92 VFR750 Rear brake problems

I recently changed my front and rear pads after neglecting such for awhile. My fronts now work great, but it seems I pulled some weird bracket loose, which caused uneven pressure on my rear pads, resulting in some nasty grinding.. But since fixing that and reinstalling the pads with much difficulty and bleeding them, it seems to be fine again (albeit with some soft squeaking, but that was there before the change).
Backstory out of the way, the rear brakes seem to kind of suck now. It's been so long since I've felt them with good pads that I don't necessarily remember how good they're supposed to be and they still stop the bike and hold it at a stop, but they feel totally underpowered.
TLDR: Are the rear brakes supposed to suck or did I fuck something up?

 

Unless they're not wearing evenly, new pads aren't likely to make your braking system feel any different, better or worse.

Did you clean the pistons with them pushed out? Clean the lever/pedal pivots?

 

Didn't clean the pistons or anything except the pads and the disc with some brake cleaner. I think I'm going to take it out for a ride tomorrow and see how it feels slowing down from speed, I might just be confused after not touching it for so long. If it's still bad afterwards, I'll probably pull out the caliper and take a deeper look at the pistons.

 

theres a spring that presses on the pads with tabs that need to be properly placed. problems if the spring is oriented incorrectly f/r.

 

From an old note of mine on another forum:

Quick note: With regard to maintenance of the braking system. Think about it like this, you have the fluid system, which you'll be flushing to remove debris and air, and you have the mechanics of the system.

The mechanics are things like the pivot at the lever, which should be clean and lightly lubed to work freely. The piston in the master should move easily and smoothly.

The pads should have enough pad on them and should be clean of debris and fluids. I clean mine with the brass brush to make them look like new before reinstalling. The calipers themselves are primarily a metal hollow to hold fluid as the brake caliper pistons and pads move in and out. The pistons should be clean as should the O-rings. An easy way to do this is to but a "pad replacement" where the pads go. That can be old pads or a piece of wood that won't damage anything.

Cycle the brakes so that the pistons move in around the "pad replacement." Note that you don't want air in the system from the top (don't overflow as you'll be pushing all of that fluid back up at the end). Be sure that the pistons don't pop out, or you'll be bleeding a dry system and cleaning up a mess. With the pistons pushed out, you'll see all of the crud on the pistons and the O-ring.

Use something rubber friendly to clean all of that with a toothbrush. I use Simple Green, at the suggestion of a world renowned expert, but like anything, you'll find people on their soap boxes about how bad that is. Use what you're comfy with. Rinse with water or brake clean.

Once done with that step, the pistons should move freely with one finger. That is how you know you've got it right. Note that pushing them in can overflow the reservoir. From there, reinstall pads/pins/locks and flush the system. The test. Id you've never done it, you'll likely discover a night-day difference.

 

Couple things:

I'm not saying your pistons don't need some love, they very likely do. Are they dragging when not applied? But they are unlikely to be the issue of poor actual braking performance in your case.

New pads can absolutely make your braking system feel worse. You mention that you neglected to change your pads for a while. Were they worn down pretty far? How many miles are on the bike? If your discs are grooved at all, and especially if they are grooved moderately to severely, your new pads are only contacting the top of the "ridges" on the discs. It will take a while for the pads to wear and conform to the used discs, resulting in more actual pad to disk contact. I suspect your rear disc is pretty grooved, they usually are from dirt and neglect.

Additionally, new pads need to be bedded in properly, and even on good discs they won't feel as good initially as they will be after some cycles.

I "rotate" my pads on my bikes when doing other work, promoting even wear on the pads and the disks. And, yep, they take a few miles to come back in. But my disks look great, even on my higher mile bikes and I can get the maximum miles out of the pads. All of my bikes have floating calipers and even properly maintained can sometimes see uneven pad wear. Call me a freak or roast me, but it works and it only takes a few minutes every now and then.

Good luck.

 

100% right on the rotors needing to mate to new pads. Sorry about that. I don't run rotors that aren't mostly smooth, so I never have this issue. I forgot...

The caliper pistons can be stuck anywhere, including in a position where they cannot adequately squeeze the rotor. I have seen this many times. It also provides a squishy lever in my experience.

 

I don't think he would have got his new, thick pads in and the calipers installed if the pistons were that stuck. He didn't mention any issues in that area.

But like I said, his pistons likely need some love. Most do.

 

I love my pistons. I'm just sayin'.

Cleaned the track day A-bike caliper pistons and lever pivot the other day for Road Atlanta on Friday. They feel like $1MM now.

 

Hell yeah. cha-ching. I did my ST1100 rear pistons a month ago when they got new pads. VERY satisfying.

 

Forgot to post an update after my ride. I think it was just the pads not being worn for the rear disc (It is pretty grooved) as after a little bit the braking performance improved massively. Another bleed helped stiffen up the lever further aswell.

Thanks for the responses.

 

If you could put your hair in a pony tail, I would call you a "Freak."

 

I bought a second hand gen3 that had a nasty rear rotor, I ended up replacing with EBC. These are 30 year plus old bikes, they do require full rebuilds of the brake/clutch components.

I took a vacation for a few weeks, came back home, charged battery and back bike out of garage to go to verk. When I needed to use the rear brake at the gate, my foot went full stroke, no rear brake. I rode it anyway, when I got home I ordered a new OEM rebuild kit for the master cylinder. A week later, I ordered another kit for my other bike since they are the same age and I figured it should be part of the maintenance schedule. Peace