Reg Evans Posted June 29, 2007 Report Share Posted June 29, 2007 Twice now this month I have had to slam the brakes on in my old 52 1/2 ton. Once on a down hill blind curve where I came upon a guy stopped in the middle of the road and backing up and the second incident yesterday. The guys brake lights and turn signals didn't work while he was stopping in front of me to turn left. My truck has the stock brakes up front and a 66 T Bird rearend in the rear with 3.0 gears for faster speed. ( Bad combo lately ) The front drums have 10 x 2 shoes and the rears,if I remember correctly,are 11 x 2.25. The stock brake lines to the front are 1/4" and the lines to the rear cylinders are smaller ( 3/16' or less ) With both panic stops only the front wheels locked up. The rears did not. Reminded me of trying to stop a motor cycle fast. This made the truck want to swap ends and rearend the vehicle stopped in front of me with my rearend. I had to keep letting off the brakes to stay straight which made Ole Yeller take WAY TOO LONG to stop. What can I do to make the rear brakes work as hard as the fronts? I'm too old for this crap. Plumb bigger lines to the rears? Add a proportioning valve somewhere? Sell? Quote Link to comment Share on other sites More sharing options...
Norm's Coupe Posted June 29, 2007 Report Share Posted June 29, 2007 Think you need the same size lines on both ends. If not maybe the proportioning valve would help. Quote Link to comment Share on other sites More sharing options...
PatS.... Posted June 29, 2007 Report Share Posted June 29, 2007 A proportioning valve is supposed to cause the rear brakes to come on a bit before the front to help eliminate "dive", so that might not be a solution. In the old days on large trucks with air brakes there was a valve that you could flip to cut the air to the front brakes in half in order to maintain steering control while braking in winter. Not sure how that would be achieved with juice brakes. Have you considered disc's for the front? Quote Link to comment Share on other sites More sharing options...
bkahler Posted June 30, 2007 Report Share Posted June 30, 2007 What can I do to make the rear brakes work as hard as the fronts? I'm too old for this crap. Plumb bigger lines to the rears? Add a proportioning valve somewhere?Sell? Reg, I may be wrong here but I don't think its the brake line size but more the bore of the cylinders. The size of the brake line has to do with how much effort it takes to stop. The size of the cylinders should define how much pressure per square inch is applied to the brake shoes. Like I said I may be wrong but it would be something to check out. The other thing you could do is something my wife would also like to do, install missle launchers under the front of your truck and use them to clear the road as needed..... Brad Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted June 30, 2007 Report Share Posted June 30, 2007 Larger brake lines will only allow more flow without restriction, but a brake system is a low flow system, so I don't believe that will help. I do agree with Brad on the cylinder size thing, though. The 66 T Bird no doubt had power brakes which can account for higher line pressure. So it's possible that they are using a smaller diameter piston in the wheel cylinders. This would account for less force being applied at your lower pressure manual brake system. That or they're just out of adjustment and not applying correctly. Merle Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted June 30, 2007 Author Report Share Posted June 30, 2007 Yesterday I did re adjust the brakes all around and went out on a country road and slammed them on. Same thing. Just the fronts locked up again. I wonder if some other similar vintage Ford product would have larger bores. Time to hit the parts stores I guess. Thanks for the suggestions so far ! Anyone else???? Quote Link to comment Share on other sites More sharing options...
Rich Gengo Posted June 30, 2007 Report Share Posted June 30, 2007 What are you using for a master cyl? Is it a dual or single type? When you bleed the brakes do you get the same pressure at all the wheels. On my T bucket I had disc on the front and ford drums on the rear and by not driving it more than a few times a year I had the rear wheel cylinders rust in place! The pedal felt great but the pistons in the cylinders did not move at all which equals to no rear brakes! Something to check. Proportioning valves are for disc/drum combo. A metering valve will let the back brakes get some pressure first and then the front. I forget how much but it isn't a lot, just enough to prevent a lot of nose dive when you hit the brakes. Quote Link to comment Share on other sites More sharing options...
Byronb3b Posted June 30, 2007 Report Share Posted June 30, 2007 Reg, I would look into installing a porportioning valve, I believe all modern trucks have them to keep the lighter tail end from doing just what your old one is up to. Quote Link to comment Share on other sites More sharing options...
Ken_Hart Posted July 1, 2007 Report Share Posted July 1, 2007 There are several things all mentioned about First is the master cylinder (what is it... please do not tell me its still a stock single reservior... if so.. very bad in today's world from a safety standpoint). Second. I believe the brake lines should be the same size to get equalized pressure (smaller line can give higher pressures) Third will be a need for a porportioning valve to dial in front to rear braking.. Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 1, 2007 Author Report Share Posted July 1, 2007 The front brakes and drums as well as the master cylinder are all stock 52 dodge 1/2 ton truck. This truck was drivin by me almost daily in my construction business up untill a few years ago. I installed the 66 T Bird rearend under it about 6 or 7 years ago. I guess I have been lucky over the years and never had to do a panic stop until recently. The smaller lines are on the T Bird rearend. Every line forward of the rear flex line is stock 1/4". The lines that go to the rear brakes are smaller 3/16" that came on the Ford rearend. Here's a photo of the truck. http://smg.photobucket.com/albums/v154/olddodges1/Plymouth%20show%2006/?action=view¤t=OleYeller2.jpg Quote Link to comment Share on other sites More sharing options...
MBF Posted July 2, 2007 Report Share Posted July 2, 2007 Reg-I would make sure that your rear brakes are working. I've seen these where the cylinder seizes up and gives you a good firm pedal, but since the cylinders are not moving-no brakes on those wheel(s). It'll even bleed like everything is ok. I'd start there. If you have the rear wheel emergency brakes hooked up, you can experiment by partially applying the e brake and trying to stop with the shoes closer to the drum and see what type of difference that makes-if any. I think that with the single stage master cylinder putting larger cylinders on the back may actually make your problem worse if the original mast cyl can't output enough fluid to those wheel cyls in a single stroke of travel. Just my 2 cents. Please let us know what you find. Mike Quote Link to comment Share on other sites More sharing options...
Young Ed Posted July 2, 2007 Report Share Posted July 2, 2007 The 55 Ford we had was like that. Great pedal no brakes! The front hoses were clogged and the wheel cylinders stuck too. Same in the back. Stuck cylinders. Reg it does sound like you need valving to equal out the 2 systems. Quote Link to comment Share on other sites More sharing options...
Dennis_MN Posted July 3, 2007 Report Share Posted July 3, 2007 I've thought about this a bit and watched for someone else from the northern climates to chime in, but no.... so I'll add my two cents. 1. A skidding wheel has no traction...... 2. What we did in driving on snow and ice was to pulse our brakes to avoid skidding. Really pulsing will help a real bad skid. 3. A skidding front wheel doesnt steer....... pulse pulse pulse We'd also learn to control a skid by turning in the direction opposite of the skid or by increasing the speed of the rear wheels to induce skid. For practice, we'd drive out on a frozen lake and practice our driving skills. With modern ABS systems, we've forgotten all of these skills. Dennis in Minnesota Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 3, 2007 Author Report Share Posted July 3, 2007 If you could see my trucks skid marks you would see 2 long black parallel dotted lines created by me pulsing the pedal trying to keep the truck straight. If my rear brakes were working as much as the fronts I probably would not have done any skidding at all. Quote Link to comment Share on other sites More sharing options...
48Dodger Posted July 4, 2007 Report Share Posted July 4, 2007 Hey Reg, Did you check your rear drums for "belling" caused by driving with the E brake on? Or a leaky rear seal that has made things "slippery"? Check contact on all drums to make sure your getting the full power of the brakes. Are all the adjusters working? Port valve will give you some control over the bias of front to rear, but if you aren't set side to side it won't help. On my 72 Stock Car my port Valve is right next to my shifter, I keep the front discs ahead of the rear drums. Rear drums coming in first usually causes you to "drag" your rear tires in a stop. Quote Link to comment Share on other sites More sharing options...
48Dodger Posted July 4, 2007 Report Share Posted July 4, 2007 Just for clarity....metering valve on newer cars/trucks controls the actual coming in of drums over disc brakes. Disc brakes are in constant contact while drums aren't. The metering valve slows the disc brakes up front to allow the rears to come in with front at the same time. The port valve controls pressure to the the rear. Less pressure is needed to the drums than the disc. Why do I mention all this when Reg has 4 drums? well, if I remember crorrectly, the front brakes have 2 cilynders and the orginal rears had one. The front bore side larger to give the rear shoe a fighting chance to keep up with the stronger front brakes. If the 66 T-bird is 3/16 tubing and a standard bore cilynder, than the rear brakes are, as far as design goes, under powered. A port valve will give more pressure to the rear, but not structural strength and leverage. I believe you need to beef up the rear-end to match the big dogs in the front. Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 4, 2007 Author Report Share Posted July 4, 2007 Thanks 48 Dodger ! When will you be coming over to fix this problem? Where would I get a port valve? What does one look like? Hey, Jim and Bob...... a project for the 6th ? Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted July 4, 2007 Report Share Posted July 4, 2007 well, if I remember crorrectly, the front brakes have 2 cilynders and the orginal rears had one. The front bore side larger to give the rear shoe a fighting chance to keep up with the stronger front brakes. Actually, you've got it backwards. On the trucks, the twin cylinder setup is on the rear wheels, and the single (double sided) cylinder is on the fronts, but one piston is larger on those too. It's possible that the T-bird brakes just don't have the stopping power needed, but proper functionality should be checked first. Merle Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 4, 2007 Author Report Share Posted July 4, 2007 Hey:eek: .....I wonder if it would be possible for the front cylinders to have been put in backwards by me years ago when I rebuilt the system. Left one on the right making the big cylinder push on the wrong shoe. Does the bigger cylinder push on the front or rear shoe on the front brakes? I'll have to check that out tomorrow along with all the other great ideas suggested. Gotta throw some meat on the barbie today. HAPPY 4TH ! Quote Link to comment Share on other sites More sharing options...
48Dodger Posted July 5, 2007 Report Share Posted July 5, 2007 Good call Merle, I checked the knowledge page on our site and allpar to see what I could find. It shows it as dual cylinder/single piston in the front and 2 single cylinder /single piston in the back. BUT, I have 3 1948 b-108's (waiting for restoration) and 2 have the twin pistons in the front. I have to think what my grandfather would have done to keep his old truck running, and sometimes "factory" don't mean crap when work needs to git done. So I have to ask Reg, what do you have up front????? The factory single piston or "grandpa's git'er done" jobber, complete with dual piston rear brakes in the front?? I image it would would grab pretty good, leaving the T-brakes in the dust. Quote Link to comment Share on other sites More sharing options...
Merle Coggins Posted July 5, 2007 Report Share Posted July 5, 2007 Here are a couple of scans from my service manual. If you can read the breakdown below the exploded view of the front cylinder, you will see the rear piston is referenced "Large" Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 5, 2007 Author Report Share Posted July 5, 2007 "So I have to ask Reg, what do you have up front????? The factory single piston or "grandpa's git'er done" jobber, complete with dual piston rear brakes in the front??" Mine has the stock single cylinder up front 48dodger.... just like the one on the top left of Merle's photo. Quote Link to comment Share on other sites More sharing options...
Reg Evans Posted July 9, 2007 Author Report Share Posted July 9, 2007 So Tim or you other guys. Is this the part I need? All of these seem to be for 3/16" lines and if I put this in line to my front brakes the lines to them are 1/4". Will I screw up it's finction if I adapt the 1/4" lines to it? http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ih=017&sspagename=STRK%3AMEWA%3AIT&viewitem=&item=270142585659&rd=1&rd=1 Quote Link to comment Share on other sites More sharing options...
48Dodger Posted July 9, 2007 Report Share Posted July 9, 2007 If you're sure that your 66 t-bird rear-end is working correctly and you believe you can live with the single resivor master cylinder, then yes that's the part. putting it between the Master cylinder and the front brakes sounds like the fix for your problem. I would seriously consider how to get a dual master involved since you're staying with a 48 front and a 66 back set-up. 48D Quote Link to comment Share on other sites More sharing options...
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