My Braking Adventure

My Braking Adventure

My brakes worked fine, in the original condition configuration, until I rebuilt the rear end to fix the worn wheel bearings. Once everything was reassembled, the boosters would not bleed. I bypassed them with short sections of brake line and could bleed the system. Even with a power bleeder, I could not get a firm pedal with them in the system. So I left them out. With the stock Special master cylinder, the pedal efforts were really high. I had heard several reports of brake pedal welds being not robust enough to handle this higher load, so decided that something had to be done.

The usual fix is to install an S2 tandem master cylinder. This has a .7" bore compared to the Special's .875" bore. Also as ususal, these parts are hard to come by and are expensive. Most places list them at $250-$300! From the Yahoo Group, Aaron Hines had reported sucess using a Datsun/Nissan F10 Master Cylinder as a replacement. This has a .75" bore. Not as low an effort as the S2 MC, but the addition of EBC Greenstuff pads should compensate. The F10 MC lists at $72 and is available at most online Nissan suppliers.

I checked E-bay on the off chance of finding one. There was one listed! $12.99, no bids and 2 days to go. I waited until the last hour and put in my bid. A week later I had it in my hands, delivered for a total of $19.89!

The F10 is almost a direct replacement for the stock unit. The mounting holes have to be elongated slightly with the dremel. The F10 spacing is just a little bigger than stock. The metric pipes exit from the left side not the right and it uses remote reservoirs.

I ordered two Tilton small reservoirs with mounting brackets from Pegasus Auto Racing Supplies in Wisconsin. Fantastic service, 1-2 day delivery to Michigan. I got one extra cap to use on the Eezibleed. I also got two of the Tilton Remote Inlet fittings. The F10 uses a large diameter hose for the remote reservoir. The Tilton parts fit right in place on the F10 and the end fittings are the same as the reservoirs. A few feet of 3/8" hose, some new brake pipe, and some Castrol LMA rounds out the parts. Including the MC, the total is just over $100! That's better than using an S2 MC. I am hoping rebuild kits are cheaper and more available also.

Everything went together pretty easily. I ran the front line directly from the MC to the splitter on the front of the chassis. Saves about 10 feet of tubing. This is the same routing as the S2 without boosters. For the rear circuit, I added a pipe to bypass the PDWV and the booster. When (I know better than to say IF) the engine comes out, I'll clean things up and run the line straight into the splitter.

The remote reservoirs got mounted next to the washer bag. The hoses go down through new holes in the body.

Bleeding was easy with the Eezibleed. One circuit at a time. The pedal was firm the first try. Time for a test drive, got to return a movie. While putting the wheels back on, a stud on the right rear stripped.

Now the fun starts. One mile from home the left rear started dragging, gets hot, drags some more, gets hotter... I turn around right away and head for home. Can't use third gear, now can't use second. Too much drag. Turn onto my street. 4,000 rpm won't move me, now I'm boiling over. At least it is a short walk home.

Get back to the car with a 7/16" wrench to release pressure on the right rear. But it is already loose. Drive it into the garage, no problems.

The end result appears to be the connection of the Master Cylinder to the push rod. The push rod exits at a slight angle, which changes slightly with brake travel. I used a flat washer to hold the rod in place. The rod was free to move and angle without any load on it. Once in the car with a load on the pedal, the ball end of the push rod can walk up the cone in the plunger. When the load is released, the ball end of the push rod is off center and keeps the MC depressed. The original Lotus washer retaining the rod has a concave surface to provide room for the ball end. That washer won;t fit in the smaller F10 MC, and I didn't want to alter it, so I made a new concave washer from a 5/16" flat washer. A little dremmel work later and it fit like a glove into the MC. The ball end now has room to rattle around, without any chance of binding.

Once the car is back on the ground, I'll finish the story, but everything appears to be fixed.

Note: One major advantage of the F10 Master Cylinder is the remote reservoir. It now takes 2 minutes to unbolt it once all the attachments are removed. Those who have struggled with the stock MC will understand.

	Original Master Cylinder Note access? to the top nut.
	The new Nissan F10 Master Cylinder with remote reservoirs. Note better access to the top nut. Screw in the middle may be bias adjustment. Will find out later.
	Tilton remote reservoirs.
	Remote reservoir mounting plate in front luggage box. Bolt heads will be painted black at some time in the future.
	New line to the front. Saves about 10 feet of plumbing!
	Boosters are gone! New lines will be fitted when the engine is out. Yes, that is a 2x3 engine cover prop.
	See the puddle. A little boil over when the right rear brake locked. Perma-cool fan is on the way. Who decided to ground the fan through the closing plate? Will check it again once assembled.
	Making a new washer on the press. This is the first try, using a 5/8" socket. I made a second one the with a 9/16" socket. It looks more like the original Lotus part. That's the ball head of the push rod poking through the washer.
	Top left is the original Lotus washer. The washer on the bottom is what came with the F10 MC. The washer on the push rod is the one I made after grinding the OD to size.
	Here's the new washer and push rod mounted in the F10 MC. Plenty of wiggle room.
	This is what happens to a sunroof when it is not attached to the car at 50 mph. It went about 15-20 straight up, landed right side up, then got run over by a Ford Explorer. The show surface of the paint is unmarked except for a section of tire rubber that needs to be removed.
	And here's the mess it all makes in the garage. A three car garage that could fit three cars two weeks ago. Now it only fits one.