Restomod Racing

The used CPS (cam position sensor) finally arrived.  The first order of business was to clean it up. 

This CPS has a tinted window on the center of the cap.  Thats a really neat set up.  Shane marked the pick up with white paint so he could see it through the window.  Now he can slip it into place with the cap on.

First, Shane put the number one piston at top dead center on the compression stroke.  He then slipped the CPS into the engine making sure the pick up was facing the right position.  He then snugged down the CPS.  He fired up the engine to see if it worked.  The engine fired up!  Now it was time for him to time the engine.  He used a jumper wire in the same position as reading the error codes.  He then started the car and set the timing to 10 degree BTDC.

Since the clutch peddle engaged close to the floor, Shane decided to check the clutch peddle higth

and free play.  His clutch peddle is 5.5″ from the floor.  The factory calls for 6.18″ to 6.57″, so adjusting is in order.  In order to get to the adjusting rod, he needed to remove the lower dash cover.  Once removed he had good access to the clutch peddle.  He first turned the clutch peddle stop out, but to his surprise the peddle did not move.  He realized that the clutch master cylinder rod was holding it from moving.  He loosened the lock nut and removed the pin from the bolt that holds the master cylinder rod to the clutch peddle.  He turned it out until he could obtain the 6.5″ peddle higth.  Now he needed to adust the free play.  This is achieved by turning the peddle higth adjuster until he has a little less than 1/2″ of free play.  Once this is achieved he tightened the lock nut.

The igniter came today.  Shane installed it, which only took a few minutes.  He started the car and

 it ran good.  He test drove it around the block and parked it.  When he went to restart it, nothing!  He checked and not spark.  He ran his checks again and the Cam Position Sensor (CPS) still showed that it was out of specification.  He decided to try starting the engine again.  Unexpectedly the engine started.  When he shut it off and tried to restart it, nothing.  He noticed that each time he used the ohm meter to measure the resistance in the CPS, the engin would start afterwards.  He came to the conclusion that the CPS must have some kind of short in it.  He surfed the net and found a used CPS for $140.  Since a new one costs $500, he ordered it. 

This morning the engine wouldn’t start.  Shane checked for spark.  None was present.  Looking

at the Supra manual, it indicated that the Igniter, Coil pack or Cam Position Sensor could be the problem.   Running the tests, the Igniter and the Cam Position Sensor both were out of specification.  Shane decided he would try replacing the igniter since it was apparently farthest off of specification.  He found a used one on Ebay and ordered it.  The reason for buying a used one is pure economics.  A used one costs $100 versus a new one costing $400.

The engine is done.  It runs like a charm!  Shane said that his clutch feels different, but the car

runs good.  Finally, he can start driving her again.

It was determined that the rubber ring around the rotor housing had given out.  Keith decided to

use the aviation type.  He also had to replace his rotor housings due to excessive wear.  He had the replacement housings bridge ported.  The choice was to use Mazda 3mm apex seals as well as a lot more stock type parts rather than their racing brothers. This turned out to be a good decision as the engine has never ran better.  The over heating problem is gone too.

Shane had his block and head milled, balanced the crank assembly and had the block honed.  He

added new pistons due to the wrist pins being slightly out of shape on his orginal ones.  Of course he replaced the usual stuff like the main/connecting rod bearings, Rings, oil pump and timing belt.  Since the engine is disassembled, a valve job was in order too. 

The old clutch is going to be replaced with a Spec clutch rated at 500 ft lbs.  The interesting thing is that the clutch is removed by removing the pressure plate bolts from an opening on the side of the trans.  Much easier to install than the conventional trans.

The Supra is showing signs of overheating like the RX-7.  Doing some research, Shane determined

that the head gasket is a weak link in the 7MGTE engine.  He decided to install a metal head gasket and ARP studs. 

The RX-7 started to over heat recently and radiator fluid started to be pushed out of the radiator.  Keith has been forced to add water after driving his car.  We suspected that exhaust was leaking into the cooling system so we used decided to inlist the help of our smog machine.  After running the engine we placed the smog machines pick up tube into the overflow tank.  We immediately saw the HC go up to 700+. 

Keith will have to replace a seal in the engine.  Apparently there are two types of seals.  He choose to use the rubber seal.  I guess that turned out to be a wrong decision.  After he removes the engine and disassembles it, we will know more.

The removing of the air in the brake system of the Corolla GT-S proved to be a challenge.  As you may

know, bleeding brakes can be accomplished by several means.  There is the method of pressurizing the master cylinder or the method of using suction at the wheel cylinder and the more common method for use by backyard mechanics, the pumping of the brakes.   When Keith was trying to remove the air from the Corolla, he ended up using all three methods.  No matter which method he used, the brakes refused to work. 

It was theorized that the air was trapped somewhere in the system.  In order to bleed the brakes he had to first fix the calipers on both the front and rear of the passengers side.  The reason was that the bleeding nipples were sheared off on them (previous owner must have broken them off).  Once fixed he started by using the method of pressurizing the master cylinder.  He first used the Motive Products Power Bleeder.  You fill the container full of brake fluid and then it is pressurize it.  The new brake fluid is then pushed into the master cylinder and through the brake system.  The air is pushed out along with the old fluid through the wheel cylinder bleeding nipple.  He started by going to the furthest wheel and moving to the closet wheel to the master cylinder.  When this didn’t seem to work, he went to the method of sucking out the air and fluid through the wheel cylinder nipple.   You use a vacuum pump that draws the fluid air into a special cup make for bleeding brakes.  When this method again didn’t seem to work he used the common method of pumping the brake peddle 3 times, hold the peddle while the wheel cylinder nipple is opened to release the air and fluid into a cup.  Once the air and fluid stops coming out, the nipple is closed.  Once the nipple is closed the brake peddle is now released.  You can not release the peddle before the nipple is closed, otherwise air will be sucked in through the nipple when the peddle is released. 

After using the three methods and none appeared to work, it was time to go back to the drawing board.  The first thing was that the brake was working before the bleeding process.  So why would it not work now?  After some research we noticed that there was air bubbles coming from the master cylinder when ever we pumped the brakes.  We decided to bleed the master cylinder.  We first started by loosening the line at the master cylinder that goes to the rear wheels.  When we pushed the brake peddle to the floor, no fluid was noted to come out.  After doing this a few times we decided to move to the front brakes.  We tightened the line to the rear brakes and loosened the line to the front brakes.  We noticed that fluid immediately came out when the brake peddle was pushed to the floor. 

We decided that the master cylinder was the problem.  To make a long story short, after replacing the master cylinder all was good.  Now the problem was to determine why the master cylinder went bad when it was working before.  What we determined was that the master cylinder piston was ruined when the peddle was pushed beyond it’s normal travel (distance pushed when brakes were working normally). 

In other words, the system was old and neglected.  Due to the neglect, the master cylinder bore became lined with small particles such as rust.  As long as the brake peddle did not move more that its normal travel, all was fine because the bore was in the clean area.  When the brake fluid was leaked out and the peddle was pushed beyond its normal travel, the pistons rubber cup now moved into the area of the bore which normally was not touched by the piston.  This part of the bore is lined the particles due to the neglect and it acted as sand paper on the pistons rubber cup.  This chewed up the rubber cup and caused it to leak.  In our case only the rear piston was affected.  The front piston was fine.  Remember that the brake system must be kept up so that the master cylinder bores stays clean.  Do regular maintance by changing your brake fluid as directed by you manufacturer.