I believe I have found the issue of why only the passenger side rear brake drum gets really hot after a short drive. It is not appear to be returning at the top to the anchor pin and I have no idea why. Is it possible that it got too hot and distorted the backing plate? I installed the low car emergency brake set up, but I removed the spreader link to verify if that was causing the issue and even removed it still did not return back to the anchor pin, even adding help with copper anti-seize lube against the backing plate and new springs. I also replaced the wheel cylinder just in case it was sticking and I do not think the new one would allow this same issue but you never know. Between research here in the Mustang forums, I have not found anything conclusive regarding why the smaller brake shoe issue towards the front of the vehicle is happening. No major grooves or anything. Just in case the flexible line is collapsing. I am going to replace it soon, but it still doesn’t explain why only the same wheel does this. Running a small bearing ford 9” with 10”x1.75” shoes. I have new shoes coming just in case. Has anyone had this issue? Picture is before removing the parking brake spreader, even without the parking brake spreader did this exact same thing:
Take the shoes off and look at the pads that the shoes ride on on the backing plate. Quite often grooves get worn in them over the years and especially new shoes with sharp edges on the rub spots will hang up on them. You can dress them up a bit with a flap wheel and then put a smear of grease on them to let the shoes ride smoother on them.
I'll also mention that springs can lose pull, although they usually discolor and yours look good. Also, if something is causing the fluid not to return, it can do this too. Easy diagnosis is to open the bleeder. I had an OT car that would do this, but it was the hose to the axle and the other side dragged a bit too, but not as much... ?
As @Mr48chev mentioned, grooves sometimes get cut into the raise pads on the backing plates. The shoes float on them. I've had to weld up the grooves, and grind them flat. A little white grease helps the shoes float again.
Switch the shoes left to right, quick test. change springs also, put in same spot I had lines on my 65 F100 that would let fluid through but not out Can you push the shoe in to the stop by hand without the other she coming off the stop ?? Ricky.
That is a pretty sure sign that the emergency brake is still being applied. Probably a cable hanging up in the rear cable housing on that side, but it could be as simple as an adjustment, or the lever inside the car isn't fully retracted. After checking to be sure the lever inside of the car is fully retracted, pop it apart and remove the bar for the E brake lever, reassemble, and see if the top of the shoe will sit against the post then. If it does, the problem is in the E brake system.
Pull the shoe outward and see if pops in against the pin. the shoe looks like it catching on the pin and adjust the brake.
The first thing I would do as was said by @RodStRace is to crack the bleeder and see if the shoe pulls into place. If it does you need a new rubber brake hose, as the inside has deteriorated and is acting as a one way valve. Or the wheel cylinder has a stuck piston in it, holding the shoe from retracting. Opening the bleeder is easy so I would do that first.
All of the above are good recommendations. The only thing I'll add is if the easy checks don't solve your problem then disassemble the entire system and clean, deburr, polish and lube as needed. As you re-assemble it check each component for proper engagement and operation. And as for the E-brake completely isolate the lever and cable assembly from the wheel and check for proper function. For me sometimes it works to go back to the beginning and work my way through it piece by piece.
Agree with BJR about opening bleeder or cracking the line loose, on that side to see if it retracts. Will it push back by hand? Being its only happening on one side of the car, if it does retract, I would suspect the steel brake line from the wheel cylinder to the T-fitting at the flex hose, has some type of restriction. If it was caused by the flex hose, I would think the problem would be on both left and right brakes. Bill
Agree with that also. Many Mustang's had a different funky looking front spring that had heavier coils with two different diameters. Here is an image of ones that I have seen. Bill [ATTACh
Hi all, thank you for the great suggestions. I believe there is a little pressure built-up not allowing the wheel cylinder to fully release pressure but the flexible hose going from the frame to the axle did not look collapsed. Even when I bled the new wheel cylinder it didn’t return though. regardless, I have a stainless steel braided version flex hose on its way just in case. I also have a new set of NAPA 10” x 1.75” shoes coming and two balanced Dynamic Friction rear drums just in case the one became too hot and is out of round. Yes, I will be keeping these original drums and will eventually have them turned but I don’t have a ton of time to run around at the moment. Regarding the spring set, this is a basic NAPA or advanced auto kit. Can someone point me in the right direction with the proper springs, including the spring for the parking brake spreader? Mine looks fairly beefy, and I believe has a more solid spring rate which could cause adjustment issues. Is this correct? One of the better threads I have found regarding the lokar emergency/parking brake is duece666’s but he added the mechanical leverage, and I do not plan on doing that immediately, or at all. He also shows a mustang like spring kit being used. https://www.jalopyjournal.com/forum/threads/need-help-with-ford-9-emergency-brake.1055620/ Again I have removed the parking brake spreader until I can achieve normal rear brake function so I can rule this out as the issue. Once I have achieved normal function, I will re-install the spreaders and start messing around with properly adjusting the transmount Lokar parking brake kit. I am running 10” rear drums, with 1.75” wide shoes, small bearing (early ford), confirmed 9” with the bottom bolt on the third member socket trick. I normally use a 67’ mustang 289 ‘base’ when searching for rear axle related components, is there a better year and vehicle to use with this combo such as a Comet? Thanks guys.
@justpassinthru picture shows the Yellow spring to the rear, not the front like OP. OP is asking which application is used to get that spring kit, sounds like a solid plan. Here's a bump and hoping the part number is posted for future HAMBers to reference.
I believe Scott Drake and Year One have the correct factory style spring kit for 10" x 1 3/4" brakes. C5ZZ-2035-DK Bill
I agree, steel line or one of the fittings are partially stopped up, allowing fluid to expand the wheel cylinder on that side, but it’s not retracting. I’d take off the line on that side and try to run some brake clean and compressed air through it. If it opens up, fine, if not you’ll probably need a new line on that side. Most auto parts stores have the short pre made lines with the fittings on them that you bend yourself to fit.
After doing more research I think the springs were installed backwards, the blue beefier one must be pulling the front smaller pad and the yellow one pulling on the back facing larger pad. Once I get the stuff in tomorrow I’ll tear everything down. In the fall/winter I will work up small Ford 9 inch ( small bearing ) write up with OEM part numbers. Apparently I got the 64.5-April 66’ mustang wheel cylinder which is 2/32 smaller in diameter, but the post April 66’ will still work and looks the same. Bought both at Napa and will take a look. Also believe the wrong wheel cylinder to brake shoe connecting pins are wrong. Hope to have everything worked out soon.
I had a similar problem once. The fix was rebuilding the master cylinder, as it was holding pressure on the rears.
Thank you for the heads up, any recommendations or brands to avoid? It looks like I will be replacing most of the brake components minus some hard lines and front disc set up. I will probably buy a new one and rebuild this current one at a later date for a spare, hate throwing stuff away that can be given new life. Does anyone have a line lock kit laying around collecting dust they would like to sell cheap? I wasn’t planning on adding one until I built or found a posi diff, but I might as well install it now if I’m removing most of the brake components and have to bleed the whole system.
Interesting.... Just had an OT 68 Mustang in the shop Tuesday, with the same rear brakes as you, to reset the brake light after owner replaced the rear flex hose. and was unable to get light to turn off. He was having issues with both rear brakes dragging and getting hot. To determine what was causing the rear brakes to drag, he loosened up the rear shoes a bunch, and still had the issue. He determined the flex hose was clogged and replaced it. Bled the rear brakes a bunch of times, didn't have great flow and could not get the brake safety valve to re-center. Then it came to me. After a bunch of farting around, we got the valve to re-center and turn off light. Then I removed the rear brake drums to readjust brake clearance. Drums came off easily, shoes were adjusted super loose. The interesting part is the front shoes on both sides were off the top pin, just like yours. It appears the front shoes were getting sort of cocked and hanging up on the top plate of the backing plate as you can see in the images. All I did was adjust the brake shoe clearance to normal. Applied the brakes on the lift with the rear wheels spinning a number of times and removed the drums again to inspect. They were not doing that anymore. Drove the car and removed the drums again and they were fine. It would appear that the excessive clearance in the brake shoes caused it. Maybe yours too? Bill
Someone installed 2 1/4” shoes where it should have been 2” as in this case they also had a 1/8 spacer between axle and drum. It looks like they still had no or best very poor rear brakes for a long time.
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