Im not sure whats going on with my brakes, but something just doesnt feel right... to the point that im a lil weary of going high speeds on the highway...

I installed all new pads and stock style rotors about 3 years ago.... probably less than 10k miles since. However, the car just doesnt feel like it stops that great... and I dont think there is an issue with the front brakes, since under heavy braking they will lock up... both about the same time, so no balance issue. But the backs feel like they arent really doing much, and its just hard to stop the car quickly. It almost feel like the fronts lock up too easily...

Now im sure this could be an issue with the back brakes not working properly for whatever reason, but could this be because I have 225 width tires up front and 275 width tires out back??

If its not the tire differences, what could be the issue with poor rear brake performance with new pads/rotors in mind? Just bleeding or calipers shot?

Im just to the point I want to overhaul the whole brake system with new booster/MC, VB&P calipers, sport rotors, and hawk pads... but that would cost me over $1k.. lol
but then again, I want this damn thing to stop on a dime... not a dollar bill!

TIA! Chris

 

Hi 74vette, I would start with an inspection of all the calipers, if there are no signs of any leaks, it's time to bleed all the old fluid. Bleed the left front and than the right then pull the rear wheels and bleed them again, left first than the right. Than do it again in the same order. There is a balance valve in the system, if the front or rear are out of balance the brake light on the dash will light up. ( it's the same light that goes on when you use the parking brake.) Brake fluid will absorb moisture, which causes rust, and will ruin the seals in our calipers.
Another problem is called runout, if the rotors are out of specs they will draw air into the system, which will compress and not give you full brakeing ability. While you are bleeding the calipers you can hammer them with a plastic hammer to free up any built up air. Also look at the pads they should be worn equally, if not you may have a frozen piston which will also cause poor braking. PG

 

What size tires are you using specifically? 225-60? 225-70? ...there is a big difference.

These cars came with GR70-15's, same tire patch and same diameter all the way around. If you alter the diameter or tire patch significantly, you will definitely alter the braking balance of the car. I have a '73 with non-power brakes and other than requiring lots of additional pedal pressure it stops very true.

I purchased a '77 new many years ago and it came with power brakes and GR70's all the way around. It would put you through the windshield if you weren't prepared for it.

Replacing the brake fluid and re-bleeding the brakes after a few years is always a good idea. It should firm up your brake pedal, but it won't fix a balance problem if you have one, and it sounds as if you do.

Good luck... GUSTO

 

Most definitely start with a good brake system bleed to completely flush out old fluid. Full reservoir before you start would indicate no system leak. Do not allow reservoir to suck air.

 

Well lemme see if I can cover all these bases...

The resevoir is definitely full all the time, so no obviously leaks.

Ill definitely get to bleeding the whole system as soon as I can get a buddy to pump the brake pedal.

Specefically, my tires are 225/70/15 (27.4" tall) up front and 275/60/15 (28" tall) in the rear... make any sense?

Ill also double check for the frozen piston, but dont think its an issue as I remember all the pads wearing about equal when I pulled them off last...


Im really hoping this is just a bleeding issue since I dont remember going through the correct sequence last time I did the pads/rotors, etc.... we shal see I guess

 

It definitely sounds like a bleeding issue. Air or moisture in the system. Most dealerships offer a power flush/clean/bleed service these days. Its cheap up here $89. I would go the dealer route. Not worth the aggrevation.

Jim

 

I had the same problem, fronts would lock up easily and it didn't feel like the rears were doing anything. I bought a Motive bleeder and bled the whole system twice. Everything seemed great for about an hour of driving then it gradually went right back to where I started from. On the advice of a forum member I picked up a new M/C. Before I pulled the old one I removed the cap and (LIGHTLY) applied the brake pedal and there were bubbles coming from the bottom of the rear reservoir. I figure the seal in the M/C was bad and was pumping air into the rear lines hence the gradual loss of rear brake pressure.

 

Note sure if a 74 sequence is any different but my 69 required lr, rr, rf, lf as the sequence vs. the traditional. I am almost positive this is through 81.