCal, and was able to get in a short test ride.
A definite improvement!

Reduced lever effort, and the lever doesn't come too close to the grip at all.

I'd call that a win!

Scott
Ride like you mean it.
User avatar
propav8r
Billet Alum. Member
Billet Alum. Member
Posts: 282
Joined: Thu Oct 13, 2016 5:00 pm
Location: Franklin, NC

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#3

Post by propav8r »

Neat. I'm less than thrilled with the 9/16" master I put on my '78. Might have to give this a shot.
Image
BigSherm
Cast Iron Member
Cast Iron Member
Posts: 62
Joined: Sun Oct 23, 2016 4:15 am

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#4

Post by BigSherm »

AV8R-

Here's how I replaced my master cylinder without having to re-bleed the brakes:
http://ngwclub.com/forum/viewtopic.php? ... ead#unread
It worked like a charm!

Scott
Ride like you mean it.
DUGG
Titanium Member
Titanium Member
Posts: 342
Joined: Fri Jun 12, 2015 8:11 pm
Location: Bellingham wa.

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#5

Post by DUGG »

propav8r wrote:Neat. I'm less than thrilled with the 9/16" master I put on my '78. Might have to give this a shot.
9/16 and 14mm are pretty much the same dimension. 9/16 = 14.28mm.
BigSherm
Cast Iron Member
Cast Iron Member
Posts: 62
Joined: Sun Oct 23, 2016 4:15 am

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#6

Post by BigSherm »

DUGG-
That's a good point.

PROPAV8R-
Are you sure you got a good, air-free bleed with that master cylinder?

Scott
Ride like you mean it.
DUGG
Titanium Member
Titanium Member
Posts: 342
Joined: Fri Jun 12, 2015 8:11 pm
Location: Bellingham wa.

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#7

Post by DUGG »

Can some tell what the stock size is for my 81 GL1100?
jb2x
Zinc Member
Zinc Member
Posts: 35
Joined: Wed May 23, 2012 4:50 pm
Location: FRANCE

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#8

Post by jb2x »

Hi,

15,85 mm

Jean
3800 Vélosolex (2)
125 MBK Skyliner
Naked 80 1100 GL almost complete
80 GL 1100 project
2003 GL 1800
DUGG
Titanium Member
Titanium Member
Posts: 342
Joined: Fri Jun 12, 2015 8:11 pm
Location: Bellingham wa.

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#9

Post by DUGG »

jb2x wrote:Hi,

15,85 mm

Jean

Thanks. So the 14mm would be an upgrade, I know whats next on my list then.
jb2x
Zinc Member
Zinc Member
Posts: 35
Joined: Wed May 23, 2012 4:50 pm
Location: FRANCE

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#10

Post by jb2x »

I don't think that is an upgrade, see Randakk's article:

https://www.randakks.com/upgraded-front ... iston.html

Jean
3800 Vélosolex (2)
125 MBK Skyliner
Naked 80 1100 GL almost complete
80 GL 1100 project
2003 GL 1800
BigSherm
Cast Iron Member
Cast Iron Member
Posts: 62
Joined: Sun Oct 23, 2016 4:15 am

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#11

Post by BigSherm »

Jean-
The proof is in the results.
Believe me, it's an upgrade from the stock master cylinder on my bike!

Scott
Ride like you mean it.
DUGG
Titanium Member
Titanium Member
Posts: 342
Joined: Fri Jun 12, 2015 8:11 pm
Location: Bellingham wa.

Re: Success with a smaller than recommended 14mm front brake master cylinder!

#12

Post by DUGG »

If I'm reading Ranakks right the GL1000 came with a 11/16 (17mm) master and that upgrading to a 5/8 (16mm) master will reduce lever effort. If the GL1100 came with a 5/8 (16mm) master than to get the same improvement s person would have to go to a smaller 9/16 (14mm) master.
Post Reply
  • Similar Topics
    Replies
    Views
    Last post

Return to “GoldWing UnderGround CustomiZing”