1971 Rear Disc Brakes

This area is for those who need help modernizing their Lincoln for purposes other than strict restoration. Such questions can be about adding an electric fuel pump, adding fuel injection, boosting horsepower or gas mileage, or tightening or lowering the suspension. Body customizing and chopping can also be here (although this practice is not encouraged by the LCOC).

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Wixomhead
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1971 Rear Disc Brakes

Post by Wixomhead »

I installed a rear disc conversion kit on my Mark III. Please don't ask me why, thank you.

Since doing so, I can't solve for (bleed bleed bleed) for soft pedal, long travel, weak braking, unsafe.

I am using original proportioning valve/bench bled replaced the master. I don't recall (need to look) but I think the metering valve is still in line where it belongs on the cross member near/under the oil pan.

I know there is a wealth of info out there re: rear disc conversions but not sure how it may apply to our particular cars vs broncos and mustangs.

Can anyone help me solve for this problem?

wh
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action
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Re: 1971 Rear Disc Brakes

Post by action »

The principals of the hydraulic brake system for a Mark III are no different than the Mustang or Bronco.
Yes the Mark III has an ABS system but it is not active if the vehicle is not moving.

The original proportioning valve is designed for disc drum and reduces pressure to the drums
If you are going to disc disc don't stop part way finish the job with a correct proportioning valve for the system. (Which will require further bleeding after the new valve is in.

You may not need the the metering valve it is usually needed for disc/drum systems to delay the application of the front disc brakes which will come on faster than the rear drum. Also that valve located near the steering gear has a pin that has to be pulled our to bleed the front brakes properly.

Didn't the kit have instructions for valving?
Isn't there customer support?

Did you know that the Mark III has big 11"drums in the rear?
(You said not to ask the why question ....)
A Mark III is not a pony car that you shoe horned a big block into. Now that pony car does not have the whoa power to stop the go power.
A Mark III was designed with a big block. And everything around it was designed to support that engine. In properly maintained condition.

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Last edited by action on Mon Jul 06, 2020 12:58 pm, edited 1 time in total.
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1996 Lincoln Mark VIII 2DR Coupe Diamond Anniversary 4.6l DOHC, 4R70W, 3.07
1970 Continental Mark III Triple Black 460 4v, C6, 2.80 (Used for Woodward Dream Cruise or just generally stored in Michigan)
1966 Lincoln Continental 4DR Convertible 462 4v, C6, 3.00
1966 Mercury Park Lane 4DR Breezeway 410 4v, C6, 2.80
Mike
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Re: 1971 Rear Disc Brakes

Post by Mike »

What action said.
Start by asking the company the conversion came from. They should be able to tell you what needs to be done.
if they can't then you're down to your own trial and error. You probably just need to replace the proportioning valve and metering valve with parts designed for 4 wheel disc brakes.
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Wixomhead
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Re: 1971 Rear Disc Brakes

Post by Wixomhead »

Thanks all. Supplier recommended their PV-72 valve but said this valve PV-24BH is identical and should work fine - (double check it's for a disc/disc and not drum/disc setup

I removed the (hood, fender, wheel well) original valve and lines; NiCopp Nickel Copper brake lines and fitting arriving today, not sure what do about valve mounting bracket but will also remove rear brake metering valve when I reinstall.

Thanks for the help and will report

wh
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