Brakes

[fiatfactory]

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[baltobernie]

I'm running stock calipers, rubber hoses, Ferodo pads, OE master cylinder, no booster, Wilwood proportioning valve. The pedal effort is quite high, and my first stop in the Corolla after driving the Fiat is Yikes!

After removing the booster from the mounting plate, you'll find the center hole 2.34" in diameter. This must be reduced to 1.5 inches, so make a plug out of 0.125 steel and weld it in. Grind it smooth, then drill the 1.5" hole one-quarter inch below the centerline. Dykem the area, then trace the M/C outline and mounting holes. Use Grade 8 bolts and do your best-ever welding job, as this plate is the only thing between your foot and the nearest tree. Enlarge the original four mounting holes for the booster to 3/8", and get some plastic hole plugs from your hardware store to keep the water out.



Spot weld the bolt heads, so that you can later service the M/C without crawling back under the dash and dealing with the Jesus clip and pinion pin.

Along with the plate, this is the only other part you salvage from the booster.



I will let others describe the process of booster disassembly to retrieve this rod. Just know that there is a monster spring inside the booster, and it was assembled with much greater robusto than the rest of the car! I think the tool of choice would be a cutting torch

This is the view looking Up from the floor.



You must have a mm or two "wiggle" in the assembly, i.e there must be no "pre-load" on the M/C. Depending on your model year, etc. you may need to shorten the rod or fabricate a spacer between the M/C and plate. Mine ended up being exactly 1/4". I can't stress enough how solid you need to make this; an average human can easily generate 100 lbs. of force with their foot.

My manual brake conversion was part of another task; replacing the 38-year-old steel fuel and brake lines. I personally feel that some sort of proportioning is required for F/R bias; either the OE compensator or the now-common prop valve. BTW, a 25' coil of 5/16" is enough to go up and back for fuel and vent, and a 12' coil of 1/4" is enough for the fuel return. I used almost all of a 25' coil of 3/16" for the brakes. The lines from front-to-rear must really hug the tunnel.



Here's the result:



My car originally had a brake distribution block near the M/C. It contained a pressure switch for brake failure indication. We merely swapped one reservoir fill cap for the new style, to maintain some sort of early-warning of fluid loss. I chose the front circuit to monitor.

I spoke with Denise about this setup; hers is similar, and she does not complain about pedal pressure. As she said, I'm getting used to it, but boy, you really gotta stand on it for maximum results. Total pedal travel is less than 3/4". Next is to road test and find the correct "dry" and "wet" settings for the prop valve. Marking with a paint pen on the dial should do the trick. Maytag, I'm expecting you to install the lever-type valve so you can adjust it on the fly from the cockpit 99% of my driving is in the dry, so I figure if I need to pull over to raise the top, I can easily pop the hood and turn the dial.

My source for lines and hardware was Federal Hill Trading company. The lines are a copper-nickel alloy that is rust proof and reasonably able to be bent by hand. I will have more info on this in a later post; we may have found a less-expensive and better source.

[kbee00]

Thanks so much for the infomation. I plan on doing the same project. Do you have any more info on the parts you used? Wildwood part number, etc.

Increasing the bore size of the MC will decrease pedal pressure and increase pedal travel - both good for proper modulation. Does anyone know of a MC used in other Fiats/Alfas that is a 7/8" or even 1" bore?

More pics would be great too!

[baltobernie]

Here is the valve:
http://www.polyperformance.com/shop/Wil ... X4products
I couldn't find a metric version, so I had to do SAE flares on the valve. As you may know, everything else on the Spider is DIN "bubble" flare and all nuts are 10 x 1.25

I see no reason why you'd have to use a Fiat or Alfa M/C.

[manoa matt]

I've seen this modification before somewhere else. There was an additional standoff bracket on the back side of the booster mounting plate. (picture #3) It would help guide the pushrod and keep it from dropping down if the pedal retracted too much.
I saved the picture on my work computer, I'll post it on Monday. Bernie, whats keeping the pushrod from coming back out, the rubber end cap? Did you adjust the amount of pedal return via the stop light switch?

[baltobernie]

Here's the link: http://www.fiatspider.com/f15/viewtopic.php?f=9&t=7125

The C-bracket Jim Scurria used is not necessary, IMO. Properly sized for your installation, the rod has the slightest amount of play, but cannot fall out of the M/C, as the ball end would need to go another 1/4" beyond the pedal Up limit to jump out of the M/C indentation. I also don't like Jim's C-bracket effectively anchoring the M/C. You can see some deformation already in his photos. I you really want a support bracket, go right ahead, but have the M/C bolt directly to the plate, then install your support. I should add to my earlier post that you should size your rod or spacer and fit to the brake pedal without attaching the return spring, so you can feel the actual clearance between rod and M/C before any spring pressure masks the effort.

The brake pedal stop is independent of the lamp switch in my car. I did have to readjust the switch actuation point, as the pedal doesn't travel nearly as far as before.

This would be a great modification for the Ultimate Spider, as you could then install twin DCOE sidedrafts with your new-found clearance. For us regular guys, the elimination of the booster makes maintenance and adjustment of the steering box much easier.

kbee00's suggestion of a larger-bore M/C is an idea worth pursuing. If memory serves, the Spider M/C is about 0.75". What would really make this a simple job is an M/C with a mounting hole compatible with the stock Spider mounting plate. Do all M/Cs utilize a ball-and-socket mating? I guess you could always fabricate an actuator to mate with whatever M/C receptacle you have.

[kmead]

Although I doubt the mount is the same, there are a wide variety of alternatives. VWs come with 19mm 22mm 24mm MCs. Some have four outlets but could go to one for the rear by capping one or?

I would think you would have greater effort with a larger MC as you are moving more fluid for a given stroke. A smaller MC would move less fluid and have a greater stroke thus less effort.

[Daniel]

wouldn't a simple yet effective up grade be 85 ¹/² rotors with a adapter for the fiat caliber ?

[fiatfactory]

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[baltobernie]

I've just removed the booster and plated the booster bracket (pretty much the same as baltobernie has done) but gone a step futher and made the pushrod adjustable... some early 850 coupes come with an adjustable push rod for the brakes, that's where I got the idea....a long steel (exhaust type) nut and a couple of threads and a thin locking nut gives you 6 -10 mm of adjustment to get a snug fit and a high pedal.

Ah, what a clever idea! How about a photo?

[mdrburchette]

I don't recall having a problem with the rod length but I do seem to recall making a plate for the rod to fit into instead of welding up the holes on the original plate. We just fit the new plate into the old one. On the Lemons car we used a m/c from a 76 Ford LTD with no issues.

[kbee00]

I would think you would have greater effort with a larger MC as you are moving more fluid for a given stroke. A smaller MC would move less fluid and have a greater stroke thus less effort.

I stand corrected. I knew what I wanted to say, but didn't write it. Geesh.... I got this idea when racing Formula Fords - change the MC's to adjust front/rear bias. Of course, some smart alec came out with adjusting systems to do it on the fly.....

So, is there some consensus on what MC to use for our Fiats? I don't mind pedal pressure, as long as modulation increases. And pedal stroke is king - in my humble opinion. I could go down to the local race shop and buy a MC - but I'd rather someone with some experience in this area speaks up to his/her experiences in this area. HELP!!!!

Thank you all for your input. I am still amazed at the collective intellect on this board.......

SteveC - did you get my latest PM????

[maytag]

I'd like to resurrect this thread for a minute, and get some input.

If I understand correctly, Without changing the pedal setup or calipers, a smaller master cylinder will provide less braking for a given distance of throw on the pedal, right? Allowing better modulation? Higher mechanical advantage, eventually, at high-speed braking? So is that the way I would want to pair-up with the idea of removing the booster?

Or do I have this all wrong?

[engineerted]

Smaller dia. master cylinder = more breaking force at the wheel, for the same input force at the pedal but with a longer pedal travel. The same thing can be achieved by using the stock MC with a larger caliper piston bore area.

Check this out! this will give you something else to think about?

http://guy-croft.com/viewtopic.php?f=6& ... ster#p2320

Ted

[maytag]

Smaller dia. master cylinder = more breaking force at the wheel, for the same input force at the pedal but with a longer pedal travel. The same thing can be achieved by using the stock MC with a larger caliper piston bore area.

Ted

Ted: is that piston bore area also piston bore volume? I'm trying to get my head around the fluid dynamics. Is the volume what we are talking about? Or is it the area, as in the size of the piston face? And how does dual pistons impact this?