Maintenance/improvement Tips - 4.2

[anchorman]

Difficulty - Medium

Time - Allow 30 minutes per side.

Tools required - After lifting and securing the vehicle you need a pair of pliers, large screwdriver, a hammer and punch if the pins are tight and some Coppaslip or similar copper based grease. The very best standard road going pads (and more than a match for most web available "performance" pads) are genuine Toyota which are available at a discounted price from Lindop Bros. Pm Parts_King for details.

Introduction

The rear caliper is of the reaction type and is very simple to work on. When the brake is pressed, the piston pushes the inner pad into contact with the disc. When the inner pad has contacted the disc an equal and opposite force pushes the caliper (which is free to slide on guide pins) backwards and this in turn is connected to the outer pad via the caliper bridge. The outer pad is then brought into contact with the disc under equal pressure and the brake is applied. There are no return springs to release the brake. Only deformation of the piston seals and the action of the disc clearing the pads allows the brake to release. In a similar way there is no adjustment of the brake as the wear is compensated for by the piston travel and the caliper sliding on the guide pins. As the pads wear, fluid is displaced from the master cylinder reservoir and there is enough capacity of fluid to cater for fully worn front and rear pads. When new pads are fitted, the fluid is pushed back into the reservoir and for this reason the fluid should not be topped up between brake pad changes unless the fluid drops below the "MIN" mark or the warning light indicates that a leak has occurred and this case the fault should be investigated immediately. The only time the fluid should be topped up is at the two year service interval when it should be changed.

Specifications

Minimum pad thickness - 1.0mm

Minimum disc thickness - 7.5mm Note; There will almost always be a lip of rust around the outer diameter of the disc and the greatest wear will always be on the wear path around 15mm from the outer edge of the disc. This is because there is a higher rotational speed at the outside diameter and also there is some "off brake" contact as the hub bearing allows some swaying movement of the disc when cornering.

Brake Fluid - SAE J1703 DOT3 Note; TGB are currently supplying DOT 5.1 which can be mixed.

Procedure

You are responsible for making sure the car is safe. For best results use a trolley jack and axle stands. If you do use the supplied jack, remember that it is only a very temporary device for changing a wheel and under no circumstances should you risk putting any part of your body under the vehicle.

Refer to this exploded view of the brake;

The pad protector is just clipped over the retaining pins so just get a screwdriver under the edge and pop it off. On the car I worked on they had corroded away! Next there is a spring steel clip that retains the two pad guide pins. It simply pulls out of one pin first then the other.

Use a pair of pliers to pull the guide pins out or if they have siezed you may have to tap them out from the back. If they are very tight take care as the caliper casting may crack or break. In this case get an assistant to hold against the casting with a cold chisel or similar heavy metal drift. This will absorb some of the shock of tapping it out. Luckily they usually come out with a bit of "teasing"!;

This shows the retaining clip out and the pad guide pins partially removed;

With the pins removed wriggle the pads out of the caliper. These calipers have a week spot. The abutments where the pad registers in the caliper are relatively small. This is a good idea in that it reduces the risk of the pads siezing in the caliper but can lead to excessive wear as the forces of braking are taken by such a small area. Examine the caliper in the area shown by the orange circle and if they are excessively worn you may have to renew them. Bear in mind that new pads may locate in a different position so try them in first before condeming the caliper;

If you are experiencing any rattling or clunking noise from the back end which stops when you press the brake pay particular attention to this - it is a common problem. Changing the disc and caliper is covered in another tutorial. If the disc is unduly worn or corroded do not fit new pads without the disc as performance will be affected and in any case excessive corrosion of the disc is an MOT failure. Equally, do not fit new discs and not new pads. Resulting damage to the disc is false economy. If you are using the old caliper clean the abutments first with a file or emery cloth. In order to get the pads in it will be necessary to push the piston back in. The Toyota method is to use a drift or large screwdriver to push it in;

Another method is to fit the INSIDE (piston side) pad in first then use the screwdriver to prize the caliper bridge outwards off the disc until there is room to fit the outer pad. In either case do not damage the wear path of the disc.

If somebody has topped up the brake fluid it will be pushed out of the top of the reservoir. Either syphon some fluid out, collect as much as you can with rags or undo the bleed nipple on the caliper and allow the fluid to be displaced. If you do the latter, follow the instructions in the caliper change tutorial for bleeding the brake. Easiest way for future reference is do not top up between fluid changes as indicated above!

Back to the reasembly This photo shows the pads being fitted to a new caliper with new disc but the process is the same. Put the pads in as above. It is acceptable to smear copper grease on the abutments and the back of the pads where they contact the caliper/piston but not essential if fitting genuine Toyota pads which are dampened for noise. NOTE: if the pins, clips and shield are unserviceable you must fit new ones (available from Parts-King)

Fit the guide pins and the retaining clip - it just stretches accross the two pins ;

.......then stretch the shield over the pins;

There is no adjustment but be sure to press the brake a few times in order to push the pads into contact with the disc. The first few presses might see the pedal go right to the floor as the pads are pushed inwards and you want to do that before you move the car!

Refit the wheel and lower the car - wheel nut torque - 103 Nm (76 ft/lbs)

[Parts-King]

Rear brake pads are £30.50 DELIVERED to any UK mainland address

You can also buy the shims, clips and pins, however this is an additional £42.10

PM me to order, we keep stocks on the shelf

Kingo

[pessimistic]

Hmmm - I changed my rear pads the other day and found that I had to remove the outer part of the caliper by undoing the two back-studs. I then changed the pads pretty much as per the method you described before refitting them and bolting back up. Have I created a potential problem for myself by splitting the disc carrier?

Also, I now have a bit of sponginess in the brake pedal travel - can you point me towards a description of the bleeding procedure?

Ithengu......

[anchorman]

Hmmm - I changed my rear pads the other day and found that I had to remove the outer part of the caliper by undoing the two back-studs. I then changed the pads pretty much as per the method you described before refitting them and bolting back up. Have I created a potential problem for myself by splitting the disc carrier?

Also, I now have a bit of sponginess in the brake pedal travel - can you point me towards a description of the bleeding procedure?

Ithengu......

There are two lots of bolts at the back. Two that hold the two halves of the caliper itself and two which form the sliding pins for the caliper and hold it to the carrier.

You should never seperate the two halves of the caliper which I've indicated in red here;

In this case the piston half of the caliper would have stayed attached to the brake and the outer Shell would have come off. If that is what you did then make absolutely sure that it is not damp around the caliper as it is rarely possible to reseal them properly. Also it will account for the spongyness unless you bled it after.

On the other hand if you merely took out the sliding pins that is OK.

So. If you did it with the right bolts why are your brakes spongy? Well the answer is they probably aren't. Go to your vehicle and with the engine off pump the pedal several times which will evacuate the vacuum from the servo. The pedal should come to the top and go virtually rock hard. Keep your foot hard on the brake and start the engine. You will find that the pedal creeps right down. This is all as it should be.

If on the other hand you did incorrectly seperate the caliper halves and the pedal is spongy after pumping the brake with the engine off then your suspicions are probably right and you have admitted air into the caliper.

I will tell you how to bleed the brake but you should take care in doing this as you could let more air in and I reiterate that you must check for the slightest signs of weeping around that joint. If it is leaking then don't risk it any further and get a new caliper.

To bleed the brake first make sure that the reservoir is full. Initially you can vent the brake by gravity. To do this get an 10mm spanner and open the bleed screw after first removing the rubber cap. Undo it about a full turn and fluid should start to emerge. If it does not then wait a few seconds or maybe try opening it another turn. When the fluid starts to run bubble free close the bleed screw (nip it tight but take care not to snap it off). Now go back and do the pump test to see if the pedal goes hard. If it does do no more. If it doesn't you may have to pump the air out. In this case you need an assistant. Get them to sit in the car. Get a pice of rubber tube that is a good fit on the bleed nipple and a glass jar or bottle. Put the spanner on the nipple then the rubber pipe and trail the end of the pipe to the bottom of the bottle as shown here;

Slaken the nipple about half a turn until the fluid can escape and allow about half an inch to settle in the bottom of the bottle then get your assistant to press the brake steadily to the floor over about a 2 second period. When they have the pedal at the bottom tell them to hold it there and tighten the nipple. When it is nipped up tell them to allow the pedal to come right back up. Undo the nipple and ask them to pump it again. Repeat the process until no bubbles emerge from the end of the pipe then tighten the nipple and do the engine off pump test.

To summarise, the nipple should only ever be open on the down stroke and only ever be closed on the up stroke. This will pump air out but not allow it back in. Keeping the end of the pipe under the fluid is a belt and braces job that would only let fluid be drawn in by accident rather than air if you make a mistake.

Check the fluid level afterwards. You should only need about an egg cup full of fluid displaced to get all the air out.

[pessimistic]

ahh b*gg** - I did split the caliper.....

Will check tomorrow morning for weeping before I go to work and if OK will bleed as described.

Watch this space for more info.....

[anchorman]

ahh b*gg** - I did split the caliper.....

Will check tomorrow morning for weeping before I go to work and if OK will bleed as described.

Watch this space for more info.....

Some calipers allow fluid behind the caliper bridge and some don't but without the opportunity for me to double check we have to assume the worst. If there is no weeping and the pedal pumps hard don't disturb it any further.

Regards

I will be back late on Thursday afternoon for your update!

[pessimistic]

After reading your last but one post I couldn't get to sleep so ended up crawling under the car at 1-30am looking for leaks! The good news is that everything is bone dry.

Will bleed this afternoon after work......

[gcams]

Changing the disc and caliper is covered in another tutorial.

Firstly, a big thank you anchorman for your tutorials, which are so clear and concise!

I stumbled upon this tutorial whilst searching for info on changing out the rear discs/pads, as it doesn't seem to be included in the pinned Technical information/hints & tips thread? I noticed that you mentioned (as quoted above) that the rear discs were covered in a separate tutorial, but I've been unable to locate this?

I'm planning on doing a full front/rear disc/pad swap this coming weekend, and I'm wondering if the "part 2" of the rear pads/disc tutorial was available for the 4.2 somewhere? I couldn't find it through various searches so I'm hoping somebody might have a bookmark saved for it.

Many thanks and kind regards,

Graham

[anchorman]

After writing that Graham, I couldn't decide whether to go ahead and do the disc tutorial because changing the rear shoes is quite difficult (fiddly). However, I will look what pdf's I've got and may throw in a couple of photo's. If they haven't appeared by about Thursday send me a pm as a reminder.

[gcams]

After writing that Graham, I couldn't decide whether to go ahead and do the disc tutorial because changing the rear shoes is quite difficult (fiddly). However, I will look what pdf's I've got and may throw in a couple of photo's. If they haven't appeared by about Thursday send me a pm as a reminder.

Many thanks indeed anchorman!! I'm hoping I won't need to change out the handbrake shoes and I'm assuming I can leave the hand-brake mechanism all in place and still swap out the rear discs fairly easily?

With the Rav coming up to 8 years old, I also opted to get the rear shim/clip/pin kit from Kingo as I figured it couldn't hurt. I've just got my fingers crossed now that I don't need new callipers!

[anchorman]

Difficulty - Medium

Time - Allow 60 minutes per side.

Tools required - A pair of 8mm bolts, screwdriver, spring release tool (can be manufactured), some coppergrease or HM grease and a selection of usual mechanics tools.

Introduction

Most 4.2 and 4.3 RAVs employ a rear disc brake and combine a drum parking brake into the design. The rear disc brake (foot brake) is a simple single piston design with a reacting bridge to the outer pad. In this design, when the inner pad touches the disc and cannot move any further, the outer pad is applied when the bridge is slid along guide pins with an equal and opposite force.

Changing the rear discs and changing the handbrake shoes goes hand in hand. Only when the shoes are in near perfect condition does it make sense not to change them. The handbrake is a "static brake", in other words it should only ever be operated when the vehicle is at a stand. For this reason, in theory it should never wear out. However, if new shoes are fitted with an old disc or vice versa, it follows that no "bedding" can take place and this is the reason that you should normally fit new with new. Having said that, there is a procedure for bedding a combination of old and new but this must be done with great care and is shown in a later pdf.

Procedure

You can see above how to remove the pads and caliper.

Have a look at the handbrake instructions here to see how to de-adjust the brake.

http://toyotaownersclub.com/forums/index.php?showtopic=77297

Then follow these instructions;

Pay attention to the order of the shims and pins. You did absolutely right buying these off Kingo - they are often overlooked.

hbrake parts.pdf

With the handbrake off and the brake de-adjusted, try tapping the disc and it may come off. If you intend re-using the disc, hold a piece of timber against it and tap it with a heavy hammer or lump hammer. If it doesn't come loose, screw two 8mm bolts into the extraction holes and wind them in progressively by equal amounts;

With the disc removed, you can see the shoes. Follow these instructions to remove the shoes but I will add a few photos for clarity.

h brake.pdf

hbrake2.pdf

NOTE - the pdf shows the LH brake and my photos show the RH brake so keep that in mind!

Trust me, the pdf makes it sound easier than it is. This is a fiddly little job and you have to work behind the hub. My advice is that you use a screwdriver to turn the hub (gearbox in neutral);

.........to line up the cut outs with those steady pins. I have the proper tool as you can see here;

The idea is to press the cap in and twist it quarter turn to align the slotted hole at which time it will spring off. You can do it with pliers as shown here;

Put your finger around the back of the brake and stop the pin from pushing through and then push and turn. You will drop the pliers many times and you will get a large collection of blood blisters but once you get the knack they will pop off. If you really struggle, ask an assistant to stop the pin pushing through while you use both hands on the pliers. When the steady posts have been removed you can see about unhooking the shoes. It is sometimes useful to take a few digital photos so you can see how they go back. Here you can see I have the proper tool but you can make one by bending an old coat hanger into a large hook and making a tiny hook on the end;

When the return springs are off you can remove the front shoe but the rear shoe has the handbrake lever attached. To unhook it, pull it down past the hub...............

......and let go. Now use both hands to push the spring back up the cable and grip the cable with a pair of long nose pliers then slid the cable off the lever;

Now you can clean everything up and remember, if you have any doubt about those shoes replace them. Here you can see I've cleaned the backplate and greased up all the contact points;

Refitting is described in this pdf;

hbrake3.pdf

It is basically the reversal of removal but take your time and don't forget a second pair of hands might make things easier if you can find a willing assistant. You need the handbrake cable hooked on and then fit that rear shoe. You then need the other shoe and the shoe strut with all the little springs. Use these pdf's and you photos to check all is OK. If you didn't get blood blisters taking the steady posts off, don't worry you will get plenty putting them back :censor: Don't forget there is a cut out in the hub that will afford some more access but it isn't exactly spacious so if you get upset, have a brew and leave it a while. When it is back in one piece it should look like this;

Now clean the linings with abrasive paper (avoid the dust) and eyeball the shoes to make sure they are concentric with the hub. Now would be a good time to apologise to your assistant for all the insults you made while fitting those steady posts - don't forget there is the other side to do. Pop the disc on and run a couple of wheel nuts up just while you adjust the shoes as shown in the handbrake instructions;

Now build up the rest of the brake (caliper and pads).

OK now if you mixed old and new you will have poor contact between the shoes and pads and as this is a static brake you will never get them to bed in. For this reason it is necessary to force bed them and think on you are working tiny brakes against a gigantic vehicle and you can soon do some damage so if in doubt to it little and often and only enough that the handbrake holds. It is acceptable to rub the handbrake with slight pressure for a few seconds from 30mph once every 6 months just to keep the linings clean.

hand brake settling in procedure.pdf

[gcams]

Thanks again anchorman, that's a big help!! I gather that de-adjusting the handbrake is necessary to ensure they don't bind when trying to remove the old disc? I'll await the next installment with baited breath. :) :)

[anchorman]

Post now complete (post No 11)

[Ravi Shankar]

These tutorials are excellent many thanks for the time and trouble to do it.

[gcams]

Post now complete (post No 11)

Thank you so much anchorman, I cannot thank you enough for all the time you've put into producing the tutorial!! I definitely owe you a pint if I find myself in the Peak District!!! I never thought about the fact I should be changing out my handbrake pads with the new discs too, so thanks for drawing my attention to that rather critical oversight on my behalf. Looks like I'll be getting back in touch with Kingo!

Incidentally, can you recommend a place I can buy reconditioned rear callipers, as I have a horrible feeling I might need them (anticipating the worst). Thanks again.. I'm going to study this very hard before attempting it. It's a lot more fiddly than I had anticipated, but my rear discs have gone onto back-order, so I've got a bit of time up my sleeve (still hoping to do front discs this weekend if the weather holds).

[anchorman]

We had some discussion about caliper prices recently. I thought I paid about £60 each (and they were blueprint boxes with brand new not reconditioned - the ones in the photos) but somebody said the cheapest they could find them was £100. Just google Partco or motor factors in your area. You could always try Kingo too. The critacal point with the calipers is the abutment where the pad fits. Try a new pad in and if it isn't snug because it is worn you may well find they rattle or clunk in service.

[gcams]

No worries, thanks for that.. sounds like it's definitely worth trying the existing ones first before jumping the gun with ordering new ones! Especially if they are around the £100!!

[Agrajag]

Thank you for this informative guide, got the shoes and springs today and is now reading and psyching myself up for the task.

Seems to be a little fiddly on the 4.2:)