Was it in bikes or cars first? Wilwood has offered wavy rotors for at least a decade for dragster (aluminium rotors anyone?) and sprint car brakes (also available in titanium).

 

I had a set of 'wavy' rotors on a track bike almost 20 years ago... to be honest, I noticed no real world performance difference from the stock rotors, but when you're chasing ounces, I guess every little bit helps.

 

I ran Willwood rear rotors, they may have been wavy, but they definitely were drilled like crazy.

 

Are not some of those contraptions designed for the cases where brakes are required by rules, not by function.

 

Yeah aside from the edges serving a similar function as a "slot", the wave shape serves no performance purpose besides weight saving. Obviously, there just isn't any iron where there's air instead. So it's lighter than a round friction ring of the same diameter.

 

One of the early claims was that a 'wave' rotor resisted warping better than a traditional rotor, but I'm not up enough on thermal dynamics to make a call on that one. If it were true, I think we'd see a lot more of them...

 

I'm stalled out on all my projects waiting on parts.... I need a Hyper update!!!!!!

 

Sitrep

I have the front right corner all welded up.
Rebuilding the wheel well involved 13 different hand made sections, including several internal support pieces to ensure load transfer isn't compromised.

I was going to move to the left side and do the same, but on the driver's side there's a complication: the tire hits the clutch master. Significantly. Yeahhh, you read that right.
So the clutch master can't be on the engine side of the firewall. The need to re-do the clutch pedal snowballed a bit, and I'm doing a full pedal box now, so the booster and 929 MC will be deleted.



A pedal box isn't a small bit of work, so that's what I've been working on for the past week and a half. It really changes the ergonomics as well. I had to re-build the throttle pedal mount to raise that pedal 2" so it is in-line with the new pedals as my heel sits on the false floor now.

Here's an in-progress shot as its sits right now. Everything is mounted and the false floor is made. I have some grippy stuff on the way for the floor. Next up is to measure and figure out each line length, fittings, etc. and get all the brake and clutch lines in the works.





A non-boosted brake system needs entirely different piston sizes at both the masters and the calipers than a boosted system. So I've been back and forth with the StopTech guys and we're swapping all the calipers out for new ones with different piston sizes to make everything right for the new configuration. Conveniently, I was already going to have to basically build a whole new brake system at each corner anyways thanks to the 5 lug change... so it's the right time to do this.

 

With practice, you might be able to drive with just two pedals once moving. If so, that opens up new areas to expolit grip/friction circle. Vegas is like this with the sequential and boosterless brakes.

 

Clutch and gas?

 

Lol, a set of Tilton under foot pedals is one of the many things I am waiting on currently and POOF ...... now Ryan has done that too! I am making the move to Tilton brake/gas just because of the trans project im working on and they seem to be the only ones with a decently priced DBW option.

Is the complexity with your brakes a result of the larger wheels and tires? When I called Tilton, I just gave them my piston dimensions and count along with a ton of car data and they gave me a size front/rear masters. I was just going to run with it but now you have me questioning it all. This will be my first car with manual brakes, INTENTIONALLY, so I have MUCH to learn.

 

You are an incredibly determined fellow.

 

Manual pedal is on my want list for a ways off. Great to see what it takes to execute them.

 

This is the equivalent of Mad Magazine not sending me a new issue in the mail for 4 months back when I was a kid! I'm sure plenty is going on with Hyper and hope all is well Ryan.....

 

Any black Friday sales on Racecar updates?

 

Man, I get really excited anytime I see a post here.

Then I realize its not Passey posting.

Now I'm just disappointed and impatient again.

 

Ryan, I have been chasing a limp mode issue on my LFX car for a while now. Did you ever confirm what was causing it for you?

Keisler has had a couple swaps with the same issue and they tracked it down to the high pressure fuel sensor (GM Part # 12635273) on their cars. It's cheap and might be worth replacing if you haven't already.

 

It's been a while! First, looks like there are some questions to answer.

I chose the 850 pedal box because it has a throttle pedal with DBW compatibility. That's removed for now since I'm using the GM throttle pedal, but when I move to a standalone ECU (more on that later), if there are any issues with the GM pedal I could switch to the Tilton pedal and DBW sensor which is easy to configure in a standalone.

The necessity to dramatically change the brakes really stemmed from two things:
A) The 5 lug conversion meant the rotor hats had to change. That of course had a domino effect; rotor hat diameter increased slightly, causing caliper interference, etc. etc. and ultimately it led to revisiting every component in the brake system on all four corners...
B) When I discovered the larger tires interfered with the clutch master cylinder, I had to figure out a new clutch pedal/MC at a minimum, and that lead things down the path of deciding a pedal box was the way to go since it would solve my clutch pedal needs, and eliminating the brake MCs in the engine bay would free up some much needed space as well.

A manual brake setup needs substantially different piston sizes than a boosted system... conveniently, I'm re-doing the whole brake system right now anyways, so I can spec the new calipers with piston sizing appropriate to the new manual setup. I worked with StopTech on choosing the right piston sizes given the variables and targets of this car.
I know guys have converted to a non-boosted system while retaining their existing caliper piston sizing that was originally run on a boosted system... with varying degrees of success. It can be done, as long as the pedal ratio, MC sizing, etc. is all set up correctly with the right math to make sure you can get the line pressure you need with a reasonable amount of leg pressure. Companies like Tilton, StopTech, etc. can usually help with that. But generally speaking, the ideal way to do a manual system is to set up the piston sizing in the whole system appropriately; both the calipers and the MCs.

I found half of my limp mode issues for sure, but the other half remains an unknown. I was getting fuel starvation in high G corners, triggering fuel pressure dips that raised a flag in the ECU. I solved that with the surge tank. But last time the car was out and we confirmed the fuel starvation was fixed, I was still occasionally triggering a limp mode due to some other unknown. That day I swapped some stuff around and felt reasonably sure I narrowed it down to a connectivity issue between the ECU and throttle body. But I haven't confirmed that yet by rewiring that and running the car again. I've seen some talk of others seeing limp mode issues under boost due to other factors in the ECU, so it may not be the throttle body at all for me.

In short, frustration with the factory ECU continues. I have some big changes planned to eliminate that completely via completely removing the DI system and going to a traditional standalone ECU so we can finally control things with zero hurdles. I've been working on that in the background a bit this past year, but right now I'm focused on getting the car back up and running on the big wheels. Once we're up and running again and competing, I'll be turning my attention 100% to solving the ECU problem. I'm actually going to remove the supercharger in the interim. First priority when we are back up and running is to get the chassis, suspension, brakes, and aero all dialed back in. That's easier to focus on with an engine package that isn't fighting us most of the time. The boost will return once I have the ECU subject solved.

 

Tubbing the chassis is finished! We now have full unhindered bump travel in the suspension front and rear, with turning in the front. It's required some substantial cutting and reshaping of the front and rear tub, side exhaust, side skirts, and suspension geometry changes. I still have the body work ahead of me, but pretty darn happy to have reached this point. Here is the suspension at full compression:



And as I mentioned previously, the change to 5x114 had a domino effect that resulted in my revising everything in the brake system. The new front setup borrows the 309x32mm rotors from StopTech's NC BBK, and uses the StopTech C43 caliper in nickel finish with SS noses and piston sizes chosen for this car's brake setup and targets. But the critical caliper bracket to fit these parts to an NA/NB doesn't exist, and that's precisely why I invested in a vertical mill this year. I machined radial brackets in house, and now have Hyper's new front brake package completed.

Started with this:



Learned a ton these past couple months figuring out the mill. Making these brackets took some creative setups and getting familiar with the rotary table. Progress:



Final brackets finished, anodized, and studs installed:



Full package for one side:



Test fit. Naturally, miles of room inside this big 18x11:

 

Nice package