Parking Brake Adjustment on C3

[Kevin Morris]

Hello all. My '72's parking brake does not want to hold. I have tried adjusting them at the equalizer (where the brake cable "Y"'s out, about 2/3 of the way back underneather the car). This did not help. Someone sent me instructions on how to adjust the parking brake by removing the rear wheels, loosening the equalizer nuts, and then sticking a screwdriver into the holes in the two rear hubs, and turning a little cogged wheel. The problem is, I can not determine which way to turn the wheel. Should it be turned up or down, in order to tighten? And please don't say "righty tighty, lefty loosey"! There's no way to determine which right or left, as all you can see is the little cogged wheel itself.

Thx,
Kevin #39927

[Joe L.]

Re: Parking Brake Adjustment on C3

Kevin-----

The procedure for adjusting the parking brake is well-described in the factory service manual. It also describes which way to turn the star wheel to tighten or loosen. Tightening the starwheel (i.e. moving it out so that the shoes expand) is accomplished by inserting an adjusting tool (e.g. screwdriver) into the hole in the rotor hat and moving your hand AWAY from the floor as the star wheel is turned. Loosening the adjustment (i.e. contracting the shoes) is accomplished as above, but moving your hand TOWARDS the floor as the wheel is turned.

As I've mentioned many times before, if you're going to work on your Corvette, you MUST obtain and use the GM factory service manual.

The Corvette parking brake adjustment is very tricky since it involves adjustment of BOTH the equalizer AND the shoes. At best, you will achieve a marginally effective parking brake. If you don't assiduously follow the procedure in the GM service manual, you won't even achieve that much.

[Kevin Morris]

Re: Parking Brake Adjustment on C3

Hehe, I feel like I have just been "called down" by the teacher! The instructions I have been following, Joe, are from a Corvette service manual(whether or not it is "the" service manual is not clear). They only state that the wheel must be adjusted. It does not state whether adjusting the wheel up (away from the floor) or down (toward the floor) will tighten the brakes. But thank you for your response...it has answered my question.

Kevin #39927

[Kevin Morris]

Re: Parking Brake Adjustment on C3

Btw, in the NCRS C3 Library, all I see a "Factory Assembly Instruction Manual", a "Chassis Service Manual", and a bunch of judging guides. Which service manual are you referring to Joe?

Kevin #39927

[Joe L.]

Re: Parking Brake Adjustment on C3

Kevin-----

It's the "Chassis Service Manual". However, depending upon which year C3 you have, it may involve obtaining one or two volumes. Chevrolet changed the service manual format several times over the years. For many C2 model years, they were Corvette-only manuals. Towards the end of the C2 years, as I recall, they went to a combined service manual for Chevrolet cars, including Corvette. This continued for C3s at least until 1975. Later in the C3 period, they went back to Corvette-only manuals. For the most complete coverage, you need to obtain the manual that was used for your specific model year. Of course, much of the information didn't change from model year-to-model year (e.g. the parking brake adjustment procedure was the same for 65-82). However, many things did change from model year-to-model year. So, like I say, it's best to obtain the correct one for your year-model.

[Joe L.]

Re: Parking Brake Adjustment on C3

Kevin-----

Many, many years ago when I was going to college and working for Safeway Stores as a food clerk, I worked in a store in Newark, CA. It so happened that the meat department manager/head butcher in that store was a fellow by the name of George Lambton who hailed from the great state of Oklahoma. For years, George used to always call me "River City Joe". I didn't know what that really meant and, at some level, I was a little uneasy about it since I thought that it might be some sort of degradation. But, I liked George a lot, so I overlooked it. Finally, one day I asked him why he called me by that name. He replied that the folks in River City always told things the way they were and that I told things the way they were. So, he called me "River City Joe". It was one of the best compliments I ever received and I cherish that moniker to this very day. In order to live up to it and George's expectations of me (may he rest in peace), I still try to tell things the way they are.

[John D.]

Re: Parking Brake Adjustment on C3

Kevin:

I hate to make this more difficult but I had my rear bearings, brakes, etc. rebult by one of the companies hailed as the best in the business. When I got them back the rotor/spindle holes were not indexed properly and they were riveted together. Therefore, I could not even adjust the E-brakes. After I drilled out the rivets, removed the rotor I found the star whell assembly had been reversed. The star wheel orientation dictates the up or down motion for E-brake adjustment. Your best bet is to move the star wheel a few clicks in one direction on each side to determine if their motion is as described in the service manual to tighten or loosen.

I agree with Joe, an AIM, Service manual, Chassis service manual and a judging guide are well worth the price.

John D.

[Joe L.]

Re: Parking Brake Adjustment on C3

John-----

Yes, you're absolutely correct. If the star wheel is reversed, it reverses the direction of rotation necessary for expanding or contracting. It's ver easy to get the star wheel in "backwards". In fact, if one is not real careful about it, I'd say there's about a 50% chance of it being this way on any car. So, your suggestion is a good one; always check the the effect of turning the star wheel one way or the other. As a matter of fact, I do this every time I adjust my parking brakes even though I KNOW that my star wheel is installed in the proper orientation.

It's too bad that you drilled out your rotor rivets to correct the problem. I hope that you didn't rotate the rotor so that the adjustment hole in the rotor matched the hole in the spindle. If your rotors were selectively aligned by the firm that did the work and then re-rivetted, you'll likely have excessive runout on the rotors now. Often times, the better shops will selectively align and, then, if they're REALLY GOOD, finish machine the rotor for minimum run-out. It's necessary to selectively align (and, possibly, cause the parking brake adjustment hole to be "blocked" in the process) so that only minimum machining of the rotor is necessary. In this case, what they did wrong was simply failing to re-drill the parking brake hole in the spindle. All you actually needed to do was re-drill the hole, using the hole in the rotor hat as a guide. The spindle is made of "tough stuff" and drills hard, but it can be done with a sharp, high quality drill bit.

[Kevin Morris]

Re: Parking Brake Adjustment on C3

Well...this is more complicated than I first thought. I pulled the right rear wheel, aligned the hole with the star wheel, loosened the equalizer (under the car, where the cable "Y"'s out) so there was slack in the cables, and then proceeded to adjust the star wheel upward (away from the floor). Do I then need to retighten the equalizer and apply the parking brake handle, to see if it holds...and if not, go through the procedure again, giving the wheel a few more turns??

Kevin #39927

[Joe L.]

Re: Parking Brake Adjustment on C3

Kevin-----

First, you need to slacken the cable at the equalizer (which, you've apparently already done). Next, you need to adjust BOTH of the rear wheel parking brake mechanisms as per the instructions in the factory service manual. Basically, you adjust the star wheel until the rotor "locks up", then you back the star wheel off about 6-8 "notches".

Next, you adjust the cable at the equalizer per the instructions in the factory service manual. Basically, you first place the parking brake lever in the 13th click position. Then, you need to tighten the cable at the equalizer until it requires an 80 pound pull to move the parking brake lever from the 13th click position to the 14th click position.

If you do the adjustment perfectly, you will then have a marginally effective parking brake.

[Kevin Morris]

Re: Parking Brake Adjustment on C3

Hmmm....I adjusted the right rear star wheel more than just a few clicks...but many clicks upward. The wheel never did lock up. I wonder if I am experiencing what John mentioned above. The previous owner had the entire trailing arm assemblies off, to replace u-joints, bearings, calipers, etc. Maybe he put the star wheels in backwards upon reassembly?

Kevin #39927

[Joe L.]

Re: Parking Brake Adjustment on C3

Kevin-----

Like I say, if he didn't recognize the fact that there's a "right" way and a "wrong" way to install the shoe expander mechanism, including the star wheel, there's exactly a 50% chance that he got it "wrong".

[John D.]

Re: Parking Brake Adjustment on C3

Joe:

Actually what I did was a little more involved. Once I realized the rotors and spindles were mis-aligned, I contacted the vendor and complained.

(I shouldn't say this on the board but here goes anyway)

The vendor who rebuilt my trailing arms, cut off 10 rivets and shipped them to me. The spindle and rotor are indexed with a stamped character, so using a 1/2 inch drill I "marked" the center ofthe rotor hole with a 1/2" drill bit. This gave me a center point mark in the spindle for drilling it out. I drilled out the rivets and put the rotor aside. Turned the spindle mark to be drilled to between the 5:00 to 6:00 o'clock position and starting with a 1/8 inch drill bit put a hole thru the spindle. I sequentially used larger bits until the hole was 1/2" and matched the rotor. Reinstalled the rotor and epoxyed (JB weld) in the 5 cut-off rivets. To look at them the rotors still look riveted.

Lesson learned was that regardless of a rebuilder's reputation, QA/QC for even the better rebuilders is only as good as the employee. Even though I paid to have the rotors indexed and riveted, to send them back would not have been worth the $75.00 shipping and who knows about the quality of the correction.

P.S. The rebuilt my A-arms with similar problems in quality.

John

[Joe L.]

Re: Parking Brake Adjustment on C3

John-----

I still don't understand why it was necessary to remove the rivets. All that needed to be done was to drill through the rotor's existing (but blocked by the spindle flange) parking brake adjustment hole and, then, through the spindle, creating a "new" parking brake adjustment hole. That's it. You're done.

If I understand what you did, it was to drill a hole in the rotor that matched the hole in the spindle. However, if this is what you did, then you end up with one extra hole in the rotor hat than was there originally. Regardless, though, all that was necessary was what I described in the first paragraph.

[John D.]

Re: Parking Brake Adjustment on C3

Joe:

Yes, I could have done what you said and saved alot of work. I was uncomfortable drilling it out blind. Murphy's law and all.

Actually the extra hole is in my spindle.

John.