Rebuilding E-Brake after Mustang Rear Disc Conversion

[Guanfy]

So I've put in quite a few spacers after doing the conversion and I still have no e-brake. I've determined my 176k e-brakes cables are stretched too much so I'm going to buy new cables and solve the problem that way. My question is, is there a cable I can buy that will work with no spacers or do I still need to buy the stock '94 cables and then put spacers on them?

 

[Tristetoker]

I just cut 1/2 copper pipe bout 2 inches long should work

 

[mikkelstuff]

I added a turnbuckle adjuster to the parking brake cable which really helped with my 2002 Ranger.

 

[Guanfy]

I added a turnbuckle adjuster to the parking brake cable which really helped with my 2002 Ranger.View attachment 54928

I like this idea quite a bit. When I get back around to buying cables I will employ it to make the bloody thing tension up.

 

[don4331]

OK, my solution for the cables was to take them to a garage door shop and have them swage new ends on the cables, about 2" from the original location. Which allowed parking brakes to work and Ranger pass safety.

As we know the Mustang rear brake caliper uses the parking brake as adjuster to compensate for pad wear.

In the parking brake applied by lever between the seats using arm strength​

In the Ranger you will be applying the parking brake using leg strength - which for most of us is substantially more. The result is the adjuster will tend to over adjust.​

​

I can remember if it was you Guanfy who I had earlier discussion about residual brake pressure differences between disc and drum brakes, but the just of it is: discs need a lot less residual pressure and the check valve in the rear brake line needs to be adjusted for this.

If you don't adjust the residual brake line pressure and/or take care applying parking brakes*, your Ranger will go through rear brake pads like they are going out of style.

*My son had issues with his Mustang going through rear pads, but he was a 300lb gorilla at time, whose arm strength probably matches many of the rest of us leg strength.

 

[Guanfy]

OK, my solution for the cables was to take them to a garage door shop and have them swage new ends on the cables, about 2" from the original location. Which allowed parking brakes to work and Ranger pass safety.

As we know the Mustang rear brake caliper uses the parking brake as adjuster to compensate for pad wear.

In the parking brake applied by lever between the seats using arm strength​

In the Ranger you will be applying the parking brake using leg strength - which for most of us is substantially more. The result is the adjuster will tend to over adjust.​

​

I can remember if it was you Guanfy who I had earlier discussion about residual brake pressure differences between disc and drum brakes, but the just of it is: discs need a lot less residual pressure and the check valve in the rear brake line needs to be adjusted for this.

If you don't adjust the residual brake line pressure and/or take care applying parking brakes*, your Ranger will go through rear brake pads like they are going out of style.

*My son had issues with his Mustang going through rear pads, but he was a 300lb gorilla at time, whose arm strength probably matches many of the rest of us leg strength.

That discussion did come up in one of my brake threads. In my case I had to cut the rear parking brake cables for...reasons. So currently I don't have the brake pressure issue. I actually have an opposite issue at the moment with too much pedal travel for my liking at the moment. I have also clipped the pressure spring in the proportioning valve to accommodate that issue. It;'s about to be moot as I have an adjustable Wilwood proportioning valve on the way to replace the janky RABS valve.

Where I'm at right now is trying to decide what is easier, taking the truck to a shop and letting them handle the parking brake cables 100% or trying to purchase stock cables and messing with them to make them work?

 

[don4331]

Whoa - proportioning valve and residual pressure valve are 2 very different things:

Proportioning valve adjusts balance between front and rear brakes - largely to keep rear from locking up and being in danger of causing back to try and pass the front.​

And you need to be very careful adjusting rear brakes - there is a fine line been adding stopping during normal stop and getting too much during panic stop and making vehicle unpredictable when you can't afford vehicle doing unexpected things.​

Residual pressure valve keeps pressure in lines (~10psi for drums/2psi for disc) to keep pads close to the braking surface (drum/rotor, respectively).​

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For the Mustang rear caliper, the parking brakes operate an adjuster more/less identical to the star adjust in drum brakes.​

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If you have too much pedal travel, you might have trimmed the spring too much* and have no residual pressure/as you don't have parking brakes yet installed, the adjusters need to be manually moved**

*You can shim the spring back to get the required residual pressure or purchase a residual pressure valve.​

**Adjusters can be manually tightened with pair of slip jaw pliers, spinning axle just like you would with drum brakes.​

And Mustang rear discs are never going to provide same braking that Ranger drums do when correctly set up. (Un)fortunately, drums are difficult to keep set up correctly, so on average, discs provide better results. But as I noted, parking brakes needed to be treated with kid gloves or you will destroy pads...

Easier is paying someone to do it; but is it cost effective when you are working with a patched together system.

 

[Guanfy]

This is some good information, thank you for that. I'm aware of the difference. I've been suspecting that my RABS/proportioning valve has been doing funny business for some time and replacements are horrendously expensive so out it goes. I know that I'll need to dial it back in to ensure the back end of the truck does not lock up before the front in a crash stop situation. I'm in a situation now where I also want the flexibility to adjust the valve when towing or hauling a heavy load. Before I do any of that though I will manually actuate the rear parking brakes and see if "adjusting" them will help with the pedal travel issue.

I'd be sold on that I messed up the residual pressure valve spring but the brake travel issue didn't start occuring, or at least I didn't notice it until the weather began to warm up. Right at the tail end of winter I identified that my brake booster was bad so I replaced it and that changed the pedal feel as well. I still want to know why the pedal feels near perfect once I've done a decent amount of stop and go driving but have the longer travel during highway operation.

 

[Guanfy]

So I found that a 4 inch C clamp worked pretty well to let me compress the parking brake spring at the caliper. I think that helped, but I lack the grunt in my hands to squish it as much as I want. Based on what you told me Don I am also going to purchase a 2lbs residual valve from Wilwood before I do any more alterations to my braking system.

Proportioning Valve: https://www.amazon.com/gp/product/B00EANSPFU/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Residual Brake Pressure Valve: https://www.amazon.com/gp/product/B01GVIM8G8/ref=ox_sc_act_title_1?smid=ATVPDKIKX0DER&psc=1

I'm thinking the brake valve will need to go south (so to speak) of the proportioning valve. Or does it really matter as long as it's placed in line with the rear brake line?

 

[don4331]

Residual brake pressure valve should go after the proportioning valve.

For a moment you had me worried that you had used BFClamp to compress the caliper back in - Mustang calipers needing the twist and compress system.

But after re-reading you were just using clamp to manually apply the parking brake - interesting method, but probably works.​

 

[Guanfy]

So... update. I installed the check valve(residual brake pressure valve) only today, after the RABS valve heading towards the rear calipers. I found that brake fluid is now quite slow to leave the bleeders on the rear calipers and the pedal is softer than before. Front brakes are fine but I think I made the rears worse. I double checked the check valve and I do have it oriented correctly. I'm thinking that because the spring that controls the check valve built into the RABS valve is still there it's causing issues. I think my next step is to pull the spring out and see what happens. Thoughts anyone?

 

[Guanfy]

I pulled the spring out of the residual pressure valve in the RABS unit and the brake pedal feels much better. Still not what I want but not dangerous to drive. The nut that holds the spring in place is a 7/8 SAE.