Rear disc swap issues

[Dmf274]

Need some help here I have swapped over to rear disc with metric calipers I replaced the proportioning valve to a disc/disc and upgraded to a 1980s B body master cylinder and booster steel braided lines on all 4 corners and have steel braided lines from master to proportioning valve and 2 piston willwoods on the front my problem is all of the braking power is to the rear and they lock up before the fronts any ideas or guidance would be appreciated I’m at my wits end with this problem

 

[Streetbu]

Are you sure you plumbed it correctly from the master to the proportioning valve? Rear port on master cylinder goes to the front brakes

 

[Malibu795]

Sounds like you got the front/rear ports in the MC backwards

Other hand most 11-12" rear disc swap have substantially more braking force then the 10.5" OEM stuff in the front... Plus reduced weight in the back

What are you running for front brakes and what size wheels are you running or planning on going to??
14/15" rims severally limit what you can do in the front

 

[Rt Jam]

Is the front doing anything?

 

[Dmf274]

I have tried both ports on the master cylinder I have willwood 2 piston calipers with stock size slotted vented rotors on front with 15” wheels on 245/60/15 tires. I am starting to think that the master is bad and will have a new one today

 

[Dmf274]

Fronts work but not like they used to before changing everything over

 

[Dmf274]

These are the ones I used

 

[Supercharged111]

These are the ones I used

Those front calipers list the piston area, what is the stock piston area? Could be that you reduced front braking force if the new calipers have less area.

 

[Malibu795]

I think you found out how bad the front is even slightly upgraded.


If everything is working as designed/capacity.. you'll most likely need to install a adjustable base valve to reduce rear brakes.
Could get more aggressive pad compound for the front...to give you more bite.

Supercharged111 D154 calipers are an upgrade over stock

Generally a 11" rear DISC needs 12" disc in the front

 

[Supercharged111]

I think you found out how bad the front is even slightly upgraded.


If everything is working as designed/capacity.. you'll most likely need to install a adjustable base valve to reduce rear brakes.
Could get more aggressive pad compound for the front...to give you more bite.

Supercharged111 D154 calipers are an upgrade over stock

Generally a 11" rear DISC needs 12" disc in the front

D154 in and of itself could mean more than 1 thing. For example:

Wilwood Disc Brakes - D154 Front Caliper Kit

Wilwood bolt-on front brake conversion kits are designed to provide superior braking performance and a highly detailed appearance over a wide range of domestic and import applications. D154 Front Caliper Kit

www.wilwood.com

If the stock caliper piston was 2.5" then a stock piston has an area of 4.9 sq/in. OP replaced that with calipers with an area of 4.12 sq/in and thus downgraded.