Front Brake Caliper rebuild

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Slappy

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I am in the process of doing a caliper seal replacement. Just got the forks redone with new internal seals shims and oil now I need to do the brakes. They are sticking bad.

What special tool do I need and where do I get it to seperate the two halves? Its an outy not an innie star.

All help is greatly appreciated

 
Just curious, what did that cost to get those forks done? Who did the work for ya?

You'll find some info here CLICKY

Gayr

 
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I did the first time with Johnny80. PITA unless you have a serious shop a lots of tools. This time around I took it to a local Yamaha shop and they charged me $300 off of the bike.

 
Slappy, before you go to the hassle and expense of rebuilding the calipers, have you gone through and cleaned the pistons really well? I've found that can make big difference to the amount the pads retract when released and the amount of drag you get.

The trick for cleaning is to exercise the lever or pedal to push the pistons out past where there have been running and then use rags and brake cleaner to remove all the built up crud. If you have any light pitting of the piston you can try scrubbing lightly with a green scotchbrite pad and brake cleaner.

If you do need to rebuild the calipers I don't believe that you need to split them. Just hydraulically push the pistons all the way out and replace them along with the rubber seals.

 
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Agree you shouldn't have to split the calipers and you really don't want to. First pump the pistons out with the brake pads still in, and see what shape they're in. If you're going to remove pistons to replace seals (I would if I went that far, especially if they are sticking and given their age), remove one brake pad (or use a piece of 1/4" plywood as a spacer) to get all the pistons as far out as possible so you can remove them more easily (hopefully by hand, no tools that will distort them). Once one piston is out, you'll not be able to use hydraulics to push the others out in that caliper, unless you rebuild one piston at a time, put it back in and use an appropriate spacer to get the next one out. Unless the pistons are really pitted, I'd bet you can salvage them with a good cleaning like Fred suggests.

 
Due to my manly fingers I need to split the calipers to get to the seals. Damn my man hands. I tried a 12point socket and got 5 of the 6 loose. One is being a bitch and I have almost stripped the head. Ill take that one in and have the shop take it apart and order a new screw. Not a major issue.

Thanks for all the input.

 
Am I understanding correctly that a Gen II caliper has 6 pistons... and a Gen 1 has 4? Just curious.

Gary
darksider #44

 
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I'm confused. Aren't calipers machined from a single casting?

I've never taken a caliper apart, just pried the seals out with a

pick or small screwdriver. What am I not understanding?

 
I'm confused. Aren't calipers machined from a single casting?I've never taken a caliper apart, just pried the seals out with a

pick or small screwdriver. What am I not understanding?
Many are, but these aren't because you have pistons on both halves which would be impossible to machine as one piece. Slappy has big mitts, so his reason for splitting them.......

 
I either never noticed ( never needed to disassemble ) or simply can't

remember. ( I have rapidly advancing CRS )

I'm gonna take a look see when I get home. Thanks.

 
Not something you'll wanna do. It's easy enough to get the pistons and seals out without splitting. If your hands are that big bring in some small hands help for those critical seals. Probably be easier than all the effort to disassemble them. And I'm not sure how I'd feel about them upon re-assembly.

I guess if I had a caliper so messed up it needed to be broken in half I'd look for replacement ones. But I still have a suspicion that if you cleaned the pistons up well they'd be good to go.

Gen II has 8 pistons, Gary.
As does the first gen. 4 pistons per caliper.

The big difference is the 1st gens have 2 pistons on each side of each front caliper working on a bigger pad (on each side). The 2nd Gens (and later) they split the big 1st gen front pads in half (probably so that they could have one pair of 1/2 sized pads dedicated to the rear linked braking) so there are now 4 separate pad pairs in the front. One piston per pad

 
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I either never noticed ( never needed to disassemble ) or simply can'tremember. ( I have rapidly advancing CRS )

I'm gonna take a look see when I get home. Thanks.

I believe the recommended cure for that is Milk of Amnesia.....................

 
FYI for all. The bolts holding the two halves together use a 10mm 6 point socket. I tried a 12 point but almost rounded it off. For those that have never done this here is the procedure. (I just did this on my 07 FJR)

1 Remove front wheel. To do this you have to compress the brake pads into the calipers. Do so using your fingers. If your hands are not strong enough ask your wife to do this for you

.

2 Once wheel is removed put a plastic pen or other soft non breakable object between the pads. Do not use a wooden pencil.

3 While observing the brake pads slowly apply the front brake. Both upper and lower pads should move together, except for the right pads. I will get to that. On the left side if all of the pads are not moving together it's time for some new seals or to just clean the pistons.

4 Once the pads hold the pen in place stop. Now the right lower pad is the linked brake. Using the foot rear brake do the same thing. Again both pads should move together.

NOTE (The term both pads refers to the pair of pads opposite each other. Each caliper has two sets of pads. For this procedure we will call them upper and lower due to their orientation when properly installed on the bike. With the right side the upper piston is larger than the lower. The lower set of pads is the linked brake.

5 Once all of the pistons are minorly extended crack the three hex bolts at the top of the calipers. You are breaking free the locktite, that is all. DO NOT LOOSEN. Just loose enough so you don't have to fight with them on the bench.

6 For the purpose of this procedure we will do a PITA brake flush. Yes there are easier ways but let's just get this done and done right shall we. Put a container below the brake calipers to hold break fluid. Remove banjo bolt and move it behind the caliper and let it drain. (This is a PITA flush because you will have empty master cylinder and empty break lines and abs box which means lots of work getting the air bubbles out.) There is a less labor intensive way to do this which several people will post after this.)

7 Once banjo bolt has been removed, remove the caliper from the fork.

8 In a clean area, place an absorbent cloth. With the caliper in this cloth remove the brake pads.

9 Once the pads have been removed, use a 10mm six point socket. Remove the three hex bolts you loosened earlier.

10 You should have two halves. Using an old inner tube or a cloth like a shammy, place the cloth or rubber between the walls of the piston and a pair of needle nose type pliers. (WARNING, DO NOT SCRATCH THE WALLS OF THE PISTONS. ANY DAMAGE WILL CAUSE LEAKS. USE A QUALITY CLOTH OR RUBBER. NO METAL TO METAL CONTACT.) Twist and pull the piston out of the socket.

11 Once the pistons are out, drain any remaining fluid. Inside the socket you will see two seals. The one closest to the opening is the dust seal. The wider one down low is the oil seal. Using your finger, move it in and out of the socket. You will feel the lowest part of the oil seal is just slightly higher than the edge of the seal closest to the opening. This is what keeps the oil inside the cavity. Remember this, it will come back in a moment.

12 Remove the old dust seal and oil seal using a very small punch or flat head screwdriver. (NOTE) I used the same screwdriver I use for the throttle body sync. Smaller the better. Use caution. Do not scratch the inside of the socket. Its not that hard but the first seal is always the most difficult.

13 Once the seals are removed, clean the socket with a clean cloth. Do not use anything abrasive. Not sure if you're supposed to use spray can brake cleaner but I did. I also used a clean old terrycloth wash rag saturated with brake cleaner to get the grime off the pistons and the caliper. Spray and rub, it comes off.

14 Once the caliper dries from the cleaner insert new seals. Before inserting new seals use caliper seal grease (ACC-SLCNG-RS-00). Put a thin layer on the entire o-ring then insert back into the grove in the pot. I like bottom to top but what ever floats your boat. Once the seals are in, rub your finger inside the socket feeling the new seals. Do you feel the bottom edge of the oil seal being more raised? IF NOT, STOP! Take it to your local shop and have them check they are properly installed. If the lower edge is not raised, the brake fluid can push past the seal and cause brake failure and possible injury or death.

15 Once seals are lubed, dip finger in brake fluid or caliper seal grease and put a film on the outside of the piston. LUBE IS GOOD.

16 Pressing straight down, slowly press the pistons into the socket. They are tight but with a coaxing they will go in. Push them all the way to the bottom until the pistons are flush with the calipers.

17 Repeat process for the right side. The only difference is you have to use the rear brake pedal to extend the lower, smaller pistons.

18 Reverse the breakdown starting with putting the two halves back together then install brake pads... This is also a good time to get out an old tooth brush and clean the threads of the caliper and the rod that holds the brake pads.

Finally, bleed your brake system thoroughly. Any air will cause the brakes not to work properly which could cause brake failure, serious injury or even death. Take your time and when in doubt call your local shop or just take the part to them and have them help. IF, after you have bleed your brakes your brake levers still feel slightly spongy do the following. With the caliper off of the fork but still connected to the brake lines, put a medium flat head screwdriver between the brake pads. Squeeze the brake lever until the pads press against the screwdriver. With the screwdriver push the pads back to their starting position where the pistions are all the way back into the pot. Do this at lease once, more is better. After that bleed brakes as normal to be sure all of the air is out of the system. If you still have spongy or questionable brakes contact a trusted shop, they will know what to do. Good luck and be safe.

 
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Reference your section 6 (PITA brake bleed) - I would have a bolt & nut ready then using the original copper washers clamp the banjo union and keep the original fluid in place (with very minor spillage). You should only reassemble these unions using new copper washers.

Other than that sounds like a good deal to me, however I would not split the callipers, just more hassle than it's worth IMHO.

 
Right on Donal.... and I very lightly lube the new seals with brake fluid before I install. And after as Slappy has done. It's all good though.

 
Thanks Slappy for your extensive writeup on a complete rebuild (not just extending pistons and cleaning). I have all new seals and bleed valves and I'm hoping to get this done this weekend but I haven't been able to find any information on how to do a proper full rebuild. The service manual is basically useless for procedures, it's got all the diagrams and torque settings which is good to have but I'm not the most mechanical minded person so some walk throughs are very useful for me. I have been desperately googling for a breakdown on FJR caliper rebuilds but I couldn't find anything useful. So again, thanks.

Quick question: when I take my calipers apart, are there going to be any additional seals between the two halves that I have to worry about?

 

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