I The two rnost common bEke fuids used n the autotrolve industry are fr ds that contaln polyalkylene q ycol ether and fuid that coniains sill.one or si cum based poymer Both fluids e common bLt very different in reoards t. the manner in uh.h they perform.i uids.ontaln n9 polyalkylene glyco ether are nrore wdey lsed and are the onlyfu ds that shou d be Lrsed n rac n9 brak€ iy(ems. Be.ause brake syn€rns may reach extreme temp€ratures brake fluid nrust have the abilily to wthnand th€se lemperatures and deqrade iap SILICONE.BASED FLUID FlLds conta ning s kon€ are geneElly us€d in m taryrype veh des and, because s kone-bdedf u dswillnotdamag€ pa nted rfaces, they e a io som€what .ommon in show.a6 Siicone basedf uidsareregarded n DoI5 f uids.They ehghy.ompreslble and can glv€ the drv€r a fee ng of a sponqy peda. The hlqher ihe bGke system temperature th€ more the .ompresilbi ty of the fu d Th s in.reases the f€e nq of a sponqy peda. Sili.on€ based fllds are non hydroscopic mean f9 thatthey w fot absorb or m x with water. When water is present n rhe brake system t w o€ate a waterifl situation. Be.arre waler bo s at approx matey 212"1 the abi ty of the bmke synem to and the neam created frorn bo ng water adds air to the syst€m. i s lmportani to .emember that wat€l may b€ present ln any bEke syn€m.5iicone bGke fuid ack the ability to dea wth this moisrure and w dramaticaLly deo€d€ a bake synem POLYGLYCOL ETHER.BASED FLUIDS F uids .onta nlng poyg ycol ether are reqarded a5 DOT 3, 4, and DOT 5.1 These types of uids are hydroscop c, meaninq that they have an abilily to nr x wth wat€r and sti perform adeqLatey However,waterwi drani.a y redl.e the boiinq point of the fu d. n a pasenger.ar ths is fot an $ue. n a Ece car t is a malor iss €, b€.ause d the boilinq po ntde.r€as€s, the performance of lhe f d also d€crease5. Po yq ycol type fluids are two t mes e$ .ompre$ ble than s con.. typ€ fl ds, even when heated. Les conrpr€srlbi tyofthebmkef uidw in(ed€ peda fee. Chang n9 fluid on a regu ar bass w lqr."atly increas€ the performaice ofthe bEke system. All bmke flulds irLrst meet federa nandard {l l6 Three Departm€nt af T6nspodation (DOT) min ma specifi.atioij for brake fluld are defn€d in this stand d. They e DOT3, DOT4, and DOTs I (forilulds based with poyakyene qlyco ether) and DOT 5 (for rllkone based f uidt ^llNlMAL bo I n9 po nts for spe.ll.ai ons are as follo s: system is a result of water that has tlrned to steam. The b dup of steam w create alr pre$ure n the rynem, someumes to the point that enough pr-p$ure i creared to push .aliper pistons iito the brake pad. This w (-"ate brake draS as the rotor and pads make conta.t aid can also reate more heat n the synem. Another way that mosture may enter the synem k throlgh dffuson. Diffuson o.cuB wh€n mostur€ eniets through rubber brake hos€s. Us n9 hoses made from EPD^4 materiah iEth ene Propyl€ne-Di€ne-[4ateials) OR itee braided brake hose with a nonjubber s eeve (rs a y Tefon) w qreatly redu.e the diffrslon THINGS TO NEMEMBER .A blake fuid's dry bollng poift B more mpo a.t than wet boiing point when u5ed ln a Gc nq blake5ystem. .Racing brake system fuld shoud be chanqed often.A system wth fr€sh fuid wi have a ower moisture content and therefore p€rfornr ben. . Never use rllkone bas€d fl ds in raclig Ne €r r€use fuid. Never mlx typ€s or brands of brake fl d. .Plrge the synem dGn) and replace the brake fuid often for maxlmum pe{ormance. 8o ng Wet Bo ng Dry DOT DOT4 DOT 5 500.F DOT5,1 518"F HTX600+ DoT 3 VS. OOT 4 and 5.1 AFCO HTX bEke f d dra matka y ex.e€ds all DOT 3,4, a.d 5.1 standards for wei and dry bo n9 polnts, lubri.ation, cotrosion protect on, and v roslty specin.aions. WET VS. DNY BOILING POINT Theterir bo ns polit,when used reqard nq bckef uid, means thet€mperatures arwhich bnkefuid w beg ntoboil. WET BOILING POINT Th€ minimLm temperatures at whi.h brake fluds w begln to bo when the brake system contains 30.6 water by volume of the DRY BOILING POINT The t€mp€Etlr€s at wh ch bGke fu d witt boillvlth nowaterpresent n the system. MOISTURE IN THE BRAKE SYSTEM Waler/nonure can be found in neaiy all brake 5yst€ms. Moistlre enters the brake sy(em in several ways One of the mor€ common ways 5 irom using od or pre opened fu d. Keep n m nd that brake fuid draw n moisture from the surrornding air. TqhtLy sealinq brake fuid bottes and not stor nq them for ong p€rods of ume wl he p k€ep moisture out. When chang n9 or bleeding bnke fluid, always replace master cylnder caps soon as po$lble to prevent nro stur€ fronr enterifg the system. Condensallon Gmall moistur€ drop eh).an form n lines and calipers.Asca lp€r and line temperatures heat Lp and cool repeatedt .oodeniauon forms, leavnq behnd an in@de n moisture/water Over time. the moisture becomes trapped in the ntema sectons of calipers, lnes,m t€r cylind€ts, etc.When thiswater reaches 212.1th€ water turns to n€am. Nlany tlmer, air ln th€ brake 136 w ww. Sp e e dw dy M ot o t t,.on