2021 TBR7 Rear Brake Adjustment

[pcreighton]

I'm a new TBR7 owner. Just finished putting it together over the weekend, but I'm having issues with the rear brakes being really "soft" I guess would be the best way to describe. They don't have much stopping power. I've bled the system and replaced with DOT 3 brake fluid, but that hasn't made any difference. The manual shows adjustments for drum brakes, but these are disc brakes. I've been searching online, but thus far haven't found a clear explanation on how to adjust them. If anyone can point me in the right direction, it would be much appreciated.

[JerryHawk250]

Is the pedal spongy. If so, it still has air in the line. Use a Vacuum brake bleeder and replace all the fluid. If it is just hard to stop it's probably because it still has the anti rust shipping coating on the disk. One of the first things you should have done before riding the bike is clean the brake rotors with brake cleaner.

[pcreighton]

It seems to be more that it's hard to stop rather than "spongy". I didn't clean the rotors, but I'll give it a shot. Appreciate the help.

[Megadan]

Originally Posted by pcreighton

It seems to be more that it's hard to stop rather than "spongy". I didn't clean the rotors, but I'll give it a shot. Appreciate the help.

Yeah, it's pretty important to clean the rotors before riding these bikes as they do come with a healthy coating of oil or preservative grease/wax.

I also recommend cleaning off the pads too, especially if you used the brakes. Just pull them out and spray down the pad surface well.

As far as the feel, assuming it is bled fully, then the actual brake adjustment is what I would look at next. There is a bolt that is used as the pedal adjustment located on the frame. You can turn this in and out to adjust the pedal and take up any slack in the system. It also might be possible that you need to adjust the master cylinder clevis in conjunction with the pedal adjustment.

[Nospark]

Good advise as always. I have the same issue on my 2021 TBR7 during my 1st, short test ride. It's been too cold to look at it. This weekend will warm up. I did flush brake fluid and I'm doubtful it's air in the line. I'm thing more clean the rotor and put some more miles on the rear brake. The front grabs as expected.
I didn't know about shipping coatings nor scuffing pads. I may do that as pulling caliper is easy task.

[pcreighton]

I've finally had a chance to get out and clean the rotors w/ brake cleaner and have also bled the system again. Still hasn't seemed to make any difference. Front brakes seem to work okay. There is a good bit of travel in the rear brake pedal before they begin to grab. Does anyone know if there is any kind of adjustment on the caliper or if it's designed to be 100% auto-adjusting? Considering going ahead and replacing the pads as a next step.

[Nospark]

pcreighton, Cleaning the rotor with brake clean made a slight improvement on mine but, still far from what I would like to see. I'm going try removing the factory pads, scrubbing and cleaning them with brake cleaner and scuffing them up a bit. If this still doesn't show significant improvement, I'll replace the factory pads.
I should be able to get to that by this weekend.

[pcreighton]

That's pretty much my plan at this point as well. Since I'm going to disassemble everything related to it anyway, I might as well go ahead and replace the pads anyway. Can anyone verify a part number or recommend a good replacement set of pads?

[China Rider 27]

The brakes will get better after more use that has been my experience but that is not to say better pads would not be an improvement. There are some interesting points in this article.

https://brakeexperts.com/how-to-brea...by-step-guide/

Here is one specific to motorcycles.

https://xladv.com/articles/breaking-...-brakes33-r35/

[Nospark]

I appreciate the article on bedding brakes and don't argue that it's a good idea and improves performance. In our situation the front brake works great but, for some reason we've yet to identify, the rear doesn't grab nearly as well as the front. I replaced my rear sprocket, greased the axle and rear wheel bearings and reinstalled the wheel myself. All before 1st start. I figured I got grubby axle grease coated finger prints all over the rotor and overlooked cleaning it prior to 1st ride. pcreighton is experiencing the same issue. I'm not convinced it's a contamination issue as yet. I'll post here what I find out. I'm still optimistic the factory rear brake components can be made to grab/stop well with a good cleaning and working through a bedding process.

[pcreighton]

I've cleaned the rotor with brake cleaner and removed the pads, scuffed them up and cleaned them with brake cleaner, but still experiencing issues. The firs two or three times I used the rear brakes after that, they seemed to work better, but then went back to barely working at all. I'm going to give bleeding the system one more shot, but beyond that, the only other thing I know to try will be to replace the pads.

[TxTaoRider]

I've had master cylinders with some type of internal leak that behaved like what you're describing. You might cough up 20 bux - probably less... and try another.

[pcreighton]

I pulled the caliper off again, removed the pads and cleaned everything really good with brake cleaner. I also flushed the system through a couple of times. One other thing I did was to adjust the brake clevis a couple of turns to lengthen it just a little and that seems to have helped a pretty good bit, at least on the brief ride I took afterwards.

[pcreighton]

TxTaoRider's suggestion about replacing the master cylinder ended up fixing the problem. After replacing the master cylinder, the rear brakes actually work. Appreciate all the help.