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Brake Booster

Started by greekz, January 27, 2018, 03:06:29 PM

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greekz

Since, the other thread appear to lost, I thought posting an up date would be appropriate.  After receiving the rebuild booster from Booster Dewey and installing new master cylinder, which caused the booster to fail, the transmission shifts perfectly and I have power brakes for the first time in years. 

New problem now is the rear brakes are locking up when applying sudden pressure.  Perhaps my proportioning valve is defective.  Never noticed before since the power assist was minimal.  Anyone rebuild these?

Pictures of the installation.

SFM 6S1134  '67 GT-350 #2339

Bob Gaines

Quote from: greekz on January 27, 2018, 03:06:29 PM
Since, the other thread appear to lost, I thought posting an up date would be appropriate.  After receiving the rebuild booster from Booster Dewey and installing new master cylinder, which caused the booster to fail, the transmission shifts perfectly and I have power brakes for the first time in years. 

New problem now is the rear brakes are locking up when applying sudden pressure.  Perhaps my proportioning valve is defective.  Never noticed before since the power assist was minimal.  Anyone rebuild these?

Pictures of the installation.
Yes, if it hasn't been rebuilt in the last 50 years then it is a safe bet it needs to now. West coast Cougar sells a kit as well as others but the Cougar guys have a nice DIY video on U tube for the distribution block and proportioning valve . https://www.youtube.com/watch?v=9kOCpaFGWGw
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

greekz

Thanks, I will check it out.
SFM 6S1134  '67 GT-350 #2339

roddster

  Rebuilding the valve is not that difficult.  However, be ready to have available that little 90 degree brake tube that attaches to it.
   Seems the spring inside deteriorates, even rusting a coil off.

   Second comment:  beware of applying any type of tire shine to the rear tire traction surfaces.  This too will cause this same type of "locking".

KR500

greekz
A few other things you should check also. Check the parking brake system. Make sure that the cables are not hanging up, not adjusted to tight and are returning fully. Check that the self adjusters are not over adjusted or rusted up. Check that the brake shoes springs are not broken or weak. Check the brake shoes for brake fluid or gear oil ( leaking wheel cylinders/axle seals ) contamination. Gear oil contamination especially will cause the brakes to be very grabby.
Rodney
Rodney Harrold,Ohio SAAC Rep,SAAC 68 Shelby Concourse Judge,68 GT500KR 02267

greekz

Quote from: roddster on January 29, 2018, 10:55:43 AM
  Rebuilding the valve is not that difficult.  However, be ready to have available that little 90 degree brake tube that attaches to it.
   Seems the spring inside deteriorates, even rusting a coil off.

   Second comment:  beware of applying any type of tire shine to the rear tire traction surfaces.  This too will cause this same type of "locking".

Thanks for the information on rebuilding the valve.  I usually only apply tire dressing to the side wall.


Thanks
SFM 6S1134  '67 GT-350 #2339

greekz

Quote from: KR500 on January 29, 2018, 12:00:09 PM
greekz
A few other things you should check also. Check the parking brake system. Make sure that the cables are not hanging up, not adjusted to tight and are returning fully. Check that the self adjusters are not over adjusted or rusted up. Check that the brake shoes springs are not broken or weak. Check the brake shoes for brake fluid or gear oil ( leaking wheel cylinders/axle seals ) contamination. Gear oil contamination especially will cause the brakes to be very grabby.
Rodney

Thanks, Rodney.  I will check those items.

Greek
SFM 6S1134  '67 GT-350 #2339

greekz

Finally had time to inspect the rear brakes and emergency brake.  First I pulled the emergency brake handle and found it barely moved.  That led me to backing off the emergency brake, that made no difference.  Removed both rear wheels and found the right rear had been dragging.  I backed off both rear brake adjustments and checked the emergency brake handle movement and it came out much farther.  A test drive yielded a minor lock up on the right rear.  It might be time to change the rear wheel cylinders as they are 27 years old and may be hanging up.  Unless someone has a better next step, that is what I will try next. 

Greek
SFM 6S1134  '67 GT-350 #2339

Bob Gaines

Quote from: greekz on February 03, 2018, 06:57:47 PM
Finally had time to inspect the rear brakes and emergency brake.  First I pulled the emergency brake handle and found it barely moved.  That led me to backing off the emergency brake, that made no difference.  Removed both rear wheels and found the right rear had been dragging.  I backed off both rear brake adjustments and checked the emergency brake handle movement and it came out much farther.  A test drive yielded a minor lock up on the right rear.  It might be time to change the rear wheel cylinders as they are 27 years old and may be hanging up.  Unless someone has a better next step, that is what I will try next. 

Greek
Make sure the long e brake cables are lubricated on both sides  and move freely back and forth. This is so they do not add to the problems.
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby

greekz

Quote from: Bob Gaines on February 03, 2018, 08:25:19 PM
Quote from: greekz on February 03, 2018, 06:57:47 PM
Finally had time to inspect the rear brakes and emergency brake.  First I pulled the emergency brake handle and found it barely moved.  That led me to backing off the emergency brake, that made no difference.  Removed both rear wheels and found the right rear had been dragging.  I backed off both rear brake adjustments and checked the emergency brake handle movement and it came out much farther.  A test drive yielded a minor lock up on the right rear.  It might be time to change the rear wheel cylinders as they are 27 years old and may be hanging up.  Unless someone has a better next step, that is what I will try next. 

Greek
Make sure the long e brake cables are lubricated on both sides  and move freely back and forth. This is so they do not add to the problems.

Will check that as well.  Thanks.
SFM 6S1134  '67 GT-350 #2339

greekz

Right rear brake locking problem was solved by turning both rear drums and replacing the shoes.  Right rear drum was egg-shaped according to my mechanic, who turned them for me.  While everything was apart I lubricated all moving parts to prevent sticking.

Now I have a transmission that shifts great and power brakes, which apparently, I have not had for some time.  Feels strange to only apply slight pressure to stop.

Thanks to all for their input while trying to solve this problem.

Greek
SFM 6S1134  '67 GT-350 #2339

Bob Gaines

Quote from: greekz on February 17, 2018, 07:26:08 PM
Right rear brake locking problem was solved by turning both rear drums and replacing the shoes.  Right rear drum was egg-shaped according to my mechanic, who turned them for me.  While everything was apart I lubricated all moving parts to prevent sticking.

Now I have a transmission that shifts great and power brakes, which apparently, I have not had for some time.  Feels strange to only apply slight pressure to stop.

Thanks to all for their input while trying to solve this problem.

Greek
Great end to this ownership chapter. ;D
Bob Gaines,Shelby Enthusiast, Shelby Collector , Shelby Concours judge SAAC,MCA,Mid America Shelby