Brake booster?
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
Brake booster?
Posted this in reply to another thread of mine in the autox section but thought I'd ask here too.
I raced at an autox on Sunday and the brakes were fine all day and all the way home (other than sucking in general for being stock 89 brakes). Today it was nice so I decided to drive her and as I pulled out of the garage I noticed the brake pedal was rock hard and would barely stop. The MC is brand new, the fluid is full and the brakes were perfectly fine when I parked her Sunday afternoon. There are no leaks and the booster has good vacuum. I looked again and found a hairline crack in the plastic case of the booster running across the front and around the side. So... Has the booster shot craps?
I raced at an autox on Sunday and the brakes were fine all day and all the way home (other than sucking in general for being stock 89 brakes). Today it was nice so I decided to drive her and as I pulled out of the garage I noticed the brake pedal was rock hard and would barely stop. The MC is brand new, the fluid is full and the brakes were perfectly fine when I parked her Sunday afternoon. There are no leaks and the booster has good vacuum. I looked again and found a hairline crack in the plastic case of the booster running across the front and around the side. So... Has the booster shot craps?
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
Crap burgers! I figured that's what it was as soon as I pressed the pedal. I guess it was on its way out and the autox sealed the deal. Time to get upside down!
I was looking at a Cardone reman unit on Advance Autos site and it said the MC rod is pre-adjusted to the right length. How accurate is that claim? It should be a straight swap, correct?
I was looking at a Cardone reman unit on Advance Autos site and it said the MC rod is pre-adjusted to the right length. How accurate is that claim? It should be a straight swap, correct?
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
Crap burgers! I figured that's what it was as soon as I pressed the pedal. I guess it was on its way out and the autox sealed the deal. Time to get upside down!
I was looking at a Cardone reman unit on Advance Autos site and it said the MC rod is pre-adjusted to the right length. How accurate is that claim? It should be a straight swap, correct?
I was looking at a Cardone reman unit on Advance Autos site and it said the MC rod is pre-adjusted to the right length. How accurate is that claim? It should be a straight swap, correct?
I believe what I did was get some grease or something, and touched the end of the rod and pulled my finger away so some of the grease left a trail sticking out. Then bolt the MC, then remove the MC and see how much of the grease on the rod got flattened out to know how close the rod it to the MC when bolted down.
Safety Car
Joined: Aug 2009
Posts: 3,752
Likes: 276
From: Melbourne, Victoria, Australia
Time for a new booster, there are metal copies available also.
http://www.parts123.com/parts123/yb....5Z50000050F~~~
Try some QUALITY BRAKE PADS, that will completely change how the car will feel. From a nervous "will she stop" when another car brakes hard, to a race car like type that inspires confidence. The slightest pedal pressure with high metal content pads will make you gasp! that standard corvette brakes can be THAT GOOD.
Get some Hawk brake pads, great for track and road use, Hawk HP Plus are fantastic on the track but can squeal when cold and daily road use.
Street type below.
http://www.parts123.com/parts123/yb....5Z50000050F~~~
Road/Track below.
http://www.parts123.com/parts123/yb....5Z50000050F~~~
http://www.parts123.com/parts123/yb....5Z50000050F~~~
Try some QUALITY BRAKE PADS, that will completely change how the car will feel. From a nervous "will she stop" when another car brakes hard, to a race car like type that inspires confidence. The slightest pedal pressure with high metal content pads will make you gasp! that standard corvette brakes can be THAT GOOD.
Get some Hawk brake pads, great for track and road use, Hawk HP Plus are fantastic on the track but can squeal when cold and daily road use.
Street type below.
http://www.parts123.com/parts123/yb....5Z50000050F~~~
Road/Track below.
http://www.parts123.com/parts123/yb....5Z50000050F~~~
Last edited by gerardvg; Mar 8, 2014 at 02:09 AM. Reason: More info
Safety Car
Joined: Sep 2004
Posts: 3,953
Likes: 550
From: Mission Viejo CA
The adjustment of the pushrod is even easier than that to check. HandsomeMike has some nice pictures! See those little ports in the bottom of the reservoir? If your pushrod is adjusted right, you'll see a spurt of fluid from the first port when you first push on the brake pedal. If there's no spurt, your pushrod is too long, and your brakes will drag when they get hot. If you have to push more than a half inch on your pedal, you need to lengthen the rod! This is an easy test that everyone should try!
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Melting Slicks
Joined: Sep 2008
Posts: 2,376
Likes: 111
From: Cherokee National Forest TN
A threaded hex fastener with a rounded tip is threaded into the booster to MC push rod.
Tip: Check & compare the length of the brake pedal push rods new to old booster to insure that those push rods are the same length. I have had 2 rebuilt units with shorter then stock rods. The brake pedal located a lot closer to the floor.
Tip: Check & compare the length of the brake pedal push rods new to old booster to insure that those push rods are the same length. I have had 2 rebuilt units with shorter then stock rods. The brake pedal located a lot closer to the floor.
Safety Car
Joined: Jan 2004
Posts: 3,759
Likes: 8
A threaded hex fastener with a rounded tip is threaded into the booster to MC push rod.
Tip: Check & compare the length of the brake pedal push rods new to old booster to insure that those push rods are the same length. I have had 2 rebuilt units with shorter then stock rods. The brake pedal located a lot closer to the floor.
Tip: Check & compare the length of the brake pedal push rods new to old booster to insure that those push rods are the same length. I have had 2 rebuilt units with shorter then stock rods. The brake pedal located a lot closer to the floor.
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
I read that the check valve could cause a hard pedal too. I pulled mine out and I can blow through it in both directions which according to what I read means its bad. Is this possible that the check valve is the culprit?
Race Director
Joined: Apr 2002
Posts: 10,036
Likes: 346
From: Anaheim CA
Theoretically you don't need the vacuum check valve. It's there in case the engine dies (or you turn it off) and holds vacuum in the booster so you still have brakes.
I replaced my booster with a genuine AC Delco (PBR) and it came with a new vacuum check valve.
I replaced my booster with a genuine AC Delco (PBR) and it came with a new vacuum check valve.
Drifting
Joined: Aug 2010
Posts: 1,704
Likes: 8
My brakes was like yours when my booster broken.i'm a skinny guy but it was a challenge for me to work upside down,you need extensions and the steering column is on the way in front of you,sometimes just 4 bolts become a nightmare...remove the seat,remember to trim the rod before mounting the new booster or your brake pedal acts too low on his travel,i didn't and now my pedal works too low ...1 hour labor is for real fast guy...i was in the 2 hour range
Race Director
Joined: Sep 2003
Posts: 16,838
Likes: 341
From: Database Error Indiana
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
Got the nuts off the MC and the nut on the right side of the booster under the footwell in about 20 minutes including time to remove the seat. The nut on the left couldn't be reached with the extension setup I have so my father is bringing all of his extensions and swivels tomorrow. Very easy job! Advance Auto has the booster on sale for $107 at my local store. Picking one up or ordering tomorrow.
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
Turns out mine was cracked that bad! After 2 hours upside down trying to get the firewall nut on the right on, I got the new one in. The MC rod is engaging low in the pedal so I will adjust tomorrow. Lots of extensions and swivel needed for that one bastard nut. If that nut was easier to get to, this would be a 1 hour job tops. I am now wearing two band-aids thanks to that nut. I hate him...
Burning Brakes
Joined: Jul 2013
Posts: 1,027
Likes: 30
From: Granite City Illinois
Turns out mine was cracked that bad! After 2 hours upside down trying to get the firewall nut on the right on, I got the new one in. The MC rod is engaging low in the pedal so I will adjust tomorrow. Lots of extensions and swivel needed for that one bastard nut. If that nut was easier to get to, this would be a 1 hour job tops. I am now wearing two band-aids thanks to that nut. I hate him...
Is it pretty much the same? You didnt have to open the system and bleed?
Thread Starter
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
Same process. Two nuts hold the MC to the booster. They come off in 1 minute. Then remove your drivers seat. Takes about 3 minutes. The bottom cushion has a clip in the front and then lifts right out. There are then four bolts holding the whole rest of the seat to the frame. Very easy. Get a few cushions to put on the seat frame to keep the metal frame from digging into your back. Three screws hold the hush panel up under the dash in the footwell. Now lay upside down under the dash with a flashlight and remove the nut from the booster on your left. It's the easy one to get to. Now add some extensions and a swivel to get to the nut on the right (left and right as you are upside down). This nut came out fairly easily. It took a solid hour and then some to get back in on the new booster. You'll have to pull out the cotter pin that holds the booster rod to the brake pedal. Very easy. Pull out old booster and put in new one in reverse order. Took 25-30 minutes coming out and would have been simple going in if not for that one nut. You may have to adjust the push rod that presses the MC so that it's not causing a low brake pedal. I need to adjust mine tomorrow. I ran out of time today. The only hard part is that one damn nut.