Releasing Front Brake Caliper Piston - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
Wheels, Suspension and Brakes
Everything to do with wheels, tires,
suspension, forks and brakes

 
LinkBack Thread Tools Display Modes
post #1 of 9 (permalink) Old 05-28-2012, 03:33 PM Thread Starter
Junior Member
 
Join Date: Apr 2012
Location: Schuyler, VA
Posts: 21
iTrader: (0)
 
Releasing Front Brake Caliper Piston

I was wondering if there is a way to push the front brake caliper pistons back into the caliper...


The PO of my '86 VN750 unhooked the front brake calipers from the rotors before storing the bike for twenty years. It looks like he then pulled the brake lever, effectively closing the brake pads on themselves.

My question is, what is a good way to get the pistons to release and slide back into the caliper housing so I can see if I have positive brake pressure?

I was thinking of taking two screwdrivers and inserting them gently under the lip of the piston and rotating them up, so the pistons slide back into the housing, thereby freeing up the front brake shoes...or is there a better way to do this? I certainly do not want to gouge the pistons, but I see no other way to get them to slide back into their calipers...any ideas would be great!

John
Dr. Frankenstein is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 05-28-2012, 04:00 PM
Senior Member
 
Join Date: Aug 2010
Location: Daleville, Alabama
Posts: 445
iTrader: (0)
 
I use a c-clamp and brake pad or a small piece of plywood. Then press them in nice and slow.

MCCT Mod
Pickup Mod
12 Volt Receptacle Mod
Memphis Shades Santa Cruz
Homemade Luggage Rack
NGK Iridium IX Spark Plugs
Harley Sportster Exhausts
Rotating/Flashing Tail Lights
170/80 Michelin Commander II
Saddlemen Highwayman Slant Jumbo Saddlebags
Bought 09/10 12.2k miles - 04/12 33.4k miles
CW-4 is offline  
post #3 of 9 (permalink) Old 05-28-2012, 10:49 PM Thread Starter
Junior Member
 
Join Date: Apr 2012
Location: Schuyler, VA
Posts: 21
iTrader: (0)
 
I wound up taking off the banjo bolt and releasing the fluid in the calipers; I applied two screwdrivers very carefully under each side of the piston and leveraged them up - they then slid right up, so I'm thinking there's a blockage in the line somewhere. At least the pistons themselves are okay...

The hairy thing was, I Finally got the brake master cylinder piston washer/cover off, intending to take out the old parts and rebuild the master cylinder...the whole circular channel the parts rest in was solidified! The bike has sat for so long the entire inside of the master cylinder piston literally petrified inside it!

I tried digging it out - all that old, caked, chalk-like substance - but it's no good, the master cylinder is shot. As a matter of fact, the master cylinder piston itself broke off inside the master cylinder tube due to corrosion. I've never seen anything like it! It's toast.
Dr. Frankenstein is offline  
 
post #4 of 9 (permalink) Old 05-29-2012, 03:21 AM
Senior Member
 
sparkingdogg's Avatar
 
Join Date: Sep 2011
Location: Omaha NE
Posts: 194
iTrader: (1)
 
Quote:
Originally Posted by Dr. Frankenstein View Post
I wound up taking off the banjo bolt and releasing the fluid in the calipers; I applied two screwdrivers very carefully under each side of the piston and leveraged them up - they then slid right up, so I'm thinking there's a blockage in the line somewhere. At least the pistons themselves are okay...

The hairy thing was, I Finally got the brake master cylinder piston washer/cover off, intending to take out the old parts and rebuild the master cylinder...the whole circular channel the parts rest in was solidified! The bike has sat for so long the entire inside of the master cylinder piston literally petrified inside it!

I tried digging it out - all that old, caked, chalk-like substance - but it's no good, the master cylinder is shot. As a matter of fact, the master cylinder piston itself broke off inside the master cylinder tube due to corrosion. I've never seen anything like it! It's toast.
and it's also the most important part of your bike. i would imagine that 65% or more of the vn750's brake force is up front on that dual disc. it's one thing to have a bike that sputters and dies. it would be quite another to have massive front brake failure in an emergency situation. find a used one but make sure it is clean too, some of the ebay dorks don't even remove the cap and look. and yes i have seen the dried gunk you are talking about, quite a nasty horrible looking mess, and should be dropped right into the trash can. one of the members here might have one, check the classified ads. and good luck bleeding it once you get fixed, quite a pain! takes a long time to get all the air out!! i need to re-bleed mine once again! i'm going to try tie wrapping the lever and letting is sit for a day or two.

2005 VN750

2003 VN1500 Nomad FI Bagger

2004 KLX400SR Dual Sport light adv bike

1969 CB750 K0 sand cast #1767

couple of nice GL650 Silver Wing Interstates, one with hack

2 and 4 stroke dirt bikes

other vintage stuff back in the corner
sparkingdogg is offline  
post #5 of 9 (permalink) Old 05-29-2012, 03:15 PM
Member
 
Join Date: Oct 2007
Location: central NJ
Posts: 95
iTrader: (0)
 
I'm junking an old frame with the front wheel and the calipers are still attached and appear functional. If you want 'em let me know, will cost you whatever the postage is on the box.
johnrwilco is offline  
post #6 of 9 (permalink) Old 05-30-2012, 11:09 AM Thread Starter
Junior Member
 
Join Date: Apr 2012
Location: Schuyler, VA
Posts: 21
iTrader: (0)
 
Yeah, I'm definitely interested! You don't happen to have the brake lines and master cylinder that attaches to them , do you?

What's your zip code?

PM me if you want; thanks!
Dr. Frankenstein is offline  
post #7 of 9 (permalink) Old 05-31-2012, 04:02 PM
Member
 
Join Date: Oct 2007
Location: central NJ
Posts: 95
iTrader: (0)
 
Sent you a PM.
johnrwilco is offline  
post #8 of 9 (permalink) Old 06-18-2012, 02:39 AM
Junior Member
 
Join Date: Jun 2012
Location: Ranger, Texas
Posts: 25
iTrader: (0)
 
I used a little different method to bleed my front brake. I took a small jar with a good sealing lid, and drilled the lid and put two fittings in the top. I hooked one line from one fitting on the jar to my vaccum pump. I took another line and connected it to the other fitting on the jar and the other end I pushed it on my caliper bleeder screw. I turned on the vaccum pump and while keeping the master cylinder full let it suck the DOT 4 through the system. I let it suck a little extra fluid into the jar and then I switched to the other caliper and did the same. The debris in the lines ended up in the jar. Brakes work great. In my case all of this was done after cleaning the master cylinder and blowing out all the lines.
WuggyBump is offline  
post #9 of 9 (permalink) Old 06-18-2012, 11:03 PM
Registered User
 
Join Date: Aug 2011
Location: GreenwoodFrickinLakeNY
Posts: 10,354
iTrader: (8)
   
Quote:
I'm junking an old frame with the front wheel and the calipers are still attached and appear functional. If you want 'em let me know, will cost you whatever the postage is on the box.
If Franken dont take it, I will...been looking for a frame to mod/cut/chop/weld...Im driving distance too...NY/NJ border, sort of. Thats with the forks too ?



Wolfie is offline  
Sponsored Links
Advertisement
 
Reply

Bookmarks

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Once registered, your User Name"cannot be changed". We can make exceptions within 7 days, but after that, it is set in stone.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome