ford74
Trainee ZX2ner
Posts: 132
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Post by ford74 on Nov 14, 2018 15:00:02 GMT -5
I have 2 o3 zx2s and I wanna put rear disc brakes on but I don't rember what all cars swap over to the zx2.I think I rember seeing something about early protege but that was on teamzx2.any help would be appreciated thanks.
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Post by davidgettle on Nov 14, 2018 15:16:34 GMT -5
Escort GT, Escort 4 door I don't remember the years.
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Post by TheEvilZX2 on Nov 16, 2018 16:17:29 GMT -5
What gettle said plus mercury tracer
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zx2mtx
Early Adopters
Posts: 8
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Post by zx2mtx on Nov 21, 2018 12:19:06 GMT -5
Any rear disk setup off the Gen3 Escorts and ZX2s 1997-2003 will fit, 2 door or 4 door. Any rear disk setup from a Gen 2 (1991-1996) Escort will fit as well, but you either need to get the entire subframe off the donor car, or you will need to fabricate a spacer for the rear knuckle to make a Gen 2 fit a Gen 3 suspension as the width of where the suspension arms mount on the crossmember and the knuckle is 1/2 inch wider on the Gen 3 than the Gen 2. Best bet is finding a Gen2 Escort GT. Worth noting that ALL the parts are different on the Gen 2 and Gen 3: Ebrake cables, calipers, rear suspension arms, brake pads are different. You can mount Gen 2 calipers on Gen 3 knuckles, but you have to use Gen 2 brake pads and ebrake cables, as the pad carriers and actuators are different.
Also the Master cylinder is different on rear disk cars, as are the proportioning valves that screw into the bottom of the master cylinder. Grab these off the donor car if you can, but a lot of the rear disc setups on Gen 3 cars came with ABS, and these master cylinders won't work for non-ABS applications. You can tell the ABS master cylinders by having only 3 output ports and no proportioning valves on the bottom. You can use either Gen 2 or Gen 3 rear disk master cylinders in a ZX2.
Other cars with disk brakes that interchange are: 90-94 Mazda Protege 90-94 Mazda 323 92-95 Mazda MX-3 GS V6
If your disk brake dust sheilds are rotted away ones from a 90-94 Protege are still available new from Mazda. I got mine from Jim Ellis Mazda online for $27 each plus shipping
If you need the disk brake master cylinder I have a couple of new in box Escort GT ones with new proportioning valves I am willing to sell.
Good Luck, getting that rear suspension bolt that runs through the two rear control arms and the suspension knuckle can be very difficult, be prepared to use a lot of heat and penetrating oil. If you burn up the rubber bushing in the rear control arm (like I did) you can still find NOS ones on EBay or modify a stock Energy Suspension bushing to fit. I went the Energy Suspension route and it works great.
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ford74
Trainee ZX2ner
Posts: 132
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Post by ford74 on Nov 22, 2018 20:51:03 GMT -5
Would I be able to use proportioning valve from the front lines on the rear ones?the threads look the same,I ordered a new master cylinder from a s/r already but forgot about that.
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Post by davidgettle on Nov 25, 2018 14:50:57 GMT -5
I'm using the ATX master cylinder that came in the car without the rear disk proportioning valves, works fine, and the pads wear evenly (front to back).
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Post by TheEvilZX2 on Nov 27, 2018 17:17:37 GMT -5
I've got nothing to add to the conversation as none of my ZX2s have rear discs, none that are on the road anyhow. I didn't do the swap on that one so IDK if the prop valve was replaced or not, it drove and braked perfectly well enough for normal street driving.
But this got me to thinking, has anyone ever run an adjustable proportioning valve instead? They're rather cheap and should be easy enough to do provided you have some brake line, the right fittings and a flare tool.
I'd be curious to drive your cars (zx2mtx and gettle) back to back and see if there is any noticeable difference.
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Post by davidgettle on Nov 28, 2018 13:19:11 GMT -5
I noticed a difference from rear drum to rear disk with the factory master cylinder for rear drum breaks. according to what I've read ZX2's with 4 wheel disk breaks are supposed to have a longer stopping distance than those with rear drum breaks. I've found the my car seams to have a shorter stopping distance than it did before switching to the rear drums, and keeping the rear drum master cylinder.
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zx2mtx
Early Adopters
Posts: 8
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Post by zx2mtx on Nov 29, 2018 0:00:12 GMT -5
The disk brake rear proportioners run at a much lower pressure than the drum brake proportioners, per Ford Shop manual. Basically the drum brakes require more pressure to get the work done. Problem is that when this pressure is applied to a rear disk setup you get rear lockup, which drives you to back off of the brakes, yielding longer stopping distances. GM tried to weasel by with their Citation X-11 by just using the master cylinder from their disk/drum setup for their regular Citation on the 4 wheel disk brake equipped X-11, yielding rear lockup, a bunch of accidents and dead people, and a national recall on the X-11 brakes. Nissan had the same problem with the 200SX, and I got to witness that one up close and personal as a passenger in a brand new one that rolled after a rear lockup induced offroad excursion.
Then again, C2 and C3 Corvettes had 4 wheel disk brakes and no proportioning valves
I was looking into adjustable ones at Summit Racing when I stumbled on some new Escort GT master cylinders with proportioning valves for cheap. They were for ATX cars, so I just used my old MTX reservoirs to get the clutch fluid feed. The only difference in the master cylinders is the 1991-1996 Escort GT reservoirs do not have the tab in the back to mount the low fluid sending wire. They have the sending unit and use the same plug as the 1997 onward ones. You can buy new 1997-2003 disk brake master cylinders with proportioning valves from Rock Auto, but they are real pricey ($145.00). They do not come up with the vehicle search, you have to specify the Wagner part number, I have the part number somewhere.
Regarding using the front one for the rear, good question. Will have to see what the manual sez about the test pressures.
I guess the long and short of it is that I am assuming Ford offered a rear disk proportioning valve with a vastly different actuation pressure than the drum brake one for a reason. I never ran my rear disk setup with drum master cylinder or proportioners, so I don't know what the effects are. I know my red car with 4 wheel disks stops better than my blue car with disk/drum, but it also has better tires, has much better springs, shocks, and sits 2" lower, has EBC pads, etc. The big advantage in disks is lack of fade, so they may stop the same on the 1st stop, but how much better will they be than drums on the 10th stop
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Post by davidgettle on Nov 29, 2018 14:43:45 GMT -5
To the best of my knowledge the rear drum master cylinder has no proportioning valves, at least they are not visible. I did however replace the master cylinder a while back, and the shop used a rear disk master cylinder, because that was what came off the car. I have not had rear brake lock up since doing the conversion, without the fronts also locking, to the best of my knowledge. My car's suspension is sitting on Mazda Protoge lowering springs and KYB GR-2 struts and sits about 1-1/2 inches lower than stock, and has the same OE equivalent break pads as are available for the ZX2 S/R.
I just found something interesting, the rear drum brake master cylinder w/o ABS for ATX and MTX have different Ford part numbers, but with ABS they are the same Ford part number according to Rock Auto...
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zx2mtx
Early Adopters
Posts: 8
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Post by zx2mtx on Nov 30, 2018 0:38:27 GMT -5
Are they all with reservoirs? The ATX and MTX master cylinders differ because of the MTX clutch master cylinder sharing the fluid reservoir with the brakes, while ATX doesn't have this. Don't know why the ABS ones would be different.
Ford74, the two proportioning valves on the bottom of the master cylinder go to the rear brakes, left rear and right rear, and are identical. Swapping them back and forth won't do any good. The front brakes tap from the top and side of the master cylinder, and do not have proportioning valves.
Not meaning to be overly cautious on this, both my cars have over 100K miles on them, and $52 was cheap insurance that I would have a fresh disk brake master cylinder with new propo valves to go with the new calipers and flex lines that I was installing at all 4 corners.
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Post by davidgettle on Nov 30, 2018 14:13:32 GMT -5
The ones I compared part numbers for all included the reservoir.
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ford74
Trainee ZX2ner
Posts: 132
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Post by ford74 on Jun 7, 2019 21:03:36 GMT -5
I figured out that the 2004 Hyundai sonata (with rear disc brakes)proportioning valves are the same threads as the 2000 s/r mastercylinder(should thread into stock also but haven't verified) and there calipers are about .010 larger(front and rear) witch should work I will post an update when I get it together
........if any one near Pittsburgh area needs/wants disc spindles let me know I have an extra set or 2nd gen
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Post by schwinnman67 on Jun 18, 2019 20:49:17 GMT -5
The proportioning valves are different threads disc/drum vs 4 wheel disc.. When I originally did the conversion I used a 94 GT m/c with a reservoir from an atx car (mine is atx). I have also seen 4 wheel discs on a station wagon.
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