Get bet­ter brakes:

It’s the lifeblood of your brak­ing sys­tem so keep it fresh for the best stop­ping power

Motorcycle News (UK) - - This Week -

Change your fluid

1 Be warned… brake fluid is evil

Brake fluid makes a supris­ingly ef­fi­cient paintstrip­per so cover body­work and have a stash of paper tow­els handy. De­fend the area around the tank and han­dle­bars against any pos­si­ble spillage. Chang­ing the fluid makes sense be­cause it de­grares over time, re­duc­ing brak­ing per­for­mance. Check in a work­shop manual for the in­ter­vals for chang­ing, and the ex­act type of fluid your bike needs: Dot 4 , Dot 5 etc.

2 Gloves on, lid off (but care­fully)

Wear pro­tec­tive work­shop gloves from now on. Re­move the reser­voir lid, some­times they are re­tained with a screw and lo­cat­ing bracket so make sure this is un­done. When re­mov­ing the lid do it slowly mak­ing sure the di­aphragm isn’t go­ing to drop off. Some­times it will re­main in the reser­voir, if this is the case gen­tly ease it off and have that paper towel to hand to catch any drips.

3 The need to bleed

Iden­tify the size of the span­ner needed to fit the bleed nip­ple. Re­move the rub­ber grom­met pro­tect­ing the nip­ple. Ide­ally use a ring span­ner and place it on the nip­ple so it can be loos­ened a few de­grees with­out hit­ting any­thing. Now fit the pipe from the bleed kit to the ex­posed nip­ple. If the pipe won’t reach the floor, hang the bot­tle from an in­di­ca­tor.

4 Get crack­ing

Crack the bleed nip­ple and ap­ply pos­i­tive pres­sure to the brake lever as if brak­ing gen­tly. Tighten the nip­ple and let go of the lever, then re­peat. When you see a clear stream of fluid with no bub­bles in the tube, you can just pump the fluid out with­out stop­ping to tighten the nip­ple ev­ery time. Watch the reser­voir – don’t let the level drop out of sight.

5 Pour in fresh fluid

You will no­tice that each time you pump the lever there will be a vis­i­ble re­duc­tion in the level, so keep it topped up. Some­times the process can be sped up by hav­ing your brake lever span adjusted out to its max­i­mum. Don’t be tempted to move the lever it­self too quickly or else it could pop the bleed pipe off and spit fluid ev­ery­where.

6 Re­peat on the other side

When you see a change in colour in the fluid through the trans­par­ent pipe tighten the nip­ple up, check the fluid level is OK and re­lease the lever. With a cou­ple of sheets of paper towel scrunched up, re­move the bleed pipe and catch and mop up any stray fluid. Most bikes have twin discs on the front, so the op­po­site caliper will need the same tech­nique.

7 Top up and check

With both calipers flushed with new brake fluid, pull the lever in for a fi­nal time, hold, crack the nip­ple and ob­serve that there are no bub­bles or air in the tube, then re-tighten. Do this for both calipers. Top up the reser­voir to the cor­rect level. Re­fit the cap with the di­aphragm, mak­ing sure it is seated cor­rectly. Fi­nally, make a visual check of both calipers, and give a wipe around with paper towel for any un­seen spillages.

8 Turn to the rear

The same tech­nique can be ap­plied to the rear brake. Quite of­ten you will need to re­move a side panel to gain ac­cess to the reser­voir. Again use the bleed kit, and pump out the old fluid while adding fresh. Note that many rear calipers are fit­ted with two bleed nip­ples, if this is the case make sure you flush them both out one at a time. And of course make sure they are both used to bleed out any air.

No snig­ger­ing as Bruce tweaks the nip­pleé

O Brake fluid bleed­ing kit from you lo­cal aut­o­fac­tor O Cor­rect grade of brake fluid (al­ways use a freshly opened bot­tle)

Span­ner for bleed nip­ple TOOLS

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