Need some brake help, please...

[EagleChief]

I'm working on redoing my brakes. 1971 C10 longbed. Disc brakes up front, drums in the back. I tried searching before I posted, but came up empty.

The original problem started when I was replacing the pads. I had the front rotors turned, put the new pads on. When I put the new pads on, they were extremely tight on the rotor. Tight enough that I had to "tap" them on with a hammer. While driving, I could hear them rubbing the rotors. I also had a vibration/pulsation when braking after turning the rotors.

Fast forward to now - after a suspension rebuild and drop kit, determined that I needed new brake lines up front and went ahead and got new rotors as well. Got the rotors on last night. Tried putting the pads on, and they don't fit! The pads are too thick to fit over the new rotors. The rotors are for a '71 (RockAuto), the pads are for a '71 (Advance Auto) - 1.25" thick. The calipers are what was on the truck - I'm assuming original.

Any thoughts?

My first 2 thoughts: 1) pads were wrong, or 2) calipers were switched out at some point for the 1" rotors? What is that, '80 and up?

Is there a way to visually determine the difference between calipers throughout the 70's? Just something that I can look at on my calipers to know if they are original or have been replaced?

[REDROCKER652002]

My son's 69 had al 72 parts on the front end. If I remember correctly, the caliper should have a stamp on it that you can use as a reference. When we did his, I had the same problem. My mechanic, who was very helpful, was going to turn the rotors but they were too thin, so he needed to order new ones. He checked the numbers for me. That is how I found out the parts are all 72. Also, I think I was told that some of those parts differ even from 71 to 72, but I could be wrong there. I have not had my first beer yet. LOL Good luck, it can be a bit frustrating. But the folks here were a great help as well RR

[3767]

If u suspect u have the later(1980 and up) calipers,u can measure the Pistons. The older calipers has a smaller piston2.910 vs the later model caliper piston at 2.940. Rr is right about the casting. Also the newer calipers look the same so u could have gotten the wrong calipers n the box when u ordered them. The pads have the same shape and length, but as u have found are different n thickness. That noise u have is the pads grinding against the rotor. They will ruin the rotor if u have the semi or metallic set of pads as they are harder that the cheap organic pads.

[franken]

Caliper pistons need to be pushed into the bore with channel pliers for example. Make sure the res doesn't overflow.

[Sheepdip]

[QUOTE=franken;8701955]Caliper pistons need to be pushed into the bore with channel pliers for example. Make sure the res doesn't overflow.[/QUOTE

^^^^^^^^^^^^^^^^^This^^^^^^^^^^^^^^^^^^^^^^

A good "C" Clamp works well too!

[EagleChief]

Thanks for the replies. The Pistons are fully pushed in. I use C-clamps for that. Here's a couple of pictures of the calipers. Maybe somebody can decipher the code stamps on them and let me know what I have.

[REDROCKER652002]

Tough to see, how about you just post the numbers? If I remember right, my sons had rh and lh near the numbers that meant anything. Either way, I know it is a pain in the tail to figure this crud out. good luck, and have a beer or two, it makes it better LOL.

Edit: It looks like the calipers are what was on the truck before you started all this? Could it be that they calipers are not even original to the truck? My suggestion is to get calipers that match the year rotor, as long as the banjo bolt will fit and the mounting bolts line up. Then you know exactly what you have, and they match all the other stuff.

If I am wrong, then disregard. RR

[EagleChief]

Originally Posted by REDROCKER652002

Tough to see, how about you just post the numbers? If I remember right, my sons had rh and lh near the numbers that meant anything. Either way, I know it is a pain in the tail to figure this crud out. good luck, and have a beer or two, it makes it better LOL.

Edit: It looks like the calipers are what was on the truck before you started all this? Could it be that they calipers are not even original to the truck? My suggestion is to get calipers that match the year rotor, as long as the banjo bolt will fit and the mounting bolts line up. Then you know exactly what you have, and they match all the other stuff.

If I am wrong, then disregard. RR

I appreciate your help and replies. From what I can tell, the front of the caliper has the following numbers:
123A
C(?)E 2(?)
67880
Then on the right side on the right side: 15

On the back side of the caliper, I can't really tell what that is - I'll try my best.
N GM 15 8470183 (maybe?)

You are correct, these were on the truck when I bought it, so I don't know if they are original. The banjo bolts are 7/16". I know that as I just replaced those. I've thought about seeing if the local parts stores have calipers that I could look at, or even take mine in to compare it to what they have for the 71.

[3767]

I noticed u said u replaced the brake lines and that the bolt was a 7/16. That suggest it’s an older caliper. The newer calipers were metric. For example...the bleed screw should b 3/8 24 . The newer calipers will have metric thread (m10x1.5). The older calipers were all wider due to the rotors. The spindle, rotor and calipers all have to match to work. If your rotors have no play, then the spindle, and rotor match. If your calipers have standard thread then they should match to what u have. Meaning u have all 1.25 parts. If your rotors are lose on the spindle, or that bleed screw has metric thread, then u have the newer parts. Even your brake line is the old style. The newer style has a 90 degree bend n it making the metal part of the line longer. It sounds like u just were given the wrong pads. I have had this problem as have many others. I believe part of the problem lies n the fact that without measuring and just looking at them, the parts wind up n the wrong box. These brake parts n general look a lot alike and fit many years of trucks making them good and bad as u have seen.

[EagleChief]

Originally Posted by 3767

I noticed u said u replaced the brake lines and that the bolt was a 7/16. That suggest it’s an older caliper. The newer calipers were metric. For example...the bleed screw should b 3/8 24 . The newer calipers will have metric thread (m10x1.5). The older calipers were all wider due to the rotors. The spindle, rotor and calipers all have to match to work. If your rotors have no play, then the spindle, and rotor match. If your calipers have standard thread then they should match to what u have. Meaning u have all 1.25 parts. If your rotors are lose on the spindle, or that bleed screw has metric thread, then u have the newer parts. Even your brake line is the old style. The newer style has a 90 degree bend n it making the metal part of the line longer. It sounds like u just were given the wrong pads. I have had this problem as have many others. I believe part of the problem lies n the fact that without measuring and just looking at them, the parts wind up n the wrong box. These brake parts n general look a lot alike and fit many years of trucks making them good and bad as u have seen.

I agree with all of what you said, as I've been researching the crap out of all of this over the last few weeks. I think the best (least expensive) route will be to try another set of pads and see if they will work.

EDIT** This is the brake pads that I purchased for the front - CarQuest WearEver Gold Semi-Metallic: Part # GMKD52. https://shop.advanceautoparts.com/p/...erm=brake+pads

[toolboxchev]

Picked up this info back at my days at Firestone and Napa. The standards OEM has for brake equipment is not the same as the Aftermarket. Aftermarket always tries to compete by using different materials, HD applications (thicker) and other things as bonded is better than rivets.

I would just focus on 2 factors, your calipers may have rust on the pistons and now that is pushed to far in past the seals. This happens from running the pads thin all the time.

The pads you have are an HD, Severe Duty rating and are simply thicker.

[3767]

When I had this problem, my first set was just like yours. I had to use a mallet and tap them into place. I could turn the rotor so with the thicker rotors the pads will wear themselves to the rotor. The newer rotors can’t due this as they will warp being thinner. Mine came from advance auto . I believe these replacement pads are just thicker(not the wrong part) n some cases making them harder or impossible to put on. U could take the caliper and press it up against the back of the rotor. Use your ruler to measure the empty space on the front side of the rotor.when u go back to the store, u will have a good idea with both pads together, what the overall thickness needs to be. If u can get a set close enough to put on without some real effort, then u can wear them into the rotor like you did originally. Best of luck and let all know the outcome

[REDROCKER652002]

Just a quick search shows you can get brand new calipers from Brothers for about 60 bucks each. Might be a good idea, that way you now that they are right for the truck. Just a suggestion. RR

[EagleChief]

Thanks everyone!

I did a little more digging on the pads. The set I bought, I couldn't find any thickness ratings/measurements for them, but the sets rated directly above and below, were showing a thickness of .50" roughly, per pad. I found another set, that had a stated thickness of .368" per pad. That 1/8" on either side, is about what I'm lacking to get them on.

So, I picked up the thinner set at the parts store on my lunch break and I'll give them a try this evening. With my rewards discount, and the online 20% off, they were only $16. I'll give them a try this evening and see what happens.

[EagleChief]

Well, just to update - the "thinner" pads I picked up yesterday were not thinner. They are actually slightly thicker than the pads I already had. So, I'm taking them back today. Brought my other set into the shop. We have a full machine shop, so we're going to shave them down a little. I should have them back on this evening. We'll see.

[3767]

I think u are starting 2 c what ive been talking about. U will have to shave them down. A milling machine will make quick work of it. The pads made now are harder and n turn will last longer but they dont fit so good sometimes. I believe once u get them cut down and back on u will b happy. I'm sure u are aware that measuring now and knowing what to take off now means a great fit later. Again ...keep us posted. U just never know how this may help some 1 out later on

[RustyPile]

I have been doing brake work for over 50 years, 35 of those were to make a living.. Professionally, if you will… I have never, I repeat, "NEVER", encountered brake pads that were manufactured too thick.. 99% of the time the pads wouldn't slide in because the caliper pistons weren't retracted in far enough.. If the piston "stalled out" it was because debris, rust or other obstruction stopped it. The other 1% was because the pads were wrong for the application.

50% of my money is on something is keeping the caliper piston from fully retracting.. Before you start shaving friction material, check those pistons closely.. The other 50% is on the pads being wrong for the application..

If you're going to the same parts store and getting these "too thick" pads, get a refund and go some place else...

[EagleChief]

Got the pads on this weekend. Had our machine shop shave them down for me. Turned out really good. They fit just like they should have. Everything is tightened up and when I spin the rotors, there's just barely a noise of the pads touching.

So, when we measured the pads, there was about 5/16" to 3/8" of material across the pad. We took them down to just over 1/4". It ended up to about .27" per pad. There was still quite a bit of material left on the wear groove, so I'm not worried about it much. Plus, they are semi-metallic and the life of the pads last much longer than they used to.

Rusty, I appreciate your concern, and I had the same check list to make sure everything was right. I can assure you, the rotors are correct, the pads were correct, the calipers seem to be correct from what I researched (casting numbers come back as 1971 calipers), and the pistons are retracted back to flush in the caliper using C-clamps. I had tried 2 other sets of pads - $60 sets and $20 sets, and all had the same issue.

[Andy4639]

I didn't see it in any of your post but the brake calipers for a 71 and 72 are different. They do not enter change. The mounting tangs for the brake hose tell you the difference.
Yes they look almost identical but they are not. This could have been your problem. Most place have no idea they are different.

[RustyPile]

Originally Posted by Andy4639

I didn't see it in any of your post but the brake calipers for a 71 and 72 are different. They do not enter change. The mounting tangs for the brake hose tell you the difference.
Yes they look almost identical but they are not. This could have been your problem. Most place have no idea they are different.

100% correct.. The rotor, the pad, and the hose have to match.. The thicker rotors will fit, but the caliper has to "match" the rotor.. Then the hose has to "match" the caliper.. That"s the only way the parts will interchange..

.27" is a lot of material to remove. 20 thousandths over a 1/4 inch.. That's about the amount of thickness difference between thick and thin rotors. The OP either has the wrong calipers (regardless of the casting #), or the wrong rotors..

[EagleChief]

Originally Posted by RustyPile

100% correct.. The rotor, the pad, and the hose have to match.. The thicker rotors will fit, but the caliper has to "match" the rotor.. Then the hose has to "match" the caliper.. That"s the only way the parts will interchange..

.27" is a lot of material to remove. 20 thousandths over a 1/4 inch.. That's about the amount of thickness difference between thick and thin rotors. The OP either has the wrong calipers (regardless of the casting #), or the wrong rotors..

I think you misunderstood the thickness. I did not remove .27" - I only took off about .04". They were measuring anywhere from .375" to .3125" (1 pad had .375", the others were closer to .3125" measured with digital calipers) of pad material out of the box. I ended up at .27" thickness of material after shaving them down.

Maybe the calipers are from a '72. I don't know. But, looking up brake pad part numbers, they were the same from '71 and up to '76. We looked them up for all of those years, and they were the same part numbers. DS52, or something like that.

I'm not trying to argue with you, just stating what my situation is. I'm learning as I go, and I'm storing your info in the back of my head for future reference. I appreciate your replies and help!

[RustyPile]

Originally Posted by EagleChief

I think you misunderstood the thickness. I did not remove .27" - I only took off about .04". They were measuring anywhere from .375" to .3125" (1 pad had .375", the others were closer to .3125" measured with digital calipers) of pad material out of the box. I ended up at .27" thickness of material after shaving them down.

Maybe the calipers are from a '72. I don't know. But, looking up brake pad part numbers, they were the same from '71 and up to '76. We looked them up for all of those years, and they were the same part numbers. DS52, or something like that.

I'm not trying to argue with you, just stating what my situation is. I'm learning as I go, and I'm storing your info in the back of my head for future reference. I appreciate your replies and help!

Oh, believe me, I know you're not arguing with me.. But you have to understand (and I realize I might be coming across as a know-it-all) but believe me, I'm the voice of experience.. First, I don't believe you ruined or otherwise, compromised those pads by shaving off 40 - 50 thousandths of the pad thickness.. But I do consider that a band aid fix, and the last approach I'd use to solve the problem.. Having studied your situation, I think, even though your brakes work as the should, you have the wrong calipers.. The pad "capture area" is too small (tight) for 1.25 rotors and new pads to fit in the same space..

As an example, last year I did a total rebuild on the brakes of my '71.. New power brake booster and master cylinder conversion, new calipers, pads, rear shoes, drums, wheel cylinders and all 3 rubber brake hoses.. The local place where I shop had only one '71 brake caliper... So I bought two '78 calipers with hoses to match.. Every piece fit perfectly and the brakes on my truck will stick your face to the windshield.. But you have to understand that experience has taught me what pieces can be interchanged and still work together..

[Resto-Rand]

Rusty, I was with you all the way until you got to 1978 calipers and hoses. If I can ask a couple of questions...

You are saying the '78's will just fit the original rotors?
And are the 78's the reason it will stuff ya into the windshield?
Larger pads?

[RustyPile]

Originally Posted by Resto-Rand

Rusty, I was with you all the way until you got to 1978 calipers and hoses. If I can ask a couple of questions...

You are saying the '78's will just fit the original rotors?
And are the 78's the reason it will stuff ya into the windshield?
Larger pads?

The '78 calipers will fit the rotors and are a direct bolt-on fit to the spindles. The calipers have a wide enough "cavity" that the full thickness pads "straddle" the rotor and will fit without shaving the pad thickness.. Pads are the same for a few years. The hoses have to match (fit) the calipers as the hose fitting at the caliper is slightly different... 1971 Rotors, 1978 calipers and hoses, power brake booster/master cylinder conversion kit from Summit..

The fact that the parts work and fit together, along with all new hydraulic components and a well designed power brake conversion kit is why the brakes work so well.. I worked as a professional mechanic for almost 35 years.. I've done literally thousands of brake jobs on all makes and models.. Over the years, I learned what it takes to make brakes work exceptionally well..

[notsolo]

Hey Rusty, did you go with the 67-72 BB-2 11 booster from Summit? I have replaced all the front and rear brake parts, except the rotors on my 71, brakes are fair.