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1978 Triumph Spitfire 1500

Sorting the Brake System

Mum's Spitfire didn't have the most amazing brakes when we picked up the car. They were adequate for normal driving though. Well, whent we went to get the car running after it's summer storage (It's often too hot to drive these cars in the summer here) the brakes went to the floor. Admittedly I wasn't suprised, but after getting to the car once it had already been farted around with I realized there was a bunch of work that needed doing!

As part of this project the following was done before starting: Safely put the car up on jack stands, remove the wheels and disconnect the negative battery cable.

Here's what I found most upsetting, look at all the paint bubbling. I hate DOT3/4 brake fluid because it eats paint! Immediate decision #1 was to convert the car over to DOT5 which is a fully silicone brake fluid and will not damage paint.

Here you can see one of the primary culprits. This little monster is the Pressure Differential Warning Actuator. It's one of those pieces that you may look at a million times, but never bother with or understand what it does, that is, until it fails and dumps brake fluid everywhere!

Here's the goodies ordered from Spit Bits: Master cylinder rebuild kit, new rubber brake hoses & washers, and a pair of wheel cylinders just in case.

First step is to remove the Master Cylinder (which, ironically isn't in the picture. :). Use flare wrenches to carefully disconnect the two brake lines that connect to the Master Cylinder. Then prise up the rubber boot. Remove the pin that connects the master cylinder to the brake pedal lever. Finally, remove the four bolts that connect the master cylinder bracket to the body (I find this the easiest route). and lift the entire assembly away from the car.

The Master Cylinder is attached to the bracket with two bolts. The upper bolt has a nut on one side. The lower bolt threads through the captive nut (shown above).

Here we have the master cylinder on the bench. Like the red overspray from the last time the car was painted? Remove the two pins that hold the resevoir to the Master Cylinder and lift it away. Also remove the two rubber rings where the resevoir mates up.

First step is to remove the arm from the master cylinder. Pry up the rubber boot that covers the connection and then get a pair of pliers in there to compress the retaining spring clip. From there you can pull the part away from the assembly. Removal of the snap ring will also cause the upper half of the inner Master Cylinder assembly to spring out.

Under where the second resevoir rubber gasket was you'll see a small pin prodtruding from the master cylinder. Carefully pull out the pin with some pliers. This releases the lower section of the master cylinder inner assembly. Once the pin is removed it should simply spring loose. That being said, sometimes that lower section can get stuck. If so, blow some compressed air through the lower hole and it should push the inner assembly out.

Here you can see the entire brake master cylinder laid out on the work bench. I like taking pictures of these as they make excellent reference photos. It's time to get to each part that's going back together and get everything all cleaned up.

With the parts cleaned up I like to additionally lay out the rebuild kit in sequence with all the parts. This ensures that you know where every bit of the rebuild kit goes, and allows you to double check the parts to make sure they are the correct dimensions.

Here we've got the internals all fully assembled and laid out. Make sure to pre-treat all the rubber bits with brake fluid as you're putting them together. This facilitates the reassembly process.

Grab the lower spring assembly and slide it into the master cylinder.

Set the pin that holds the lower assembly in place. It's very likely that you will have to shove a screwdriver down the cylinder to compress the lower assembly before you set the pin.

Go ahead and set the rubber pieces that seal between the master cylinder and the resevoir. Coat them with brake fluid so that they reassemble more easily.

Insert the upper spring assembly. Put the large rubber boot on the connecting rod and then press the end of the rod into place. Using a pair of pliers to compress the spring clip which will hold in place.

Finally slide the large rubber boot over the end of the master cylinder. Reattach the brake fluid resevoir. Bench bleed as needed.

The rubber boot that goes over the bottom of the master cylinder has definitely seen better days. In the past I've had pretty good success letting parts like this soak in Meguiar's Vinyl and Rubber protectant. This one, however, was too far gone. I didn't think to order one of these as a replacement, so I'll have to add it in the next time I work on the car.

Now the mount has definitely seen better days as well. The original paint was pretty destroyed. There was also a nice coating of painting overspray as well as grease, oil, brake fluid, etc. While everything's apart we might as well clean this up.

Here you can see it from the "front." We'll go ahead and sent it through the media blaster.

Here's the bracket after sandblasting and a coat of paint. We need a little time to let the paint dry.

Now it's time to turn our attention to the Pressure differential warning activator. There's no preassembled rebuild kits for these. If you don't know how they work I recommend reading this good article by Charlie Brown on the Vintage Triumph Register. Carefully remove all the brake lines from this unit using the correct flare wrench.

Here you can see the unit up on the bench. It's a fairly unassuming looking piece considering exactly how much brake fluid it can rapidly dump out.

Very carefully remove the switch. It's a nylon part and requires a 19mm wrench for removal. You need to clean and dry this part out.

Remove the end cap bolt using a 24mm wrench. I had to place the part in my bench vice to get the bolt to come loose.

Pull the innards out by hand. I can guarantee that the innermosto-ring will be stuck inside the unit. Here you can see my fancy o-ring removal tool (a bit of bent wire).

Here's an exploded assembly photo showing all the parts.

This was one of those middle of the night repairs. With some searching and fiddling at Autozone I found some O-rings that fit really well. I've included the package in the photo. They're actually for Ford fuel injectors. I also opted to use a Stat-O-Seal washer (Napa seems to be the only store that carries them) for the main bolt.

Apply some brake fluid to the O-rings, and then press them on to the shaft. At this point you press the shaft back into the pressure differential warning activator, tighten up the end plug with the new Stat-O-Seal washer, and reinstall the brake switch. To install it back into the car start threading all four brake lines by hand, then bolt the part down. Finish by tighening up the brake lines with the correct flare wrench.

Now it's time to replace the front rubber brake lines. First disconnect the flare nut from the rubber brake line. The line is held in place on the frame bracket by a nut/washer combination. Once disconnected put the washer and nut back on the brake line. Then disconnect the line from the caliper. Repeat this process for the passenger side.

Then go ahead and remove the rear brake hoses. They are held on to the car in the same fashion. We're removing them all at once because we need to purge as much of the old DOT 3/4 brake fluid from the system. With all four rubber brake lines removed wrap the ends of the hard brake line with shop towels. Then use an air gun to blow through the brake lines to clean them out.

With the brake system purged it's time to install the new brake hoses. Connect the line at the caliper first. Ensure that you use a new copper washer. Never reuse the old copper washers because they have a good chance of leaking. If you do so, and your brake system leaks, then don't come whining to me. :)

Remember the nut and washer we saved along with the original brake hose? We need these to connect up the new brake line. Push the other end of the brake hose through the bracket and add the washer and nut. Leave it a bit loose for the next step.

Now here's why we left it a little loose. These flare nuts can be difficult to thread right, and if you're not careful you can muck up the threads. The slack allows you to align the brake hose to the flare nut. Once you have it threaded go ahead and tighten up the nut and star washer and the finish up by tightening the flare nut with the correct wrench. Repeat this for the other side of the car.

Here you can see the rear flare nut connection. It's shown as is because the spot is hard to see.

Unlike the front there are flared connections at each end. Rescue the nut and washer from the old line, and then install just as the front was done.

Repeat this for the connection from the brake hose to the brake line.

Here you can see the brake hose completely installed. Repeat the steps for the other side of the car.

The paint has dried on the Master Cylinder mount. Reattach the master cylinder to the mount and then bolt it down onto the chassis. With it in place you can reconnect the flared brake lines.

Reconnect the brake lever to the master cylinder with it's pin.

I'm filling up the resevoir with brake fluid. As mentioned before we're using DOT 5 brake fluid instead of DOT 3/4. Once the resevoir is topped off it's time to start bleeding the brakes.

Here you can see the catch container mostly full of DOT5 brake fluid. I used my vacuum pump to draw the brake fluid through the brake lines.

Once you've bled the brakes go over every connection and part in the system looking for leaks. If you find any leaks you'll need to fix them and then re-bleed the brakes. At this stage you should have a good firm brake pedal.

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Contents copyright 2008, 2009 - Jody F. Kerr

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