AU series 1 - brake pad change:
The following is a record of my brake caliper & disc rotor change on the rear axle of our 1999 AU series 1 Futura Wagon:
Rightly or wrongly, this is the way I did it. Please feel free to join in discussion on this topic by visiting our dedicated Trueblueford Forum & leave comments, share your experiences or ask questions!
You can visit Duggy's Visitor's Cars page by clicking HERE...
Here we are, ready to start - everything accounted for. Making sure you have everything needed before you start a job like this is critical - especially if you rely on the car you are working for, for transport! Therefore I strongly suggest reading to the very bottom of this article before you try anything similar, so you have at least a bit of an idea of what you might encounter before you start...
After 'chocking' the front wheels (safety first) and making sure I had both jack & jack stand handy, I always make a habit of loosening the wheel nuts before I lift the vehicle. While it is possible to loosen the wheel nuts while raised on the back of a vehicle (due to the hand brake) it's a good habit to practice meaning you won't forget when doing the fronts... And besides, you are going to NEED the hand brake off to complete this job - but more on that later.
And before you ask about those tyres - click HERE to find comments & them and read discussion on different people's experiences with different brands, types & sizes! And no - my experience with the Khumo Ecsta's wasn't a good one despite the rave that had been built up around them...
Never EVER attempt to work under a car or on any part of it that may fall on you without using a jack stand! As you can see by the re-enforcement on the base of the stand I was using, this is not the ultimate type to use with it's thin sheet metal base. However it was what I had at the time...
Here is a picture of the brake / axle assembly once I took the wheel off.
This picture shows the brake caliper after it has been removed. However this was the best shot to demonstrate what I was looking for when assessing pad thickness. You can see from the picture the relative thickness of the remaining pad material to the backing plates themselves (made of steel). I had identified the pads were in need of a change during inspection made when doing a service earlier (a torch or lead-light is a great help when doing this).
When doing this inspection, I make sure I check all four wheels - checking both inner and outer pads as it is possible for the pads to wear unevenly due to caliper seizure (I have seen one pad out of four go metal-to-metal due to the caliper equalization slider seizing - so it always pays to check). It is also important to check individual pads for even wear across the surface - indicated by a consistent layer seen at the edges of the pad while inspecting as described below. Uneven wear is a sign of trouble that should be referred to an experienced mechanic or specialist brake shop.
Above you can see photos of me checking the thickness of the brake rotor itself - something that you should be doing during your service routine (but many don't). As the rotors themselves wear with use (as do the pads) doing this check at each service interval is critical. The tool I am using to measure this is called a vernier caliper' (I will do another article on it's use later - as measuring brake thickness is just one of a myriad of uses for it). Used correctly, it can be used to measure up to + / - 0.05mm.
You will notice I am holding thin washers against the wearing surface of the disc between the jaws of the caliper - and these are there for good reason! As a disc wears, the pads cut a deep, wide groove in the wearing surface leaving quite visible steps on the sides. If these are not taken into account, they will give a false reading on rotor thickness - hence the washers, to make sure I was measuring the actual surface to surface dimension and not just from lip to lip...(I also measured the thickness of the washers and subtracted this from the overall result).
(you can see the 'lip' more clearly in this shot, right at the edge of the wear surface)
A micrometer can also be used to measure disc thickness and is more accurate - although that level of accuracy is not required for this job. However, one other advantage is you will not need to use washers to get around the wear-lip with a mic vs. a vernier But as I only had a vernier handy at the time...that's what I used!
A rotor has both maximum and minimum thicknesses - the maximum rarely needs to be worried about but is the maximum dimension recommended for operation within that caliper / pad set up. Any bigger and assembly may be difficult - if not impossible!
The minimum thickness is determined by the OEM's (Original Equipment Manufacturer) engineering department as being the minimum safe reliable thickness for the disc and is also the dimension at which the vehicle becomes un-roadworthy. In short, take your vehicle to a roadworthy or pink-slip inspection with rotors that are less than this and your vehicle will fail - full stop.
Failures that can result in going below this dimension range from simple warping due to overheating & not enough material left to maintain structure - right through to loss of brake effectiveness due to again - overheating or from the piston overextending on it's seals. In extreme situations, the rotor (particularly where a vented rotor is used) can shatter or wear right down to the vanes! Do not let this happen to you - it is sheer stupidity and puts the lives of everybody on the road at risk - including your own. Put simply, replace the rotors at the appropriate time.
Information on what the max & minimum rotor thicknesses for your vehicle can be found either cast into the rotor itself (Ford's OEM parts typically have this) or in the maintenance manual for your vehicle. Worst case, you can try ringing a brake specialist, parts supplier or mechanic & hope they're friendly enough to look up the information & read it out to you over the phone - but remember, if you ain' t paying their bill - they owe you nothing!
In the above picture you can see the OEM rotors as removed from my car, and the min-thickness information as cast into their surface.
In my case, I already knew my rotors needed changing as they were within 0.5mm of minimum thickness so I thought it was about time...
You can buy aftermarket rotors & pads, there is no need to go OEM in this department as there are some quite good alternatives out there (that said, it always pays to ring your local Ford dealer because sometimes they do have some good specials on offer).
My advice however is not just to buy anything you find (there are some cheap copies out there that are definitely NOT worth using) but seek specialist advice from those who fit them for a living on what brands can be trusted and what cannot. This is especially true if buying an unknown brand. I gained my advice on what to buy & purchased my rotors and pads through Jim at ABS in Geelong - a specialist brake repairer - and knew that since they had to hang their reputation on what they fitted, then it had better be good.
When buying, make sure you specify not only what make, model and year your car is - but have the build date handy just in case there was a mid-model update. You just never know with some of these things now-days!
On Jim's advice, I fitted a set of Lucas pads & have not looked back since, being a lot less aggressive on the rotor material than the Bendix pads (who, at the time of doing this job were the OEM supplier also) and I have found produce less of that insidious black brake dust that always seems to coat your wheels...
I have since fitted a set to the front also, and have noticed (seat of the pants) a slight drop in 'initial bite' vs. the OEM / Bendix pads, however this was very easily made up for by slightly increased pedal pressures. The only time I have not been happy with these is with the car packed to the hilt (camping) & having to do an emergency stop from 110km/h in SA due to a kangaroo cross the road in front of me. However, as I haven't done this type of stop so fully loaded with the Bendix / OEM pads on board, I cannot tell whether the lack of performance came from the pads themselves or the AU1's relatively small sized brakes under the extreme load conditions we were applying to them that day.
This photo shows me beginning to remove the caliper retaining bolts. Notice that I am using a spanner here - DO NOT be tempted to use a shifter / adjustable wrench, as this will most likely slip on the bolt heads damaging them, and even yourself! A ring spanner, open end or socket (if access is available) are all adequate for the job, make sure you have the right size though as one that is too loose will slip, and again have a similar result to using a shifter...
Once both caliper retaining bolts were free, I wriggled the caliper clear of the rotor - the wear lip on the outside was holding it back a bit - which is to be expected. The wriggling motion simply moves the pads back a bit until they can pass clearly over the top. I chose to leave the flexible brake line still attached (this is normal practice) to avoid having to bleed the brakes, therefore saving time, mess & money.
It's at this point that if the brake pedal is depressed at all, all of the fluid will rush to the corner you have just taken the caliper off of pushing the piston out of it's seals causing brake fluid to leak all over the floor. This is undesirable for a number of reasons - the least of which is the mess it creates and the need to bleed the fluid.
Be careful not to drop the caliper or place stress / tension on the flexible brake line - you don't want to damage the rubber in any way. While you are there, inspect the rubber line for any wear marks or perishing (cracks), leaks or otherwise...
While we are on that topic, I thought it worth while to mention that bleeding the brake fluid is typically required for one or more of the following reasons:
1/ most brake fluids will absorb water if left open to atmosphere. With time and a little bit of water by-passing seals here and there, the fluid will become relatively saturated with water and cause corrosion internal to the brake components, eventually chewing out seals, seizing components & generally requiring lots of money... Flushing by bleeding the brakes at the recommended intervals will help avoid this. There are brake fluids available that avoid this, however they are expensive and require a complete change of seal types & flexible hoses to use as well as flushing of the braking system. - And in short, most people aren't that keen on their car!
2/ everything wears with use - brake systems included. These wear particles will act as sand-paper within the braking system if left in place, ultimately wearing it out leading to leaks and in-efficiency. Flushing by bleeding the brakes at the recommended intervals will also help avoid this.
3/ as air is compressible, any air that enters the braking system will cause the brake pedal to feel 'spongy' and limit the force that can be applied to the braking system overall and at particular locations throughout the system. Air can enter either from leaks, or as discussed - by opening the system at some point whether deliberately (eg. during repair) or accidentally - for example while depressing the brake pedal while a caliper is un-restricted.
Next, I removed the rotor retaining screw. Again, make sure you use an appropriately sized Phillips head screw driver so you do not damage the screw socket. Of course, by this time I would also have the caliper removed...hmmm, must have staged this one not thinking of what I was doing! Ooops...
...And this is a picture of the hand-brake mechanism once I had taken off the caliper & rotor. As you can see, the hand brake on most late model Falcons operates a mini-drum inside of the disc rotor itself! So if you are having trouble getting the rotor off, make sure you've got the hand-brake off or else you won't be going anywhere at all...
Make sure you inspect the hand brake pad material for presence and wear while you're at it - I am told the pad material can easily come loose from the shoes themselves (to which it is normally glued) especially where a vehicle has been used for doing "hand-brakies". You've been warned!
The 'wrinkled' piece of tin you can see behind the hand brake shoes is actually the ABS tone wheel. In short, it is what the ABS sensor uses to sense that the wheel is still turning (i.e. not locked) as it senses each 'lump' pass the sensor...or not. If it senses that the wheel has stopped prematurely (i.e. before the speedo says it should have) then it fires the ABS modulator in the engine bay to momentary release the brakes to that wheel / branch.
A picture of the inside of the brake rotor itself. Notice the machined surface (or 'drum') that the hand brake shoes run in? Your new brake rotor should also have this...
Right, onto the next part of the job - fitting the new brake pads...
Now here is a trick you will need to take note of. To fit the new pads, you will need to force the piston back to a position able to accept the new pads with their pre-worn friction material thickness. This is the way I did it - by using one of the old pads to drill & tap a hole in, using an old piece of threaded bar I had lying around the workshop to make the jacking screw from. Again, I used an old pad to drive against, avoiding any damage to the piston itself (which is often made of soft, easily damaged aluminum).
Notice how far the piston has been extended as the original pad material wore? The black rubber you see surrounding it is a dust boot - something you will need to check to make sure it has no externally visible holes or damage (i.e. don't pull it off). Repair is probably a job for an expert so if you find trouble, so just finish the job and make a booking to have it repaired by a qualified mechanic or specialist brake repairer.
...And this is a picture of the piston in it's completely retracted position. I then removed my improvised piston retraction device (ala old brake pads) and used an old brush to carefully clean away some of the old brake dust. I spent some time doing this around the caliper piston dust seal too, and anywhere else a large build-up was found. Remember to clean all build-ups from the axle mounting face especially. I also used a small piece of wet and dry to sand any rust from this face...
BTW - just in case you were wondering, the big round black thing behind all of this is the dust shield, supposedly to help keep dust away from the disc & caliper itself. It works...sort of!
HOWEVER, it is at this point that I should warn you - the dust created by brakes can be quite dangerous to your health and you should make every effort to avoid breathing it in. Some early brake pad materials contained asbestos - even up until latter years, so be careful because you don't really know what you'll be facing and some imported product may still contain traces.
In hindsight, perhaps the safest way to remove it would be through an old vacuum cleaner and most workshops now-days under Work-Safe are forced to use some quite complex equipment to protect their workers from this. You've been warned!
Now, onto the caliper...having already removed the pads themselves:
Here I have just removed the carriage (pulls straight off the slider pins which you can see still covered in grease). These are troublesome on the AU and should be cleaned & inspected for wear / corrosion / resistance to free running. These are so troublesome in my experience that I do not do a pad change without having a caliper seal kit on hand - required to obtain new seals if needed as well as the correct grease required for assembly / lubrication. Correct grease is a zinc based grease. Don't use normal bearing grease as this will melt under the high temp and run away
The sliders themselves are required in allowing the caliper to self-centralize, with only one piston available for force distribution. Put simply - if they fail / restrict movement due to binding / corrosion, then force will be applied unevenly, and one pad will wear more than the other - accelerating the need to change pads and reducing brake effectiveness.
If any signs are present that the pads have not been wearing evenly (eg. one pad worn more than the others) this is a sign that the caliper sliders need work and extra attention should be paid.
Note also the small rubber cap covering the bleeder opposite to the brake line connection - make sure it is still in place once you re-fit the caliper itself as it helps keep water (stopping corrosion) & dust out of this.
Here is a picture of the caliper seal kit that I obtained - it has more components than I needed (they were not available separately at the time) so you will note the larger piston seals included. Note the grease sachet & smaller slider seals.
Note in the picture above, the caliper sliders cleaned and with new seals applied. I recommend doing this one pin at a time so that you always have one to refer to in making sure you don't fit these backwards...
This is a picture of the opposing pad carriage which I have cleaned carefully in solvent to remove any contaminated grease from the slider bearing surfaces...
And a close-up of the seal-mounting ridge. Make sure this area is clean (to enable the seal to seat properly) and free of corrosion. When assembling, carefully slip the seal over the edge of this lip so that it is retained when the caliper body & carriage move independent of each other. I gently tested this by slowly pulling them slightly apart to make sure the seals were retained properly.
Assembly was pretty much just a case of making sure that everything is assembled in the order that it came out in, making sure the appropriate Loctite was used on the caliper retaining bolts and that the anti-rattle shims were installed correctly between the caliper & the pads themselves - sorry, no photos of these!
And here is a photo of the new rotor installed including new brake pads! Remember to clean the rotor wearing surfaces (both where the pads run & where the hand brake acts on) with degreaser, as these areas are often covered with a corrosion inhibiting oil which will do no good for your nice fresh new brake pads what-so-ever...
Making sure to remember to fit the retaining screw as per the original too...
So there you go - and after completing both sides I hit the road for the critical road-test and then handing it back as the family truckster once again... But there's one thing about brakes - since they are a significant safety item, if you are at all unsure about any of this - hand it over to a professional. It's not worth the risk if you get it wrong...