Need advice on how to adjust parking brake,car did not pass inspection today and although I really never use it I must have it for inspection

 

Make sure that the mechanism inside the rotor are free and adjustable. That will probably be the first stumbling block. Then adjust the shoes inside the rotor. After this is completed adjust the cable tightner under the car. After you get them the best that you can, go find an inspection guy who understands that these things werent worth a damn in the first place.

 

remove the rear wheels you will see two small holes in the rotor,turn the rotor 'till you see the star looking adjuster inside.use a flat tip screw driver to adjust the brake.turn the adjuster untill the roror wont turn,then back off the adjuster 6to 8 notches.make sure there is no slack in the cable under the car.the emer. brake lever should not pull up much past half way.

 

You can have a C3 or you can have a parking break but you cant have both

 

C3 parking brakes are difficult for shadetrees to correctly adjust due to some design issues that aren't well addressed and just experience shortfalls.

If you try to adjust the shoes by turning the star wheel until you feel a drag on the rotor/drum you'll confront the design issues. They have to do with the halfshafts going into a bind when the rear suspension is in full droop and the limited slip driving the opposite wheel which will also be in a bind as well as contributing to drag and shoe friction. There is a very specific adjustment method that must be followed, otherwise you'll not have full shoe contact and may also destroy the shoes.

The meat of the issue is that you have to loosen the adjuster cable to the point where there is no tension on the cable. The cable moves the top of the shoe out in an arch. The bottom part of the shoes only pivot. So, for the most part, what you are adjusting with the star wheel is the bottom part of the shoe. Once you have the bottom part of the shoes adjusted on both wheels, you can put tension on the cable so that when the handle is pulled, the shoes come into equal contact with the drum.

The tricky part, again, is knowing when you have the bottom part of the shoes in proper contact. If you are off, you'll have contact difficiencies in either the top or bottom of the shoes on the drum. With improper adjustment, the brake mechanism will perform poorly or you'll destroy the brake lining...or both.

So, how does the shadetree deal with this? Not easily. The best way is to disconnect the halfshafts at the spindle flange (not the differential stub axle) so that both rear wheels are not connected to the differential and are free to rotate without any halfshaft binding, opposite wheel drag, or drivetrain drag. Doing it this way will allow you to have a very good tactile sense of when the bottom part of the shoe is contacting the drum. You want light contact so that you can hear the shoe contact throughout the full revolution of the wheel. Once you have the bottom shoes adjusted on both sides, you can tighten up the cable. With the handle fully retracted, you start adjusting the cable until you hear and feel the full shoe lightly contact the drum. It should be an equal feel and sound on both sides. The drag from the contact friction should be very, very light. Once you think you have the right cable adjustment, pull up on the handle. You should get around three clicks and then strong resistance. If all seems well, button it up and give it a test.

You can do it without disconnecting the halfshafts but, again, for a shadetree, you'll be fighting the ills and your experience level. You'd at least have to jack up both sides of the spindles to put the halfshafts at ride height so you can keep them from binding. Of course, in adjusting the star wheel, you are essentially doing the adjustment based upon your experience in doing it this way. For the most part, you're working from hearing only since you have drivetrain drag contributing to the brake friction.

It does take longer to do it by disconnecting the halfshafts but the outcome is usually better for the shadetree. And it's not like you'll be doing this every couple of months. If you have a good parking brake assembly, you should have to do this only once. So your time is sort of like an investment in the outcome.

 

I agree.... and that is the exact method I use. But.... wombvette is also correct... the system never worked.

My 66 327 300HP would pass the test.... but barely.

My 70 454 would never pass, no matter how new my parts were, or how perfectly the system was adjusted. The torque at idle is almost enough to overpower the system. So when a 19 year old inspector lets the clutch out, and the brake doesn't hold, he slaps a fail sticker on the car.

This is with new rotors, new shoes, new cables (all) and new hardware, adjusted with the halfshafts disconnected, per spec.

 

You didn't say what year, but on my 72, and on my neighbor's 73, there is a very careful discussion of the adjustment procedure in the GM Service Manual, under Brakes. I won't try to paraphrase the procedure but it gives a step by step procedure. Do you have the GM manual for your car? I would not use Hayne's or Chilton for this. If you need the manual, you can get one quickly at www.ncrs.org and click on the store logo. Go to your particular year and order away.

Gary

 

While I agree that the parking brake system is not great, I can usually get the p.b. to hold pretty well. On both my 68's I can kill the motor. When they are adjusted, I run it up and down the block to seat the pads to the rotor, by repeatedly pulling up and releasing the handle. Don't over-heat the pads. On my 68's, I can get the rear wheels to lock from 5 mph!

 

You are either very lucky or a genius... or maybe even a lucky genius. LOL

So... I guess you would have no problem with parking on a steep hill, wheels straight ahead, slip her in neutral and walking away with the parking brake on?

Wow. Brass ones.

I've worked on a lot of C2 & C3 Vettes over the years, and I know wombvette has also. I just don't have that kind of faith in the design.

I can make the adjustment so it holds enough on a slight incline, but not on a hill, and never good enough for an inspector who has no clue.

I've had to take the car back for a second inspection with the brake adjusted way over-tight just to pass, and then re-adjust it later. That was in both NY and NJ. Over-heats the rotors big time. Haven't had the problem here in NC.... they don't hassle you with it here. Just pull it up on the way in, and let them pull it off to pull the car forward.... they assume it works then.

I have had better stopping power with the OEM shoes though.... they seem to be a little softer and stickier than the SS version. Definitely a factor, IMOP.

I've adjusted them without disconnecting the half-shafts, but it is tough to do a good job that way. I start by following the GM procedure (lockup, then loose 11 ticks?) but that always ends up with a sloppy adjustment that doesn't work. Then I improvise until I get the best lockup with no constant drag... which usually takes the adjustment way off from the factory spec.

Oh.... I just noticed.... you're in Texas. No hills there. ha ha

 

We have lots of hills where I live, and YES, the p.b. will hold well. The way I set them is with a little drag in the foward rotation,(they always seem to work better in reverse.) I have probably done 300 or more p.b. set-ups over the years. Some work better than others. Come to Texas and watch my p.b. lock the wheels!...lol BTW, ALL my Vettes are sticks, so you know I value a good p.b.

 

One of the problems with the parking brake is that the cable stretches over time until the proper adjustment is just not achievable, you run out of threads to tighten any further. I had to remove the front locking nut completely and tighten it to full stop to get a good lockup. Those that gripe about it not working, may be running into that limitation. Time for a new cable.

 

Okay.... your on. But only in Round Rock.

 

gerry72 has an excellent description of how to adjust the parking brake. With that procedure you will be able to lock the rear wheels at 25MPH, which used to be the test.

I'm curious BARRY L-48...how did they test it?

When I first got my car the parking brake worked flawlessly...locking the rear wheels at 25 and bringing it to a stop fairly quickly at any speed. But, when a shop rebuilt my rear control arms after I broke a spindle the emergency brake no longer worked right. I tried adjusting it and it would not hold going forward, but going backward the brake would lock up without pulling on the brake...weird. They charged me for used brake parts even though my brakes were fine...I think they screwed it up. When I got the car back there was a pair of vice grips on my cable...they idiots crushed my cable as well as screwing up the brakes.

I think much of the problem is getting the system installed properly. I'm going to install some new hardware and see if that does the trick. It could just be the springs have lost their sproing.

 

If I rebuild the rear bearings for someone I set the shoes to a drag then just back off for free spin. This is on the bench-no cables,1/2 shafts,nothing but the shoes. I let the owner adjust them on his car.

I don't use them on my own cars. I had my 69 PB set to hold on the Kwiklift angle(30*?) and it locked up nice in neutral. Rotated the wheels and didn't feel or hear any dragging, drove 5 miles and the rotor/wheels were hot as a pistol. Backed them off and left them like that.

I'm not sure a 2x4 or brick wouldn't be a better design!
Gary

 

I think FeedVaal should put on a seminar at his place, and we should all go there. Haven't been to Austin (Round Rock) in about 20 years... it's time for a visit. Plus I'll learn something.

All kidding aside, I adjusted them with a slight forward drag as well, to get them through inspection, but as Gary pointed out, the rotors start to turn Cherry. Since I did these jobs in my shop/business for 30 years, I was able to get resaonable results most of the time with all new components, but never would guarantee "flawless" operation to any of my customers. I could not let the cars go out with a "slight forward drag", because the amount of drag is not measurable or consistent... and I would end up paying for the damaged rotors etc myself. Can't run a business that way. So now you understand my "doubting Thomas" syndrome.

When you're working on your own car, you can compromise. When you're doing it as a business, you can't take chances with brakes.

I don't doubt that certain cars will have a great PB... it happens, and I have seen a few that actually do work. But my experience is that most C2/C3 systems are weak and hard to adjust.

FeedVaal seems to have figured it all out... so we need a "white paper" on it. Git 'er done!

 

thank god i'm a state inspector and don't have to deal with it if i don't want to on my own rides

 

I was a State Inspector in NY back in 1974, so this issue has a "sweet spot" with me as well. That's how I know it is a problem. In NY, the station doing the inspection was also allowed to make the repairs. So it was easy to fail a Vette on the parking brake issue to make $$$... but I never did unless it was actually broken. As posted above, they lock up great in reverse, but marginally in forward. We were required to check them in forward under light engine load... and they usually did not hold.

 

It seems there is a mix of parking brakes that work and one that don't. Mine work. My master cylinder went bad a few years ago while I was out of town. I had no problem driving home knowing that the power brakes were iffy and I would have to rely on the parking brakes. Naturally I drove slower, never got too close to cars in front of me, and anticipated all stops. I can put my car in gear(auto) and the parking brake hold fine.

 

A quick true story...In 1978 I was on a cross-country trip with my 68 vert.(I still have it). I left Houston, Long Island bound. I blew a rear caliper around Harrisburg, Pa. I drove to my destination, 200 miles away, with only the 4 speed trans and a good parking brake! Going thru Jersy mountains and N.Y.C was a trip....wow....memories

 

I spent a lot of time examining these things. The mechanism inside the drum has to be fairly loose so that it does not bind up. But... it also needs to be tight so that most of the cable movement isn't wasted in just pulling all of the gizmos together. So what we have is a compromise. If the drum gizmos are all new or unworn (including the shoes), and the cable is not elastic (stretchy), and the system is adjusted properly, then it seems to work relatively well. This is a rare case though. The cable loses its tension pretty fast, and becomes elastic... especially if it gets used a lot. With this cable elasticity and a few worn parts like the actuator at the top, it takes several "clicks" of the handle just to take up all of the slop, and there isn't enough reserve to put sufficient pressure on the shoes to produce any holding power. Add SS shoes with their "hard" linings with less "stickyness", maybe a rotor with a worn inside drum, and you have a parking brake that won't hold. A lot of the force needed to push the shoes against the drum is lost in the elasticity of the cable as well.

I have also driven with just the parking brake. But I have less than admiration for the system as a whole.