Fj1100 1985 dot 5 in brake M/Cs

[iridewheelies]

So im getting to the end of the endless maintenance ive done to my bike. 20-30 parts ive bought and installed. I lnow the bike needs pads, but since they are so worn out would it cause the calipers to hang up and make the bike hard to push? Would dot 5 help rejuvenate the old seals in the pistons? Id rather not spend the hard earned money and rebuild the calipers, (which i will probably do if they still hang after new pads), when dot 5 and new pads and some light easy riding could free them up. Thanks guys. Waiting on randy's clutch kit and she will be ready to rock.

[FJmonkey]

DOT 5 is not compatible with other brake fluids. Stick with the DOT 3 or flush it out.

[balky1]

DOT 5.1 on the other hand, is.
Put some new in (not DOT 5), flush the system a couple of times, try working the pistons in and out a couple of times (watch the fluid level in MC during this). If that doesn't help, best thing is to rebuild. That means that rubber seals got too rigid.

[FJ1100mjk]

If the calipers haven't been rebuilt before, and/or if the bike has had poor maintenance with previous ownership, my money would be on frozen, or partially frozen calipers being your problem. You could, drain, flush and backfill your braking systems with silicone brake fluid, and maybe get lucky. However, after owning three of those FJs, that experienced some, or the same types of problem you've described, I found that age-hardened caliper seals, and corrosion in the caliper seals' grooves/glands, to be mostly the culprits causing those problems. You may find that the state of your master cylinders are kind of sad too.

I did it all, including new EBC HH pads (highly recommend), and stainless steel-braided brake hoses, and systems' backfill with silicone brake fluid. Braking feel and power is vastly improved afterwards.

If you run with sticking calipers, you'll experience poor braking power, decreased pad life, and maybe accelerated disc wear. Better to go through the brake systems thoroughly and replace what is needed. You'll be safer and happier afterwards.

Unless, you find a well-cared for, low-mileage example, these old bikes are money pits. Once you're in deep with all the required refurbishment costs and elbow grease, you may as well go all the way when you run into something like your describing, so you can enjoy the bike to its potential, and not have to deal with the problem(s) again.

[Motofun]

Just my 2 cents....Stick with DOT 3,4 or 5.1.  Once the system is clean and rebuilt all it takes is a fluid flush every other year to keep things in shape.  When you pull the calipers for a tire swap that is the time to clean up the slave pistons with some brake cleaner and a tooth brush. 

[iridewheelies]

 

If the calipers haven't been rebuilt before, and/or if the bike has had poor maintenance with previous ownership, my money would be on frozen, or partially frozen calipers being your problem. You could, drain, flush and backfill your braking systems with silicone brake fluid, and maybe get lucky. However, after owning three of those FJs, that experienced some, or the same types of problem you've described, I found that age-hardened caliper seals, and corrosion in the caliper seals' grooves/glands, to be mostly the culprits causing those problems. You may find that the state of your master cylinders are kind of sad too.

I did it all, including new EBC HH pads (highly recommend), and stainless steel-braided brake hoses, and systems' backfill with silicone brake fluid. Braking feel and power is vastly improved afterwards.

If you run with sticking calipers, you'll experience poor braking power, decreased pad life, and maybe accelerated disc wear. Better to go through the brake systems thoroughly and replace what is needed. You'll be safer and happier afterwards.

Unless, you find a well-cared for, low-mileage example, these old bikes are money pits. Once you're in deep with all the required refurbishment costs and elbow grease, you may as well go all the way when you run into something like your describing, so you can enjoy the bike to its potential, and not have to deal with the problem(s) again.

Great advice. Every m/c has been rebuilt by me as well as the slave. Ill flush with silicone brake fluid and see how she does. Just itching to take it for a first ride. Its 60 here in nebraska today. So im going to work on the bike! Just got all my parts today as well! Ive done everything under the moon to this thing.

[iridewheelies]

Im going to slap a good pair of pads on it and flush then see how it brakes. Still need stainless lines, but thats about it besides going trough the forks. I just want to get this pile of parts turned into a bike!

[PaulG]

Id rather not spend the hard earned money and rebuild the calipers, (which i will probably do if they still hang after new pads)

Of all the things you should spend money on when rebuilding a bike, definitely brakes are near number one on the list. IMO. The piston seal kits are relatively cheap in relation to their overall importance.  Brakes don't just seize closed. They will seize open also.

I bought my '92 in 2007. I rode it for the first summer until I had a front caliper seize open while exiting an off ramp from the freeway. Luckily with several pumps of the lever it freed up just as I was entering traffic. So I took it off the road despite several weeks of riding season left. Upon rebuilding the calipers I realized they hadn't been touched since the bike was originally bought 3 owners previous.

You're obviously mechanically adept enough to rebuild the bike so I won't tell you how to do it.  I would just urge you to rebuild them regardless. It would be a shame for all that hard work to go to waste on a minor fender bender or worse.

Good luck and post some pics of your ride. 

[Pat Conlon]

^^^ +1 Listen to Paul. Your life may depend on it.

If you live in a wet climate, I would not recommend DOT 5.
You want a hygroscopic brake fluid that will absorb any moisture in your system and hold that moisture in suspension until you flush.
DOT 5 is a non-hygroscopic fluid, thus will not absorb moisture (nor eat your paint).

That said, I've used DOT 5 in my FJ for 25 years now, but I live in the dry desert.
However, I have seen some evidence of slight water corrosion on the lower part of my clutch slave piston and piston bore.

When you flush, the bleed port is located in the upper part of the chamber, necessary to bleed of any trapped air....however DOT 5 is lighter than water, so water accumulates at the bottom of the chamber and can remain after the flush.