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OnTrack Maniac
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NOW UPDATED WITH PICS:

http://www.nagtroc.org/forums/index.php?s=...st&p=588178

ORIGINAL POST
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First off, I just want to make clear that these AMS rotors are from a company up in Canada and are in no way affiliated with AMS Performance up in Chicago. I believe that AMS Performance does high-quality work and want to make sure that this post does not negatively affect their company name. If I had known these rotors were not from them before I purchased, I would definitely have asked around to see if they were worth buying. I just assumed it was from the same company since it had the same name (and we all know what happens when you assume...).

Now, for the main topic:

Although I do plan to run the AP J-Hooks on my car at some point, my first brake upgrade was a set of AMS slotted rotors with new hats purchased from GT-RR. The reason I chose these was primarily as an in-between upgrade between OEM and the AP rotors but also to obtain an extra set of hats to make future brake changes easier. After putting these on my car, I began to hear stories from others who have had trouble with these rotors. I've heard of bedding problems, warping, and also that the rotor surface can detach from the inner vents, all of which are major issues. I didn't expect them to be the same quality as the AP discs but I certainly expected them to be better than this.

I'm just curious to know how many others have had trouble with these rotors and what sorts of problems you've seen. If you would prefer to PM any details, that is fine too, but I thought it might be a good idea to post it here so others don't end up in a similar situation after "upgrading" to these.
 

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GTR Nerd
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5,335 Posts
The GT-R is a heavy car. Stopping a heavy car puts a lot of heat into the rotor. There are different grades of materials and metals available for brake rotors. The better the material, the better the QC, the more expensive the rotor.

I can tell you from personal experience with an un-named company that on the R34 World Challenge car, we would warp the front rotors, and knock the pads back at every event. We tried a number of ways of bedding, different pad compounds. We tried anti- knockback valves. Tried new wheel bearings every event. Ran more and larger ducts. Changed the front bumper. In the end, the brake rotors were for a street application, and a lighter car, rather than what we were trying to do with them.

We fixed the brake issue by paying more money for a heavy duty rotor, from a known company. The rotor cost about twice as much, but we didn't have the issues again. One $40k crash was attributed to knocking the brake pads back, and the driver saying he had no pedal, while we were testing at Sonoma. Brakes are not an area to try and save money.

The AP J-Hooks use one of the most expensive, and best materials possible in an iron brake rotor. http://www.stillen.com/product.asp?id=STIG...&model=GT-R
 

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OnTrack Maniac
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Discussion Starter · #3 ·
I wasn't really trying to save money on brakes, I was mainly picking a new rotor that used standard-sized hats I would be able to use on the J-Hooks later. Like I said, I wasn't expecting them to be as good as the AP's, but I didn't think I was purchasing a street-only rotor either.
 

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GTR Nerd
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I wasn't really trying to save money on brakes, I was mainly picking a new rotor that used standard-sized hats I would be able to use on the J-Hooks later. Like I said, I wasn't expecting them to be as good as the AP's, but I didn't think I was purchasing a street-only rotor either.
Nearly everything is a street only rotor. Even the factory rotors. When Nissan did its testing here in the US and in the UK, they replaced pads and rotors nearly every night.

The car is heavy, and just eats them up. For 95% of the owners, stock its enough brake rotor to work.

For me, on a heavy car that I would be tracking, I wouldn't accept anything but the big 3. AP, Alcon, Brembo. For a street car, daily driver, no big deal.
 

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Premium Member
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Sean hit it on the head. For street use, you can get away with just about any rotor. For the track use you are enduring, stick with AP, PFC, and the other companies that race-test their products.

I have seen lesser quality rotors, crack, warp, separate...you name it....after 1 track session. AP has been rock solid for us. The amount of heat these rotors have to absorb and shed is enormous, compared to many other cars. 4000+lbs with driver, and massive straight line speed is no joke. Be careful.
 

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Like Sean and Sharif said, cheap rotors crack when used hard on track, in particular without adequate cooling.

I designed a set of brake discs front and rear and had them machined by Coleman in the USA for the GT-R, and bolted them up with AP Racing hardware identical to OEM. No idea where their blanks come from, but rotors did not last more than 3 days on track, with large cracks developing, and they were slotted, not drilled. One of the problems was that they only had one blank to use for front and rear, and it left the disc face too thin for the rears, but fronts cracked as well.

So I bought a set of PFC's as that gives you a full extra set of hats (non OEM compatible though) and allows you to keep your street rotors intact without having to change out 36 bolts, 36 nuts and 36 McLaren clips plus the slow torque procedure. The PFC's are doing very well so far, much much better than the Colemans I had made up. I thought Coleman would have good stuff as a USA based company serving many racing types, but they just cracked. There are virtually no foundries in North America casting rotors (PFC may have one of the only ones left), and virtually all makes of rotors are now cast in India and China, including Brembo for many of its rotors. Unless the company making the rotors or ordering them has strict quality controls on metallurgy, treatments, etc, quality is likely going to be poor.
 

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Well, it's very interesting that this subject has come up because I have had problems with the AMS rotors warping. I am currently involved in a "heated discussion" with AMS regarding the matter so I shall say no more right now other than I am very disappointed.
 

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Brake maven
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I thought Coleman would have good stuff as a USA based company serving many racing types, but they just cracked. There are virtually no foundries in North America casting rotors (PFC may have one of the only ones left), and virtually all makes of rotors are now cast in India and China, including Brembo for many of its rotors. Unless the company making the rotors or ordering them has strict quality controls on metallurgy, treatments, etc, quality is likely going to be poor.
Coleman specializes in making economical rotors for lightweight oval track racers. The GT-R, even unmodified, is well outside of their core strength. PFC does manufacture in the USA (maybe elsewhere also). There are many other places rotors are made outside of India or China. I will remain silent on "AMS" as I don't know for sure where they source from, nor am I very interested in finding out.

The bottom line is casting iron is as much art as science. As you alluded to, controlling of the alloying elements, tooling technique, melt and pour processes, heat treating, rough machining, stress relieving, finish machining, etc., is not trivial.

I am constantly approached by companies/individuals who promise the moon with "offshore" sourcing. Sadly, nearly all of these companies specialize in taking shortcuts to meet cost targets. They know the only way into the market is on price, as our society has driven that notion into their heads. We asked for this situation and we are getting it -- we are foolish to blame 'them'. If we all only bought quality product (at fair prices), not only would a lot of the crap go away, but the price of all better-quality goods would drop based on higher volumes. Until that day arrives, it is solely up to the individual to seek out sources that follow a more traditional philosophy of quality and craftsmanship -- for as long as they are able to survive.

I believe that those who drive GT-R's and other fine vehicles as a direct result of their own personal commitment to excellence will fully understand what I really just said.

Chris
 

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Premium Member
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Coleman specializes in making economical rotors for lightweight oval track racers. The GT-R, even unmodified, is well outside of their core strength. PFC does manufacture in the USA (maybe elsewhere also). There are many other places rotors are made outside of India or China. I will remain silent on "AMS" as I don't know for sure where they source from, nor am I very interested in finding out.

The bottom line is casting iron is as much art as science. As you alluded to, controlling of the alloying elements, tooling technique, melt and pour processes, heat treating, rough machining, stress relieving, finish machining, etc., is not trivial.

I am constantly approached by companies/individuals who promise the moon with "offshore" sourcing. Sadly, nearly all of these companies specialize in taking shortcuts to meet cost targets. They know the only way into the market is on price, as our society has driven that notion into their heads. We asked for this situation and we are getting it -- we are foolish to blame 'them'. If we all only bought quality product (at fair prices), not only would a lot of the crap go away, but the price of all better-quality goods would drop based on higher volumes. Until that day arrives, it is solely up to the individual to seek out sources that follow a more traditional philosophy of quality and craftsmanship -- for as long as they are able to survive.

I believe that those who drive GT-R's and other fine vehicles as a direct result of their own personal commitment to excellence will fully understand what I really just said.

Chris
Amen.
 

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OnTrack Maniac
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Discussion Starter · #11 ·
I fully agree. But, when I bought these, I did not know they were not affiliated with the AMS Performance that's on here. With the AMS name on it, I assumed it was from the same group so I trusted the quality of the parts based on this. From what I've seen, I would trust that AMS Performance wouldn't release anything that hadn't been properly tested or wouldn't hold up to a given standard of quality. It was only afterwards that I found out that it was a completely different company. Had I known this ahead of time, I would certainly looked into this further before making the decision.

Prior to getting these, I had also tried buying used hats from several members on here who were selling the OEM rotors but no-one wanted to separate the rotors from the hats for sale on their own. I guess what I would like to see (in a perfect world) is an option to get rotors with new hats made by AP.
 

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Piman, the OEM hats are reusable many times over. Fresh hardware is used of course. I am on my 5th set of front rotors...same OEM hats.
 

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Piman, the OEM hats are reusable many times over. Fresh hardware is used of course. I am on my 5th set of front rotors...same OEM hats.
I believe he stated he wanted to have essentially 2 sets of rotors, so he could fast swap rotors, instead of the fun that is swapping hats!
 

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OnTrack Maniac
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Discussion Starter · #14 ·
Piman, the OEM hats are reusable many times over. Fresh hardware is used of course. I am on my 5th set of front rotors...same OEM hats.
I know the OEM hats can be re-used but, from what I understand, a good amount of the time spent changing brakes is involved with mounting/torque-ing the hats to the new rotors. A second set of hats could be pre-mounted to a new set of AP discs and ready-to-roll when it's time to change them. I'm just trying to make brake changes a little more convenient by doing some of the work ahead of time.
 

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SuperFly TrackGuy
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PFC have worked well for me.
 

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OnTrack Maniac
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Discussion Starter · #16 ·

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Well, it's very interesting that this subject has come up because I have had problems with the AMS rotors warping. I am currently involved in a "heated discussion" with AMS regarding the matter so I shall say no more right now other than I am very disappointed.
Ditto. Though maybe not "heated"... but just a discussion.

I have 4 AMS hats & hardware I'd sell if anyone cares.
 

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GTR Nerd
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I too had problem with warping..end up shaving part of my caliper off. :-(
That is too bad. Did you run the car hard? Are these things just warping with street driving?

If you need some AP Curved vane rotors, let me know. Most people really seem to like the J-hook, and slotted versions. They are not as cheap as the AMS, but then again, they are not as cheap.
 

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Premium Member
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That is too bad. Did you run the car hard? Are these things just warping with street driving?

If you need some AP Curved vane rotors, let me know. Most people really seem to like the J-hook, and slotted versions. They are not as cheap as the AMS, but then again, they are not as cheap.
 
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