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Thread: Forza Brake Rotors

  1. #1
    Registered User Reedy's Avatar
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    Forza Brake Rotors

    So I bought a couple of sets of Forza brake rotors cause they were half the price of the Alcons that I needed to replace and were supposed to be the goods, but I have run into an issue and wanted to see if anyone else has tried these out and can share their experience.

    Basically they have only lasted 1 track day before some really bad vibrations under braking started happening. I pulled them off and had a closer look and the rotors seem to be developing hot spots and the surface is getting scored pretty badly.

    I've used the same pads (Carbotech XP10) for years with DBA 4000/5000 rotors and more recently with a set of Alcon rotors and never had anything like this happen before.

    At first I figured that I had fucked up the bedding in process (for the first time ever) but then I installed a second set, bedded them in word for word according to the pads instructions, then drove around on them for a whole month with a few brisk drives along the way just to make sure I had done it right. After 4 weeks of that shit I went to a track day at Luddenham and these brand new rotors were doing the same shit again before we even hit lunch time.

    Now I dunno about you, but I am not a fan of having to get a set of rotors machined twice for every track day I attend so I got in contact with the seller and Forza have pretty much just dismissed me as an idiot who doesn't know how to bed his brakes in properly, despite the fact that:
    1. I have used DBA 4000/5000 rotors with these pads for 6 years and never seen anything like this happen.
    2. The Alcon rotors that came with this brake kit had no issues either.
    3. After the first set failed I thought that it might have been a bedding in problem, despite never having seen this issue before. So I was extra careful with the second set.
    4. With the XP10 and DBA combo in previous years I have been able to throw a new set on and hit the racetrack immediately without even trying any kind of bedding in procedure, and I never had any kind of issues like this. As I said, I wouldn't have mentioned this if it didn't happen a second time after I had been so careful.

    Here's a few photos, you can kinda see the hotspots and scoring on the surface thats causing this shit. The scoring is deep too, way beyond just the transfer layer.




    Am I being a flog here or has someone else had experience with Forza rotors?

  2. #2
    Registered User Shane001's Avatar
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    Never even heard of Forza rotors before. Clearly they're shit!

    Even if you didn't bed em properly, that simply shouldn't happen.
    Last edited by Shane001; 13-09-18 at 12:04 AM.

  3. #3
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    Wheel bearings ok? Pad taper is extreme - to go with the cooked and grooved rotors though in that case.

    To paraphrase Sol, might be the usual, cast iron ain't cast iron.

  4. #4
    Registered User lukevl's Avatar
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    Quote Originally Posted by Reedy View Post
    ...so I got in contact with the seller and Forza have pretty much just dismissed me as an idiot who doesn't know how to bed his brakes in properly...
    I wonder if it's the same company that sells Forza that I (and many others) get screwed around by waiting for stock and being told that we are silly... When i was concerned my pads were very savage on my rotors and chewed them up I was told that I wasn't driving hard enough so it ate the rotors. When I gave them a description of my driving up to that point (hard) I was told that i was driving too hard for the track pads. Just excuse after excuse for a bad product it feels like.

    IF it is the same company that sells brakes direct to the the end user I'm sensing a pattern. I'm also seeing that Forza seem to be exclusive to them and hearing bad reports from a few areas on those rotors.

    As a side note stress relieving rotors is apparently a thing. Haven't researched much but I have a hunch that a ground and stress relieved rotor would last a lot longer than a direct-from-the-foundry-to-lathe Chin-wa rotor that is turned only.

  5. #5
    Non Compos Mentos Gammaboy's Avatar
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    That looks like casting porosity in the rotor?
    "Where can we get hold of a Vincent Black Shadow?" "Whats that?" "A fantastic bike," I said. "The new model is something like two thousand cubic inches, developing two hundred brake-horsepower at four thousand revolutions per minute on a magnesium frame with two styrofoam seats and a total curb weight of exactly two hundred pounds."

  6. #6
    Registered User Reedy's Avatar
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    Quote Originally Posted by gxxr View Post
    Wheel bearings ok? Pad taper is extreme - to go with the cooked and grooved rotors though in that case.

    To paraphrase Sol, might be the usual, cast iron ain't cast iron.
    Wheel bearings are near new. Had them replaced less than 12 months ago.

  7. #7
    Registered User nelsonian101's Avatar
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    I've got a pair of fronts on the Turbo Taxi.
    Taken them to Wakefield once with H16-03 pads.

    Seem to be holding up a bit better than yours. To be honest, they seem good so far. Will report back when worn a bit further though.

    As with many Chinese products, manufacturing inconsistency is prevalent.

    Found a possible answer here:

    https://cr4.globalspec.com/thread/68...n-Brake-Rotors

    "...…….Generally, steel castings would be either cast in sand, shell. or investment. Permanent molds are not used to the best of my knowledge to cast steel parts since most permanent molds are made either from cast iron or steel and neither would be suitable to cast steel into.
    ………….. This is not a cast to size part requiring the expense of investment casting.
    As mentioned before it could very well be a poor gating system or it could even be just a lousy pourer who allowed air to be aspirated into the sprue, forming oxides as it mixed with the steel. This often happens if he slows down or interrupts the pouring as he fills the mold. It also could be that there was excess moisture in the molding sand at the sand-metal interface and steam was given off from the drag side face and traveled up into the metal again forming oxides inside the casting. Another possibility could be a sand wash where pieces of the molding sand broke away and washed into the mold cavity with the metal and was entrapped inside the casting just below the machined surface.
    If it was a gas issue a magnification of the defects would show the cavities to have smooth walls whereas a sand defect would have irregular surfaces. A foreign material such as an oxide formation often has grayish powdery areas exhibited although they might disappear due to the nature of the brake drum service and the weathering of the surfaces. As to steel "vaporizing and causing bubbles" it is true that water vapor does break down over a hot surface of molten metal and aluminum and bronze will absorb the hydrogen and cause gas porosity. I am not sure that that also happens with steel but I do know that it is not the metal itself that vaporizes and causes the gas bubbles.
    In any of those cases "real time" radio-graphing (digital x-rays) of the parts, magnetic particle or eddy current tests would find such defects and allow the defective parts to be removed. As to the quality of the parts produced in China, well as the man said, "You get what you pay for" and if you pay cheap you get cheap. While there are many well funded and quality producing foundries in China, there are probably ten times more that are still pretty basic and antiquated and producing "cheap and dirty castings" at cheap prices...……………….."
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    Last edited by nelsonian101; 14-09-18 at 01:59 PM.
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  8. #8
    Registered User Reedy's Avatar
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    Those ones have exactly the same heat checking that I am used to seeing so yours seem to be a good batch. Both of mine came from the same batch and they took like 4 months to arrive so to have them shit the bed in this way is a bit of a bummer.

    You also have the same Rotor hat design as mine, what size are your rings? Mine are 332x28mm. Also which pads are you using?
    Last edited by Reedy; 14-09-18 at 04:22 PM.

  9. #9
    Registered User nelsonian101's Avatar
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    Quote Originally Posted by Reedy View Post
    Those ones have exactly the same heat checking that I am used to seeing so yours seem to be a good batch. Both of mine came from the same batch and they took like 4 months to arrive so to have them shit the bed in this way is a bit of a bummer.

    You also have the same Rotor hat design as mine, what size are your rings? Mine are 332x28mm. Also which pads are you using?
    360mm X 36mm Floating, ventilated, directional

    Meaty 25mm thick Project Mu H16-03

    http://pmuracing.com/pad-compound/metallic/h16-03/
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  10. #10
    Registered User brypar's Avatar
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    Have you checked for run out to see if they are actually warped? It looks as though there are two issues there.

    1. The dark marks leading and trailing the grooves looks like pad deposit. This will give the same symptom as a warped disc.

    2. The markings between the two grooves in the zoomed in picture looks like either a sand inclusion in the casting or porosity.

    It is hard to see things from images like this.

    If you have not had the rotors checked for run our I would suggest that should be your first check.

    Hope the advice helps

  11. #11
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    Did you run a micrometer over them to check for thickness variation? I'm guessing that's the cause of the vibration.

    Sounds like you got a dud pair, if that brand can survive on Nelsonian's taxi, they must be able to make some decent quality ones.... just not consistently, apparently.

  12. #12
    Registered User Reedy's Avatar
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    Quote Originally Posted by brypar View Post
    Have you checked for run out to see if they are actually warped? It looks as though there are two issues there.

    1. The dark marks leading and trailing the grooves looks like pad deposit. This will give the same symptom as a warped disc.

    2. The markings between the two grooves in the zoomed in picture looks like either a sand inclusion in the casting or porosity.

    It is hard to see things from images like this.

    If you have not had the rotors checked for run our I would suggest that should be your first check.

    Hope the advice helps
    Yea if it was just the pad deposit shit then I wouldn’t be so worried but the scoring of the surface is what has me bothered. I haven’t had a chance to send them to a machinist but I’m pretty sure they’re not warped. I also don’t want to waste money machining them if they are just going to do this again.

  13. #13
    Registered User Shane001's Avatar
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    Quote Originally Posted by Reedy View Post
    Yea if it was just the pad deposit shit then I wouldn’t be so worried but the scoring of the surface is what has me bothered. I haven’t had a chance to send them to a machinist but I’m pretty sure they’re not warped. I also don’t want to waste money machining them if they are just going to do this again.
    Good luck finding anyone in Sydney to machine them anywhere near true. Don't get them machined on a lathe.

  14. #14
    Registered User Reedy's Avatar
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    There’s quite a few people out there using these rotors now and I am the only one that’s had issues so far.

    I wonder if there’s such a thing as a bad batch of brake pads. I’ve blown through dozens of sets of these XP10’s over the years and they are supposed to be rotor friendly. I had the same set of pads for both sets of rotors so if something fucked out in the bonding while I was bedding those in then that might explain it.

    They are going to warranty me a new set on the condition that I use the pads they supply, so at least that’s a good outcome. Will report on how they go.

  15. #15
    gslrallysport.com gslrallysport's Avatar
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    Quote Originally Posted by brypar View Post
    Have you checked for run out to see if they are actually warped? It looks as though there are two issues there.

    1. The dark marks leading and trailing the grooves looks like pad deposit. This will give the same symptom as a warped disc.

    2. The markings between the two grooves in the zoomed in picture looks like either a sand inclusion in the casting or porosity.

    It is hard to see things from images like this.

    If you have not had the rotors checked for run our I would suggest that should be your first check.

    Hope the advice helps
    It speaks volumes when the only person to comment in this thread who would benefit directly from Forza being a poor product (a direct competitor) came to the same conclusion that Forza did about pad deposits (ie, not being bed in properly). Thank you Brypar!

    Full disclaimer here, I'm the person between Steve and Forza on this one, and to say this thread is causing us issues is an understatement. Of the now over 300 pairs of Forza rotors we've supplied only 3 we've had issues with. 2 pairs are the ones in question here, the third being a pair of rotors on an MY15 STi (standard rotor size) doing production racing (quick, heavy car with small brakes). They had their brake ducting pointing at the inside face of the rotor (not into the middle and up thrown the vanes) then wondered why they cracked a rotor during a cold night race. One side of the rotor is at full temp, the other side has 10°C air blowing staright into it. It created a huge temperature differential across the rotor, and I would've been concered if they DIDN'T crack a rotor under those circumstances as it meant they couldn't have been driving too hard. This was 100% user issue that caused this, but as with Steve, we warranted a new set of replacement rings on the condition that they fix their ducting and send us photos.

    With regards to the spoken about batch issues, two pairs of the EXACT same rotors from the EXACT same batch as both of Steve's (even running the exact same Alcon CAR98 calipers!) have run faultlously on the Skid Control 86, and recently won outright the Lakeside 300:

    https://www.facebook.com/dylan.cothi...61074388260089





    The look exactly the same as Paul's rotor above (albeit, different size).

    As a motorsport specialist I can't fault the quality of the Forza product, and I know what a wide range of vehicles they're used in, right down to Group N(C) Torana's which are ridiculously hard on rotors due to their limited size (256mm!). If you want to fault them for anything, look at their lead time on some products, but that's a completely different story and something that is rapidly improving...
    Last edited by gslrallysport; 10-01-19 at 11:18 AM.

  16. #16
    Non Compos Mentos Gammaboy's Avatar
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    So, was that porosity in the disc casting in the photo?
    "Where can we get hold of a Vincent Black Shadow?" "Whats that?" "A fantastic bike," I said. "The new model is something like two thousand cubic inches, developing two hundred brake-horsepower at four thousand revolutions per minute on a magnesium frame with two styrofoam seats and a total curb weight of exactly two hundred pounds."

  17. #17
    gslrallysport.com gslrallysport's Avatar
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    Quote Originally Posted by Gammaboy View Post
    So, was that porosity in the disc casting in the photo?
    Having not seen the rotors first hand, I'm not even going to speculate on that sorry.

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