[Rotorav8r]

Hi Folks,

This rotor is used on a lot of cars as OEM. It is the 340 X 30 front rotor and can be found on variations of the following:

F20/F21/F22/F23/F30/F31/F32/F33/F34/F35/F36

In talking with Mike @ GiroDisc, there is opportunity to build this rotor as a drop in replacement in a 2 piece rotor with aluminum hat and cast iron curved vane disc. He wants to see some interest though.

I live in Washington about 2 hours away from their shop. I would be more than willing to drive up there so they could get any and every measurement they would need. I already have the drawing for the disc itself, but happy to do my part to make this happen.

Mike is looking for commitment from 10 people to buy a set to do the work.

My question: Who is interested in a 2 piece rotor design? Don't answer yes unless you are willing to buy. I want to be fair to Mike on this.

I'm assuming in the $800-1000 range looking at the other rotors they do.

So if you are interested, please PM me and put a comment in the post so others can see what interest there is.

Thanks.

[230iZTR]

That looks amazing. I'm still another year or two away from needing it, but would buy that when it's time. What's the time horizon you're looking at for commitment and when might they be ready? Is this like weeks, months, or a year out?

[ggggbmw]

Sorry, as cool as those are, the price is just too much for me. That's about 3x the cost of the BMW OEM aluminum hat rotors. And since the OEM is already an aluminum hat, I don't think they would save that much weight either.

For a dedicated track car, maybe it would be worth it. Not seeing the value for a street/HPDE car.

[Rotorav8r]

I agree with you; if you are just daily driving, it is hard to beat the stock rotor. I'm interested in these because I do track the car and want more cooling capacity. The stock brakes are quite good, but with R compound tires will get pretty hot.

[Rotorav8r]

230iZTR I'll put you down for in the future. I think that is an honest answer for me to give Mike in people being interested. Thanks for letting me know.

[pikcachu]

Originally Posted by Rotorav8r

I agree with you; if you are just daily driving, it is hard to beat the stock rotor. I'm interested in these because I do track the car and want more cooling capacity. The stock brakes are quite good, but with R compound tires will get pretty hot.

With R compound tires the motor will granade due oil starvation anyway

[dradernh]

Originally Posted by Rotorav8r

I agree with you; if you are just daily driving, it is hard to beat the stock rotor. I'm interested in these because I do track the car and want more cooling capacity. The stock brakes are quite good, but with R compound tires will get pretty hot.

Thanks, as I was wondering what use case you envisioned for these rotors.

The temps I saw driving my car on a handling track with a single heavy-braking zone make me question how much difference any 340mm rotor is going to make. If I was still doing DEs, however, these are something I might consider.

With little opportunity to duct air into the front rotors' centers, our Brembo front brake systems are going to get very hot no matter what we do. After six events, my blue calipers have cracked dust boots and are in need of a teardown. I wouldn't be surprised if the boots had cracked after the first couple of events. For DEs, I think high-temperature dust boots and piston seals would be a good idea.

The price is not bad for a small run of a two-piece rotor like this.

[Rotorav8r]

dradernh You definitely have some valid points.
Your 370mm rotors have more thermal mass but no better cooling capacity/efficiency compared to the 340mm. It is pretty easy to cook the dust seals in our calipers. (and dis-color the rotors for that matter...green is the new blue I guess). The biggest reason though is there is no way to take the heat away. Curved vane rotors will increase the cooling capacity dramatically. They physically pull air in and pump it out where the posts just stir it up. This creates way better heat transfer to take the heat away, reducing overall temperatures. Maybe I'm too optimistic, but having these rotors will definitely not hurt compared to stock.

BTW, for those interested, Millway makes a set of steel pistons for our calipers that are similar to AP Racing pistons.

https://www.millway.se/stainless-ste...rt-brakes.html

These pistons with a good set of seals may be helpful.

[Rotorav8r]

pikcachu At the risk of opening a big can of worms, has anyone with a Stage 1 or stock engine grenaded the engine. I do see drops in oil pressure, but I wonder more if people are getting pre-detonation which is the bigger contributing factor to killing the rod bearings and the engine.

To be perfectly honest though, it is enough of a concern still to me that I'm either going add a baffle (MMR) & accusump (~$1000 ), or switch over to the M2 oil pan/pump (@$2600, )

So far oil analysis has been perfect on my engine. I will get another in a month or so that will have had 16 track days. So we will see....

[dradernh]

Originally Posted by Rotorav8r

dradernh You definitely have some valid points.
Your 370mm rotors have more thermal mass but no better cooling capacity/efficiency compared to the 340mm. It is pretty easy to cook the dust seals in our calipers. (and dis-color the rotors for that matter...green is the new blue I guess). The biggest reason though is there is no way to take the heat away. Curved vane rotors will increase the cooling capacity dramatically. They physically pull air in and pump it out where the posts just stir it up. This creates way better heat transfer to take the heat away, reducing overall temperatures. Maybe I'm too optimistic, but having these rotors will definitely not hurt compared to stock.

BTW, for those interested, Millway makes a set of steel pistons for our calipers that are similar to AP Racing pistons.

https://www.millway.se/stainless-ste...rt-brakes.html

These pistons with a good set of seals may be helpful.

Yeah, the 370s were more for bling than anything else. The (still!) blue Brembos needed a refresh and it was easier to get the MPBK and have it installed.

Having looked at the front rotor opening, and there's little of it, what I question is how much air is going to pass through the vanes, regardless of how well they're designed. Ideally, you'd have at least a 3" hose ducting air directing into the rotor opening. As that's an impossibility, the vanes are going be doing all the work.

If you do go with a set of these rotors, it would be interesting to see your before and after rotor edge temperatures. I used this product for years and found it a handy guide to what was going on temperature-wise: https://www.amazon.com/Genesis-Brake.../dp/B000UZEI6C.

On an E36 race car I owned with AP Racing race calipers and rotors, the temps came back well within pad and fluid limits. The car was very high-performance, but with a 3" duct feeding the rotors they never got particularly hot even on a very heavy-braking track like Watkins Glen. On a track like Mont Tremblant with its moderate demands on the brakes, I blocked off the brake ducts - that's how effective they were.

It was just the opposite with my F22. This was helped by the fact that it weighs 724# more than the E36 and will reach much the same top speed on a long straightaway. The temps were way off the scale on both the rotors and the calipers.

If I'd decided to keep at it for a few more years, I'd probably have gone with a StopTech BBK or the less expensive AP Racing kits offered here: https://www.tomwrigleyperformance.co...vpf-ymm-search.

Best of luck with it - every little bit helps!

[230iZTR]

Just wanted to update this thread after reaching out to Girodisc today...they still are looking for 10 people to commit in order to justify a small production run.

If thats off the table for now, I think im looking at ECS, EBC, or just another OE/Pilenga set.