One Brake Upgrade To Rule Them All - D1 1995 (pre-GEMS, pre-OBDII) Stopping Power Brake Fix

p m

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Apr 19, 2004
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My 2002 F-350 powerstroke dually hauls to a stop vastly better than the disco1 does. ;-P
Probably because its brakes are designed to stop something like 15 thousand pounds.
D1 brakes aren't bad, but nothing to brag about. I find it funny when people complain about RRC brakes and want to swap the entire setup to D1 vacuum servo - RRC brakes are vastly superior, and [when the pump works] they can be used with a dead engine.
That all said, when you upgrade the calipers to 110 front and rear (even with the same rotors), and fit a proper master cylinder (even to the same vacuum servo), you should see a great improvement.
To give you an idea - my prop valve seized about two years ago, and I drove the D1 on 31.5" tires for a year without even knowing I had no rear brakes at all.
 

DiscoClay

Active member
Probably because its brakes are designed to stop something like 15 thousand pounds.
D1 brakes aren't bad, but nothing to brag about. I find it funny when people complain about RRC brakes and want to swap the entire setup to D1 vacuum servo - RRC brakes are vastly superior, and [when the pump works] they can be used with a dead engine.
That all said, when you upgrade the calipers to 110 front and rear (even with the same rotors), and fit a proper master cylinder (even to the same vacuum servo), you should see a great improvement.
To give you an idea - my prop valve seized about two years ago, and I drove the D1 on 31.5" tires for a year without even knowing I had no rear brakes at all.
I am pretty familiar with the how's and whys. :) the f-350 certainly has bigger brakes, though they are actually very much undersized for the rated combined weight. Ford started getting serious about brakes *after* the venerable 7.3 powerstrokes were retired.

The volume and area ratios for those particular brakes are actually less favorable than the D1's.. the key difference is the leverage boost provided by hydraulic boost vs. Vacuum boost. Also, it is worth noting the hydraulic booster has more *dead engine* reserve boost that the stick vacuum tank. Indeed, with a stickshift (as my d1 is) the power steering pump can continue to generate pressure as the wagon decdecelerate.

The D1 brakes are garbage. You can get by with them if you don't tow and if you don't try to haul it down from 80mph. As per another comment in this thread, the disks and calipers are D90s rather than 110s I believe. I included a link to them as well so please correct me if you know otherwise :) the keys updates are: I put ventilated front calipers & rotors on both axles and I am installing hydraulic boost.
 
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DiscoClay

Active member
Yeah I get it. I'm pretty sure you could have made it stop with $75 worth of pistons and seals and rotors.
Nope $75 worth of rubber, iron & steel didn't get it done. It has all new **everything**. Calipers, rotors, master cylinder, reduction/prop valve, vac booster, hard lines, flexible lines, ABS unit... and it still stops like a crippled old van. Perhaps my standards for stopping are high. :)

As I originally stated: I want it to stop like a *new car*.. not a 1995 land rover. ;-P
 

DiscoClay

Active member
Interesting, thanks for the insight. I wonder if one of my boxes is salvageable.
My word vomit made that whole statement challenging...

TLDR: top cap "pocket wear" causes shaft eccentricity causing lower seal failure... Combined with valve failures = leaky box.

A friend machines the top plate pocket and presses in a bronze bush.