brake upgrade complete, the saga

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brake upgrade complete, the saga

Post by miker » Fri Aug 09, 2019 11:51 am

I am declaring an end to my brake upgrade project, about which I've posted many threads. I'm not sure how useful this will be to others as the Whoa brake kits seem to be permanently out of stock. Maybe my fits/starts/blunders can be a cautionary tale no matter what project you are doing.

I started my quest for better brakes several years ago with the Whoa Series II kit, purchased from Jon Logan. I ordered the basic kit, as I have 13" CD-39 wheels and the advice at the time was that the larger rotor kit would not work with 13" wheels.

A few months ago, I saw a $15/each price on larger rotors from Chris Obert and bought them to see if perhaps the calipers would clear. The measurements Chris lists make it seem like these are not the Pininfarina rotors, but a bit smaller. I was encouraged by what I found, so I ordered the larger Whoa upgrade kit, which comes with the correct rotors. Oh. The rotors in that kit are identical in size to what I got from Chris. So now I have spare $15/each rotors :/. In any event, the larger rotors made little difference in how the brakes felt, although I'm sure they would dissipate heat better.

The next step was to install a new, larger, brake booster and master cylinder sold as being from the Volumex Spider. This combination was used on many later Fiat models, too, which is why it's available. However, the master cylinder on these uses 10x1.0mm brake line nuts (as do most European cars) and not the 10x1.25mm brake line nuts used on Spiders. So I learned to fabricate brake line ends. I only had to replace one line, the one to the driver's side front. I replaced the metal low-brake fluid valve and the line to that valve from the driver's side is not long enough to reach all the way to the MC. I had switched to a single, later-style supply tank some time ago, so I bought the float cap for that as my low brake fluid indicator. I only needed to add one ground wire for that; the hot side wire reaches without a problem. Some bending of the other lines was required, too. At first I installed the new booster upside down. I could tell when the yoke didn't intersect the pedal properly. It also made it interfere with the inner fender, which I needlessly banged a fraction of an inch to fit. Once it was right-side up, it fit fine, fortunately covering up the evidence of my banging.

The Volumex MC I got with the booster did not come with the correct size rubber inlet grommets, but my old MC grommets seemed OK and I put those in. Hmm... what if they were not?

When I started bleeding the rears, I found that the DS rear caliper bleed screw was stripped out. Someone (me?) had apparently forced a larger bleed screw in at some point in the past. Anyway, aware of the checkered history of these rear calipers, I bought new ones, assuming that bigger was better as I ordered 38mm piston rear calipers.

And then I bled the system. And bled. And bled again. I pressure bled. I wife-pumps-the-pedal bled. I SpeedBleeder bled. I never vacuum bled because air comes in the rubber inlet. Everything I did ended up with a mushy pedal.

When I replaced the rear calipers, I also removed the rear compensator. It was old and suspect. I already had the braided bypass hose, having switched to braided lines some years ago. More bleeding. More of the same result. I was seeing the rears lock before the fronts, so I decided to put a (new) compensator back on. More brake fluid, same result - mushy pedal.

I adjusted the acorn nut out one turn. It helped with free play by the 5mm one would expect (1mm less clearance which feels like 5mm at the pedal), but otherwise, the brakes felt the same. I have gotten to the point where I can feel when the plunger touches the MC piston!

Several people suggested that the 38mm rear calipers were suspect. They are not Fiat OEM. Folks on X-web disassembled some and discovered excess play in the parking brake self-adjusting mechanism. My parking brakes were the only part of this project that was working at this point! I did recently measure the gap between pad and rotor and it is less than .5mm. So maybe some 38mm calipers are bad, but the ones I have are just larger, which could affect front/rear balance. So I started this brake math project, but finding out the specs for the Wilwood calipers in my kit was a wild goose chase. It never occured to me to just measure the damn bores. First I was told that they were 1" pistons. Then 1.25".

Steve Cecchele suggested checking for excessive runout in the rotors (which would 'kick back' the pads). I bought a $30 dial indicator and found excessive runout in the passenger side rear rotor, which was caused by a bad wheel bearing, installed by me (improperly) 8000 miles ago. When I installed it, I banged it home and damaged the bearing. This time, I used a gear puller to press it gently into place. I didn't notice much difference in the brakes, but at least I had actually fixed something.

From the start of my bleeding process with the Volumex MC, something didn't feel right. I had changed rear calipers and the MC at the same time, so I had to toss a coin - where to start? The Volumex booster and stock booster don't have the same actuator rod, so going back to a stock MC was not going to happen (I had already thrown them both out anyway), so I started researching new Voumex-compatible MCs. The price difference between OEM, branded aftermarket and generic is 3:1. I finally settled on an FTE branded master cylinder, p/n H2292901. When I went to install it, the dangers of "interchange" part numbers became apparent. The FTE unit is shared by several Fiats and Alfas, and is designed to use a MC reservoir that sits directly on top of it. It has narrower inlet passages machined into it and grommets from a stock or the Volumex MC are too large. Argh! I have 8mm brake supply lines, I didn't want to re-engineer all of that! Finally, I found some inlets that would work with the smaller grommets and 8mm hoses: ... 13-611-153. The 8mm hoses are snug, perhaps the inlets are for 9mm?

After a couple of months, I was able to properly install the FTE MC. More brake fluid. I was definitely getting better at brake bleeding! And the upgrade MC did make a noticeable difference. Is it because it's better? Or because it has new grommets? I have the one that came with my Volumex booster in case anyone experienced would care to inspect it. The FTE MC did feel better. I was making progress.

At this point, my father-in-law died and I started a series of trips to Michigan to help out my mother-in-law. To keep my sanity, I thought about the brakes and asked questions. Wilwood was unequivocal that 1" pistons on the front would be too small. When I was told that they were 1.25", I thought, why not upgrade to 1.375? If I suspected front/rear balance, why not go to larger fronts? So I ordered 1.375" piston Wilwood fronts. Before I did, I investigated versions of this same caliper that would work with wider vented rotors. I had measured front caliper deflection and it seemed a little high to Steve C (14 thousandths) but Wilwood said that was OK. But anyway, why not vented rotors too? I found some candidate rotors in the Brembo catalog but decided against this move, mainly because I feared the result would not fit under my CD-39s without a spacer. And I already had *two* sets of Pininfarina-size 10" rotors.

Here is a tip: do not order *any parts* for your car on the road or when life is distracting you. I ordered the 1.375" bore version of the calipers and installed them when I got home for this week (back to Michigan tomorrow). When I took off the original Wilwood calipers - they also have 1.375" bores. I was informed incorrectly. Or maybe some versions of the kit did have 1.25" bores. It doesn't matter. Why did I even ask when I just could have measured?

Pointless new Wilwood calipers, more brake fluid. I did two rounds of bleeding this time, and I was VERY careful. New vinyl hose. Brake fluid waste bottle above the car so that air isn't drawn in around the hose at the bleed screw from a siphon effect. Thread lock on the SpeedBleeders. Use the pressure bleeder in round one to make sure the system is filled, then the SpeedBleeders with pumping on round 2. Get the rear higher in the air to make sure the MC is level Get the rear even higher in the rear to make sure the Wilwoods are as vertical as possible.

The brakes feel good now. Could they be better? Maybe. But I'm so done for this year. It has been an expensive and time consuming education. I *think* my problem was a bad Volumex MC from the booster/MC combo. Maybe.

Thanks to all of you who have offered advice.
MikeR ( since 1995)

1977 Fiat 124 Spider
Previously owned:
2012 Fiat 500 Prima Edizione #236 (now owned by my son David)
'86 Bertone X1/9
'81 Fiat Spider 2000 #236
'78 Fiat 131 four door
'76 Fiat 128 4 door
'74 Fiat 128 4 door
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Re: brake upgrade complete, the saga

Post by 18Fiatsandcounting » Sat Aug 10, 2019 3:19 pm

Mike, thanks for taking the time to put all this down in writing. Just a hunch on my part, but I'm guessing that this won't be the end of your project...!! ;)

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Re: brake upgrade complete, the saga

Post by San Jose Steve » Tue Aug 13, 2019 11:49 am

I sure hope most of this activity was during the "off season" and in the Summer. I usually find it therapeutic to occasionally go for a short spin even if things are not totally dialed in less I forget the pleasures of driving it and start looking longingly at 2019 Fiat 124 Abarths. Ha! -Steve
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Re: brake upgrade complete, the saga

Post by rridge » Tue Aug 13, 2019 6:10 pm


Your saga reinforces some things I've learned over the years. The first is that I am not an automotive engineer. Particularly on parts that affect the safety of the vehicle I need to have a compelling reason to depart from the original design or at least the benefit of the experience of others who have installed and validated a particular modification.

Second, I while I'm not the engineer, I am most certainly the quality control inspector on all new parts that go on my car. Many of the unbranded replacement parts that are made for our cars are made in small batches by shops that have simply copied original parts and that do not have access to original drawings and specs. How large could the total replacement market for Volumex Spider master cylinders be? Perhaps 50 units per year? What are the odds that the original supplier of almost any 40 year old Italian auto parts is still in business, let alone still making parts for the tiny aftermarket we represent? What are the odds that the specs and materials of parts that have stayed in production, perhaps for more modern cars, have changed over time?

In the past I have been too quick to toss original parts without doing careful comparisons with replacements. I've learned to keep some measuring equipment handy in the shop and take pictures of original hardware before tossing it. I've also come to do more rebuilding and less direct parts replacement. And yes, I've learned to overcome the impulse to buy parts based mostly on price and to value OEM hardware.

Third, particularly as I am slowed by age with both declining physical abilities as well as energy, everything takes longer than I think it should. Which means that almost any serious projects I undertake stand a good chance of being interrupted by both health and life events. And every long term interruption is as good as going back to the start, worse than that if I have not kept notes on what's already been done. So I try to expect interruptions and to break larger projects down into a series of smaller projects with discrete stopping points that allow testing of work to date.

They say we only learn from our own experiences. I think smart people manage to learn from the experience of others as well and I think you're story is an excellent learning resource for anyone who plays with old car hardware. Thank you.
'81 Turbo Spider
Rockville, MD
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Re: brake upgrade complete, the saga

Post by MikeGreer » Tue Aug 13, 2019 10:10 pm

Richard, those are some words of wisdom. I'm very particular about what goes in/on my spider, some new parts are fine and others not so much. Some parts can be rebuilt by an amateur and others, well not so much. The ground is definitely further away than it used to be. I've had other old sports cars in the past, but now when I look back, one was only 6 years old (MGA) and the other 20 (XK140) at the time I had them, not 40 like my spider is now. Even the first restoration of this car, it was only 20 years old. It feels odd to be working on such an old car. I suppose we're lucky we can still get parts and keep them on the road. I haven't pitched an old spider part in quite awhile, you never know when you might need it.
45 years with a spider, that's a long time
Restoring the '79 for the second time, you're never finished ;)
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Re: brake upgrade complete, the saga

Post by davedecker4 » Wed Aug 14, 2019 3:13 am

Excellent posts and sharing of knowledge here Mike and Richard. And a great bit of wisdom from Mike too. Thanks guys!
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Re: brake upgrade complete, the saga

Post by Mr.Pic » Sun Aug 18, 2019 8:20 pm

I did almost what you did... You need more pressure to be able to lock the front. The brake booster only give you more pressure to the MC. So the bigger the booster is better. So we use the volumex kit but the MC is bigger than original so more volume of oil but less pressure since it's bigger. I enlarge the original MC to be able to fit it on the volumex booster. I also replace the rear brake with Fiat 500 2012 disc and caliper. you need to remove 10 thousands from the center of the disc and one of my friend made the braket to hold the caliper. Finally a real handbrake. My next move will be to replace the wilwood front pads for EBC Yellowstuff
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