Posts tagged #Brakes

Hydraulic Brakes. Make Them Like New Again.

Hydraulic Brakes are one of those components that everyone wants to have and then, when things go wrong, they bail and become anti fluid and pro cable actuated. I will admit that there are some good cable actuated discs out there that are very good, the Avid BB7 for instance, however, nothing comes close to the feel and operation of a good hydraulic system. That is why it is a shame when people ditch them. Even some bike shops are more than happy to sell the hydro's but don't want to mess with them afterwards for service. A hydraulic brake system can be ordered as a kit, hoses attached and filled with fluid. You can always tell a system that has come this way as it will have 3 feet of extra hose in a big loop off the bar, just waiting to be snagged by a passing Moose or even a tree limb. Now sometimes this is just laziness on the part of the mechanic but often it is fear of cracking the system open. So here is a little primer on the hydraulic disc brake system...

I have already mentioned Avid above, apart from making the BB7 they also make some great hydraulic units, the older Juicy and Code plus the newer series of Elixir and Trail. All of these models are easy to service and durable apart from working very well. Shimano also make a range that are popular and again easy'ish to service and repair. Other companies that we are fans of are Formula and Hope, both of these produce disc systems that also qualify as works of art, sadly they also  have price tags similar to a minor work from Rembrandt...

So, back to my point. What do you do when things start to go sideways? Well you service them.  Below I have taken some pictures of the complete internals of a set of Avid Juicy levers and calipers. These brakes recently came to us from a customer at the Lake of the Ozarks and they were in dire need of some TLC. These brakes are very common but basically all hydraulic brake units are following the same principles, so with a spec sheet of your particular make and model you will be in good shape.

These particular units had developed one of the common issues of older neglected sets. They had developed the sticky lever syndrome. Another common issue is a soft lever which means air is in the system either through the need of a good bleed or the hose has developed a hole or an o ring has failed on a bleed port. The sticky lever however means that the internal plunger in the lever is in need of replacing or that the caliper pistons are beginning to stick and corrode. My rule is; do both, if one end is gummed up and failing the other ain't far behind.

Wear gloves as DOT fluid is not something you want to be bathing in all afternoon and a pair of safety glasses, you would be amazed at how often I have shot myself in the face with a full syringe of this stuff.

I usually start with the lever first and, with a new bag of the correct internals, start cracking it apart. Below is what you end up with, again this is a Juicy so you will have a different looking pile of bits but they will be doing the same job.
Once the lever blade is removed it will reveal the circlip that needs to be removed to slide out the reach adjust mechanism and the plunger.

Reach adjust mech is next. If yours is a more basic model this will be missing.
In this case the parts were worn
All the parts laid out ready to clean. In this instance everything is being replaced except the body the blade and the reservoir cap.
The main culprit of the sluggish lever return is the plunger unit, in the above picture it is the thing with the spring attached to it. However when you are pulling it apart you may as well replace all the bits as they are all in the rebuild kit anyway.

Once the lever is rebuilt I attack the caliper. Again disconnect the hose first. The only way to get into the pistons is to split the caliper body in half. this is achieved by undoing the three bolts. Once you have the body in two the fun begins. The way to get the pistons out of their press fit home is with the use of compressed air. You cannot get them out any other way so don't be jamming screwdrivers in there or you will damage the body itself and you will get fluid leaking out and the whole unit will become a paperweight. The compressed air does a great job of popping them out. Warning; Make sure you don't have the thing aimed at anything soft and fleshy, it will hurt...
Waiting to be cracked open like a walnut...
The main culprits in here are the quad rings (the square edged rubber washers) and the round pistons.All of which will be replaced.
Once the caliper has been rebuilt all that is left is to run new hose, to the correct length as mentioned earlier to avoid lassoing stray Moose... Also never re-use banjo fittings or crush washers. Once they have been tightened up they have to be replaced. That's it, job done. Go ride.
Good as new.



Posted on April 13, 2014 .

Brake Reach Pitfalls

           We have a vintage Raleigh "Competition" road bike in the workshop for a complete makeover at the moment. It is an interesting project and will probably feature again in this blog before the transformation is complete. One thing that has cropped up already and is very common when doing these kinds of makeovers is 'brake reach'. It is not however just a problem with older style bikes it can cause issues on modern frames too, especially on those catch all frames that are designed to be built up in a variety of styles and need to accommodate a wider range of tire widths than a standard 23 or 25.
            Brake reach is basically the distance between the caliper mounting hole on the bridge,  to the center of the brake wear track on the rim.

            On a modern standard road bike this distance is going to be around 39-49mm and a standard short reach caliper from the big 3 will work just fine. Lots of manufacturers nowadays though are producing frames that can be equiped in various formats, a bike for all seasons if you will. This is where the brake reach figure can differ from standard and purchasing a short reach caliper is probably not going to work. The pads will hit somewhere on the tire instaed of the rim. Another problem scenario is with the older style frames as we have mentioned, the mounting bridge on these guys are usually set for the older style center pull styles that had a reach of around 61mm. Therefore a standard 39-49 short reach is never going to work.  Even what we commonly refer to as medium reach will have trouble as their range usually runs from 47mm - 57mm. The last tool in the box for a modern caliper is a long reach 55mm - 73mm.
             All this goes to show that you can never take anything for granted when changing parts on your bike. Measure, measure and measure again.
Posted on October 30, 2012 .

Check the Pads



Tis the season to pay special attention to your brake pads, wet conditions are notorious for embedding grit and debris into your brake pads, I am sure you have all heard that long shoooshing noise the first time you apply your brakes after riding through a wet section or a puddle, that is the sound of grit being sandwiched between your pad and rim. What happens next is a lot of that debris gets pushed into the rubber of your pads and from then on gets applied to your rim every time you brake. Now, what also begins to happen is that little pieces of your rim get chiseled off and they end up in your pads as well. It becomes a vicious circle.
                You should keep an eye on the condition of your brake pads throughout the year but especially after wet or very dusty rides. Keeping the pads free from debris makes a big difference to your rims wellbeing.
                If you do see some grit and rim material in the pads the easiest way to remove it is by buffing the surface of the pads until you reach new rubber, free from the junk. Use 80 grit emery-cloth on a small block, if you just use the cloth on your finger you will place a concave profile on the pad. Do not use sand paper for wood, that stuff will put more grit in than it takes out.
               Also periodically check the rims for digs or rough spots caused by contaminated pads. Any rim trouble spots can be addressed by carefully using a 120 grit cloth. If in doubt come see your friendly bike mechanic.
Before; A road pad (top) and a mountain pad (below), both with rim material embedded
After; Same road pad after some buffing. Good as new.

Posted on October 28, 2012 .