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Just thought I'd post this because I know a lot of ISF folks get their Brembo calipers custom powder coated...
So we had this ISF in the shop yesterday. Owner had the calipers custom powder coated years ago by a local powder coating shop who apparently is very reputable.
A few weeks ago he had a leak from one of the banjos and had to tighten it. When we looked at it yesterday while doing a brake job, the problem became very obvious, and this is certainly something you all should take notice of if you have had your calipers powder coated.
Bottom line is that the sealing surface to the banjo copper crush gaskets must be masked when coating, or tightening against the powder coat will work.... UNTIL the calipers get really hot (such as doing a track day). At that point the powder coat softens and compresses, and the banjo bolts become loose, creating a potentially serious and life threatening situation!
Pic below shows the depression in the powder coat that develops as the powder coat softens and banjo loosens. All the banjo bolts on this car were totally loose, actual tightening torque might have only been a few ft-lbs!
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These are my calipers.
Everything was fine and dandy until I started pushing the car more aggressively at the track. My brakes completely went out a week after my last track day while I was parking (isn't that fortunate).
These are my calipers.
Everything was fine and dandy until I started pushing the car more aggressively at the track. My brakes completely went out a week after my last track day while I was parking (isn't that fortunate).
Cant believe the other 3 calipers didn't leak... banjo's were literally almost finger tight.
Rafi
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This is also true for any of the caliper mounting bolt surface. I had a buddy lose a caliper mid-race due to the powder coat softening on the surface around the bolt and the mounting bolts vibrating out.
Thanks Rafi for that information, you could have potentially just save someone's life. You know Rafi and Simon aren't just great vendors they're truly part of the Lexus community once again thank you guys for all the great work and information you provided.
no, he is saying that if you do get your wheels powder coated, make sure they do not coat the mating surfaces.
There is another reason to be careful with powder coated wheels. Most powder coats require 400F cure temperature for about 30min. This is in the range of the heat treatment temp of aluminum. 30min@400 is not really enough to degrade the alloy, but you usually have to do multiple coats (inc clear coat) and temperature in most powder coat ovens is not that well controlled, so you could be getting 450F hot spots. So once you start getting into that 450 range for 1hr+ the degradation in strength will be noticeable. Most OEM wheels are extremely over-built and will be less sensitive to this than a lightweight aftermarket wheel, but everyone should be very cautious with these things.
There are special low temp powder coats that bake at approx. 300F, so that is worth considering.
Rafi
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All HRE wheels come from the factory powdercoated. It is certainly possible to do it right, and as Rafi says above, it is possible to do it wrong. When I had my wheels done, the refinisher recommended paint first and clear powdercoat to finish for protection and gloss. They do a LOT of high end cars and have a long standing reputation in Atlanta for being the best at what they do. I was fine with them powdercoating my wheels and asked about their process and temperature control to be sure I could be safe with these wheels on the track.
Originally Posted by http://www.hrewheels.com/faqs
This is one of the questions we get asked the most and it's one of the most important; the answer is both simple and complex. The simple answer is, "To create the best you must start with the best". What this really means is at every step, we don't cut corners and are continually trying to improve our materials, processes, facility and team to make sure it stays that way. We start with extremely talented people to design and engineer every HRE from sketch to testing, programming and prototyping. From there, only the best materials are used from our forgings, assembly hardware and powder coats. Next, our artisans hand prep and brush every wheel by hand spending hours perfecting finishes that only HRE can offer. From there our wheels move to a hand washing process that again shows the care and attention to detail needed to produce our finishes. It then moves to our in-house powder coat process which produces astonishing yet durable colors that complement even the most exclusive vehicles in the world. If it's a 3-Piece wheel, there's still more to do. After powder coating, a 3-Piece wheel needs to be assembled, sealed and checked for runout (making sure the wheel is perfectly round). Even our assembly bolts are designed for HRE by HRE and are produced in the USA by ARP. Before any wheel is considered an HRE, it goes through an extensive quality check ensuring it lives up to the HRE promise. And one of the most commonly neglected parts of a forged wheel is its packaging. This often leads to blemished and damaged wheels so at HRE, we don't skimp here either. Our packaging is specifically designed to keep your wheels safe regardless of how far they are traveling because we want them to arrive just as perfect as when they left.
I wonder if the Temperature concern is the same for Cast vs Forged wheels. I'm aware that OEM wheels are typically more robust than after market wheels, hence the reason I have RCF wheels on my ISF. And no issues with bore size.
11-14-17, 06:27 AM
Warning about POWDER COATING YOUR CALIPERS!
