Brake booster adjustment?
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Melting Slicks
Joined: Jun 2011
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Brake booster adjustment?
A couple years ago I replaced the factory brake booster on my 82 for a new one not that it was bad but the finish was gone and looked terrible. Well When I replaced it I did not check for adjustment (rod length) b/c I didn't know. Well I bought a new Wilwood master cylinder and in the instructions it says to do so and got to thinking maybe that's why my pedal was always at the floor?? Not spongy just to the floor. So I added some lipstick (wife) to the booster rod and sat the m/c in place to see it it made contact and it did not. So how do you adjust the booster rod?
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
Like you already have lived with IE, rod too short ,pedal goes further before it starts moving the master cylinder internals and activates the brakes .
OR rod too long and brakes are on all the time ,sometimes they are only JUST on but that causes brake drag, overheating etc.
OK , when I bought a new aftermarket master cylinder it came with the rod that goes between the vac. booster and into the back of new master cylinder. It was way too long ,that was done on purpose as it was a generic fit all type so it had to be cut down . what I did was measure the length from where the rod sat in the booster to the flange (join face )when the pedal was full back... and again in the New master cylinder to the flange face and added them up and then took off 3mm which gave me slack so NO pressure on master until I put foot on pedal
Last edited by bazza77; Jan 15, 2017 at 06:34 PM. Reason: give my example of new cyl fitting .
Had a 1976 L-82, 4-sp
Joined: Mar 2011
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From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
My new booster from Tuff Stuff had the (threaded) rod adjustment with two locking nuts from the brake pedal to the back of the booster. The rod from the booster to MC was non-adjustable.
Thread Starter
Melting Slicks
Joined: Jun 2011
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Likes: 15
No , you must have the correct length rod in there , otherwise you have problems ,
Like you already have lived with IE, rod too short ,pedal goes further before it starts moving the master cylinder internals and activates the brakes .
OR rod too long and brakes are on all the time ,sometimes they are only JUST on but that causes brake drag, overheating etc.
OK , when I bought a new aftermarket master cylinder it came with the rod that goes between the vac. booster and into the back of new master cylinder. It was way too long ,that was done on purpose as it was a generic fit all type so it had to be cut down . what I did was measure the length from where the rod sat in the booster to the flange (join face )when the pedal was full back... and again in the New master cylinder to the flange face and added them up and then took off 3mm which gave me slack so NO pressure on master until I put foot on pedal
Like you already have lived with IE, rod too short ,pedal goes further before it starts moving the master cylinder internals and activates the brakes .
OR rod too long and brakes are on all the time ,sometimes they are only JUST on but that causes brake drag, overheating etc.
OK , when I bought a new aftermarket master cylinder it came with the rod that goes between the vac. booster and into the back of new master cylinder. It was way too long ,that was done on purpose as it was a generic fit all type so it had to be cut down . what I did was measure the length from where the rod sat in the booster to the flange (join face )when the pedal was full back... and again in the New master cylinder to the flange face and added them up and then took off 3mm which gave me slack so NO pressure on master until I put foot on pedal
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
Does the booster on now have the same type end as in 75 pics ?
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You may have a difficult time bleeding the brakes id the rod that pushes the master cylinder piston is too short.
Use your hand to gently push on the brake pedal so you can "feel" when the "slack" is taken up between the booster rod and the master cylinder plunger.
That will give you an idea whether or not the booster rod needs adjusting or replacing.
You also may need to adjust the brake pedal threaded clevis under the dash once the booster rod is correctly set/adjusted.
Then you can bleed the brakes.
Use your hand to gently push on the brake pedal so you can "feel" when the "slack" is taken up between the booster rod and the master cylinder plunger.
That will give you an idea whether or not the booster rod needs adjusting or replacing.
You also may need to adjust the brake pedal threaded clevis under the dash once the booster rod is correctly set/adjusted.
Then you can bleed the brakes.
Thread Starter
Melting Slicks
Joined: Jun 2011
Posts: 2,096
Likes: 15
You may have a difficult time bleeding the brakes id the rod that pushes the master cylinder piston is too short.
Use your hand to gently push on the brake pedal so you can "feel" when the "slack" is taken up between the booster rod and the master cylinder plunger.
That will give you an idea whether or not the booster rod needs adjusting or replacing.
You also may need to adjust the brake pedal threaded clevis under the dash once the booster rod is correctly set/adjusted.
Then you can bleed the brakes.
Use your hand to gently push on the brake pedal so you can "feel" when the "slack" is taken up between the booster rod and the master cylinder plunger.
That will give you an idea whether or not the booster rod needs adjusting or replacing.
You also may need to adjust the brake pedal threaded clevis under the dash once the booster rod is correctly set/adjusted.
Then you can bleed the brakes.
Thread Starter
Melting Slicks
Joined: Jun 2011
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No mine the '82 is different. I'll take a picture.
Melting Slicks
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My '72 has a threaded adjustment on the end of the booster rod.
Believe by '82 they did away with that?
There has to be some clearance between the booster rod and master cylinder piston.
Here's some info: http://priorautomotive.com.c1.previe...s_PushRods.htm
Believe by '82 they did away with that?
There has to be some clearance between the booster rod and master cylinder piston.
Here's some info: http://priorautomotive.com.c1.previe...s_PushRods.htm
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
That looks the same as my TS booster. The rod had a thick plastic washer on the booster end. I believe it was to make up for the indentation on the front of the booster. I measured from the tip of the front booster rod to the rear clip on the rear brake booster rod on my old oem booster. I then measured the new booster the same way and adjusted the rear locking nuts to make the distance equal to the original. Maybe I got lucky but it worked the first time.
Last edited by resdoggie; Jan 16, 2017 at 03:13 PM.
Thread Starter
Melting Slicks
Joined: Jun 2011
Posts: 2,096
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That looks the same as my TS booster. The rod had a thick plastic washer on the booster end. I believe it was to make up for the indentation on the front of the booster. I measured from the tip of the front booster rod to the rear clip on the rear brake booster rod on my old oem booster. I then measured the new booster the same way and adjusted the rear locking nuts to make the distance equal to the original. Maybe I got lucky but it worked the first time.
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
Yeah , I have seen the same type and it caused the same problem you have with too much pedal travel with a non corvette master . My solution after trying to adjust as much as possible was to weld on some extra rod to make up the extra reach . That car has been working fine ever since.
But if your bleeding the brakes already it must have worked out ok with the new master then .
But if your bleeding the brakes already it must have worked out ok with the new master then .
Last edited by bazza77; Jan 16, 2017 at 06:36 PM.
Had a 1976 L-82, 4-sp
Joined: Mar 2011
Posts: 5,338
Likes: 1,213
From: Some days your the dog and some days your the hydrant.
Royal Canadian Navy
Because the MC rod on my new booster is non-sdjustable for length as the oem, the rear rod is threaded for rod length adjustment whereas the oem had no adjustment on the rear rod. The two nuts obviously locked in the adjustment. Also, the adjustable MC rod would not fit properly in the new booster.
Last edited by resdoggie; Jan 16, 2017 at 06:07 PM.
Thread Starter
Melting Slicks
Joined: Jun 2011
Posts: 2,096
Likes: 15
Yeah , I have seen the same type and it caused the same problem you have with too much pedal travel with a non corvette master . My solution after trying to adjust as much as possible was to weld on some extra rod to make up the extra reach . That car has been working fine ever since.
But if your bleeding the brakes already it must have worked out ok with the new master then .
But if your bleeding the brakes already it must have worked out ok with the new master then .
I looked under the dash which is almost impossible and don't see or feel any adjustment. Also though however the pedal doesn't feel firm when it's not running so either I still have air in the system or it's the booster??? Ever since I replaced the booster I've had non stop problems with the brakes. So what's my options now?
Thread Starter
Melting Slicks
Joined: Jun 2011
Posts: 2,096
Likes: 15
Because the MC rod on my new booster is non-sdjustable for length as the oem, the rear rod is threaded for rod length adjustment whereas the oem had no adjustment on the rear rod. The two nuts obviously locked in the adjustment. Also, the adjustable MC rod would not fit properly in the new booster.
Melting Slicks
Joined: Jul 2010
Posts: 3,176
Likes: 633
From: perth western australia
on the end of the threaded rod that comes out the back of the booster is a screw on piece , that piece is a y shape and goes over your brake pedal arm with a pin securing it together , to adjust it you must undo it from the brake pedal and wind it in or out to lengthen or shorten the rod throw. that's your adjustment .(with a lock nut to nip up against that y piece to stop it undoing by itself )