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post #1 of 13 (permalink) Old 09-09-2015, 01:53 PM Thread Starter
 
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Braking Issue

I am experiencing a couple of brake issues on my "68" I have 4 wheel drum non power. Yes I plan to upgrade to frond disk, just not yet.

First, when I step on the brake for am extended period of time it sinks to the floor. I am thinking the MC might be bad. I bled the MC and am in the process of bleeding all the brakes to see if that fixes the issue. I don't notice any leaks. If I replace the MC I was thinking of getting this one from JEGS. Right Stuff DBMC11, Right Stuff Master Cylinders | Right Stuff

Would I be better off with a OEM? don't care about originality.
I like it because it has the bleeder valves.

Next I can't seem to get the parking brake to work. The cable is tensioned properly and I can see everything operate. Could the drums need adjusting?

Thanks for your input.

John
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post #2 of 13 (permalink) Old 09-09-2015, 05:37 PM
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Your present master cyl is bypassing internally. Replace it with whatever you choose, as long as it's a dual unit. You will be fine. Bench bleed it first. You can't adjust the drums...you adjust the cable. If the cable is tensioned properly, you have other issues, like frozen arms in the rear brakes or a frozen cable. Pull the rear drums and inspect the cable arms. When the cable is pulled, the arms should move, spreading the shoes. Very simple to check and fix. I've been running 4 wheel drums on all my GTO's for over 35 years with no problems. When properly maintained, they are dependable and work just fine.
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post #3 of 13 (permalink) Old 09-09-2015, 06:56 PM
 
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You can't adjust the drums...you adjust the cable. If the cable is tensioned properly, you have other issues, like frozen arms in the rear brakes or a frozen cable. Pull the rear drums and inspect the cable arms. When the cable is pulled, the arms should move, spreading the shoes. Very simple to check and fix. I've been running 4 wheel drums on all my GTO's for over 35 years with no problems. When properly maintained, they are dependable and work just fine.
Hmmmm. My '68 has a star wheel that spreads the shoes apart inside the drum. Adjust this first, then adjust your cable.

I would pull the drums, inspect them for wear as they may be slap worn out or previously turned to the limits and the thickness of the drum wall will effect your adjustment -just as worn shoes will. You also want to make sure the star wheel is turning. Often corrosion or rust gets in there and it will not adjust. It has a self adjusting cable that is attached to the brake shoe and when the brake expands, it will pull a lever which in turn rotates the star wheel to keep the brake shoes self adjusted. Won't work if the star wheel is locked up. (Also, this self adjusting feature works best when you back up and hit your brakes a couple times.)

Personally, for what it costs, do a complete rebuild. New drums, spring kit, and brake shoes. I like the softer cheaper shoes as they seem to grab a little better and don't wear your drums out quick. If you get lifetime shoes, they are usually metallic and are harsher on your drums so they eat them up. They are also typically a harder compound so they never seemed to me to grip as well as the softer cheaper shoes. Now the metallic will work better the hotter the brakes get, so that is where they excel. But I find in everyday traffic, you aren't going to be getting the shoes hot enough to take advantage of them unless you drive at high speeds and do long panic stops, in which case your front drums will be useless to you (my opinion & experience) and you definitely want discs up front. I drive a little fast, so front drums don't really do the job and I have to give myself a lot of distance between me and the car in front. You can also assist braking with a downshift if needed.

While apart, you can also inspect for any leaking wheel cylinders and axle seals.

If your brake cables are too stretched from use over the years, which they often are, you can only tighten so much and it may not be enough. They have a hokey fix that looks like a "J" hook you can use to further take slack out, but again, not a true fix, and its hokey.

Take my advice, and I am sure others will chime in, in todays crazy driver world where idiots get their drivers licenses out of Cracker Jack boxes and you can't trust a darn one of 'em to drive safe, let alone cut you off or pull right out in front of you while you are doing 60 MPH, your brakes will be the most important part of your car IF you value it. Have one "pucker 10 factor" and the need to change your shorts because you just missed the idiot who locked up his 4-disc braked Toyota in front of you like it was put in reverse and you will be ordering that disc brake conversion kit on your cell phone as you get on your knees on the side of the road and kiss your car because it didn't get wrecked. Might not be so lucky next time and you could be offering up your car in the "Parts For Sale" section and not sharing the car as a driver with us.
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post #4 of 13 (permalink) Old 09-09-2015, 07:32 PM
 
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A few years ago when the brakes went to the floor on my 67, it turned out to be the wheel cylinders. No evidence of leaking.
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post #5 of 13 (permalink) Old 09-09-2015, 09:01 PM
 
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Was working on a customers 1969 camaro ( fixing a dent in the rear 1/4 panel) ....he left it outside my shop and handed me the keys. After lunch I opened the garage door to bring the camaro in....fired her up and got it up the slight incline and onto the concrete floor...going 2-4 mph....hit the brake pedal.....and it went straight to the floor....and I drove that camaro into a metal filing cabinet and a wooden work bench !!!! Now Iam a swearing sailor......I called the customer.....and he said ..I forgot to tell you,that you have to hit the brake pedal twice to stop it....I said REALLY !!!!! It was leaking by at the Master Cylinder ...if you put your hand up under the dash ..you could feel the brake fluid.
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post #6 of 13 (permalink) Old 09-09-2015, 10:32 PM Thread Starter
 
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Thanks everyone for the wealth of information. After removing the the rear drums, the right side had no parking brake spacer bar and a spring or 2 missing on the left side. Strange because both right and left have new pads and spring hardware.

Is there a way to tell if the drum is beyond spec? at $110 each don't want to replace if I don't have to.

Already plan on getting new hardware. The cylinders show no sign of leaking so I will probably keep them.

I have not been able to get the front drums off yet. Tried using a SFH, should I use a BFH?
Was afraid of damageing them. Is their a trick?

John
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post #7 of 13 (permalink) Old 09-10-2015, 07:20 PM
 
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Originally Posted by Layzdude View Post
Thanks everyone for the wealth of information. After removing the the rear drums, the right side had no parking brake spacer bar and a spring or 2 missing on the left side. Strange because both right and left have new pads and spring hardware.

Is there a way to tell if the drum is beyond spec? at $110 each don't want to replace if I don't have to.

Already plan on getting new hardware. The cylinders show no sign of leaking so I will probably keep them.

I have not been able to get the front drums off yet. Tried using a SFH, should I use a BFH?
Was afraid of damageing them. Is their a trick?

John
John, most brake shops should be able to use a set of calipers to tell you if they are within spec, need to be turned, or can be turned. Some brake drums actually have the maximum ID stamped on the drum.

The front drum is removed as the drum/hub assembly. You have to pull the dust cover and remove the cotter pin, spindle nut, and then the bearing. It should slide off. BUT.......

The shoes could be hanging up on the inside lip of the drum that has been formed from wear. The drum may not come off to easily. That's where you need to back off the star wheel inside the brake assembly. Put your outer bearing back in and put the nut back on the spindle to keep the drum/hub in place. You will see an oblong slot in the backing plate down near the bottom to the rear. It may still have its rubber plug in place, but most get removed and tossed out. You need to push in and hold the automatic adjusting lever away and off the star wheel with a screw driver while you use the star wheel tool which looks like a wide blade screw driver with an angle on it so you can manipulate it up and down to turn the star wheel (I use a small flat bladed screw driver if it will fit, but the brake tool is so much easier). Not sure which direction to go, but if you use one of the rear star wheel assemblies from the same side you are working on as your guide, you can determine which way to turn the star wheel. You want to screw it in to compress it and allow it to clear any ridge that may have formed on the drum and could hang up the shoes. My '68 manual says that right front & rear adjusting screws have left handed threads while left front & rear have right handed threads. All adjusting screws must be installed with the star wheel end of the screw toward the rear of the car.

You can try and pull the drum/hub off without messing with the adjusting screw/star wheel first to see if it will pull off without much effort. But if it is hanging at all, don't force it, just turn in the adjusting screw/star wheel as noted previously. Hopefully it is not stuck with corrosion.

Check your drum to ensure it is good and useable. You want to bring the bearings with the drum/hub to your local brake shop if you get it checked out and if they need to turn the drum - they need the bearings to do this.

Install your new shoes and brake parts kit. Note which shoe is the primary and which is the secondary by the amount of shoe surface each brake shoe has. The shorter primary shoe goes to the front, the longer secondary shoe goes to the rear.

You can clean up your bearings to inspect them for wear or blueing. Check the races for pitting or wear. If they look good, repack them with grease by placing a glob of grease on your palm and drawing the bearing down and over the bearing. You want to get the grease packed into the bearing & race and should see it pushing out the top and sides throughout. The inner bearing has a seal and you want to replace this with a new one, I never re-use the old one. Pull the seal off and the inner bearing will fall out. Do the same procedure on it as the front.

Install a new seal, BUT it can be tricky and you can easily bend/damage the seal. I got a cheapo 18 piece Seal Driver Kit from Harbor Freight to do this. I typically do it without, but when I saw how cheap the kit was, I bought one and can't believe I didn't buy one sooner. The kit is made by Pittsburgh Automotive. I suspect other stores or even the auto parts store may sell or rent one of these.

I put a little grease on the ID of the seal and then gently install your drum/hub on the spindle keeping it level and square so as not to tear up the seal. While still holding the drum/hub on the spindle and somewhat centered, install your smaller outer bearing to support the drum/hub and keep it centered on the spindle. Hold it in place and install the big washer, & then the spindle nut by hand. I then like to tighten the nut down snug with a wrench or pair of slip joint pliers, not overly tight, and this will seat the seal drum/hub. Then back it off just a little and spin the drum to seat things. Tighten snug again and spin just a little and the drum/hub should feel a little tight and not spin so readily. Then back the nut off just enough so you can put the cotter pin in. You don't want to go tighter to line up the spindle nut with the hole in the spindle as this will make it too tight. Better a tad loose so you don't burn up a bearing/spindle. Install the cotter pin and spin the drum one more time. It should spin fairly easy and not be sloppy. If it doesn't spin well, then the nut is too tight. I have been doing this so long that I can tell by feel. If it spins OK, then bend over the cotter pin and install the dust cover.

Adjust your brake shoes at this time using the star wheel and brake tool. I like to spin the drum just to the point where I can feel/hear the brake shoe rubbing on the drum. (After you drive it a little, you can use the self adjusters to zero in on the brake adjustment by putting the car in reverse and doing a couple of easy stops.)

Mount your tire and you should be able to freely spin the tire by hand with no problems. If it doesn't spin well, the spindle nut is too tight or the brake adjustment is too tight, and you will need to correct this. But if you adjust it correctly in steps outlined, you should have no issues.

Now, should your front drums be in poor condition, you knock the hub out of the drum and then get a new front drum as a replacement using your old hub and follow the above procedure.

This is all by memory as it is easier for me to be actually doing it as I go, so I think I got it right.
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post #8 of 13 (permalink) Old 09-10-2015, 09:46 PM Thread Starter
 
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Jim,

Thanks for the "wealth" of information. This is my first experience with drum brakes. I wanted to get the front drums off and check the brakes before I ordered parts. Let you guys know how it goes
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post #9 of 13 (permalink) Old 09-11-2015, 01:06 PM
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The missing spacer bar will do it every time! That tells me that a non-qualified person was in there messing around...these bars lock in place and do not fall out. That said, as the others said, now is the time to overhaul the brakes with NEW hardware and do it right. It'll last for years and years. Also, DO NOT use white lithium grease on the brake adjuster or backing plate tabs. Use silicone grease. White Lith turns into cement and will seize up your adjusters.
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post #10 of 13 (permalink) Old 09-11-2015, 04:04 PM
 
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There is a maximum diameter measurement on the ouside face of the brake drums. On the rear drums for GM 9.5" diam drums, the measurement is 9.59". Nice sets of original drums are getting tougher to find, so if you are parting out muscle era GMs, and the drums are not pitted and are nice and thick, doesn't hurt to save 'em. GM A body's from '64-72, used over 6 different styles of drums, '64-69 Olds F85, Cutlass, and 442 received their own style, Chevy got the smoothie style. etc, so for th picky restorer I gets tough.

Have performed more drum brake jobs than I would like to remember and installed nearly 2 dozen front disc changeovers. GM Abodys, F bodys, and a few Novas. For some cars a disc swap makes sense. If you drive like an idiot on the street, I'd even suggest the biggest 4 wheel disc calipers and rotors and big whels and tires you can fit, as you will need them, in my experience, it will also help to own your own body shop.

On two of my 4 wheel drum '71 455HO cars, their days of terrorizing the street are over. Its the same with as several of my customers '64 and 65 GTO converts, and quite a few friends RA IV cars. Occasional dragstrip and showfield use is about it. In order to improve stopping distances and be given an extra margin of safety, here is what I have been doing. First, am not doing disc swaps on high end purpose built restorations. Disc conversions add weight, and on higher point level cars, they are flat out of place. About 15 years ago discovered special matrix ceramic brake shoes from Praise Dyno Brake (the last 6-7 years theirbname has been Musclecarbrakes.com). Their brake in a box kit includes the special matrix ceramic shoes, higher pressure return springs, along with the star wheel adjusters. The special compound shoes, stiffer springs, along with cry'oed brake drums allow for quite a bit shorter stopping distances.

On drums, if I was made of $$$ and didnt care what the replacement drums looked like , I would spend alot more and buy MCB's new drums. Deal is, I have several tall stacks of thick correct original style GM drums and appearance is also very important to me, not just better brake performance. Locally, a circle track buddy uses a company that cryo's about anything. Last time down there, I had 6 brake drums and 2 boxes of razors cryogenically treated for $95. After I send a pair of alum front drums to Chicago to be relined, they along with 2 pair of nice thick G body alum drums are all going to be cryo'ed. Am also all about weight savings. The G body alum rear drums save a hair over 10 lbs from the rear axle mass. A little here, a little there.
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