60 Veloce two shoe Brake Problems

[alfabits]

Many of you have followed my restoration posts at My Veloce restoration nearing completion. - Alfa Romeo Bulletin Board & Forums
Ever since the completion of my complete nut and bolt restoration I have had problems with my brakes. I now only have 250 miles on the car. The problem is very bad braking. I have to literally stand on the brakes to get it to stop. Here is what has been done to the braking system: All the lines have been replated in zinc. All but two wheel cylinders have been rebuilt with Centerline rebuild kits. New Centerline master cylinder. Shoes have been relined by Ott's Friction Supply here in Portland and they were profiled to the skimmed drums. I purchased another set of shoes lately just to try a different compound and it made no difference. I have very even wear pattern on the shoes. So I don't think it's an adjustment issue.

Has anyone else had a similar problem? I have driven many of these cars and the brakes were always perfect. What have I done wrong?

I am out of ideas.

Help!!!

George

[Gordon Raymond]

George, I can't remember if I asked you this. Any chance you have used the larger bore Master Cylinder from a 3 front shoe set up? That will give you a hard pedal.

[alfabits]

Gordon, Not that I am aware of. Centerline only sell the one for Giulietta's. . It is a 1" bore?

G

[pathung]

George,

Are you sure that your new liner's of the correct thickness? Comparing to my 3-shoe's, yours seem thinner in relation to the shoe's backing plate thickness..., then again 2-shoe vs. 3-shoe may be of different original specs. Just throwing out some first-impressions.

[Andrew]

Presumably the shoe/drum thickness is such that you're getting good contact and the pedal isn't going to the floor? Sounds like it from what you say.

Tom Sahines mentioned this same problem on an SZ, that one or two supposedly correct shoe compounds just didn't provide good braking, and finally switching to what I believe Alfastop had did the trick. Might be wrong on the source of the material, but the idea was that some compounds didn't work at all, and some worked great.

Andrew

[Britalia]

George,
Lovely car. Your lining thicknesses look fine compared to what I have on my car. You didn't mention adjusting the set screws at the rear of the backing plate so the shoes are parallel to the drum surface. It is a tricky adjustment. I use a special tool that I made, but there is a factory equivalent. Are you sure that the shoes are located on the top of those positioning screws ? I have also found that the toothed eccentric adjusters may be worn and may not hold the correct adjustment. I wound up filing the teeth on mine so they would hold better. Check to see that the adjusters are positioned properly and run them through a full adjustment cycle with the drums off to see that the shoes move as you would expect. I wound up putting some arrows on my backing plates so I would know how each adjuster must be moved in order to expand the shoe.
I have also found that adjusting the rear brake shoes is critical. If I don't have the rear brake shoes adjusted out as far as possible, the pedal will be low. You may be able to simulate this effect by pulling on the emergency brake a bit and seeing if that helps to increase the brake pedal height.
I hope this has been of some help. When adjusted properly, the brakes really are very nice. Do a few practice stops and then check the temperatures of the drums. They should be quite warm to the touch at all four corners. The fronts will be warmer.
Good luck
Chuck in NC

[Gordon Raymond]

While it is true that some of the newer materials used for street applications in American cars offer no squeaks, no air pollution, long life and so on, many are made for power brake and ABS applications, and may lack the friction quality of the old materials. I had a real, very early RHD 260 Cobra for one track outing, years ago, and the brake pedal made me look down to see if I had not accidentally put my foot on a frame rail. The brakes were totally useless until they were hot. That said, a reputable brake shop should know the correct material for the application. You might phone Jack Beck, @ Orion Motorsports in Nebraska or Richard Jemison (Alfar7) here on the BB for opinions, rather than continue to try to sort it out yourself. I know if I had hands on it, I could probably get it right, as it is a reasonably simple system with an excellent reputation. (I'm too far away, but curious just the same!)

[Mikes4C1300]

George,

I think you might want to consider a different lining material. I went through the same rebuild process a few years ago and had a woven, riveted Ferodo type material used on the front. They feel excellent and have way more stopping power than the 155 tires can handle. Have you tried this material in the past?

Mike Hollinger
Atlanta

[Andrew]

I believe it was a Ferodo material that Tom Sahines said did the trick.
Andrew

[Alex]

There was a tip in an old UK Alfa Club magazine many years ago that re-profiled Rolls Royce brake lining material was the one to use, after stocks of the original material dried up. Maybe that was Ferodo too?

[alfabits]

Gordon, Patrick, Andrew, Chuck, Mike, and Greg (off line).

Thanks for your replies. I will try to answer a few questions and add a little more information to the story. First the shoes have been squared to the mating hub so they are seating correctly (the shoes are parallel to the drum surface). There is even wear at all four wheels on the shoes. There is a nice contact pattern on the entire surface of the shoes and some evidence of brake dust when disassembled. So it does appear the shoes are making full contact. I can apply full braking, hands off the steering wheel and there is no pulling to either side. All the lining materials are the same at all four wheels. I recently purchased installed some decent OEM shoes on the front just to see if it made any difference and after a fairly short drive I concluded there was no real difference. All the connections are tight and none of the hydraulics is leaking. I use ATE Super Blue fluid. I have bled and re-bled the system several tomes. I have used the two-person pump and bleed system, I have used a power bleeder (pressurized brake reservoir), and I have a one-man vacuum bleeding system. When I depress the brake pedal there is a fair amount of free-play before I feel resistance, then there is a fairly firm pedal.

I purchased the new master cylinder from Centerline. According to their catalog it is a 1” bore. Is this the correct size for the two shoe system?

What about the adjustment of the M/C plunger rod? Anything special there I should be concerned about?

Well that’s about if. Any and all thoughts welcome.

George

[Alex]

George,

Here's another thought. Did you disassemble and inspect the new MC before you fitted it? I bought one from a UK supplier some years ago (for a 105 Sprint GT) and discovered that there was machining swarf inside the cylinder . I cannot think of anything else that might be wrong, although you could try adjusting the plunger rod, as you suggest.

Good luck!

[Britalia]

Regarding the plunger rod adjustment... I have only adjusted mine once. I had to do it because the brakes would stay on and not release. Apparently there is a small pressure relief hole that must be uncovered, or else the pressure in the brake system will keep the brakes on. It was a very small adjustment and made all the difference. So, it is possible to get the rod too far to one end. Other than that, I don't see why the length of the rod would affect the height of your brake pedal.
I am pretty sure that one inch bore on the MC is right, but that is from memory. Have you tried putting the car up on jackstands and applying the brakes. Then have a helper go around and see if they can turn each wheel ?
Maybe this will help you to diagnose the problem.
Best of luck. I am sure there is an answer
Chuck

[Gordon Raymond]

I'm a little in the boat with Alex here. The standard size Master Cylinders, I believe, from memory and notes, are 7/8, Disc brake front. 1, Two shoe and 1 1/16, Three shoe front. Now, that said, the only fooling with these I've done are switching three shoe for disc. When that is done, the front disc set up gets a nice firm pedal in place of it's spongy pedal with it's stock master cylinder. I've never swapped around cylinders only brakes. With my disc cylinder, when I ran 2 shoe drums in place of my discs, I had a nice firm pedal. So... crud in the cylinder?

[alfabits]

Quote:

Originally Posted by Britalia Regarding the plunger rod adjustment... I have only adjusted mine once. I had to do it because the brakes would stay on and not release. Apparently there is a small pressure relief hole that must be uncovered, or else the pressure in the brake system will keep the brakes on. It was a very small adjustment and made all the difference. So, it is possible to get the rod too far to one end. Other than that, I don't see why the length of the rod would affect the height of your brake pedal. I am pretty sure that one inch bore on the MC is right, but that is from memory. Have you tried putting the car up on jackstands and applying the brakes. Then have a helper go around and see if they can turn each wheel ? Maybe this will help you to diagnose the problem. Best of luck. I am sure there is an answer Chuck I'm a little in the boat with Alex here. The standard size Master Cylinders, I believe, from memory and notes, are 7/8, Disc brake front. 1, Two shoe and 1 1/16, Three shoe front. Now, that said, the only fooling with these I've done are switching three shoe for disc. When that is done, the front disc set up gets a nice firm pedal in place of it's spongy pedal with it's stock master cylinder. I've never swapped around cylinders only brakes. With my disc cylinder, when I ran 2 shoe drums in place of my discs, I had a nice firm pedal. So... crud in the cylinder? __________________ Gordon Raymond Illinois SNO Chapter DIRECTOR