458 458 Brembo Caliper Bleed Nipple Issue *happening now…urgent!*

Thanks for the kind words there Brad.

Another thing I wanted to mention in regards doing this repair, if a Time-sert is used:

The lower, inside edge of the Time-sert (the part which has the M10x1.00 threads in this case) is not threaded totally to the end. That's something you need to be aware of.

So, when using a Time-sert, if you require the bolt - or in this case the bleeder screw - to be able to pass through when it reaches the bottom, you are going to need to either pass an M10x1.00 tap through the Time-sert prior to installation in order to cut some threads clear through (no easy job, because the Time-serts tend to be brittle and crack prone prior to installation) or you are going to have to grind off the bottom edge of the Time-sert itself. Failing to recognize this in advance can produce a situation where the bleeder valve either can't touch its seat and/or it could inadvertently fracture the Time-sert during final torquing.

I've made this mistake myself and have had to go back and tap the Time-sert post installation, which typically isn't a real fun job.

Anyway, I woke up this morning in a cold sweat, realizing I had forgotten to mention that to @FerrariCognoscenti last night.

Also, cutting the countersunk rim for the Time-sert can be a little tricky. If not done exactly right, the Time-sert will not sit perfectly flush when installed. In my experience, it's better usually to cut it a fraction too deep than not enough and then back fill with a bit of JB weld. If you end up with the insert sitting up too high, usually your only option is a file or grinder the lip down. In this particular case (on the Ferrari caliper) it shouldn't matter too much either way, but with repairs where two flanges or surfaces need to mate perfectly flush, it can be a factor to watch out for.

Ray

 

That alignment tool they sell sometimes does more harm than good, so be very careful. I have them also and have found that generally they interfere too much while trying to work in tight areas and can sometimes actually cause the threading part to go off track. I never use them anymore and typically just go slow and eyeball things from all angles when starting the tap.

Ray

 

I had a broken bleeder screw that had to be drilled out. Ferrari repaired it with a helicoil. I agree that a timesert is better. My helicoil repair did hold up. Even on the track.

I would remove the caliper and take it to a brake specialist. They will fix it and it won’t be expensive. Then if you want get yourself stahlbus bleeders. Ferrari race team here suggested them to me. Problem solved and bleeding is a breeze.


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I've used Speed Bleeders on my sport bike in the past. They are handy. However, you can accomplish basically the same thing by just sticking a 1/4 section of clear tubing on the end of the nipple. That's how I usually bleed brakes. The air bubbles go up the tube and when you release the pedal, fluid is pulled back in only.

As far as I'm concerned, all Helicoil repairs should be outlawed. That's how bad those usually are.

Ray

 

The Helicoil is basically just a wire coil, which you thread down into the hole; then you thread the bolt into that. In some cases, not all of the previously damaged material is removed. So you can end up with a repair where the wire Helicoil sits inside a damaged hole (depending on how badly damaged the original threads were). In fact, to remove a Helicoil, you often times can just grab the upper part of the coil with needle nose pliers and pull it right out of the hole in a spiral. It's not exactly what I would consider a permanent, longterm repair.

A Time-sert, on the other hand, is a machined metal sleeve - generally available in either steel or stainless steel. During installation you totally drill out the previously damaged threads and take the hole back to clean bare metal. Then you cut perfect, fresh, brand new threads, which the Time-sert sleeve threads down into. This actually produces a stronger threaded hole than before. In fact, in some cases, I have machined parts where instead of just taping a threaded hole into the part itself, I specifically design it so I can later install a Time-sert; this allows me to have an aluminum alloy part, but a steel and/or stainless steel threaded hole for additional strength as compared to just a raw CNC threaded hole into the base alloy.

Also, as you have found out, repeated threading and unthreading against aluminum threads (if you aren't super careful) can end up galling the threads after a while. By having a steel threaded insert (which is then threaded into, as opposed to the bare aluminum) you can not only extend the strength of the hole but also not have to worry about thread degradation nearly as much.

If you combine the Time-sert with Loctite 680 or JB weld, it will end up being far stronger than just a typical threaded hole into hee base metal alone.

A Helicoil can save your ass in an emergency, like if you are stranded on the side of the road or something. But to effect a really suitable, long term repair, the Time-sert is where it's at.

Ray

 

Thanks man.

I'm kinda curious to see how this job turns out. Keep us all posted!

Ray

 

hey just a thought. it's gonna see over 1000psi under braking. make sure time-sert sleeve can hold that pressure. I love the time-sert system but i never used them on pipe thread situation before... just for repairing mounting holes.

the best repair would be to weld, machine, and tap it. you may need repaint if you're using a weak TIG.

 

I would ask the time-sert directly or look for data sheet on their website. unless someone here has repaired thread before in a hydraulic system using time-sert or heli-coil and want to chime in.

 

It's always good to point all that out and make sure nothing is about to explode. However, your statement there regarding TIG welding being "the best repair" isn't totally true, especially if strength of the final product is a concern. Also, just because brake line pressure might be 1000 PSI, that doesn't translate into the bleeder actually seeing 1000 lbs of force on it.

Let's examine the issue of force on the bleeder first:

PSI is an expression of force pressing across 1 square inch - aka "pounds per square inch". True, brake line pressure may be 1000 PSI, but unless the surface area of the bleeder is also 1 square inch, then it won't be subjected to the full 1000 lbs. of force.

This somewhat odd byproduct of hydraulic systems is exactly how braking systems turn 30 ft lbs of pedal force into enough pressure to stop your 4000 lb car when it's flying down the road at 90 MPH. When you press on the brake pedal (applying around 30 to 40 lbs of force), there is a force leverage multiplication factor with the pivot point of the brake level relative to the piston in the master cylinder. This translates the mechanical lever force into a piston pushing on a fluid, which results in hydraulic line pressure inside the brake lines. This line pressure then exerts hydraulic pressure on your brake calipers, which have pistons inside them. The brake fluid exerts force directly across the face of the brake caliper piston and this is when forces become multiplied based on square inches. As such, if the total surface area of your brake caliper pistons is 3.5 square inches, then the total force will be 3.5 square inches multiple by the line pressure of 1000 lbs per square inch. The result is 1000 lbs times 3.5 and your brake rotor then experiences around 3500 lbs of clamping force (also dependent on the coefficient of friction of the brake pads you're using, among other things).

You get the basic idea.

So, interestingly, this works the same in reverse. If the total surface area of your brake bleeder is only say .100", then you have to take line pressure (e.g. 1000 PSI) and divide it by 10 (because .100" is 1/10th of 1 full inch) in order to arrive at the actual force being exerted on the bleeder valve - and in this case that would be approximately 100 lbs. That's well within the pressure ranges that the Time-sert inserts can handle; so we are good to go there.

Also, it's worth pointing out that the brake bleeder isn't using a pipe thread (which has a very slight taper to it in order to accomplish sealing) like a NPT or BPT thread. It's simply a straight thread (in this case M10 x 1.00) and the bleeder valve has a 90 degree sealing seat angle at the tip, which is what accomplishes the sealing of fluid.

Finally, with regard to TIG welding... yes that's one possible option. However, is it really "the best" option here? I'd say maybe not and here's why:

You have to keep in mind that TIG welding aluminum will generally weaken it and/or compromise at least some of the strength characteristics of the base aluminum alloy. This can be especially true if you are dealing with forged aluminum alloy structures (e.g. Brembo brake caliper housings) because the micro grain structure is strengthened during the forging process and TIG welding erases that. No matter how skilled you are at TIG welding, when you melt the base metal, it's altered. Now, if the brake calipers were steel, then welding could actually strengthen things. However, when you are dealing with metals such as aluminum, generally speaking, TIG welding will weaken it in the area of the weld.

Even when you aren't dealing with specialized, high strength forged aluminum components, in most cases, TIG welding will negatively affect the yield strength of aluminum alloys by anywhere from 40% to 50% or more. So while you can repair it through TIG welding, the final result will most likely be weaker than when you began.

By going the Time-sert route, you will definitely end up with threads which are stronger and more durable. Typically the steel used in the Time-sert is going to have a yield strength anywhere from twice to as much as 5 times (or more) than the original aluminum of the Brembo calipers.

The short answer is still this: Repair it with a Time-sert.

Ray

 

well ray, I can't argue with that! yes, if the bleeder screw has straight thread, the sealing surface isn't the thread. is the sealing surface at the bottom of the hole?

hey OP, can you shoot a photo of the bleeder hole so I can see the bottom? or just be careful when drilling to not damage the sealing surface. could be tricky if it's shallow.

 

Yeah, that doesn't look too bad. It might even provide its own seat, which could be handy.

Given the limited area you are dealing with on that Brembo caliper (specifically that boss in the caliper that you're going to need to drill and tap) I think I'd probably opt for whichever method requires removing the least amount of aluminum to accomplish the repair.

I'd be super careful you don't accidentally remove too much material and weaken that outside edge area (see photo)

Ray

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Yes, the tip of the bleeder screw has a 90 degree angle which presses into a 90 degree seat. The threads don't really provide much in the way of sealing, although sometimes they do put some thread sealant on just to cut down on weeping.

Some brake calipers do use NPT fittings on the brake lines. For example, the forged narrow superlite Wilwood calipers I run on my pickup truck have a 1/8-27 NPT inlet on the back for the brake lines:

https://www.wilwood.com/Calipers/CaliperProd?itemno=120-11783-BK&appid=0

Ray

 

I would remove it ideally. You can plug the hole with grease and a countersunk steel screw, which can be cut off to form a plug. As long as the screw is steel, you can remove it using a magnet. The main concern is aluminum shavings getting back into the inner caliper piston seals and cutting them.

You're going to need room to turn a T-handle tap wrench most likely, although in a very tight area you can use a wrench.

Ray

 

i think the bleeder seals at the bottom of the hole against the angled hydraulic mating surface. don't damage this while you're drilling. measure the depth then put a stop collar on your drill to make sure it doesn't go past.
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When my car was done by them I was also skeptical. I wrote to the factory about the repair and they assured me it was fine.

Ask a Ferrari dealer near you what they do in this situation or what the factory repair recommendation is.

Who knows they may just say it no good or they may say it’s fine. You never know.


For what it worth I had it in writing from Ferrari it was fine and that its was the factory spec repair. They did offer me a new caliper at cost after complaining as they originally broke the bleeder screw, I never purchased it.

Bleeder screws snap. They weak. Par for the course on cars.

After asking around ( brake specialists and machine shops ) the helicoil repair seemed fine, and it has been ever since. No problems and no leaks


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