Brake upgrade and bias

[Lankstarr]

Evening all,

I'm lost in research on a brake upgrade at the moment, leaning towards a BBK front and rear upgrade possible with a new calliper set up on the front.

An issue with this option is that it throws the brake bias massively, Dali has a useful table showing several different set ups and how they compare with OEM.

Looking at a thread on Prime I then came across this comment:
BTW: Hrant I almost forgot.... those figures in Dali's table are way off for 97+ because it was based on piston size, etc and the 97+ brakes have a "secret" inline brake bias valve. I say secret because it's only mentioned once in the manual and it is not in the brakes diagram page in the service manual it's only shown on the parts diagram. 91-96 don't have this part.
So only Honda really knows what the bias is of the 97+.

part is 46210-SLO-003 VALVE ASSY., PROPORTIONING
It is under System Name / Component : BRAKE LINES (2)

Interested in whether anyone has come across or thought about this and what issues I'd get if I went for a kit overly biased towards the front. I can always choose a more aggressive rear pad to dial it back in a bit but not from 75:50 to 55:50!

For interest, kits being considered are racing brake, stop tech and ferox. I can't see there's much difference between them but welcome any experience or opinion.

Thanks,

Luke

[m666 edd]

I have currently:
Front discs 325/30 with HiSpec 4 piston slimline calipers
Rear discs 328mm with OEM rear calipers

This retains the handbrake mechanism and gives a good balance, similar to what it says on the dali page.

[nigel]

Luke,

Why not give KAZ a quick e-mail on the proportioning valve question and see what he has to say.
This is the first i've heard of it and i'm also thinking of a '97 brake upgrade to my '92 and would like to hear his inside input on the valve and its effect on the upgrade with or without it, (the valve) installed.

Cheers
nigel

[Lankstarr]

I have currently:
Front discs 325/30 with HiSpec 4 piston slimline calipers
Rear discs 328mm with OEM rear calipers

This retains the handbrake mechanism and gives a good balance, similar to what it says on the dali page.

I'm definitely not doing rear calliper upgrade but will check out the hiSpec kit, iirc though your kit was bespoke and Kevin went to a lot of effort to get it right. I want plug and play!

Maybe BBK all round will be plenty, at 30k miles my calliper should be fine but a big shiny one at the front does appeal!

Nigel - if anyone knows about the secret bias valve it'll be Kaz! Hopefully he'll see this and reply so others can see the response.

Thanks for your comments, btw I meant tarox not ferox!

Luke

[Kaz-kzukNA1]

Hi, Luke.
Before I start writing the long post, could you clarify the following points?

Is your NSX 2004 model as in your signature?
What is the objective of this modification?
What tyre (and wheel size) do you use?
How many days do you track your NSX per week or per month?
Do you mind sharing any specific stories that made you think the necessity of the modification?
Or, is it more of the ‘looks’ of the BBK?

Addition to the above, it will help a lot if you can share the following info.
Are you using OEM damper/spring/rideheight or are you corner weighing using the aftermarket coilover kit?
Do you have any modifications on your NSX especially in the area of engine, suspension, bush, weight distribution, alignment, etc?


By the way, there are thousands of correct and wrong information on the web. I have seen so many people flooded with the amount of information and unfortunately, from time to time, with the wrong ones.
You just need to evaluate the info first based on your knowledge and experience to determine whether it is likely to be the correct info or not.


There is no such thing as a ‘secret bias valve’.
There is no so called ‘Proportioning Valve (PV)’ in the brake system for the 91 – 96 models or on the 97 and 98 ones.
ABS tuning is different depending on the year model especially on the 97-98 model against 91-96 ones but it won't be activated until the ABS kicks in so it's not really a PV.

If your NSX is 99+ models or if you have upgraded your ABS to the latest one-body solution like me, then you already have the PV on your NSX.
If your NSX is indeed 2004 model, then you already have it.

I’ll get back to here once I get some extra info from you as above and after reading further posts from other owners.


Kaz

[Lankstarr]

Hi Kaz,

in answer to your questions...


Is your NSX 2004 model as in your signature?
Yes
What is the objective of this modification?
Not happy with brakes, have judder and discs are low so looking for complete replacement option.

Was also thinking of overhauling the calipers, if I do this plus discs and pads price is creeping up so maybe better to replace the lot.

What tyre (and wheel size) do you use?
OEM 17 and Goodyear eagle f1

How many days do you track your NSX per week or per month?
None

Do you mind sharing any specific stories that made you think the necessity of the modification?
Or, is it more of the ‘looks’ of the BBK?
Looks are good, but heard very good things about them. In reality I did less than 2000 miles last year so probably not necessary!

Addition to the above, it will help a lot if you can share the following info.
Are you using OEM damper/spring/rideheight or are you corner weighing using the aftermarket coilover kit?
If I order something from Dali I'm considering also getting his lowering springs and sway bar set (1.25" down)... Lmk if this is a bad idea, again focused around look

Do you have any modifications on your NSX especially in the area of engine, suspension, bush, weight distribution, alignment, etc?

No spare, cf bonnet, Tubi exhaust and procar airbox.

How are you getting on with the ebc kit? I have pretty much new ebc pads but have been advised to get a new set if I want new discs.

Thanks,

Luke

[Senninha]

Hi Luke,

New RB discs, fresh pads and a caliper overhaul would improve what you are currently experiencing and 'feel' better straight away. I would suggest about £2k to do this work.

If you're going for looks, then the Stoptech I believe is built to the same balance (or very close) as the OEM set up and have the added benefit of fitting within the OEM 17" wheels. you will be into around $5k plus shipping and taxes for the complete plug and play set up.

regards, Paul

[NSXGB]

Racing Brake also sell a big brake kit for the NSX incorporating a 324mm front disk and 330mm rear on standard calipers.
They also sell caliper upgrades.

There is a UK supplier for them too.

[Nick Graves]

Hi Luke,

New RB discs, fresh pads and a caliper overhaul would improve what you are currently experiencing and 'feel' better straight away. I would suggest about £2k to do this work.

If you're going for looks, then the Stoptech I believe is built to the same balance (or very close) as the OEM set up and have the added benefit of fitting within the OEM 17" wheels. you will be into around $5k plus shipping and taxes for the complete plug and play set up.

regards, Paul

This.

And what Kaz say.

Once you start b uggering round with different tyre sizes and different brake specs. the original algorithms (there is a lot of diff. calculus & stuff involved) all go out the window. Even my AD08s probably have a coefficient of friction they would have presumed only for the very best track tyres back them.

You might gain better initial bite, but find you have premature lock-up in extremis.

All I know is, I don't know enough about it an thus I only make microscopic modifications to what Honda's engineers and their Kray did.

Put it this way; if they felt the NSX-R set up was as good as it gets for this old car, that's probably what to go for.

IME, Honda brake pedals go a bit 'blergh' later in life. I think this is due to non-flat disk surfaces, softening hoses or soggy M/C seals. I've tried pads & calipers, but it seems to make things worse if anything (Civic & Lude).

I'd go for an official 'refresh' . Mine has Project Mu disks, pads and I believe, braided hoses and it's the best stopper with the hardest pedal. The S2000 has lost its (fantastic) edge in feel, due to hard use of disks, which look like records.

[Kaz-kzukNA1]

Hi, Luke.

Based on what you wrote, you already have the later spec brake setup (larger disc and caliper piston setup to shift the bias a lot more towards the rear compared to the pre-97 models) plus the latest ABS package.

Your chassis setup is almost OEM but using the Eagle F1 tyre and while I don’t know how good you are in controlling the weight shifting while driving your NSX, it is clear that your NSX is almost 100% used only on the street and not on the track.

Based on this, personally, I think the most cost effective thing to do is instead of getting the BBK, invest the money into good tyre, pad, disc and have your OEM latest brake system overhauled.
After test driving nearly 100 UK based NSX, only one NSX passed my brake testing.

My NSX is 94 model so it came with the smaller disc/caliper with 2nd generation ABS.
I touched on this somewhere in this forum but I really hated the brake bias being too much to the front with this setup and so replaced the entire system with the 97+ ones including the upgraded ABS.
You are very lucky to have these parts on your NSX from the factory.

When NSX was first introduced to the market, lots of comparison were carried out against other makes and while there were lots of praise for our NSX, one thing I really didn’t feel comfortable was the brake balance.
Compared to other high power cars including the ones over 500hp, when you apply hard braking, you can feel your body is like being thrown into the air or to the front and not like squashed down to the ground like you can feel on other high performance models.
The brake balance was just simply too much towards the front and with my fairly low skill, I could easily lock the front and because I couldn’t use the ancient ABS on purposely, I ended up either not being able to generate enough traction early enough on exit or simply just caused too much understeer.

Also, over the years, I started to feel that the classic ABS was not consistent under every situations and some of my friends even experienced dangerous cases (pedal felt like going to the floor when there was no leak/air on the system when on purposely used the ABS) because of the ABS so that was one of the main reason to upgrade to the latest spec.


You can’t do anything above what the tyre can do and in order for the tyre to work, you need to apply load onto it.
Instead of focusing on just front or rear, it is important to make all four tyres to work for you so this is where the shifting of the weight comes.
Driving is like understanding the theory of lots and lots of physics.

The moving mass has kinetic energy and in order to reduce the speed or stop it, you need to convert this energy into something and for this, you use the brake to convert the energy into the heat.
To do this, you need the tyre to generate enough friction against the road surface but the road surface condition changes every centimetre and it’s not entirely flat so the load also changes every second at each tyres.
The brake has certain amount of limit in its heat capacity and with all other factors such as the inertia, air temperature, inclination, slip angle, etc, the driver needs to feel what’s happening to one's tyres and brakes.

So, even if you have nice looking BBK, if your car was setup wrong for your driving environment, your tyre won’t be working for you and thus, not enough heat was generated at the brake and you don’t get the benefit from your BBK. Same goes for the engine tuning. If you can't transfer the energy through the tyre to the road surface, you are wasting your engine power.
Again, the importance of thinking about the car as a package and also understanding the physics around the driving.


For the specific points in your thread....

If you feel judder, you can use track day pad for a few days or max 1 week through your ordinary daily driving mode and it will skim your disc surface. That’s what I recommended to another owner recently.
As your disc seems to be at the end of their useable thickness, just replace them with the one from major companies.
For street driving, nothing special required.

The pedal touch/feeling is significantly affected by the pad and as you know, the characteristic is different so something felt good for one driver doesn’t mean the same for another one. OEM is fine for the street usage and you have lots of choices such as EBC, Dixcel, Project u, etc.

Regarding the EBC, long time ago I heard only the bad thing about it.
However, after they made several changes and based on other owners feedback, I wanted to try them and so far, I’m happy with them.
Soon, I’ll be replacing my front disc and pad so I’ll have better idea as a package.


Again, everything I wrote here is just my personal view/feedback and it could be quite different for your case.
For example, I compared all sorts of combination of the parts such as the Type-R front/under bars, Type-R and S sway bars, front/rear tower bars, BBK, high lift camshafts, etc on several NSX using the same test course and despite the praise from many owners especially from the Targa ones, I didn’t like the Type-R front/under bars nor the Type-R front sway bar.
Shows everyone has different taste so just try keeping the OEM brake setup but use good disc/pad/tyre to start with and if you still feel like not happy, then may look into the aftermarket setup.

My head is not clear after going through all the software upgrade of my new mobile phone (where is my case and micro SD card.....) so some of my English may not make sense.....

Time for mowing the lawn followed by glass of wine..... It's hot but the humidity and temperature are much better than working in Japan or Malaysia....

Kaz