Brake bias - legal on a road car?

[Mad Kiwi]

Back in the day, you could fit a bias adjuster so long as it was not adjustable via the cockpit.

I presume this has changed since the boy racers started wrecking things for us all but can some one confirm or enlighten me on the current rules?

FM do a really nice bias kit for little money ($69.00 US if i recall).

With my new 1800 front brake setup, lowered, stiff coilovers etc moving the bias backwards a bit is probably going to help improve the braking a lot from my reading up on the subject.....

Comments and suggestions welcomed!

[WideOpenThrottle]

Does this adjuster then just shift to the rears some of the gains made by the front brake upgrade?
Wouldn't you need to upgrade the rears too first and then balance the bias' other-wise the factory standard rears take more strain than the upgraded fronts which seems to negate the gains!???

[brownie]

You should really use the Brake Proportioning Valve off a 1800 as well,
They are different part number to the 1600 part,Will have different valving internally.
And also I agree if you are going to do the front,do the rear as well.

[Mad Kiwi]

Cheers guys.

Actually a full 1800 setup will be the end result. I have a full 1800 subframe with LSD and brakes etc attached on order with Ross when he gets himself setup in his new premises.

The reason I ask about the brake bias adjustor is that the miata turbo guys and miata forum guys say the balance front to rear is very conservative on the standard car and if it is lowered, with stiffer suspension etc (i.e less nose pitching than the standard car) significant gains can be had by moving the bias back towards the rear.

(As a lifelong motorcycle racer I am very familiar with front to rear braking ratios and the advantages of getting it right as opposed to the consequences in misjudging and hitting the ground!)

I also figure that this being the case considerable wear and heat will be relived from the front brakes if the rear can do more of the work.......

Thus a brake adjustor would (possibly) benefit.....IF legal for road use.....?

[Kieran]

From what I have read I wouldn't track or street with to much rear bias it will cause the back of the car to be very loose with a tendancy to swing out uncontrollably under heavy braking unless your building a drift car go more front bias with a slightly higher bite rear pad and slightly lower bite front pad

[Angreal]

Cheers guys.

(As a lifelong motorcycle racer I am very familiar with front to rear braking ratios and the advantages of getting it right as opposed to the consequences in misjudging and hitting the ground!)

Whenever I got my bike serviced they loved to raise the height of the rear brake lever and I'd always end up with way to much rear brake until I got a chance to re-adjust it. Ah I miss the bike

[Euen]

I've got mine on the tunnel just behind the gear lever on the TG but when I got the car complianced I was told it had to have a cover over it so it couldn't be adjusted while driving. It was not mentioned on the compliancing plate so under the bonnet should be OK. Best to check on the LVVTA web site or talk to one of the LVVTA inspectors.

[Mad Kiwi]

Thanks Euen, if it could be in the cockpit would be way better, I dont mind a cover for general use but track day access would be good. I presume once it's set you wouldn't play too much with it?

You couldn't take a reference photo of yours for me could you?

Did you plumb it up or get someone to do it?

Cheers

Mark.

[Euen]

I don't adjust it much at all.

I will have to get some photos later.

I bought mine from Cardwells and plumbed it in myself as I was building the car from scratch. If you are looking at fitting one, you will need to get new bundy tube to run the brake lines as the original Mazda stuff is almost impossible to rework or flare. You will also need new flarenuts for each end and metric to imperial adaptors to go in and out of the adjuster as the Wilwood ones only come with imperial threads.

[Mad Kiwi]

Great advice thank you.

The fact you can't work the original lines is more than a little off putting (and VERY helpfull to learn ahead of time!!!)

I don't think I am up to replacing the existing lines just yet.

Will play around with pads for front / rear balance as has been suggested in the meantime.

Cheers.