I went in to to have my pads changed and told them to check the caliper pistons. Here's what we found on the driver/front:
In my case, the passenger/front was not as bad - maybe just starting to show signs of corrosion but it was evident on most pistons.
We just re-assembled the fronts with no additional disassembly because the pads were maybe only half worn and they could not be fully serviced/fixed right now and they seem to work fine for the time being so I wanted to leave as is.
My rears seemed to be okay to maybe slightly showing signs of corrosion or all looking good. They were almost all the way worn down so we replaced the pads on both sides. Mine did not wear at an angle, I asked the guy at the shop what he though and he said they might wear at an angle if the pistons were sticking. Something to think about because a lot of people report that tapered or angled wear.
I could not get as many and as good of photos as I would have liked, but this may be more common than we think. Cannot wait until the next chat session to see what the SRT engineers have to say about it. Lord knows an actual Chrysler dealer would probably be worthless about this. I have 22,900 miles on the car.
Edit: Couple thoughts, the rears which both showed minimal to no signs of corrosion had a metal plate between the pads and the caliper pistons. The fronts did not. My mechanic said he sees brakes all the time like our rears and the pistons in them were like all those he has seen on other Brembo equipped cars, he had not seen any like our fronts before - and that backs up your research Tony that our fronts are unique to our cars. They certainly seem to corrode WAY worse than the rears.
Eric
__________________
2006 Chrysler 300C SRT8
AFE II intake, 185 t-stat, BT catch can, Predator with CMR tune, CORSA & MF cats
*Stock best with AFE intake only: 12.949@109.17 w/2.009 60' - 8.406 1/8 mile on 10/11/07 DA +100 Tri-State Dragway Cincinnati
*With a tune & intake: 12.649@113.98 w/1.945 60' - 8.219 1/8 mile on 5/28/08 DA +600 Muncie Indiana Dragway
*Intake/exhaust/tune 12.54@112.1 on street tires!
Recieved my remanufactured calipers from the Brake Warehouse yesterday. Some observations:
The pistons are of the solid design:
All my talk of them being made of steel was only partially true. The center section which includes the mounting bracket is steel. The outer portions (where the brembo logo would be) are not. I assume they are aluminum???
You can see that my hi speed $200 Snap-On refrigerator magnet sticks.
My stainless piston idea would require sleeving.
The nicest thing about them is that they appear ready for paint.
The dealer had no caliper parts available other than dust boots. They were more than willing to sell me calipers to the tune of $400 each. I have since fixed the problem for considerably less than the cost of just one new caliper.
In my opinion, this should be handled as a warranty repair, as the design of the caliper is clearly an issue. The center section is steel. The outer aluminum halves are machined to accept the pistons and are bolted to the steel center. This is a recipe for galvanic corrosion and that's exactly what's happened to your calipers.
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On a side note the rear pads showed a bevel or taper to the wear. (see pic below)
Not surprising, given that the pistons are all the same size. A typical Porsche caliper (also manufactured by Brembo) will use staggered pistons to provide an offset force to hold the pads parallel to the rotor, despite the pads wanting to rotate. These are Brembo "lite" calipers and nothing at all like the Brembo brakes found on Porsche, Ferrari, Lamborghini, etc.
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What is the purpose of the shim on the rear pad and it's unusual shape? (pic below) Would not the fact that the piston is bisected by the edge of the square holes cause binding of the piston in the bores? Just curious?
That's quite common. It allows the piston to come in contact with both the stainless steel shim and the composite shim that's glued to the backing plate. I'm not sure of the physics here, but I see this design all the time in my work.
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Have you noted other failures of this nature?
I'll bet they have, but I doubt they'll tell you!
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Have materials or design changes to the SRT8 calipers been made since the production cycle began?
Yes. As you noted in your later post, the calipers on my 2006 SRT8 (built 10/2005) have hollow pistons.
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If another experienced this problem and was willing to let a dealer tech work on the car would it be a warranty item?
I think it should be covered beyond the normal 3 year/36,000 miles. This is a safety issue.
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Would custom stainless steel pistons work in the caliper without other alterations?
This would not be a good idea, since the thermal expansion of steel pistons would not be the same as the aluminum portion of the calipers that houses them.
Finally got things back together today. Just haven't had time to wrench on it.
Painted and baked in the gas grill to cure the VHT caliper paint prior to putting on the logos.
Hi-temp vinyl logos off e-bay.
Next to the stock peices just for comparison. The logos are bigger than stock and the paint obviously is not clearcoated. I could not find rattle can clearcoat that I was confident in. I have four extra logos so if I have to redo them it will be pretty easy. They are a reasonable approximation to the originals.nt:
Mounted up prior to bleeding. Sat like this for four damn days. nt:
The pads.
Initial impressions after the bedding procedure recommended by EBC is that they feel a little stronger than the stockers. Not sure how long the brake-in compound lasts or if you would notice a difference when it is all worn away.
Quiet under moderate to hard braking. Squeels like a worn out city bus under light braking when rolling up to stop signs. Hope that dosn't last long. People are staring at me.
In the end with shipping, brake fluid, paint and stickers it cost around $300 to replace both front calipers. $100+ less than the cost of one caliper from the stealer.
My build date is 03/2006... later than yours. Not sure if we will find a rhyme or a reason to when and where the different piston designs were used.
Been doing some digging and it turns out the cup design (hollow) caliper pistons came first. The solid piston design that corroded is the current one. I'm trying to find the VIN breakpoint, and will post if I'm successful.
I'm discussing with StopTech the possibility of designing a 6-piston caliper upgrade for the SRT8 that utilizes the stock 360x32mm rotors. It would be significantly less than the current $3295 price of a complete front big brake upgrade with floating 380x32mm rotors like the one I've got on my car now. And it would open up a great number of possibilities for different street and race pads, since the D1247 shape is available in a much wider variety of compounds than the D1149 OEM pad shape.
Here's a photo on an SRT8 (not mine) with drilled rotors. Mine has slotted rotors.
Does a 6-piston caliper upgrade appeal to anyone? It would include brackets, calipers, stainless lines, and Performance Friction PFC1038 dual-use (street & track) pads.
Current pricing on an upgrade kit for other applications that already have StopTech 4-piston kits installed is $1695. I would guess pricing on an SRT8 conversion would be a little higher, since it would also include new stainless lines, banjo bolts, and crush washers.
DaveZ,
Thanks for chiming in here. FYI my build date is 04/2006. Please let us know what you come up with as when they switched piston design.
Eric
Since skeletonizer's car was built 03/2006 and the solid piston design came after the cup design, then it's a pretty safe bet that you've got the same set-up as skeletonizer.
If we can't get the information from the manufacturer, then we'll at least be able to collect data points from members of the forum. What we know now is that the design changed some time after 10/2005 and before 03/2006. So we're pretty close already. We just don't know about cars built 11/2005 - 02/2006.
I'm working with Centric Parts to see if we can offer rebuild kits consisting of boots, seals, and new pistons. We're going to be examining skeletonizer's calipers first, so the root cause of the corrosion issue can be determined and, if possible, corrected by different design rebuild parts. I'll keep you posted.
This is a gem of a post guys. Thank you. I've ordered a '09 Chally SRT and this is an eye opener. Are drilled rotors a good idea? I seem to remember hearing something like they warp easily?
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nt:
Hope that dosn't last long. People are staring at me.
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