1973 Power Front Disc Brake's

by **patrick** » 28 Feb 2008 4:28

Recently, as some of you know, I replaced the front disc pad's on my 73 Chally. I have most of it taken care of. Except, when the brake's are not applied, and going down the highway, I can feel a slight vibration. Nothing big but, it's there all the same. Rotor's are fine. Brake's have been bled corectly. I can take my hand's off the wheel, and dump the brake's, and, "Big Nose Dive in a Straight Line". :thumbsup:

But, as I go down the road, the slight grumble and vibration starts. But not all the time. Tap on the brake's, and it's gone.

Wierd thing is. It never did this until, I replaced the pad's. They were getting low but, not metal to metal. Again, I try to fix something before it break's and, S.N.A.F.U. :oops:

My calipers has clip's on the outside of the caliper pin's, facing the fender well. They look like flimsy metal, meant to bend as the brake's wear. I did not change these and they fit a little loose. Is that what I hear? :s006:

Thank's, Pat

by **Jimiboy** » 28 Feb 2008 9:51

Maybe the springs are some sort of anti rattle spring, meant to be beant above the bolthead. Are the calipers ok? if the piston is harsh, not getting back enough? If the pads have been to small, the piston can have been getting out too much and maybe got worn? You should have noticed if they went back easy when you replaced the pads(?)
Did you replace the discs aswell? I thought maybe they are not flat?
I hope the guys can help you out, that sounds no fun! :hmmm:

by **fbernard** » 28 Feb 2008 10:07

No way those clips can give vibrations. Sure they can rattle a little, but I doubt you would even hear it from inside the car.

In my opinion, possible causes are :
- piston does not retract fully,
- pads can move inside the caliper (and/or piston retracts too much)

I'd rule the first out since you didn't have the problem earlier (besides, you'd have uneven drag left to right when the brakes are not applied).

Are there any clips that should be on the pads, to help them stay put in the caliper? can you move the pads up and down (radially speaking, from the disc's point of view), or sideways (there should be no play between pads and disc, so you should not be able to move the pads sideways).

With the wheels off the ground, how freely can the wheel turn with no brakes applied? It should not be able to turn too much, some drag is necessary (both from the wheel bearing and from the brakes).

by **dave-r** » 28 Feb 2008 10:44

If the pads are just held in place with bent tabs you normally have to give them a tap with a hammer before installation to make them a tight fit.

by **Eddie** » 28 Feb 2008 14:29

Pat, did you turn your rotors or replace them when you put new pads on? If not it's probably due to the new pads not seating yet. I think Jimi hit it on the head!!

by **fbernard** » 28 Feb 2008 20:12

dave-r wrote:If the pads are just held in place with bent tabs you normally have to give them a tap with a hammer before installation to make them a tight fit.

I'd say Dave's right on that one, I remember reading about that (the need to alter the pads quite a bit to make sure they don't move around in the caliper) in one mag or another (Mopar Action probably).

I'd like to have a clearer memory of that though. Might come in handy sometime again. I don't remember exactly how, but the pad tabs should be bent during the installation.

I just checked MA's web site, and ther's some info about it :
http://www.moparaction.com/tech/archive/disc-main.html
I didn't even know the pads were different (inner/outer) on Mopar slider-type calipers.

The tapping and bending thing is for slider-type calipers.

by **dave-r** » 28 Feb 2008 21:34

I have sliders. Which is why I thought of it. I couldn't remember doing it on pin type calipers but mentioned it just in case.

by **patrick** » 29 Feb 2008 5:26

Thank's for all the input, guy's. I have pin type floating caliper's. The pad's can't move at all. The rubber bushing's are in excellent shape. The pin's slid through but remained snug. I did not have my rotor's turned. I know it is alway's recomended but, I recognized the wore pad's before the rivot's attacked my rotor's. No groove's. I will investigate this some more. The piston's did push back in fairly easy. No foreign matter on the pad's or rotor's. The car doe's track down the road in a straight line. When I hit the brake's hard, just short of locking them up, it stops in a straight line. Big nose dive with no pull, one way or another.

One thing I might add is, the pad's are Police type. I wanted this for longer pad life. Maybe, this has something to do with the problem. Or maybe, I should just put a few more mile's on the thing, and make sure the brake's have seated. I have about 80 mile's on them now. If any of you guy's have any more idea's, PLEASE, let me know. :bonk:

Thank's Again , Pat

by **patrick** » 29 Feb 2008 5:35

Oh, by the way. Doe's anybody know what those spring gizmo's are for on the caliper pin's? The one's in the picture's. I have a "73" Service Manual and it doesn't say anything about them bugger's. Ugh, one more thing. The book states that there is a thicker and a thinner sized shoe. "And this statement refer's to front disc brake's." :roll:

The thinner one is stated to be the outboard side, with adhesive backing. The pad's I got were all exactly the same size, with no adhesive backing. :s012:

by **Eddie** » 29 Feb 2008 14:24

Pat, first of all, the pads are nomenclature,(name), for the disc pads. The shoes are for the drum brakes. Your rear brake drum shoes have a primary and secondary shoe. They are different sizes the primary or front shoe contacts the drum first and "pulls" the rear shoe into position thats why they are different thickness and length. The front 'spring type clips' or positioners in Chrysler literature help keep tension on the fastener keeping it from loosening, kinda like a lock washer keeps tension on the fastener preventing vibratory loosening of the fastener. The front pads cut into the rotor much like a lathe, it leaves a ridge at the very top of the rotor as it wears. When you put on new pads the new pads ride on this ridge until they are seated, a little spirited driving will seat the pads after a little seat time first, you dont want to 'glaze' them over. Most O.E.M. repacement pads are metallic based unless you specifucally ask for organic based pads, which dont last as long but are easier on the rotors. I always turn the drum/rotor when replacing pads to avoid the problem you describe. You dont have to cut a lot, usually .020-.040 will remove all light grooving and the top ridge,(Much like a cylinder ridge on a piston). The 'adhesive backing' is to prevent rattling and squeaking, it's really only a viscous fluid damper. Didnt the pad(s) have a inboard outboard marking on them? Hope this helps Pat!! :mrgreen:

by **fbernard** » 29 Feb 2008 14:49

There used to be a time when people used copper grease on the back of the pads to lower the noise (old school trick, no one really brings grease this close to brake systems anymore). That's what the adhesive is for.

I'm wondering if the annoying clips that stopped being snug circa 1976 are not called 'anti-rattle clips'. :disbelief:

I had the same problem with one caliper on the convertible. Took it apart, never found anything. Tried several pads. Loud noise but car steers straight. It's not fixed now, I've just got more important repairs to do to this car, so the calipers will be replaced wit the ones I currently have on the hardtop.

by **patrick** » 01 Mar 2008 5:16

airfuelEddie wrote:Pat, first of all, the pads are nomenclature,(name), for the disc pads. The shoes are for the drum brakes. Your rear brake drum shoes have a primary and secondary shoe. They are different sizes the primary or front shoe contacts the drum first and "pulls" the rear shoe into position thats why they are different thickness and length.

Eddie. I only used the word shoe because, my 73 dodge service manual uses the same word. :roll:

I don't know either. Disc's have pad's. Drum's have shoe's. We've all known this since the seventie's. I bet your manual say's the same thing. I found out about the different size brake "shoe's", with my 68 F-100. No manual, just put them back together like I took them apart. I did notice the difference between the front and back side. That was in 1989. :oops:

Previous owners son did a brake job on the thing. Truck was all over the place for a year before I bought a Haynse's book and pulled my head out... :s006:

Back to the Present. Have you seen Disc "Pad's", with different thickness like discribed. Also, beside's the " 73 Dodge Chassis and Service Manual." What's a good book to have? "Chilton", "Haynse", "The Dodge Challenger Service Manual For the Complete Idiot"? Don't know if they make that last one but, had one for my V.W. Bug. That book was Awesome. It even told you when you need to take a brake. No punn intended. :lol:

I have that front line on back order from Fineline's. I think I'll take it all apart again, and resurface those rotor's. I'm cheap, and I usually have to pay for that. :wink2:

Talk to you soon, Pat

by **Eddie** » 01 Mar 2008 13:51

Pat, www.autobooksbishko.com has factory service manuals. Is that what you are looking for? I'm sorry for trying to correct 'your' terminology just thought you were mistaken, no biggie, I would first measure the thickness of the rotor and compare it to the thickness spec stamped on them. This will tell you how much material you have left to machine. Remove only enough to true the surface. Then see if you still have this problem! Some pads are thicker due to the caliper adaptor being either full floating, semi-floating, fixed I would assume :mrgreen:

by **patrick** » 01 Mar 2008 16:22

Thank's, Eddie. :thumbsup:

But, that outfit is offering the exact book that I have. I do have the official Dodge service manual for 73 Challenger. I also thought it was funny that they used the word "shoe" pointing at what you, I, and everybody else calls "pad's".

by **Eddie** » 01 Mar 2008 20:12

patrick wrote:Thank's, Eddie. But, that outfit is offering the exact book that I have. I do have the official Dodge service manual for 73 Challenger. I also thought it was funny that they used the word "shoe" pointing at what you, I, and everybody else calls "pad's".

LOL, I didnt know that Pat! I have the factory 70 manual. Maybe it was written by an AMC guy! :mrgreen:

BTW, on the thickness, maybe the fixed, semi, full floating calipers all had different thicknesses depending on the type of mount the caliper had and a pad cross references all of them in that same size. The thickness of the pad shouldnt matter as long as the caliper is centered over the rotor as it should be or close to it because the pads are a little different. I have done many different cars&trucks and never seen a thickness difference on the pads on a disc/rotor type of brake. Maybe I didnt look close enough!! :lol:

The rear drums are a different matter altogether and I apologize for misunderstanding you. BTW, Pat let us know how the vibration problem turns out after the rotors are turned clean. :mrgreen:

by **patrick** » 02 Mar 2008 2:50

I'll let you know. Soon, I hope. I think I'm gonna give this prodject to my super Guru Tech, Nephew. He can get brand new rotor's for a little more than what it take's to turn them. :thumbsup:

I'm gonna play with them a little bit but, if I'm unhappy with the brake's anyway. I'll give it to Mike. :thumbsup:

I'll have him throw in that front brake line while he's at it.

He is so much better at this stuff, than I am. :biggrin:

by **patrick** » 03 Mar 2008 1:40

It was a beautiful day today.

Nosed into those pin's again. pulled them out and bent those flimsy spring's a little. I went down to our local N.A.P.A. store,yesterday to see if I could get more info on those bugger's. I stood behind the guy at the counter so I could see the computer screen. The rebuild kit has everything but, those darned spring clip's. I kept referring to them but, the part's guy was looking at me like I was from another planet. Anyway, I pulled the pin's out, straightened the clip's, just a little. Took the car for a sixty mile ride, and hey, No vibration at all. :mrgreen:

Not even at the start. Smoothe as can be, all the way back to my driveway. I'm very particular with that car. I'm starting to wonder if I imagined the whole thing. :s022:

Either that, or the brake's were seated when, I parked it the other day. I'll turn or replace the rotor's on the next set of pad's. This time, I think I lucked out. :p:

by **Jimiboy** » 03 Mar 2008 12:16

Nice you got it fixed!

I remember one time when i got my daily a new set of rubber, and had some strange sound and vibrations after, my old dad told me to check the wheelbolts, and i thought it would be the last thing, because i had the job done by the shop... But it was! The guy on the tireshop that mounted the wheels did'nt do the job right, scary! :s008:

by **Eddie** » 03 Mar 2008 12:19

Cool, glad to hear it's back to normal Pat. :thumbsup:

by **patrick** » 04 Mar 2008 5:20

Thank's Guy's!

When I get that new hard brake line for the front, I'm gonna tackle the back brake's while I'm at it. I'll have to bleed the system while I'm at it anyway. Brake's are low but, not scraping yet. Look's like it's time for new wheel cylinder's as well. And yes, I'm gonna have those drum's turned. :s002:

I wouldn't want you guy's to have to hear me crying about another brake subject. :s022:

by **patrick** » 04 Mar 2008 5:31

Jimiboy wrote:Nice you got it fixed!
I remember one time when i got my daily a new set of rubber, and had some strange sound and vibrations after, my old dad told me to check the wheelbolts, and i thought it would be the last thing, because i had the job done by the shop... But it was! The guy on the tireshop that mounted the wheels did'nt do the job right, scary!

I'm glad you caught that Jimi. The same thing happened to a friend of mine. Only, he lost a front wheel. Totally killed his aluminum magnisium mag. Didn't wreck the car though, just the wheel. Shop payed for the wheel and repair's on the front end. How it didn't tear the fender up, I don't know. After that story, I alway's check the torque on the lug nut's. You know, "Ounce of Prevention...."

by **Eddie** » 04 Mar 2008 14:28

Yeah, I get angered when I see the dealer techs with a 3/4" drive 300 lb. ft. air gun fastening all the 1/2" lugs at 200Lb. all the time! :mrgreen:

And they wonder why brake jobs every 20k is 'normal' :biggrin:

(Warped rotors).

Re: 1973 Power Front Disc Brake's