Symptons: On hard application of brakes, car will pull to the right. Light to moderate application of brakes...stops straight. If you stomp on the brakes to the point of ABS, car stops straight. Recently had new tires installed, same results. Tires removed had no uneven wear. Last alignment was 1.5 years ago. I have been advised I should have all the calipers rebuilt. Anyone concur? FYI, car had new Porterfield R4S pads and Goodridge stainless steel braided lines installed about a year ago. Brakes were bled again, just three months ago.
I'd love to know if there is a rebuild kit out there for my 348 (which may share calipers with early 355's).
You havn't put any extra kilos on in the last 1.5 years have you? Seems odd that it pulls to the right though, maybe worn wheel bearing/stub axle? Is your a RHD or a LHD?
You might want to try switching your pads L to R and R to L first to see if that's the problem. Also look at the rotor and pad surfaces carefully. If one side shows different color, texture, or wear rate then it will give you some clues as to what's wrong.
FYI: Girodisc makes up custom caliper rebuild kits with genuine Brembo piston seals and dust boots. Most kits for 4 piston calipers are in the $100 per caliper range. If memory serves, the 348/355 calipers are 36mm and 40mm pistons. Easy to put together. Suppose I should make others aware of this in a different thread, or just update my website... when I get some free time.. Martin Image Unavailable, Please Login
Excellent advise. I've seen one out of four front pads not bed in the same as the others and cause this exact result. FYI, this caliper and piston sizes are common on many Porsche applications of the same vintage regardless of whether it's an Ate or Brembo caliper. Best, Rob
Thanks for the info guys...I have scheduled an appointment at a race shop a few minutes from my house (next week), and they plan to take a close look at the pads, calipers and suspension....and decide where to go. They are leaning toward caliper rebuild on the front, but want to wait until they see it first. Will report back what they find. Girodisc Martin, Chris and Joe say "hi" from Group 2! Great guys, they do all my tire and alignment work...just put new tires on my 355 a couple weeks ago. http://www.group2inc.com/aboutus.htm
I agree with switching parts side to side. Your car is kind of new to be having problems with sticking calipers. For reasons I have never really figured out I have seen pads and rotors cause a pull. All it takes is time. You might also consider a hose that is swelling internally and restricting pressure. Have seen that lots. Have also seen them delam and have fluid go between the layers under high pressure. Didn't have hose problems until about the time 355's came out. Been replacing them regularly since then on all models, even under warranty.
Thanks Brian....which hoses? The ones going to the calipers? They were replaced with Goodridge ss lines last year, at the same time I had Porterfield R4S pads installed. I will mention that since this pull to the right thing started this summer, I have had a lot of brake squeel to. But the squeel is only when braking pretty hard, not under more sedate braking. Pads are cheap, would you suggest I just throw on some new ones for starters and have the rotors turned too? I will mention that the rotors were not turned when the new pads were installed last go around...could there be some pad deposits causing this?
Those are the hoses I was talking about. I guess we can forget that assuming none have been damaged, crushed, whatever. Porterfield pads are really good. Sounds like you have a pad/rotor/bedding thing going on. Either take a Saturday and start swapping parts around or take the rotors out and have them resurfaced and see what happens. FWIW I have had no problems with R4S pads and noise. I always bevel the leading edge as the OE pads are and lube the leading and trailing edges of the steel backing on the pad. Brembo makes a really gooey, sticky copper anti sieze grease that is just the ticket for that if you can find some. That reminds me, I need to ask Martin if he can get it by itself.
Here is FBB's quick low buck repair. This works because someitmes with age the pistons stick in the bores or do not release properly to contribute ot a bedding/pad/rotor problem. New bleed brakes make for a cleanly working hydralic system. Loosening bores help to get the pistons to free float as designed. Smashing the brakes helps to remove some glazing and reaching the limit of operating temp burns off all the crap that is on your pads..... So jack car up take off wheels. Push bake pads in toward the caliper with a screwdriver as evenly as possible so that the pistons retract in the bores. Leave the driver in there to hold the pad. Do this on the other side. Tke this time to suck out the brake master with a turkey baster (you probably have old fluid in there anyway). Pull the drivers and bleed your brakes (do the rears too) allowing the pistons to remake contact with pads. Now go out and heat those pads up with some spirited stops like on a racetrack or trackday and really smash them. Get them good and hot. Now go back to normal use and see what they do. It is quick and easy and solves lots of non-use minimum use brake issues for just the cost of a can of brake fluid.
Update: The shop removed the front pads and found the ones on the left side definitely were glazed (Porterfield R4S installed last year on all four corners, about 5,000 miles ago). They removed the glaze on them (sanding?) and did the same on the right side as well. Did a test drive and thought it was fine now. He is going to take the car out and test again in the morning, and then inspect the pads again. He did mention that after several hard stops, the brakes were giving off a distinct odor, and didn't think they should as he was not working them that hard. He was wondering if these pads may be defective, or just not up to this car? I know many people here are using them successfully, so I doubt it is a compatibility issue. He was suggested switching to Ferodo DS2500? Anybody? What would cause the glazing? I drive pretty moderately, but will occaisionally go out in the country for some pretty "spirited" driving....could one of those sessions have caused the glazing issue? Is it likely to happen again?
Glazing usually happens due to improper bed-in such as dragging the brakes with very light pressure over longish distance or too hard too quickly and over cook the pad material before bed-in has occured. Spirited driving after properly bed-in is usually not the problem unless you really cook the pads on a track doing many hot laps. Don't know what is Porterfield's recommended bed-in process, but for 360 Challenge race cars using Ferodo DS3000 race pads, OEM procedure is to do a series of ten stops from 120kph down to 80kph, then a further fifteen stops with medium to normal pressure going from 150kph to 80kph. Obviously these stops are done with some cooling time in between each stop and not done immediately one after another. If we follow this procedure exactly on track it is usually a 30 minute session. We have found a higher bed-in success rate (ie. better grip and longer rotor/pad life) if we stretch the bed-in process to two 30 minute track sessions. For your street pads, maybe you can use the above race pad procedure as some sort of guide line as starting point. At any rate, you definitely should not stop the car without letting the pads and rotors cool down reasonably well. Otherwise you risk warping the rotor and/or glaze the pads as they sit on one spot of the still hot parts.
Spirited driving will not glaze R4S pads. Sane spirited driving that is, it means different things to different people! I have seen a glazing issue once before with the R4S compound on a lotus elise that was tracked quite a bit. I took them in and showed them to Andy Porterfield and his response was "these aren't track pads, why do people run them on the track?" Basically he told me the proper breakin for these pads is to drive them "normally" right after installation, no high temp breakin required. The torque will continue to increade over a few days of regular driving and then they are good to go. The glazed pads did show white around the edges which is a clear indicator of high temps as it is the residue of the resin binders burning out. Normal to see that on used track pads but not what you want to see on street pads. "Only you know how fast you were going!";-) With regards to the DS2500's, they are great pads. Super initial bite, excellent modulation, inexpensive, dust like hell, probably will squeal at low pedal pressures ie. stop and go traffic, parking lots etc. Gotta pay to play... FWIW Martin Oh yeah, Group2 is a great bunch, Chris there is about as sharp as they come. Still can't figure out why they think Alfa's are fast... maybe it has something to do with the 350hp 3.7 liter motors they are bolting in those things!!
Thanks for your advice Martin...Chris said he has been talking to you, and is ordering a replacement set of pads, as these are making a lot of noise still, after he drove the car some more today. Chris says you guys are surmising either I am driving harder than I claim (maybe... ) or the pads are defective...anyway, Chris will order replacements from you. I swear that I am not THAT hard on them....but do get a little crazy out on the East King County backroads now and then....just don't tell the Snoqualmie Police or King County coppers... I always thought the R4S was an upgrade over the stock 355 pads, as I really like the initial grab, and seem very fade resistant. And the stock pads were noisy around town and dust like hell. The R4S were perfect until I glazed them, then the strange pulling to the right, and lots of noise coming down from a hard stop.
