355 Rear brakes seizing after a major and Master Cylinder Replace 97 f355 spider

Hi all,

So appreciate of the knowledge here and need some help diagnosing an unusual brake problem on my f355 ‘97 spider - I’ve researched and don’t seem to find a similar problem here. It’s a bit of a long story to establish the issue:

Spider has just completed a well done major, including all the fixings by a reputable independent. Water pump, Hills tensioners, all gaskets and seals, proper Kevlar belts, etc. When I came in to pick it up, took for a test drive and the brakes were soft - way too much travel (like 3”) to engage and so they re-bled the rear brakes. Tried again, same and bled the fronts. No better. We determined it’s likely the master cylinder so last week they found a brand new oem cylinder and installed. Phone call that all is well after install and test drive by independent.

This morning went to pick up feeling good- but within 3 miles it felt like I was losing power when in fact what was happening is the rear brake pads were engaging on own - slowly over about 3 minutes til locked in place and the car would not move. Stopped on side of road. Power off or on made no difference - completely held in place by the car on own. Independent comes for roadside assistance, suspects the adjustment rod at the master cylinder and releases some tension there under the carpet at the cylinder with a simple spanner wrench and and the brakes release. We take back to shop where he ensures this adjustment is solid and I leave again feeling like it’s solved (and trying to enjoy the amazing sound and feel of the recent major - motor is tight, powerful and running better than ever) only to sense the brakes engaging on own again and pulling over after about 5 miles. This time made it to a parking lot and left for the independent. He made it there an hour later and at that point the brakes had released on own it seemed.

So WTF? I’ve left the car with them as this is very unnerving and I don’t have confidence in the master cylinder itself - or perhaps it’s something else. Anyone else ever experience anything like this on their f355?

Many thanks for the support diagnosing ... Ed


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I've not experienced this on a 355 but have on other cars. In my case it was the result of a new master spending an eternity on the shelf (or so I surmise) and the result is what you describe.

Not sure the abs unit could even influence this. If properly bled and adjusted I would still think this comes down to the master.

Experienced Ferrari techs may have a different opinion based on experience, just my opinion based on experience of others.

 

hard to guess what another shop might do right or wrong. Lets say everything is right then what about a WAG? Here is my WAG. Every major IMO should come with a brake system flush not just a reconnect and bleed. Why did master die when it was fine before major? Well often the master say has a 2 " stroke but in use over years your active stroke is say 1.5" so you got 1/2" of master that never gets wiped over by the seal. So sharp crap build up in there. Mechanic does a bleed and full strokes your pedal the whole 2". The sharp stuff violates the master and forces all the crap into your lines. Your master is now dead. So you have to replace or rebuild the master. If a bleed is done and not a full flush perhaps you got debris blocking the residual pressure valve so that the aft of the valve line pressure is higher than it should be thus activating the rear brakes especially with heat.

Solution flush the crap out of the lines and see if you get lucky to clear the valve. Sometimes you have to remove and replace or remove and clean the valve. A quick check of the valve might be to force the rear caliper pistons back into the caliper with the same force you use when you change the pads. If the force is higher suspect the valve or really FU'ed caliper piston seals. Action on the pedal should bring the pistons right back home against the pads and rotors.

It is also possible to have FU'ed piston in a caliper but if both sides are grabbing that is unlikely. Pushing pistons back into the caliper then moving them out with the pedal is a good thing. Upon release the rotor should turn with just a few lbs of force. sometimes you get some dragging and sometimes you get free spinning that's car dependent. But rotors should turn without any pedal pressure. If you can't move the rotor easily it is in the piston seals or the residual valve holding too much pressure. You can prove the valve by cracking the connection like when you bleed brakes and if the connection leaks out some fluid and the rotor now turns you got your answer.

Hope that gives you some ideas.

 

Thanks for the info - and suppose that could be part of this issue as the new MC is truly new - oem and never used before (as the rebuild time for the current was 6 weeks) - so its likely years old. But appears in great shape of course...it’s just very odd that it did this twice in a short time frame - adjusted the first time but released on its own the second - after sitting.


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Thanks for this - yes the entire system was properly flushed as part of the major and engine /rear reinstall. So some of these ideas are definitely worth doing - I particularly think the whole system needs another flush for sure ...


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You can confirm that indeed both left and right rear brakes are sticking on? Interestingly, the park brake adjustment also is disturbed during the engine oit major..

 

I don't entirely disagree with FBB, but the odds of crap in the MC or lines blocking the lines to the extent that they would hold enough pressure to lock the brakes is a stretch. My opinion is that the shop eff'ed it up; the shop is responsible to fix it. What I don't like in the OP's post is the "We determined...." If the shop told me it was probably the MC I'd be like, "If you replace it and it don't fix the brakes it's on your dime."

Are you sure they didn't get air in the ABS modulator when they replaced the MC? That requires a little more complex bleeding. Did they prime the MC before installing? Typically this needs to be done with dual/split braking systems.

 

How did they bleed the brakes initially? And was the master cylinder bled at that time?

 

Can you confirm whether it has the Teves system or the Bosch system?

 

Parking brake adjusted too tight? Seen that more times then I care to think of with old drum brakes .

 

That’s exactly what I was thinking and would definitely look into before I went any further with the actual brake system. The e brake could be dragging and when they heat up they expand and start to lock up. The first time it happened and he adjusted the MC rod it may not have actually done anything the ebrake just had a chance to cool off and let the wheels turn again... until you drove and heated them up again.

Maybe it’s wishful thinking but it’s something simple you could check before getting any deeper.

 

3 things happen to the rear brakes during a major.
The line is disconnected and capped.
The parking brake cable is disconnected
The brakes are bleed when finished.

It's gotta be related to those 3 things. Although now your mechanic has introduced a 4th item, the new master.

I wonder if it's possible he left whatever he capped the brake line with in the line when it was reconnected?

Parking brake seems reasonable. Have them totally loosen it for test drive purposes.

How is he bleeding it? Pump and crack?
Try a pressure bleeder.

 

Thank you all for the responses and good thinking. Have been top to bottom on the brake system and all seems well. We have seemed to find the culprit and the purists are gonna love this - there was one more variable I didn’t mention - as hadn’t considered it a possible issue given all those others who run them - wheel spacers. As part of a treat to self when returning from the major, had 15mm spacers placed on all 4 corners. All signs point to the rear spacers creating excess heat, perhaps applying pressure to the bearings, and causing the rear brakes to seize. Spacers off and have driven 50 miles without incident - brakes are back to normal, tight pedal and all seems well. Suppose it still could something outlying in the system but can’t get the issue to repeat with them off (this is where Dave R gets to bloat it he wants Had also confirmed proper torque and long bolts when spacers were loaded.

Shame as I loved the look of the spacers but not at the cost of the brakes seizing...

Meanwhile, have a set of four 15mm spacer if anyone interested! . Fit most analog Ferrari’s well...

Ed


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Wow. Thats a new one for me.

 

I had this once on a different car when the master cylinder reservoir was overfilled. Quick check to take it out of the equation.

 

Im not buying it that explanation.
You said it happened after a few minutes of driving? So pushing the wheel out a tick over 1/2" caused the rear calipers which aren't even in contact with the bearings, to heat to the fluid over 600* and seize the brakes??
My vote is it was fixed with one of the other troubleshooting efforts and/or its a gremlin that will come back later.
I say drive it a few weeks and through the spacers on there again.

 

That makes absolutely no scene at all and I would say is very close to completely impossible. There’s just no way spacers could have the effect you were talking about. No, just no way.

 

I'm not buying it at all either
Only spacer deal I can think of is too long a bolt holding them on and when it gets hot the bolt expands, hits inboard locking them up, metal on metal sound

 

Yes, not buying it. My guess would be it could have been from incorrect bleeding of the ABS unit and the pressure relief valve for the rear brakes. Or maybe aliens. Pretty sure it was aliens now that I think about it.

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Spacers cannot cause that. You have a different problem.

 

Fail.

 

I think you can put them back in now.

 

If it was indeed the spacers, they would have had to have been heated up to the point of changing colors.

My bet is still on an improperly adjusted parking brake. By now, perhaps enough of the shoe material has been worn away that the issue 'self-corrected'.

 

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Yes agree with you all - highly unusual and never heard of something like this before, etc etc. You all never fail to hold back.

But upon further investigation - have a look at the image - the fitment of the spacers on the rear - not good. Going back to the manufacturer as something is not right as the diameter is too small - not marrying to the interior dia of the wheel and this is surely allowing for way more flex and physics than the hub was ever intended to handle. All symptoms line up with this, heat, brake lines and caliper pressure - and it’s not 600 degrees and boiling brake lines needed to get the fluid to expand enough to engage the pads - and by the way - with the spacers removed the condition is gone. After diagnosing every other part of the brake system this was the only variable that remained.

I’m hoping with a properly fitted spacer that the problem does not return (for context I run type 2 spacers on my 456 and no issue but they fit better than these...) Once get spacer corrected will reload and test and keep you ladies abreast.


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