Front Brakes

The drive in Canada really made me realize that I needed to address the front brakes. The car would pull to the left upon light braking and then to the right when heavier braking was done. This made it quite interesting getting set up to take a curve using trail braking. You were never quite sure where the car would be with respect to the line, so I would have to brake early, get everything set with regard to braking and then get back on the right line for the curve.

Since everything is apart on the front suspension now, I'm taking the time to work on the brakes as the car is already on the lift for a while. I took off the brakes and sent them off to White Post Restorations to have them re-sleeved in brass, new pistons, new stainless steel cross-over pipes, etc. They came back a couple of days ago and look really nice.

I also took off the hubs to have the rotors lightly turned. I actually used the hub puller from my toolkit. I had never thought about why the hub puller had threads on both sides. The threads for the knock-offs are different on each side of the car. This tends to make the knock-offs tighten when the car is moving forward rather than tighten on one side and loosen on the other. So the hub puller also has to have right and left hand threads. So when moving to the other side of the car, you have to unscrew the T-handle and screw in it from the opposite side.

After removing the hubs, I found that one of the outer bearings had been replaced with a non-standard one. I was happy that it was an outer bearing since they are only tens of dollars rather than the hundreds that the inner ones are. This hub also had a couple of thousandths of end play that I hope will be remedied with the new bearing. Removal of the bearings is interesting.

The parts 7 and 8 are locking rings that hold the inner bearing (6) in place. Part 7 is right hand thread and locks the inner bearing. Part 8 is left hand thread and acts like a lock nut for part 7. The real problem is that removal and installation require a special tool that has 4 pins at the end that fit into 4 holes in each locking ring. The machine shop I took the hubs to does quite a bit of work on Ferraris, so they had made this tool for some previous job. The outer bearing (2) is held in place by a C-ring (4). Here you can see the holes and the two locking rings with the inner bearing below them.

So I've got a new outer bearing on the way, but until it arrives, not much else can be done.

It turns out that the non-standard bearing is the type that is now available. So I ended up keeping the original bearing and returning the new one (which was the wrong one anyway). The machine shop adjusted the end play by changing the shim (part 3) inside the hub. Here's one of the machined rotors and the new seal ready to be installed.

One of the last things in having the rotors machined is to calculate the proper shims so the rotors are centered between the calipers. The shims are part 12 in the diagram above and fit between the brake assembly and the backing plate.

One side is .547". The other side is .517". So I need shims of .015" which will leave a distance of .532" on each side. As the shims don't seem to be available, I'll just order some shim stock and make them. They are just thin washers with an outside diameter of 1" and an inside hole of 1/2". They should be pretty easy to do. I need to do the same measurements on the left brake as the distances probably won't be the same. Each time a rotor is ground, the distances change depending on how much material is taken off each side of the rotor.

Making the shims for the brakes is not as easy as I thought it would be. I'm using a 1 1/8" hole saw (inner diameter of 1") to cut the outside and a regular 1/2" drill bit for the inner hole. It's hard to get both the 1" and 1/2" holes in line with each other. I've done a dozen or so using my drill press, but only satisfied with 2. The problem is that my drill press has too much wobble in the spindle. I ended up going back to my neighbor Mike's shop and using his big drill press. It has a 3/4" spindle, so no wobble. Here is a shim that needs cleanup on the left and a completed one on the right.

Side	Original dimension	Shim	Final Dimension
Left Outside	.697"	.010"	.687"
Left Inside	.679"	.010"	.690"
Right Outside	.709"	.015"	.693"
Right Inside	.673"	.015"	.688"

The front brakes are now centered with new brake pads, ready to be bled. I'll bleed them after I replace the clutch slave cylinder as that will need to be bled too.

After all of that, the front brakes still pulled some. Further, the right front dragged some. I talked to White Post and they said to send that brake back and they would take a look at it at no charge. However they thought it was probably the brake hose having a collapsed interior. The brake fluid would push out under the brake pedal pressure, but would be slow to flow back, preventing the brake from retracting properly. I ordered a new brake hose and installed it at the same time. That cured the dragging, but the car still pulled a little on braking. I figured that if one hose was collapsed, the other couldn't be far behind and perhaps was preventing the fluid from flowing to the left brake as easily as the right. So I got another brake hose and installed it too.