Hydraulic Disc Brakes - Formula B4

[will]

Recently I installed a set of Formula B4 disc brakes.

They are incredibly light and the calipers are actually a beautiful design.

However... these brakes have a huge appetite for air bubbles.  [smiley=diaper.gif] They are also nearly impossible to bleed. Hydro brakes with air bleed problems are about as much fun as broken glass in the bedsheets.

Most of the problems with the Formula brakes are in the levers. They are made of delicate magnesium castings and the reservoirs tend to leak easily. Any kind of decent wipe-out will destroy these levers every time. Argh!

SO... Is it possible to:
1. Use another brand of levers with these brakes?
2. Switch from brake fluid to mineral oil?
3. Buy levers only from some compatible brand?

Any voices of experience would be greatly appreciated as this could take a pound off the bike and a ton of frustration off my mind.

Help!  Will

[kiwi]

i thought the newer b4s had overcome the breakage problems...sprucey sprucey!!!!!!!

[Simon]

Will, I've been running B4's for a long time now and the only problem has been losing a lever reach adjuster(tiny thumb wheel),are yours the Gold caliper type ???I believe the newer B4's (black caliper with pro written on it)aren't the same quality as the older units (sprucey will be the best bet to answer that),
as for bleeding them have you got the formula bleed kit ???with this I find its an easy job but translating the instructions can be tricky so I just done it my own way,with the adaptor fitted to the reservoir and a syringe attached to that filled with brake fuild,I then attach another syringe to the caliper bleed nipple,I open the bleed nipple and pull on the brake lever and hold against the bars with an elastic band,I then operate the syringe with the brake fluid until the syringe at the caliper end is about half full and no air appears to be coming through,I then lock off the bleed nipple,then release the lever,before removing the syringe at the reservoir end give it a bit of pressure to ensure the bladder is full after releasing the lever.
This works for me though you may be using the same method,just thought I'd pass this on just incase,
Simon.
Ps I use Stendec crystal fully synthetic DOT 5.1 brake fluid

[will]

Thanks guys.

Yep, they're the olden golden calipers.

And, YES, they must have improved the breakage issue. I fixed mine with JB Weld (How 'bout that Junkster!) and broke them again, but the JB held firm.

The biggest headache is the leaky plastic reservoirs inside the levers. Wow. What a pain in the  [smiley=diaper.gif] when the fluid drips on anything!

I did do the bleeding process, Simon. And yes, it was like reading Beowulf! With the leaks in the levers, the bloody bleeding (British joke) didn't help.

So... would shimano/magura/avid juicy levers work?

I'm lost at sea & need the RNLI! Sprucey?

[Simon]

Sounds like you need a new bladder/s (for the brakes,not you)
I'm sure there's a modified unit available,do the levers sound squelchy when you pull them on,this is the sign of immenent failier of the reservoir,
by the way the older B4's (gold one's)are far better than the new offerings,
I'm very happy with mine but if I did change it will be to Hope mono mini's,nearly as light,reliable, second to none back up.
Simon.
this page on spruceys site may be of assistance
http://www.ukbikestore.co.uk/acatalog/Secure_Online_Shop_FORMULA_SPARES_183.html

[Sprucey]

Hi Will,

I use Formua brakes, have a lot of experience with them and also sell all the spare parts.

I don't know how old your brakes are but there have been a number of important rolling upgrades over the last two years.

1) The master cylinder (lever) reservoir membrane has been up graded. It is now slightly larger (more volume to cope with expansion from hot fluid), an improved material and most importantly, now comes with an aluminium (aluminum for our US friends!) mounting frame. This makes a much better seal under the membrane.

In my view, the membrane is a consummable item and should be replaced annually. You should (do as I say, not as I do!) bleed the brakes annually, changing the fluid.

2) The lever piston has been changed slightly. It is now made from a slightly softer nylon so the front tabs which hold the "Dogbone" lever connecting part do not break so readily in a knock and you don't loose the dogbone/barbell.

3) The Plastic torx screw on the front face of the lever reervoir can now be replaced with an alloy one, avoiding the usual breakage when closing after bleeding.

When you bleed the brakes using the two syringes, attach the lever one at the grubscew in the hose connector. BEWARE - there is a small (I mean V.SMALL) Oring under the grub screw which is easy to loose under the fridge! Very important part to stop air getting in the system.

After you have done everything Simon says (See what I did ther? The kid's game "Simon says"  [smiley=nod.gif] loosen the bar clamp, swing the lever vertical so the lever faces to the ceiling (or sky) and take out the torx screw. All the air under the membrane will have gone to the top and can be burped out through this hole by gently pressing on the membrane with your finger. Put a few drops of fluid back into the hole and replace the torx screw, letting the fluid overflow. DO NOT over tighten the plastic torx screw - see notes above! Eh, voila!

The final way to improve the feel is to leave the bike overnight, up right, with the lever strapped into the bar, opening the fuid circuit. Any small bubbles in the fluid should rise to the reservoir and can be burped using the procedure just described.

A few drops of air under the reservoir will not affect brake performance as long as you don't levae the bike upside down for prolonged periods (when the air could rise to the caliper).

DO NOT USE MINERAL OIL WITH YOUR FORMULAS - THE SEALS WILL ROT.

You can upgrade to higher quality Dot fluid - I use Dot 5.1 rather than Dot 4.0.

You can also now buy aftermarket stainless steel braided hoses from Goodridge and now Hope - that is supposed to improve the sharpness of the brake - as well as looking like the "Dogs bollocks!" Simon has Goodridge on his Oz and I am going to fit the Hope hoses sometime this year.

As for the lever structure itself breaking, there is not a lot one can do there. It is a casting and can be bought as that part only as a spare. I have never broken that part but I believe the area round the lever blade hinge has been beefed up and there is also a newer stronger design of corner cover kit - the plastic dust shield around the lever blade hinge.

This is where a lot of the weight is saved. There is no such thing as a free lunch - there is always a trade off between weight & strength.

I hope that helps? feel free to call or email if you would like any other help.

Best regards,

Sprucey

Mark Spruce
www.ukbikestore

02392 528 932