buickbrothers Posted February 3 Share Posted February 3 Ok gents, I'm confused as to which shoe (primary or secondary) mounts in the front or back. When I took this car apart, the rear passenger side drum had the primary mounted on the back and the secondary mounted on the front. Parking brake bracket was mounted to the primary. See first picture: When I reviewed the shop manual, there are two graphic's which seem to contradict one another. The first graphic indicates it's the right rear but it would depend on what they are indicating is the right rear (looking from the front of the car vs. back of the car). If it's passenger side vs driver side. If it is the passenger side then it matches my original picture. The other graphic indicates the rotation of the wheel and position of primary vs secondary. This is indicating the primary should be mounted to the front of the drum vs. back based on rotation. However, this would mean the original picture before I took the shoes off had the primary on the wrong side - should have been front side vs backside of drum. So, I'm totally confused now! Help! Link to comment Share on other sites More sharing options...
packick Posted February 3 Share Posted February 3 BuickBrothers: The small shoe goes on the front. I have attached two pictures. Both are from the left side, one front and one rear. These are on my '55 Century. Hope this helps. 2 Link to comment Share on other sites More sharing options...
buickbrothers Posted February 3 Author Share Posted February 3 So that brake action diagram is incorrect based on your pic's and my original pic before I disassembled. Primary is always on the back side of the drum and secondary is on the front side of the drum. Thanks for the verification! Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 4 Share Posted February 4 The primary shoe is the one with the shorter brake lining of the two. The primary goes to the front of the car on both sides. The manual shows that correctly as does Packick's pictures. 3 2 Link to comment Share on other sites More sharing options...
Buicknutty Posted February 4 Share Posted February 4 Just my few cents worth here. I have seen them mixed up many times over the years, Kudos to the OP for questioning this to make sure. 2 Link to comment Share on other sites More sharing options...
Frank DuVal Posted February 5 Share Posted February 5 Yep, primary shoe of this system is the shorter lining shoe. The secondary shoe has the longer lining. 👍 Link to comment Share on other sites More sharing options...
buickbrothers Posted February 5 Author Share Posted February 5 Thanks all. Shoes, drums and tires are reinstalled, and I've expanded shoes. I did front wheels first and expanded shoes until you can "just turn the wheel by hand" per the book. How firm or how much drag should this be to "just turn by hand"? The book indicates the drag should be equal at all wheels. However, as you read on, and get to the rear wheels, it's having you back off the adjusting screw so rear wheels are "free of drag". So, how can you have equal "drag" at all wheels and just turn the tire by hand and no drag on the rear wheels? What is the correct approach here? I've shifting to working on the parking brake cable adjustment while I wait for feedback from the forum experts on the shoe adjustments. I can't seem to get this dialed in to eliminate the cable slack and get the parking brake operational again. I've run out of adjustment thread. I had it working before. However, I ended up pulling the whole axel and torque tube out as a unit in order to fix a leak in the tail of the transmission and replace the seal on the torque tube. Unless the cable between the rear tires grew in length, I'm not identifying why and where else to make adjustments for slack. any thoughts are helpful. Thanks. Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 5 Share Posted February 5 Allowing that I misunderstand the manual, I thought each wheel had the brakes backed off. But in answer to your question directly, the parking brake cable should be backed off till slack, then adjust the rear brakes to tight and then backed off per the manual, then tighten the parking brake cable. You won't get all the slack out of the parking brake cable but the parking brakes should hold the car when the pedal is half way down. Link to comment Share on other sites More sharing options...
JohnD1956 Posted February 5 Share Posted February 5 I almost forgot, do the anchor pin adjustment before any brake adjustment. And always make sure the way is clear before roadtesting new shoes. Very often unburnished shoes feel like they wont stop the car. Can be scary! 2 1 Link to comment Share on other sites More sharing options...
EmTee Posted February 5 Share Posted February 5 43 minutes ago, buickbrothers said: How firm or how much drag should this be to "just turn by hand"? I wouldn't worry too much about how tight they are initially; take time to get them all as close to the same as you can. New shoes will wear-in a lot initially which will make them considerably looser after the first few stops. Let them cool after the first drive and then set per the shop manual. Like John said, i have seen some years call for adjusting to the point where the wheel can just be moved by hand (i.e., heavy drag) and then the adjuster is backed-off XX 'clicks'. Other years simply say to adjust for 'light drag' (or something like that). I'll usually set newer shoes a little tighter figuring they will continue to loosen a bit as they wear-in to match the arc of the drums. After a couple thousand miles I typically set them for a light drag. I occasionally shoot each wheel with my IR thermometer following a drive to assess brake adjustment. I have found that a balanced adjustment will yield temperatures within 5° F between the wheels on the same axle. If a wheel is hotter, back-off 2 or 3 'clicks'. On manual brake cars, pedal height gives a good indication of the overall adjustment (or need for a touch-up). 1 Link to comment Share on other sites More sharing options...
60FlatTop Posted February 5 Share Posted February 5 I look at the primary shoe as the actuator or pilot shoe to initiate the self energizing feature of drum brakes. The rear shoe does the majority of braking. This is one reason I do not favor converting a drum brake car to discs. You lose the self energizing feature. Something I learned from the 1959 McGraw Hill mechanics books my Mom helped me buy in 1959 and could never get across to the Hot Rod Magazine readers. Here is a pretty good explanation. 5 1 Link to comment Share on other sites More sharing options...
Shootey Posted February 5 Share Posted February 5 I’ve adjusted my new 1941 Buick matching shoes and drums. Some of them exhibit an eccentric contact, that is as I rotate the drum it will get tight with contact in a spot and the run free in most of the rest of the revolution. Is this ok? Does it mean I don’t have the anchor pin correct? The anchor pins can adjust vertically only. Thanks. Link to comment Share on other sites More sharing options...
EmTee Posted February 6 Share Posted February 6 20 hours ago, Shootey said: Does it mean I don’t have the anchor pin correct? If the shoes are wearing mainly near the top or bottom, then yes. If wear is even across the face of the shoe (i.e., lining wear at the top and bottom is even) then the periodic rub is most likely caused by distortion of the drum from repeated heating/cooling. Some runout is acceptable, however, the drum should be turned to re-true it if out-of-round exceeds the specification in the shop manual. 3 1 Link to comment Share on other sites More sharing options...
Shootey Posted February 6 Share Posted February 6 The drums and shoes have been turned and arced so they fit each other. 1 Link to comment Share on other sites More sharing options...
Hans1965 Posted February 7 Share Posted February 7 May I ask a question? If you switch - out of error - primary and secondary shoes all around, so having at the end on all 4 wheels the shorter brake shoe rearwards instead of forward, what kind of effect would this wrong installation have on the brakes and brake feel? I am asking because i observed that on my 47 Super sedanet when I had bought it. When I hit the brakes hard sometimes they looked up and only released themselves after a few minutes. Quiet scary!!! I reworked the master brake cylinder, corrected the brake pad installation and changed the wheel cylinders all around and so far it didnt happen again. But still wonder what it caused. The little pin whole in the master cylinder to release pressure was always intact. Any idea? Thanks. Link to comment Share on other sites More sharing options...
EmTee Posted February 8 Share Posted February 8 My guess is that the brakes might not be quite as effective and the secondary shoe (the self-energizing one) might wear faster. If everything is adjusted properly I wouldn't expect any pull to one side or the other. 1 Link to comment Share on other sites More sharing options...
buickbrothers Posted February 25 Author Share Posted February 25 Ok friends, I have a new problem and need some insight. I believe I am losing reactive pressure on the power brake booster. Without the engine running, I have a hard brake pedal. I have bled the brakes 3 times to ensure there is no air in the line - I get clear results. I have no brake fluid leaks - levels remain unchanged in the fluid reservoir. When I pump the brake without the car running and hold the hard pedal down, I pass the test that the pedal moves forward when the car is started but it does not stop. With the car running, and full pressure on the brake pedal, it slowly goes to the toe board. The brakes engaged and held the car in place but as the pedal reached the toe board, they let go. Based on descriptions in the shop manual, I believe it is reactive pressure loss. I did take the booster apart. Cleaned, replace primary plunger seal and gaskets. The housing did have some interior corrosion/pitting at a low-level position in the housing. The brakes were working with this condition before and I thought the cleaning, polishing of the interior of the housing, new seal/gaskets/refresh of the part would only improve things not degrade the booster to where the brakes don't work. What's your opinions and recommended fix or additional tests to narrow down to root cause? Thanks. Link to comment Share on other sites More sharing options...
Wayne R Posted February 25 Share Posted February 25 (edited) On 2/6/2024 at 12:16 AM, buickbrothers said: Thanks all. Shoes, drums and tires are reinstalled, and I've expanded shoes. I did front wheels first and expanded shoes until you can "just turn the wheel by hand" per the book. How firm or how much drag should this be to "just turn by hand"? The book indicates the drag should be equal at all wheels. However, as you read on, and get to the rear wheels, it's having you back off the adjusting screw so rear wheels are "free of drag". So, how can you have equal "drag" at all wheels and just turn the tire by hand and no drag on the rear wheels? What is the correct approach here? I've shifting to working on the parking brake cable adjustment while I wait for feedback from the forum experts on the shoe adjustments. I can't seem to get this dialed in to eliminate the cable slack and get the parking brake operational again. I've run out of adjustment thread. I had it working before. However, I ended up pulling the whole axel and torque tube out as a unit in order to fix a leak in the tail of the transmission and replace the seal on the torque tube. Unless the cable between the rear tires grew in length, I'm not identifying why and where else to make adjustments for slack. any thoughts are helpful. Thanks. I think i can see a problem here ,---your adjusting nut is mounted wrong,---should be turned end for end. am i correct.--from picture just under Frank Duval. forum above. Edited February 25 by Wayne R (see edit history) Link to comment Share on other sites More sharing options...
Beemon Posted February 25 Share Posted February 25 (edited) 19 hours ago, buickbrothers said: Ok friends, I have a new problem and need some insight. I believe I am losing reactive pressure on the power brake booster. Without the engine running, I have a hard brake pedal. I have bled the brakes 3 times to ensure there is no air in the line - I get clear results. I have no brake fluid leaks - levels remain unchanged in the fluid reservoir. When I pump the brake without the car running and hold the hard pedal down, I pass the test that the pedal moves forward when the car is started but it does not stop. With the car running, and full pressure on the brake pedal, it slowly goes to the toe board. The brakes engaged and held the car in place but as the pedal reached the toe board, they let go. Based on descriptions in the shop manual, I believe it is reactive pressure loss. I did take the booster apart. Cleaned, replace primary plunger seal and gaskets. The housing did have some interior corrosion/pitting at a low-level position in the housing. The brakes were working with this condition before and I thought the cleaning, polishing of the interior of the housing, new seal/gaskets/refresh of the part would only improve things not degrade the booster to where the brakes don't work. What's your opinions and recommended fix or additional tests to narrow down to root cause? Thanks. Did you replace the hydraulic piston with the new seals? The old piston can corrode and cut the seal cups, creating a leak path. Your primary cup (yellow) if leaking will show some type of bleed back in the reservoir. The secondary cup (blue) will weep through the vent wire. The tertiary cup (green) will suck fluid into the engine - check your vacuum line for wetness. When the pedal is applied, the piston equalizer holes will be in the main hydraulic cylinder and the fluid should not be able to move from the cylinder to the reservoir. If you have any leaking symptoms from either of these locations, then most likely the cast iron hydraulic body is pitted around one of the cups and may need to be sleeved... this is not common though, and the cups as I'm sure you noticed in your rebuild, are an interference fit. In an ideal state, the tertiary cup should always be dry. Also in the rebuild kit is the seal and check valve for the proportioning block. Although I don't think this is your problem, if you don't rebuild the check valve you can end up with lack of pedal feel due to loss of residual pressure in the system. If there are no signs of leaking, the piston assembly can potentially bleed down through the control valve. Put a vacuum gauge in line to the booster before the reservoir. The unit vents to atmosphere through the air cleaner, so if you lose reactive pressure due to a vacuum leak, you will see vacuum plummet. The engine may not see this because there is a check valve on the valve cover to prevent loss of engine vacuum. You would need to disassemble the entire piston by removing the unit, pull all the snap rings that hold all the fingers and plates together, and assess the seals. It's been a while since I've been in mine now, but the rebuild kits should come with all the o-rings and seals, and the control valve diaphragm to rebuild the piston assembly. The shop manual says to lubricate everything with silicone grease, so if you install dry it does have the opportunity to tear or prematurely fail. Hope this helps. Edited February 25 by Beemon (see edit history) 3 Link to comment Share on other sites More sharing options...
buickbrothers Posted February 26 Author Share Posted February 26 Hi Beemon. Thanks for the information. Here's my response to your questions and some actions I took yesterday: 1. No, I didn't replace the hydraulic piston. May need to now, as it did have pitting. I've provided some photo's (before/after). It was a judgement call, right or wrong, based on the fact that the power brakes were working before. The pitting was in the vacuum chamber level and not the secondary cup. However, the corrosion may have been aiding in sealing and once removed it has now accentuated a leak? My concern is the cylinder housing had some pitting as well and this part I can't find. I'm wrestling with a decision of buying a restored power booster from Harmon Classic Brakes or risk buying individual parts to fix this one - if I can find the parts: 2. Yesterday I added ATF to the air chamber to eliminate a possible dry piston. No change. I adjusted the push rod thinking it might not be going far enough back into the secondary cup. No change. Then I pulled the main vacuum supply line off the engine and inspected/clean the piece I believe to be a check valve on the vacuum supply line. The book is not clear on this line and this end piece (no clear references). No change. What role does this piece on the end of the main vacuum line play? 3. When I ran the engine without the vacuum line being connected, my brakes are in "manual mode", correct? The pedal is solid and doesn't go to the toe board. I have not discovered any fluid leaks. Nothing at the wire vent. Nothing in the vacuum line. No change in the reservoir level. My diagram also notes a "check valve" in the upper right corner but doesn't indicate location - I believe this is the piece on the end of my main vacuum supply line? Not sure how to test if this piece is good and the book seems to indicate this affects reactive pressure. Link to comment Share on other sites More sharing options...
buickbrothers Posted February 26 Author Share Posted February 26 One new update. I talked to Harmon Classic Brakes to get clarity if they have a restored unit on the shelf or you have to send your unit in. It's "you send your unit in". They don't have the cylinder housing so I could be sending it in only getting it returned that they can't restore it. So, I'll end up doing this myself but here's my concern. I found the hydraulic piston at oldbuickparts, but not the cylinder housing. I have no problem replacing the piston, but until I know the root cause of not having reactive pressure (pedal slowly going to the toe board) I'm reluctant to just assume the two pitted parts need to be replaced since the brakes were working before. The more tests that people in forum can throw at me to try, the better, in order to find root cause. Thanks. Link to comment Share on other sites More sharing options...
old-tank Posted February 26 Share Posted February 26 Harmon Classic Brakes used to sell all those parts that you need. Link to comment Share on other sites More sharing options...
61polara Posted March 8 Share Posted March 8 This image has been flipped. The E-brake leave is always to to back of the drum. Link to comment Share on other sites More sharing options...
Frank DuVal Posted March 8 Share Posted March 8 I don't follow what you are saying. Flipped what? The image you posted is the exact same as the one in the first post. Same parts in the same relation with the same labels and the parking brake lever is to the rear of the assembly (mounted to Secondary Shoe). Right rear brake assembly. Link to comment Share on other sites More sharing options...
Fr. Buick Posted March 8 Share Posted March 8 The picture above shows the Right Rear brake assembly, since the parking brake cable enters from the front of the plate and pulls forward. 1 Link to comment Share on other sites More sharing options...
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