How to: Replace front brake discs/rotors, pads, and lines on a 308 QV

A how-to for those that need a step by step process.

You will need:
Discs- I used OEM brembo from superformance UK
Pads- I chose Hawk pads
Lines- Girodisc (can't go wrong)
a dial gauge
a vernier caliper or micrometer
vise grips3
brake fluid
17 mm wrenches
10 mm wrenches
5/8 wrench if you go with Girodisc lines
brake cleaner
optional speed bleeders for all 4 corners

Disassembly

The firrst thing you need to do is get the car up and all 4 tires off.

To remove the disc you need to remove the caliper first. Before you can remove the caliper you have to remove the connection to the brake line.

There is a rubber flexible line that attaches through a bracket to a solid steel S shaped line that runs from the back of the caliper to the bracket. Use the 10 mm wrench on the steel line nut and the 17 mm on the rubber brake line nut. Start with that top steel lien connecton first and then undo the other end of the steel S line that goes into the caliper. Take care when removing these steel lines as they can bend and brake...I mean break. Have smething ready to catch the brake fluid that wll run out.

Time to remove the pads. This can happed before or after you remove the caiper. To do so, knock out the 2 pins on the rear of the caliper that hold the spring steel in place. Pull each pad out with your fingers or pliers.


Now you can remove the caliper. It is held on by two 17 mm bolts on the rear of the caliper at 12 and 6 o'clock. Take note that there should be very thin spacers that mount between the caliper and spindle that are used to assure that the cliper and disc are parallel. Don't lose them. Just loosen the top bolt holding the caliper on and remove the lower bolt. Move the caliper around a bit to shake any lower spacers out. Put them aside with the lower bolt and now you can remove the top bolt with spacers and caliper. The caliper should just slide off.

Next you can remove the two 10 mm bolts that hold the disc on to the hub. They are the 2 bolts that help you align your wheel when you put it on the car. Once they are off you will have to work the disc off by hand or with a rubber mallet. It walks off the hub.

Last order of biz is the sometimes pain in the azz brake line removal. Tackle the end that connects to the steel caliper S line first by removing the spring clip using whatever you have. I used a vise grip clamped on the tab and a small hammer to knock it up and off.

The other end connects to the steel line above the A arn. This is the hard one to reach. I used a $1 tiny vise grip from Lowes Depot to clamp on to the 10mm steel line nut. You need to have that clamped so when you turn the 17 mm nut on the rubber line you don't twist the steel line breaking it. This takes a little inginuity so do what you will.

It only took me about 1hr per side to remove all of these components.
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Great photos. My front rotors are stuck nicely, so I'll probably invest in a dead blow hammer before the job.

 

Assembly coming up next.

 

Do you have to resurface the new rotors for their true flatness?

 

With the Brembos that I've got, I'm going to clean them up, install everything and just properly bed them in. No machining prior to installation.

 

The Caliper

Once you have the caliper off it time to put it on the bench and inspect it. Clean it up with some simple green or brake dust cleaner. Yes the caliper piston looks upside down and inside out. And yes it has an uneven notch in it. That's all normal and I'll get to that in a bit.

You need to inspect the piston dust boot for tears. If you need to replace or rebuild them there's a post for that. If all is OK then you need to push the pistons into the caliper. There are tools you can buy to do this or like many shade tree mechanics you can use a set of large pliers with something to cushion the teeth so it doesn't mare the piston or caliper and squeeze. This is when you will find out if you have frozen piston. Mine pushed right in and watch out for flying brake fluid from the brake line hole. Plug the hole where the break line goes in to the caliper with a shop towel so you don't spray the brake fluid everywhere.

Next you need to set the caliper piston angle at 20 degrees. This angle is important to keep the brakes from squealing. Use a template, which you can make from thin cardboard. The template is just a triangle about 4 ½ inches long with a 20-degree hypotenuse. Slide the 20 degree angle tool into the caliper to see if the 2 notches line up at 20 degrees. If they do not then you need to turn them. I used a punch on the lip of the piston and a hammer to rotate the piston with light taps.

If you have new bleeders now is the time to put them in.
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The rotors/discs

Before you just slap these things on the car you need to do a little checking for brake rotor parallelism. This is where you use your micrometer to measure the thickness of the rotor/disc at 8 points around the rotor/disc at about 1 inch in from the edge. You want an even thickness to prevent vibration. I found the OEM Brembos to be within spec.

Use some brake cleaner to remove all of the factory dirt and oil from the rotor/disc. Take care to really clean the inside of the mounting surface. Use a brush attached to your drill to celan the face of the hub on the car. You want that surface super clean and even so that there is little to distort the rotation of the disc. Once everything is clean mount the disc to the hub and secure it with the 2 retaining bolts.
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Great write up, does anyone make a two piece rotor to save some weight?

 

Measuring runout

Also known as warpage. When you rotate the disc you do not want it to wobble. To check runout on the disc you will need a dial gauge. I mounted mine to a jack stand with a small vise from the Depot. Place the tip of the dial gauge near the edge of the disc and pull it up a few times tapping it against the disc. Rotate the dial to zero and begin turining the disc by hand. What you want is less than 5 thousandths on an inch in movement. Those are the specs for the brembo discs. Anything above that and you might experience vibraton or excessive brake pad/disc wear. You really want to be below .004 though. One of my discs was a .001 and the other at .002. I made a shim for the one disc and brought the runout down to .001. I'm picky.

For more on runout measurement and correction see this video

[ame]http://www.youtube.com/watch?v=SSxCNbjKi-0[/ame]
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At this point you can install your new brake lines if you have them. Just do everything in reverse order and dont over tighten the new lines. Go for snug and then a bit more to prevent leaks.

Also, don't leave your wrench on the line when you tighten the other end...
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Installing the caliper

It's time to bolt it back up and the hard part is those damn little spacers. These spacers are important to aligning the caliper and pads with the disc at 90 degrees. If the caliper were at an angle you would have the top of the inside pad and the bottom of the outside pad making contact wh the disc first. That's no good for many reasons. So we want to make sure that everything is parallel.

If you find, like me that your car had no spacers you will have one pad close to the rotor and the other far. See my photo. I measured the gap with a feeler and split the difference. I had some copper shims on hand that were the right thickness. You can see the improvement in the after photo.

FYI There is zero room to get the shims on with that brake dust cover so I used a dab of red silicone gasket because it's so sticky. Once you have everything parallel install the pads and retaining hardware the same way they came off.
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Time to bleed the brakes

Do a web search on the process and maybe buy some speed bleeders for the car. Part number for the FRONTs is SB8125LL (8mm x 1.25 ) and the part number for the
REARs is SB7100 (7mm x 1.0)

http://www.stoptech.com/technical-support/technical-white-papers/bleeding-brakes

Be careful not to empty the master cylinder and allow air in.

 

Girodisc and others do, but I'm not sure of the weight savings. They tend to be quite a few more bucks though. Since I don't race the car, I'm not worried about it.

 

Bedding the brakes.

This is the process I used and it worked perfectly.

For a typical performance brake system using race pads, the bed-in procedure must be somewhat more aggressive, as higher temperatures need to be reached, in order to bring certain brands of pad material up to their full race potential.

We typically recommend a set of ten partial braking events, from 60mph down to 10mph, followed immediately by three or four partial braking events, from 80mph down to 10mph. Alternately, a set of eleven stops, from 80mph to 40mph, or a set of seven stops, from 100mph to 50mph, would be approximately the same. As with street pads, each of the partial braking events should achieve moderate-to-high deceleration (about 80% of the deceleration required to lock up the brakes and/or to engage the ABS), and they should be made one after the other, without allowing the brakes to cool in between.

Again, depending on the make-up of the pad material, the brake friction will seem to gain slightly in performance, and will then lose or fade somewhat about halfway through the first set of stops. This does not indicate that the brakes are bedded-in, except where race-ready pads are being used. This phenomenon is the same as that which occurs with high-performance or street pads (except that, when race-ready pads are used, they do not exhibit green fade, and they will be bedded-in after just one complete set of stops).

As when bedding-in any set of brakes, care should be taken regarding the longer stopping distance necessary with incompletely bedded pads. This first set of stops in the bed-in process is only complete when the recommended number of stops has been performed - not before. As a general rule, it would be better to perform additional stops, than not enough. The system should then be allowed to cool, by driving the vehicle at the highest safe speed for the circumstances, without bringing it to a complete stop with the brakes still applied.

After cooling the vehicle, a second set of the recommended number of stops should be performed, followed by another cooling exercise. In some situations, a third set is beneficial, but two are normally sufficient.

Racers will note that, when a pad is bedded-in properly, there will be approximately 2mm (0.1 inch) of the pad edge near the rotor, on which the paint will have turned to ash, or the color of the pad will have changed to look as though it has been overheated.

In summary, the key to successfully bedding-in performance brakes is to bring the pads up to their operating temperature range, in a controlled manner, and to keep them there long enough to start the pad material transfer process. Different brake system designs, pad types, and driving conditions require different procedures to achieve a successful bed-in. The procedures recommended above should provide a useful starting point for developing bed-in procedures appropriate to individual applications.

 

I have an '88 1/2 Mondial w/ ABS, so the system procedures should be the same. My question is, what type of brake fluid do most people recommend? The Castrol LMA or others?
Thanks.

 

Thanks.

 

Castrol LMA is great stuff and is fine for these cars. Just be sure to bleed all of the old completely out, it's worth the time to take all the moisture, etc. out with it.

 

Great write-up. I have one question: those copper crush washers crush, that's what they are supposed to do. Wouldn't that cause the calipers to losen with time?

 

I had the same concern but they were tightened so hard that I don't think they could crush more but I'll be checking them in a few hundred miles.

 

A little super glue work great to hold the shims to the calipers. They won't slide around.

 

Thank you for the great photos, Steve.

 

For the concerned: yes I used copper spacers which aren't ideal because the steel ones were on order and would not arrive in time for an event. The F part steel spacers will go in in a week or 2.

 

While the it's apart it might be a good idea to repack the wheel bearings.

 

Excellent work!

 

The wheel bearing end float was checked and all is well