Wilwood Brake Bias Valve

[tasroadster]

How do you fit this valve, they suggest that it is fitted in the rear brake line?

I am thinking that it may have to go in the front line ?
The goal is to increase rear braking right ?????

Any help would be greatly helpful.

PS.. the Wilwood Brake Bias Valve is $86 from Performance Friction in Brisbane.... I thought is was a fairly good price....

Thanks

[Daz 27]

why do you need to change your brake bias?

[tasroadster]

I have fiited 4 piston RX7 front calipers + 255mm RX7 disc's + braided lines.

Using STD. rear brake setup with Endless Pads.

Thanks.

[bigdog]

My understanding is that the valve would go into the line from master cylinder to rear brakes as it acts as a restrictor to the rear brakes - less fluid moving to the rear means less piston travel/pressure. I every car I have worked on there is a proportioning valve in that line... but I am no expert and stand to be corrected by wiser ones than me....

Edit - just re-read your last post. You appear to have 'over braked' the front? If this is the case you will need to look at your master cylinder size & fluid displacement. Normal practice when upgrading brakes is to look at the donor car and adapt the complete package - master cylinder and front & rear calipers & discs. If this is not possible then you need to do some measuring and try and replicate the cylinder sizes, fluid displacements and piston travel to approximate the original (donor) design. Failure to do so will result in an ubalanced system.

[tasroadster]

Don't MX5's have a proportioning valve (pressure valve) already installed std. to limit rear pressure bias. So therefore, the fronts will lock up first for safety reasons?

Does this valve have to be removed to fit the Wilwood valve?

What does the racers do?

Thanks

[CT]

Don't MX5's have a proportioning valve (pressure valve) already installed std. to limit rear pressure bias. So therefore, the fronts will lock up first for safety reasons?

Does this valve have to be removed to fit the Wilwood valve?

What does the racers do?

Thanks

This is why you should properly plan upgrades like this. You should have done the piston area calculations first to ensure these calipers were suitable. You defintely cannot use the OEM valve and a wilwood adjustable valve. You definitely should not use an adjustable prop valve on your front brakes. You might just have to upgrade the rear calipers too to get enough clamp so your brakes work properly. The MX5 factory master cylinder might not be the right size to feed your front calipers. Do you know what size the RX7 M/C was the calipers came off?

My race car is setup like this:
No brake booster, standard master cylinder (15/16 3 port), removed factory prop valve, wilwood adjustable valve in cabin, standard 1.8 calipers F&R, DBA 4000 standard sized rotors and hawk blue pads F&R.

[Matty]

The brake goes in the rear line!

The OEM valve is also on the rear line. Remove it. The Wilwood can be adjusted to give less reduction in rear line pressure (ie, more pressure) than the OEM valve. At full setting, there will be no reduction in rear line pressure (ie, no proportioning, just like having no valve in there).

this will help restore some braking balance that you have undoubtedly lost with the oversized front brakes...

You will need a union fitting to join up the line to the front brakes. In the OEM setup, this line goes through the prop valve, but not in the Wilwood.

[Daz 27]

I have fiited 4 piston RX7 front calipers + 255mm RX7 disc's + braided lines.

Using STD. rear brake setup with Endless Pads.

Thanks.

what model RX7 did they come off?
if the rotors are only 255mm it sounds like an older model, were the brakes very heavy?