TBK's Time Attack Build: MK-BRX

[PowerGetter]

great progress. Plans for additional weight shedding?

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[TBK]

great progress. Plans for additional weight shedding?

Thanks! And yes.

I do have plans for dropping weight (it's actually my priority), but i'm a bit limited by the class i'm competing in, Street Mod. Currently i have a titanium exhaust, seats, battery, lighter wheels and a front BBK.

When i move up to Track Limited next season, i'll be looking at doing a few more things to drop weight:
- door cards
- CF roof
- Lexan sides and back.
- Surge tank (allowing me to run a lot less fuel in the tank)

Can't really think of anything else tbh. There's not a whole lot of info on some creative ways to drop weight compared to some other platforms. Perhaps it's a (relatively) low volume platform thing. Created a thread to discuss door cards because there wasn't one, and even that got no traction

 

[i3igpete]

I think it's the fact that they did such a good job, there's really not much else you can do besides the obvious panels you mentioned, and deletion of electronic/engine subsystems. Any other platform, aluminum subframes and fiberglass hatches would be one of the final upgrades you would do.

 

[TBK]

These are very nice...

 

[TBK]

Round 5 of the Grid Master's time attack was yesterday. Got 2nd place. It got so humid after the first session that it was impossible to put down any faster times. I regret not pushing harder in that first session.

It was my first time on this layout (Yas Marina North Circuit). Not the most technical layout, but was still fun.

No bueno...

Not really an F1 guy, so I also discovered the F1 tracks have "yellow sausages" in some places.....? At Yas Marina that would be a turn 1. Guess how i found out?

 

[TBK]

I think i'm leaving quite a bit of time on the table with braking. The braking setup is good, the winmax R7 pads are quite effective, although i'm not the biggest fan of their modulation. That's not the issue though of course.

I don't want to reduce front camber either. I'm not running too much front toe out either (1mm) for that be an area of optimization.

Here's my plan...i think

- I need even stiffer springs. I'm at 685 lb/in front and 913 lb/in rear currently. I believe the front end is diving a bit too much under heavy braking, taking the rears completely out of the equation when it comes to braking. That little help from the rears would surely make a difference. Thinking of moving to 913 lb/in front and 1,142 lb/in rear. Seems a bit high though when i look at the numbers, so i'm also wondering if should first try a midway point.

- Increase front compression +2 to reduce dive and make the initial braking a bit more reasonable.

- Increase rear rebound +2 to slow the rear rising under braking/reduce rear lightness.

This is how it's reflected in my suspension/alignment tracker. Top is the current one set in Dec and bottom is what i'm considering. Should probably add spring rates to this as this would be my 3rd change. In red is what is being changed from the previous setup.

Text on the right is so i keep track of why i made the changes.

o

 

[razorlab]

I think i'm leaving quite a bit of time on the table with braking. The braking setup is good, the winmax R7 pads are quite effective, although i'm not the biggest fan of their modulation. That's not the issue though of course.

I don't want to reduce front camber either. I'm not running too much front toe out either (1mm) for that be an area of optimization.

Here's my plan...i think

- I need even stiffer springs. I'm at 685 lb/in front and 913 lb/in rear currently. I believe the front end is diving a bit too much under heavy braking, taking the rears completely out of the equation when it comes to braking. That little help from the rears would surely make a difference. Thinking of moving to 913 lb/in front and 1,142 lb/in rear. Seems a bit high though when i look at the numbers, so i'm also wondering if should first try a midway point.

- Increase front compression +2 to reduce dive and make the initial braking a bit more reasonable.

- Increase rear rebound +2 to slow the rear rising under braking/reduce rear lightness.

This is how it's reflected in my suspension/alignment tracker. Top is the current one set in Dec and bottom is what i'm considering. Should probably add spring rates to this as this would be my 3rd change. In red is what is being changed from the previous setup.

Text on the right is so i keep track of why i made the changes.

o

I can't remember, are you true coilover rear or divorced spring? Because if you are divorced, your rates are basically 685f/538r.

Have you done the brake coding yet? That will add more rear braking force.

 

[TBK]

I can't remember, are you true coilover rear or divorced spring? Because if you are divorced, your rates are basically 685f/538r.

Have you done the brake coding yet? That will add more rear braking force.

Divorced, so yeah the actual rates are diff

No i haven't. Tbh i've never done that before so i'm not sure how to. I'll try to look for instructions. Getting the rear brakes to do more work would be great.

 

[razorlab]

Divorced, so yeah the actual rates are diff

No i haven't. Tbh i've never done that before so i'm not sure how to. I'll try to look for instructions. Getting the rear brakes to do more work would be great.

In my spreadsheet, under the Protool tab --> Brake Coding

 

[TBK]

In my spreadsheet, under the Protool tab --> Brake Coding

Oof this is excellent, thanks man, much appreciated. So does that do anything to the fronts as well?

Going by the instructions real quick doesn't seem like something i can tinker with...right? So how is this going to affect brake bias, in real world terms? edit: never mind i just checked the codes. Still not sure what to expect though. And if we're ticking all the boxes there or if some of those should just be left alone, like the one about the electronic proportioning valve.

 

[Bug2th]

Hmm. I’m curious too. Did some searching for brake coding and didn’t find what it does exactly (do you have links to where the info came from?). Are there any negatives to doing this other than a bit more rear brake wear?

 

[TBK]

Ok looked into the brake coding, and for anyone interested, here's a breakdown of the codes:

- removes brake drying. Basically when the pads nip the rotors to get water off of them
- removes the electronic brakeforce distribution for the front
- I think this just eliminates the physical pad wear sensor from working, since we only have 1, and so the wear for the other 3 is done via estimation
- This sounds excellent tbh. Removes brake prefill. if you lift off really quickly, the car assumes you're trying to emergency stop and pre fills the lines and moves the pads closer to the rotors. So what ends up happening is an inconsistent brake feel
- The car increases hydraulic pressure so the pedal still has firmness when the brakes get hot. It seems this masks brake fade, which could be dangerous at the track. So this eliminates that.
- This also seems excellent. removes panic brake assist. When you brake hard the car sometimes assumes you're panic braking and goes immediately to 100% braking.
- This disables the electronic proportioning valve...i guess this creates static brake bias? I'm not sure how that's going to feel.

Overall these mostly seem good, although i'm not sure how this is going to improve rear braking specifically vs just improve braking feel/consistency overall. Maybe the last one?


edit: why is my brain like this? i just noticed that Bryan's sheet actually does include the meaning of each. For whatever damn reason my brain just skipped the english words and copy pasted the code.

 

[TBK]

Ordered the new springs and they should be here soon

Progression of my setup, including the incoming springs:

Can't help but think that this is going to be very stiff. These are my current settings:

And here's what i'm considering doing to accommodate the much stiffer setup. Basically soften LSC, HSC and rebound. Will also soften both sways from middle to soft.

I'm also considering moving up from -3.8 front camber to -4.0, because the stiffer setup means i'm going to get less dynamic camber gain.


That's a lot of changes all at once, which I generally don't like doing. But it's a fairly big shift in rates. Am i 100% confident about any of this? Absolutely not. But it makes sense to me....


This is what my setup will look like basically. (bold red means it's changed since the last setup)

 

[razorlab]

I'm also considering moving up from -3.8 front camber to -4.0, because the stiffer setup means i'm going to get less dynamic camber gain.

The front is strut, there is no dynamic camber gain. There is however, camber loss.

 

[TBK]

The front is strut, there is no dynamic camber gain. There is however, camber loss.

Derp. That's correct. Same conclusion though. MORE CAMBER.

Edit: will def be interested in seeing if i feel any difference there. If the camber still feels good, then i likely could've gotten away with more camber before the changes, since it's effectively going to be just that. So camber stays at 3.8 for now, thanks for that

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