Here is a copy of the e-mails I sent to both MP Brakes and Wilwood Engineering:
My question:
I have a 1979 Chevy Malibu that I am installing rear disc brakes on. Currently the car has the stock disc/drum combo valve (prop. valve) in place. I know I need different bias front to rear with the rear discs. I plan to remove the stock combo valve and install one of your adj. prop. valves in the rear brake circuit to achieve the proper bias front to rear. Then I will run the front brakes straight off the front port of the master, to a T fitting, and off the T fitting to the front calipers.
Now, removing the stock combo valve is raising some concern for me safety wise. I know the stock combo valve has a metering valve and a warning light switch built in along with residual valve for the rear drums. I know I don't need the residual valve for the rear discs, but do I need the metering valve? Also, if a leak was to develop in one circuit of the brake system (front or rear), would I still have the safety feature of fluid being transferred to the circuit without the leak still allowing me to stop safely? I assume this feature is controlled by the master cylinder and not the combo valve correct? Are there any other concerns with doing away with the stock combo valve?
MP Brakes Response:
An adjustable prop valve for your rear disc brakes is adequate. If there is a failure in your system, you will still have half of your brake system (because of the dual master cylinder). This will enable you to get home and/or get your car to a repair shop without total system failure. The warning light exists because the average driver has no clue (not their fault) that there’s a problem with their brake system. Based on your questions, you have a clue
Thanks for contacting Master Power Brakes.
Randy
Tech Support
888.351.8781 x206
http://www.mpbrakes.com
Wilwood Engineering's response:
Thank you for using Wilwood products.
Stock combination valves serve many purposes, but transferring fluid from one set to another during a fluid loss condition is not one of it's duties. There is no safety concern about removing the stock valve. A tandem outlet master cylinder will provide the safety feature of being able to stop if one of the hydraulic systems is compromised.
035
My question:
I have a 1979 Chevy Malibu that I am installing rear disc brakes on. Currently the car has the stock disc/drum combo valve (prop. valve) in place. I know I need different bias front to rear with the rear discs. I plan to remove the stock combo valve and install one of your adj. prop. valves in the rear brake circuit to achieve the proper bias front to rear. Then I will run the front brakes straight off the front port of the master, to a T fitting, and off the T fitting to the front calipers.
Now, removing the stock combo valve is raising some concern for me safety wise. I know the stock combo valve has a metering valve and a warning light switch built in along with residual valve for the rear drums. I know I don't need the residual valve for the rear discs, but do I need the metering valve? Also, if a leak was to develop in one circuit of the brake system (front or rear), would I still have the safety feature of fluid being transferred to the circuit without the leak still allowing me to stop safely? I assume this feature is controlled by the master cylinder and not the combo valve correct? Are there any other concerns with doing away with the stock combo valve?
MP Brakes Response:
An adjustable prop valve for your rear disc brakes is adequate. If there is a failure in your system, you will still have half of your brake system (because of the dual master cylinder). This will enable you to get home and/or get your car to a repair shop without total system failure. The warning light exists because the average driver has no clue (not their fault) that there’s a problem with their brake system. Based on your questions, you have a clue
Thanks for contacting Master Power Brakes.
Randy
Tech Support
888.351.8781 x206
http://www.mpbrakes.com
Wilwood Engineering's response:
Thank you for using Wilwood products.
Stock combination valves serve many purposes, but transferring fluid from one set to another during a fluid loss condition is not one of it's duties. There is no safety concern about removing the stock valve. A tandem outlet master cylinder will provide the safety feature of being able to stop if one of the hydraulic systems is compromised.
035