Re: [Amc-list] Disk Brakes conversion

[Frank Swygert <farna@xxxxxxx>]

John, I've had this problem on all the trunnion equipped cars I've converted -- 58-66 models. There isn't much difference in the 67-69 trunnion suspension, so I'm not surprised you have the problem. The 64-69 American/Javelin/AMX trunnion is different, that might be why some have not had the problem.

There are four possible solutions I've used:
1. The 71-74 brake hose has a long steel section near the caliper, 2-3" IIRC. Use a tubing bender and bend it to clear the trunnion. 

2. The Bendix four piston hose is the same as a rear brake hose -- it has a fitting for a steel line on each end 4-6" long (don't recall exactly). You can get a length of new tubing from any auto parts store and bend to fit. You may need an adapter to fit the tubing to the caliper, I don't recall. Unbolt the bracket that holds the line to the trunnion if necessary and relocate it. You can use a zip tie to hold the hose to the trunnion somewhere instead of the bracket if that seems to work better. 

3. Buy a banjo hose kit and adapter bolt from Speedway Motors (http://www.speedwaymotors.com/p/938,13_Banjo-Brake-Fitting-Kits.html) or some other hot-rod supply. You might try www.mpbrakes.com, but I'm not sure they have the fittings. They do have excellent general brake tutorials on the site though. On the Speedway site, IFF is Inverted Flare Fitting (standard brake lines -- 45* flare), IFM is Inverted Flare Metric, and AN is "Airforce/Navy" specification fittings -- a 37* flare with tight tolerances. The AN fittings are an industry standard now. 

IIRC the fellow I assisted in putting one of the kits together used new AN lines with the 7/16"-20 banjo bolt and banjo end, and a IFF to AN adapter on the other end. I believe the calipers were disassembled and the inlet drilled and tapped for the bolt, since the normal inlet is NPT threads (National Pipe Threads). The calipers are easy to take apart -- just pop the piston out with air pressure. Or with brake fluid pressure -- take the caliper and pads off and press the pedal, the piston will pop out! Messy, but works. Brake fluid should be changed occasionally anyway...

There is supposedly a Ford banjo hose and bolt that will fit. I've been told it was a mid 82-88 Ford EXP hose, but haven't been able to verify that. The regular Escort didn't use a banjo hose as far as I remember, and the EXP was derived from the Escort's drivetrain. A Jeep Cherokee or AMC Eagle banjo hose and bolt will fit, but you have to have a banjo bolt that will fit your caliper. The 82-88 GM calipers use a different size than earlier calipers. Earlier ones I believe use the 7/16"-20 bolt, 82-88 GM Metric. I don't know if there is such a thing as a NPT thread banjo bolt though. I haven't been able to find one that specifically states that. I believe the 7/16"-20 thread banjo bolt will fit NPT threads just good enough to hold. NPT threads are tapered, so as long as the bolt fits the bottom part of the tapered threads it should be fine. Banjo bolts use copper sealing washers or crush washers to seal, so if the threads are a little lose that's fine as long as the banjo end
  can be pulled down tight. I'd rather drill and tap the caliper body for the correct bolt size though, that way there's no "ifs" or "shoulds" -- those aren't good in a brake system! 

4. This is what I'm using now, but probably the least desireable due to a greater potential for leaks (though I have had none in seven years of running). I use a "trailer T" in the caliper. This has one male and two female openings. I used copper washers on the male end and screwed it into the caliper. One side has one washer, the other side has two washers to get the T to turn the right direction to clear the trunnion. One of the female openings has a plug in it, the brake line goes into the other. More connections = more potential for leaks, plus there is the stacked copper sealing washers on one side. I've never had a leak, but the potential is still there. I used a Trailer T because I couldn't find a 90 degree fitting that would work. There were no banjo fittings available a few years back either. 


------------
Date: Sun, 21 Oct 2007 13:27:14 +0100
From: "John Eckersley" <john.eckersley@xxxxxxxxx>

I am finally getting time to fit the disk conversion that I got a
while ago from APD to my 1968 Rebel SST convertible.  I've hit the
problem Jeff Barfield mentions in his excellent piece on this job on
the internet.  Namely, the flexible hose coming from the caliper has a
straight part on it that fouls the trunion.  Jeff says (on his
website) he got around this using a tube bender, but mine really
doesn't want to move.  He also says others haven't had the problem, so
I'm looking for help/inspiration from the list.  What I'm doing (in
slightly more detail) is fitting 82 concord disks, spindles, caliper
brackets and associated hardware to the car in place of the old 4 pot
bendix setup.  I'd ask Doug at APD, but it being Sunday, they aren't
around, and come Monday I'll have to wait another two weeks (min)
before I can get to work on the car again, so if anyone has any bright
ideas, I'd love to hear 'em.  Thanks.

-- 
Frank Swygert
Publisher, "American Motors Cars" 
Magazine (AMC)
For all AMC enthusiasts
http://farna.home.att.net/AMC.html
(free download available!)


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