Recall - Front Brake Hoses Can Crack and Leak Fluid (ARB0) - June 19, 2024 -- [2020-2025 Taycan]

[Murph7355]

and

(from the 1st post on this thread).

Wouldn't giving the hose an "increased bend radius" naturally mean it was a longer hose? From the pictures posted of the hose, it would seem they're trying to ease the point where the hose can crimp?

Can't tell from the photos, but would it be more inclined to crimp when the suspension's in one of the lower positions?

There's a suspicion some of us have that there's potentially dangerous tyre wear on the inside rear shoulder of the tyres, and the common factor seems (from the few examples on the thread) to be on cars that do a good chunk of miles in the lower settings too.

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[whitex]

I love how the report mentions there was one accident at 120 km/h due to this but they were speeding. As if 120 km/h isn't a totally legit speed on many roads.

"Our manufacturing defect caused an accident but it's totally okay guys ... as the car was going faster than the posted speed limit at the time.".

Welcome to liability lawyering. "Out data indicates you were traveling at an illegal speed at the time of the brake failure, at least 1km/h over the legal limit, therefore liability falls squarely and completely on you."

 

[whitex]

So disappointed that my carbon ceramic brakes has the same €5 hose as everyone else

Be happy they don't have $1,000 ceramic hoses. I hear those are even more brittle when bending.

 

[whitex]

Sounds like accountants running the design team.

Or the old guard retired, and this is the result of the new generation of Porsche engineers (and/or contractors). Welcome to the "I got up in a good mood this morning, and I didn't want to ruin it by going to work, so I called in a mental-health day" generation.

 

[whitex]

well okay, not sure why people are so hellbent on assuming incompetence here. Do you really think they only designed/tested this for driving in Normal/for 80% of the suspension travel?

If this was a 21st century born company like Tesla, Rivian, or Lucid, I would understand. But a company that has been making cars for a better part of a century, and famous for their brakes, you'd think all that experience would allow them to avoid pitfalls like that. When Porsche markets "we've been making sports cars for 75 years", the assumption is that they have perfected at least things they have been doing for 75 years, like reliably routing hydraulic hoses to brake calipers, no? I'm thinking the fact that Taycans use recuperation braking for 90% of the time (percentage from Porsche marketing) actually made them not catch this issue until recently, which suggests to me they build things blindly like the new upstarts - build it, see if it fails in the field, fix it via recall. 75 years of experience is apparently not that much (or any) advantage with that approach.

 

[Vim Schrotnock]

This is just poor engineering. The brake hose needs to do one thing. Transfer the brake fluid under high pressure to the calipers without leaking. Period. I've worked on projects that require testing of the product for cracking, leaking, etc., during a lifetime of bending and flexing. Bend/flex testing is a standard in the industry, and uses a simple fixture simulating use, bending etc. over the lifetime of the product under simulated conditions. We'd run the bend/flex fixture for weeks to simulate a lifetime of use. There is nothing in the use of these brake hoses that was unusual or outside the design specifications. They simply did not do the proper testing.

 

[WasserGKuehlt]

Wouldn't giving the hose an "increased bend radius" naturally mean it was a longer hose? From the pictures posted of the hose, it would seem they're trying to ease the point where the hose can crimp?

Can't tell from the photos, but would it be more inclined to crimp when the suspension's in one of the lower positions?

There's a suspicion some of us have that there's potentially dangerous tyre wear on the inside rear shoulder of the tyres, and the common factor seems (from the few examples on the thread) to be on cars that do a good chunk of miles in the lower settings too.

Having seen @bsclywilly picture, it is now clear that is what they meant. I hadn’t had a chance to pull my wheel off, and looking at an older picture (the one i posted) i was looking at the wrong part. With that context, I had assumed Porsche meant “increased bending radius” to be a characteristic of the material (again, stiffer rubber/reinforced fabric, so that it won’t kink as easily).

 

[hifi239]

The hose bend in question is just behind the upper ball joint

Thanks very much for this photo. I'm looking at mine soon. You can see how the fitting edge is pushing against the hose. Not good. May I ask if you think the air ride setting would stress this more at one extreme or the other?

 

[bsclywilly]

Thanks very much for this photo. I'm looking at mine soon. You can see how the fitting edge is pushing against the hose. Not good. May I ask if you think the air ride setting would stress this more at one extreme or the other?

Based on the trajectory it looks like a lower ride height or compression would be worse but it’s really at full steering lock that it becomes a problem. I think the worst case scenario is turning at full lock while compressing the outside wheel over a bump or incline.

The hose could really use an extra 20mm of length or more to relieve that bend. There is no clearance issue with the tire and steering to lock in the other direction doesn’t bend the hose nearly as much.

 

[JWreck]

Am I reading this correctly that every Taycan will be eligible for the new hoses?

 

[hifi239]

After bsclywilly's post I looked at the ones on my steel spring base Taycan and they look just as stressed. See yellow arrow. Instead of stainless braided hoses (which you can get), they put this spring around a conventional one. The spring doesn't help with the pinch point at the fitting. Note that even conventional brake hoses are not just rubber. They do have a braid under the rubber to contain the pressure. As said, a few more inches, and these would have been fine. It is true that these are relatively easy to inspect by turning the wheel away from the side you're going to inspect and looking in from the back and upward, and pulling the spring back. Photos are without removing the wheels, with the flash on.

 

[Fish Fingers]

Even to a layman (like me) it looks like a potential future issue.

So why would they not have just made them slightly longer?

Is it to save money, or is there any advantage keeping them as short as possible?

Or just poor design?

 

[DougFrisk]

Based on the trajectory it looks like a lower ride height or compression would be worse but it’s really at full steering lock that it becomes a problem. I think the worst case scenario is turning at full lock while compressing the outside wheel over a bump or incline.

The hose could really use an extra 20mm of length or more to relieve that bend. There is no clearance issue with the tire and steering to lock in the other direction doesn’t bend the hose nearly as much.

If it's stressed at the lowest suspension setting add lowering links to the equation and it likely makes it worse. Nonetheless, I'd expect it to be designed so that the hose is not at maximum bend even with the steering at full lock and the suspension fully compressed or extended.

 

[whitex]

Even to a layman (like me) it looks like a potential future issue.

So why would they not have just made them slightly longer?

Is it to save money, or is there any advantage keeping them as short as possible?

Or just poor design?

There is a chance the engineer to speced/designed this hose connection never even sat in a Taycan, much less seen it in use. I see this more and more - all digital design, people who design hardware or write software never ever seeing the end product in person.

 

[PSUEric]

Appears that fitting instead of being straight should be at an angle (30, 45 or 60 degrees). This should be easy to determine the angle via computer simulation with the suspension at full compression and full extension.

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