Popular Post Hunter Posted October 20, 2020 Popular Post Share Posted October 20, 2020 (The name of my new band) This post is a mix of post-stress relief, and perhaps food for thought. The situation My Cayman was due a brake fluid change, and some pipes were badly corroded so I booked to get them changed as well: Full credit to the specialist: they took me aside ahead of time and said that there was a worst case scenario in which the bill would be pretty large. In a portion of these cars ("maybe one in twenty"), the various fitting points on a caliper can corrode to the point of seizure and snapping upon attempted removal, especially where they haven't been removed in a long time. Part of the cause is poor material choice by Porsche: aluminium calipers with mild steel inserts, resulting in galvanic corrosion. The pictured line has been an advisory on my car for 3 consecutive MOTs. The previous owner was otherwise reliable when keeping on top of repairs, so with hindsight I see that this was an iceberg just waiting to be struck. Friday I dropped the car off Thursday evening, still innocently hopeful of an uneventful service. I was wall to wall with work Friday, so not once did I look at my phone until about 6pm. Turns out, the specialist had had a hectic day. The car had been on stands since the morning, when they discovered that corrosion was indeed a problem. Generous quantities of penetrating oil and heat cycling allowed a couple of fittings to be freed, but by 3PM several had already snapped and almost all are threatening to snap. In total, there are 5 insertion points per caliper: 2 bleed nipples (inner & outer) 2 link pipe fittings 1 brake supply fitting By end of day, they had successfully removed all outer bleed nipples and some pipe fittings. Only the outer bleed nipples: that's important, because it suggests the specialist used by the previous owner for 6+ years did a half-ass job when changing brake fluid, only utilising the outer nipple. The really bad bit? The brake fluid which has been sitting in the other side of the caliper has therefore not been changed in the better part of a decade. Brake fluid is hygroscopic, so imagine what a decade of water absorption means for mild steel? Monday Over the weekend, the calipers were stripped from the car and taken to a local engineer. The fittings which had snapped (the majority, it turns out) or seriously corroded were machined and stainless steel inserts with stainless steel fittings were put in place. In theory, stainless fittings will avoid future dramas. I had requested braided stainless steel hoses be put on too (which, by that point, was a drop in the bucket). Picked up Monday evening after a successful MOT. For the sins of another specialist/previous owner, these guys put in more work than could have been reflected by the bill, and I feel pretty well looked after. The brakes are rock solid too, and now I have one less worry on my mind (besides the perpetual risk of catastrophic engine failure). Conclusion The obvious stuff: if there's a repeated advisory on a car you're buying, be skeptical. It might be a big bill. The less obvious: if you're having a brake fluid change, consider asking your garage to check corrosion on all the caliper fittings. You could also prod your garage to see if they use both inner and outer bleed nipples. Apparently, even some specialists cut corners. That said, if a fluid change/brake bleed is all you need (i.e. the pipes/hoses do not need changing), you can get away with leaving corroded fittings in place... until said pipes/hoses do need changing. Finally, if anybody needs a recommendation for an indy in the south, I've now got one for you. Give me a message. 2 Link to comment Share on other sites More sharing options...
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