STRIP­PING THE FRONT BRAKES

Land Rover Monthly - - LRM Technical -

ON THE ear­lier Tdi Dis­cov­ery, Range Rover and De­fender mod­els, chang­ing brake discs could be a tricky job. On those mod­els not only did the brake pads and caliper need to be re­moved, but the hub had to be taken off the axle in or­der to re­move the old disc. This in­vari­ably ex­tended to re-pack­ing bear­ings with grease, re­plac­ing the oil seals and fit­ting new hub gas­kets.

It’s eas­ier with the P38 Range Rover and Dis­cov­ery 2 mod­els. Each disc is held on the hub by a sin­gle grub screw. When that is re­moved, the brake disc slips straight off over the studs.

THE DE­SIGN of the rear brak­ing sys­tem on Dis­cov­ery 2 and P38 Range Rover is very sim­i­lar to the set-up on the front. How­ever, un­like the front discs which are of the vented type to as­sist cool­ing, the rear discs are solid metal and the calipers are much smaller (front brakes do most of the work be­cause, un­der brak­ing, the weight of the ve­hi­cle tends to load onto the front wheels). But ev­ery­thing is dis­man­tled in a very sim­i­lar fash­ion. Again, there is no need to re­move the hubs, thus mak­ing the job faster and eas­ier than on ear­lier mod­els.

RE­BUILD­ING THE front and rear brakes on the Dis­cov­ery 2 and P38 Range Rover is as easy as tak­ing them apart in the first place – or ar­guably eas­ier, with­out rusty or seized parts to deal with. How­ever, the brak­ing set-up is the most vi­tal of sys­tems and must be built up in an or­gan­ised and me­thod­i­cal man­ner to en­sure that there are no er­rors. The old adage of check and dou­ble-check again is very im­por­tant with brakes. With that said, there is lit­tle that can go wrong, par­tic­u­larly as the strip­down has just taken place and is fresh in your mind and all is cor­rectly bolted up.

The front brake caliper is held to the car­rier by two flange head bolts. Th­ese bolts are re­moved with a 12 mm hexag­o­nal socket wrench. With the two bolts re­moved, the brake caliper can be eased off the car­rier and pads, us­ing a suit­able pry bar or large screw driver. As the brake caliper is lifted clear, the brake pads are re­vealed. They are held in place by slots in the car­rier and ap­pear to be quite worn.

The old brake pads are eased out of the car­rier and are dis­carded into the metal re­cy­cling bin. Brand-new brake pads will be fit­ted all round. The brake car­rier is fixed to the hub by two spe­cial bolts, with a 12-sided head. They are re­moved with a 14 mm bi-hex socket wrench. It is good prac­tise to re­place th­ese bolts as a mat­ter of course. With the rusty head, they will prob­a­bly round at any fu­ture at­tempt at re­moval.

Af­ter suc­cess­ful re­moval of the bolts, the car­rier is with­drawn and in­spected. They are gen­er­ally re­us­able un­less the up­per springs have seized. The brake disc is held to the hub by one screw. Cor­rect Pozidrive #4 screw­driver pre­vents head dam­age. If tight, try tap­ping the disc’s cen­tre hub. A gen­tle tap with a soft ham­mer will prob­a­bly be enough to ease the old disc off the hub, and over the wheel nut studs.

All four of the brake discs on the Dis­cov­ery are well worn and near to the end of their life, so new discs and brake pads are the min­i­mum re­quire­ment. The brake calipers will be re­placed too, so flexi hose is dis­con­nected. Oth­er­wise the caliper could be safely tied up, with the hose still at­tached.

As the sin­gle-pot rear brake caliper is re­moved, it can be seen that the cylin­der it­self is rusty. This will stick if pressed in to fit new brake pads. The rear brake pads are well worn and look some­what glazed, so their brak­ing per­for­mance will be well down on what it should be. The rear brake car­rier is re­moved in much the same way as the front one, us­ing a 14 mm bi-hexag­o­nal on the 12-sided bolt head.

The car­rier is now with­drawn af­ter the bolts have been re­moved. The spring ac­tion will be tested, checked and lu­bri­cated ready for sub­se­quent re­fit­ting. The screw se­cur­ing the brake disc to the hub is re­moved and the disc tapped off over the wheel studs as be­fore, us­ing a rub­ber-faced mal­let. The rear discs are not show­ing as much wear as the front brakes, but will be re­placed with fresh new ones, due to some groov­ing in the sur­face.

The rear brake calipers are in poor con­di­tion, and ex­ter­nally pit­ted (though this will not im­pair per­for­mance) and they’re ready for re­place­ment. Fol­low­ing re­moval of the flange bolts, the caliper is lev­ered off the car­rier in a very sim­i­lar way as the front calipers were re­moved.

The new bolts have clean, sound 12-sided heads, which will be re­mov­able at the next brake ser­vice. Old rounded heads are dif­fi­cult to re­move. The caliper car­rier bolts are ini­tially tight­ened us­ing a 14 mm socket wrench. They should then be tight­ened with a torque wrench to 129 lb ft. The new front brake calipers are OEM qual­ity parts from the Brit­part range and come com­plete with new bleed screws and bleed screw cov­ers.

The shiny new vented brake disc is fit­ted over the studs and onto the front hub, en­sur­ing that the screw hole is in line with the threaded hole in the hub. Cop­per grease has been ap­plied spar­ingly to the disc se­cur­ing screw thread, be­fore it is tight­ened in po­si­tion us­ing the Pozidrive #4 screw­driver. New OEM qual­ity bolts are used to fit each of the four brake caliper car­ri­ers – front and rear – with thread lock adhesive ap­plied to all of the threads.

Be­fore each of the brake calipers are fit­ted, new brake pads need to be put in place. Th­ese brake pad kits are supplied with new guide pin bolts. The new brake pads slot into the car­rier in such a way, that they are con­ve­niently held there, ready for the caliper to fit over them. The pis­tons in the new calipers are fully re­tracted, so fit­ting the caliper in place is very easy, with lots of clear­ance over the brake pads.

The front brake discs on Dis­cov­ery 2 are of the vented type – the two fric­tion sur­faces are sep­a­rated by an air cool­ing gap to im­prove ef­fi­ciency. All of the new brake discs are cleaned us­ing a brake cleaner sol­vent so­lu­tion to re­move the pro­tec­tive greasy coat­ing ap­plied at the fac­tory.

The old and tired orig­i­nal rub­ber brake flexi hoses are be­ing re­placed – and up­graded – with this set of braided per­for­mance hoses. The brake flexi hose is fit­ted to the caliper with a banjo bolt. New cop­per wash­ers are supplied with the hose kit. The front hoses will be at­tached to the brake pipe ends, still plugged with blank con­nec­tors (ar­row) to keep fluid in and the ABS pump primed.

At the rear, a new cop­per brake pipe has been made and con­nected to the braided flexi hose – and fixed to the mount­ing bracket. The four brakes are now ready for the brak­ing sys­tem to be bled via a vac­uum bleeder, pulling new fluid through each cir­cuit and ex­pelling air.

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.