Isuzu Trooper Owners Club UK™

[Rhanagar]

I originally wrote this up in my readers drives, but thought it would be easier to find here. Dunno if a mod wants to make it a sticky as well.

Mk.1 rear brakes. They are notorious for the handbrake being dire. I was kind of forced into the situation after a failed MOT, so went out and bought a new set of pads and disks for the rear.

Whipped the wheel off and found this:



and after removing the calipers was greeted by these bad boys



Funnily it passed the efficiency test, but was failed on lack of movement (read siezed)

Anyways to recon your rear brakes here is how I did it. Wheel off and look at the caliper. You will need to loosen several things before you can take everything off. Don't forget to clamp the flexi hose or you will end up with brake fluid all over your driveway ... well more than you need.

I have highlighted the areas that need to be undone in the next few pictures. As said don't take the bolts out, just loosen them so you can undo them with your fingers.




1) Chock front wheels and let off the handbrake.

2) Jack up both rear wheels and rest car on axle on axle stands, then remove rear wheels.

3) Under the car in line with the front passenger seat is the handbrake cable adjuster. Using a 12mm spanner slaken it right off.

4) Undo Flexi hose (Part "1") with a 17mm socket and move it out of the way. Make sure you have clamped it somewhere on the rubber bit to prevent excess fluid loss. This has a copper washer above and below the banjo union. Don't lose them.

5) Remove split pin and handbrake cable pin (Part "2")

6) Parts "3" are two 6mm allen bolts. These are the caliper sliders. They are hidden under two rubber caps. Remove the rubber caps (the top comes off completely, the bottom has a plastic cap). Slaken them both off but dont remove

7) Parts "4" are the bolts that hold on the caliper mount on. Again using a 17mm socket just slaken them

8) Once this has been done you can remove the entire caliper. Start with the slider bolts and take them out completely. The caliper should come off now pulling towards the rear of the car.

9) The caliper mount can also be removed now by undoing its two bolts.

10) The old disk can now be removed either by hitting it with a hammer from the inside. If it was anything like mine it might require quite a bit of persuasion.

11) Clean and Copperslip the face of the hub and wheel bolts so you have something like this:



12) On the caliper mount you will notice two metal clips that hold the pads in place. Mine were cruddy as hell, so I popped them out and used a dremmel wire brush to get them all nice and shiney again. Cleaned up the mount and popped the metal clips back in again.

13) Put the new disk back onto the hub and re-attach the caliper mount. I held the disk in place with two wheel nuts to prevent it wobbling about, as you can see in the final picture.

14) The caliper is made up of a spring loaded arm that the handbrake cable attaches to, a piston, and on the rear face a hidden 4mm allen nut that is behind a thin faced 14mm bolt. If you look on the back of the caliper you can see the bolt (item "5" in the picture below). Take it off using a socket and you will see the allen hole. By turning this allen nut you can wind the piston backwards and forwards. I found that the piston wouldn't wind back far enough on the drivers side (after I had unseized it). Turns out that the piston is slightly more complicated than I thought.



How to free a seized piston:

i) With caliper in hand remove the ring that holds the rubber seal around the piston.

ii) Remove the rubber seal by pulling it off. Careful not to tear it.

iii) Get your 4mm allen key and work the nut until you cannot feel any resistance. It has a tolerance between moving the piston in and out where its doesn't do anything. You have several revolutions like this. Turn it until you have the middle of this slack point.

iv) Get some molegrips and clamp the very outside end of the piston (the bit that is exposed when the seal is on) and give it some movement back and forth by 30 degrees or so either way Until its free. Some WD40 will help here.

v) Now if you have found out that you can wind the piston out with the allen key, but cannot wind it in you have a greater issue (as I had). The piston had a funny gubbins thing inside it that is held there by a great circlip. This has a thread in the middle which locates onto a bolt that is turned by the allen key. When the piston cannot be wound back in the gubbins thingy (GT for short) has popped out the back of the piston. Not a great issue if you know what you are looking for ... pain in the proverbial if you don't. To get the GT back into the piston you have to wind the piston out as far as possible and then gripping it with the molegrips gently work it out completely. If you look inside the chamber you can now see the GT. You can now twist off the GT by spinning it with your finger. Note which way it came out. When looking closer you can see it has a chunky wire circlip, and several teeth. On the bottom a spring held in with a circlip. To put it back into the piston just place the piston on the ground and tap the GT in square with a soft mallet making sure you have the spring end of the GT facing you.

vi) Getting the piston back in again is a bit of a chore, but possible. Slide it in as far as it will go. Get a 10mm spanner and use it as a lever in the cutout against the face of the piston, then gently wind the allen head in to draw the piston past the seal. If you hear a "ping" and the piston doesn't move you have pulled the GT out again and you have to re-insert it. If you can get a third hand its easier if you gently twist the piston back and forth as your doing it to get past the inner seal. Its the inner seal that makes things difficult here.

vii) Once you have wound it in about halfway, replace the outer seal along with its metal clip.

Back to the original job in hand

15) Wind the piston in as far as it will go. Take your inner brake pad (the one with 3 clips on the backplate) and pop it onto the piston.

16) Slide the outer brake pad into the metal sliper plates on the caliper mount after copper slipping the slider plates.

17) Copper slip the slider bolts, and push the caliper into place on the caliper mount and push the slider bolts back in. The "normal" bolt goes in the top, and "stepped" bolt goes nto the bottom. Make sure you push the handbrake cable though its guide hole on the braket on the caliper as you place the caliper. Tighten up the slider bolts with a 6mm allen key. Replace the plastic/rubber caps.

18) Re-attach the brake flexi and handbrake cable. You should now have something like this:





Now go and do the other side.

Next post ... bleeding adjusting the handbrake

NOTE: You do not have to undo the brake flexi if you are just replacing the disks and pads. Item "1" can be left in place. I only had to as I had to free up a siezed cylinder and therefore needed the caliper off completely. If you can wind the piston in completely without hassles then feel free to ingore this part. If however you manage to hear a "ping" while the cylinder is being wound in and the piston stops moving ... then your gonna have to take it ALL apart.

Now for the most annoying part of it all.

The easy bit is the bleeding. Now if you haven't removed the brake flexi you can ignore this stage as you should still have a nice dry driveway/garage. If you had to take the flexi off and dismantle the caliper then you will have brake fluid all over the shop, in your boots and eyes and all the little cuts and grazes. Brake fluid is a pain like that.

Bleeding:

1) Pop the bonnet and take the cap off the fluid reservoir

2) Go to the passenger side and put on your bleeding kit (I use a one man kit from Halfords. Does the job and not too expensive)

3) Crack the bleed nipple open and pump your brake pedal. Double check the fluid levels in the reservoir and top up as necessary.

4) Tighten the nipple when bled

5) Repeat for the drivers side

Adjusting the handbrake:

1) First off you need to adjust the pistons in the caliper both sides. They should be all the way in at the moment. Remember that flat 14mm bolt I told you about that had the secret 4mm allen adjuster under it. You need to sit behind the wheel and adjust the allen nut until you can feel/hear the pads biting. You will also see the spring loaded arm the handbrake cable attaches to start to move when the piston starts to bite. When you do remember the position of the allen key and undo it till you get to that slack moment I described between pulling and pushing the piston out. Pull the piston back a touch to free it again then spin the allen until you are in the middle of the slack point. I assume the slack point is a period when the piston is free to float in and out regardless of the postion of the GT.

2) Repeat for the other side.

3) Get someone to sit in the drivers seat and start the car then pump the brake pedal. Double check you are getting braking on the rear wheels. You shouldn't be able to turn them. For gods sake don't put the car in gear. All the while double check the fluid levels as you may get some loss as the brake system starts running at full power.

4) Adjust the pistons each time until your happy with the results, but switch the car off each time you go underneath.

5) Now the fun part of the handbrake. You need to get underneath the car and wind in the 12mm nut until you can pull the handbrake untill about half its length and the rear wheels cannot be turned by hand. You may find you need to adjust the allen nuts and the 12mm nut for hours on end until you get the right balance. Sometimes its there first time ... mostly its not.

6) Once done lock the handbrake cable tensioner into place with the other (the one towards the front of the car) 12mm nut. Then replace the two 14mm bolts that cover the 4mm allen nuts.
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

[Google]

[john (smiffy)]

nice wright up and some good pics

only one complaint you could of done it 3 weeks ago when i did mine    
_________________
cheers

[Rhanagar]

Lol ... cheers for the compliment. As you probably found out its a pain to get the things adjusted properly. Had to back out again today to tweak things, they were still biting a bit after a test drive and settled in.

Sorry about the timing, have yet to develope my psychic talents
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

[Rhanagar]

Useful Pictures:

The Gubbins Thingy in the back of the piston:



The allen screw that adjusts the piston:



The threaded bit the piston screws onto:


_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS

[MuZILLA]

Cheers for the great write up!  

[MuZILLA]

All good mate. I got some sleep and re-read over your post which has cleared it up for me.  
At least i didnt try to force anything while i was fatigued.

[Rhanagar]

Glad you sorted it. Apologies for not replying. I was abroad with little to no internet access.
_________________
1990 Isuzu Bighorn LWB Mk.I 2.8TD Manual Lotus Edition
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto Lotus Edition

Deceased
1994 Isuzu Bighorn LWB Mk.II 3.1TD Auto LS