CALIPER REBUILD

 

Did not know what to expect when I started on the calipers.  The car was obviously under water for some time and I assumed the calipers would be a possible total loss.  I first started with the rear calipers as I wanted to modify the rear struts for height adjustability.  Looking at the calipers, they appeared bad, rusty and caked with mud and grease.  

 

The first challenge was to remove the emergency brake system, but this was a mystery as the only attachment point was a hinge pin that was in a blind hole (only one way in or out) so you could not just punch them through.  These pins also acted to attach the emergency brake pads.  After some superficial cleaning, I noticed that the pins were threaded internally and made the assumption that they had something to do with removing them.  The threads were 10-32 so I cleaned the threads with a tap and threaded a new screw in.  The pin was rusted in place, so any hopes of just pulling them out was not in the cards.  I had to fabricate some sort of puller.  Decided to use a 1/4" tube cut 1/2" long.  Screwed in a nut on a 1" screw and then placed a washer on the tube.  Screwed the assembly in as far it would go on the pin and started to turn the nut out effectively pulling the screw up and the pin along with it.  It worked like a charm.

 

Trick is to use lots of penetrating oil.  And the pads must be removed prior to removal of the pins as the pads hook onto the smaller diameter center part of the pins and will lock them in.  After the initial tug breaking the mechanical hold on the pins, the pins draw out very easily. 

 

Disassembly of the emergency brake is fairly straight forward.  Unhook the spring and remove the two hinge pins at the bottom that are secured with cotter pins.  There is an adjustment screw that has a special ridged nut that spins on a spring that indexes or locks the nut in place.  Be careful not to lose the spring as I think it is no longer available.  

 

 

Next step was to pop out the pucks.  Sometimes easy, sometimes not so.  Peel off the rubbers protecting the pucks and remove any rings.  The Lotus has steel rings on the front calipers but not the rears.  Unfortunately, water had gotten into mine and there was lots of rust.  Again soak with penetrating oil.  I use a "C" clamp to first try to break the mechanical bond of the rust by pressing the puck inwards every so slightly, just enough to see it move.  Then I used air pressure through the brake line passage to pop the pucks out.  First I placed a 1/4" breaker bar in between the pucks so they don't go flying across the garage or worse yet in your face.  I also hold a towel over the caliper for any excessive oil spray that may happen when the pucks release.  The air should move both pucks out which will hit hard on the 1/4" breaker bar.  At this point, both pucks will still be seated in the caliper halves.  Using you "C" clamp again, hold one puck in the caliper and apply more air until the other puck pops out.  You may have to squeeze the puck back in a bit to allow clearance for the opposite puck space to be withdrawn from the caliper.  Now if you are lucky, the air will pop the one puck out, and the second puck can be pulled out by hand.  If not, you may need to reinsert the other puck, hold that one down with a clamp and use air to pop out the first puck.  But since the puck had just been removed, you should be able to muscle it out.  

 

 

Now for the no so easy.  From time to time you get a very stubborn puck that will not budge no matter how much air, oil, or heat is applied.  In these cases the only hope that I had found was to use a pneumatic grease gun.  the grease gun develops so much pressure as grease will not compress as much as air.  But it is a messy job. You will also have to fabricate an adaptor from the 1/8" NPT thread of the grease gun to what ever thread you have on the caliper.  I used an Aluminum hex rod, mill down one side to thread for the caliper, bore a hole, and tap for the 1/8 NPT.  A couple of pumps and the puck is out, albeit in a mound of grease that tends to splatter as the puck exits.  But you have to do what you have to do.  I know some people will hone out the puck pockets during a rebuild, but I never understood the rational for that as the pucks really do not touch the caliper walls, or at least they shouldn't.  The only thing the pucks should be in contact with is the rubber seal inside the pocket.  So unless something is wrong with the alignment of the puck, honing is not necessary.

 

   

While the factory manual warns that splitting the caliper halves should never be done, I didn't see this as a problem as I have done this numerous times before from Porsche to Jags with no issues.  As long as you can get the rubber seal that sandwiches between the halves to seal the oil passage you are good to go.  But I did check first and yes, they are available for $2.50 each from RD Enterprises.  Each caliper front and rear takes one seal.  I was very happy to see that there was no corrosion.  

 

 

Finally with all the parts disassembled, it's time to get them clean.  I use Muriatic Acid on all steel or iron parts.  Muriatic acid is the main ingredient in all rust removal products and in its pure form it only costs $8 a gallon.  But this is serious stuff at full strength, you cannot put anything aluminum in it as it will react with it in a real bad way.  But for steel or iron, it will only dissolve rust leaving any good metal intact no matter how long you leave it in the dip.  A plastic tub is fine for containing the acid, just make sure it is outside as it will throw fumes when working.  Also have a bucket of baking soda and water nearby to neutralize the acid when finished soaking.  I tend to leave the parts in overnight, pull them out and right into the baking soda and water.  Wait till the fizzing is done and then wash the parts in hot water and saop.  After drying, I will wire brush them lightly and the parts are like new.  

 

 

With all the parts cleaned and wired brushed it was time to paint.  I found some Caliper paint from Auto Zone made by Dupli Color.  They only had Red or Black, so Red it was.  I have to say, I was a bit disappointed with the paint.  It was a brush on and it didn't cover very well.  I ended putting about 8 coats to get the color to be even and opaque.  And it tend to chip easily, maybe it needed to go through a few heat cycles.  I also bought a spray can of caliper paint in silver, just to give it contrast, also made by Dupli Color and it worked a lot better.  Not so sure if it will last as long as the brushed paint, but application was easier and covered faster.  

 

 

Now with the paint dry, it's time to rebuild the calipers.  

 

Use a good quality brake grease liberally and anti-seize for any moving parts not in contact with brake fluid.  
First step is to install the Puck seal inside the bore.  Lube the seal and set into place.  Since it will be a while before these caliper will be in service, I also coated the entire bore in grease.   
Despite the great cleaning job, these pucks have seen better days.  Rust had eaten away a ring around these pucks so they had to be replaced.
This a trail fit of the rubber boot on the new Stainless Steel pucks I got from Tony Thompson.  The top seals into the groove on the puck, but notice the bottom, this seals inside the bore, also in a groove, and is trapped between the puck and bore acting as a second seal.  Because of this, the boot has to be first installed on the caliper half before the puck is inserted.  
Lube up the rubber boot and work the bottom lip of the boot in to the groove in the bore.  Use your fingers to push the lip into the groove and make sure it is fully sealed all around. 
Now the tricky part, inserting the puck.  You will have to first get the puck past the rubber boot without pulling the bottom lip out of the bore.  The easiest was to place the puck at a 45 degree angle, then rotate the puck 360 degrees around the boot hole while still keeping an angle on the puck.  As the puck begins to slip on the boot reduce the angle, but still keeping some pressure in a downward direction.  After a few rotations the puck will push into the top boot hole completely.  Once in, align the puck and push down to seat the puck into the bore seal.   NOTE: this picture is of the front caliper, I forgot to take a picture of the rear caliper insertion technique.  This is not how to insert the front caliper puck, rather only the rear.  The front caliper puck is inserted first, and then the boot boot is installed.  Sorry for the confusion, but you get it.
Once the puck is seated, work the upper part of the boot to seal in the groove of the puck.  Tug around the bottom of the boot to double check if the lower lip has come off the bore.  If good, squeeze the puck home into the bore.  The new Stainless pucks are so pretty.  
Next is to assemble the two caliper halves.  But first you have to insert the fluid seal.  Use the brake grease to locate the seal and to insure it doesn't fall out.  I also covered the bare metal in grease to promote rust proofing on both sides.  
There are 4 bolts that hold the halves together.  Wipe the threads with anti-seize and torque down to 35 ft. Lbs.  
I got some Minitex Racing pads from TTR and dropped them in, literally, they just loosely float inside the caliper.  The two pins just traps them in and do not guide the pads.   
Reassemble the parking brake and insert the pins back in taking note that the internally threaded side is on top.  Install the parking pads.
Finally done

   

The front brakes are much easier and follows the rear caliper rebuild.

 

Insert the bore seal lubing it well
Unlike the rear caliper, the puck goes in first on the fronts.  Just line up and push in half way.  
Dress the puck with the boot, sealing the top of the boot in the groove on the puck.  The bottom/outside of the boot is held down with a steel spring ring.
The steel spring ring is a bit tricky and has a tendency to slip off.  Just make sure it sits inside the groove of the boot and is firmly squeezing the boot into the channel around the bore.  
Insert the fluid seal between the caliper with grease.
There are 3 bolts holding the fronts together, torque to 35 ft. lbs.  Also using the Minitex Racing pads from TTR which came with rubber stickers the shape of the pad material.  At first I didn't know what these were for?  I thought since they matched the pad face perfectly they should go on the pad itself, but why?  The rear pads had a red thin layer on the pad face, but that was some kind of friction material.  But why rubber?  I finally figured it had to go on the back of the pads for noise control.  The fronts also had stainless plates that went on the backs of the pads for anti squeal.  I guess the front brakes are inherently noisy. 
Brakes finally done, front and rears.