Vacuum Brakes

[Dreamcar86]

I purchased my car with vacuum brakes and upgrades the cyclinders, combination valve and lines. My question is, are they supposed to be firm or a little spongy? They hold fine on the line and seem to work well on the street however they just feel mushy. Maybe I am spoiled by the newer cars brakes these days.

 

[zeus87gn]

They probably are neglected and need a good flushing with new fluid. Most likely have air from old fluid that has boiled from a panic stop somehwere in its past.

If your brake fluid is dark, cloudy or black it is old and in need of replacement. Get some DOT4 fluid and give the system a flush.
You, and your TR, will be glad you did.

 

[Hot Air]

Buy a set of the braided stainless steel brake hoses (front and rear). That should firm up the pedal a bunch.
Conrad

 

[zeus87gn]

I would agree that braided lines are a plus and definitely help, but your problem is air. Bleed them.

 

[Dreamcar86]

I would agree that braided lines are a plus and definitely help, but your problem is air. Bleed them.

Any place better than another to purchase the stainless braided lines? That does sound better than the cheap factory ones.

Thank you for the tip guys!

 

[zeus87gn]

Don't know for sure. I would guess one is just a good as the other. Regardless of vendor they are still SS. Fabulous corrision resistance and much added strength and integrity due to the brading.

I'm sure any vendor that sells them backs them 100%. Personaly, I would buy from one that is part of our wonderful Buick community.

 

[Dreamcar86]

Don't know for sure. I would guess one is just a good as the other. Regardless of vendor they are still SS. Fabulous corrision resistance and much added strength and integrity due to the brading.

I'm sure any vendor that sells them backs them 100%. Personaly, I would buy from one that is part of our wonderful Buick community.

I found them at gbodyparts.com. Thank you for the input and I have an order to place.

 

[Dreamcar86]

Still scratching my head with these vacuum brakes

Ok guys, here is the update on project vacuum brakes. I have now installed the stainless braided lines front and rear, brass combination valve, upgraded S10 wheel cylinders, new master cylinder and my wife is tired of helping bleed these things (1 quart of brake fluid) and would you believe that the pedal still goes half way to the floor. There is no problem with stoping power however I thought the pedal would be a little more firm and go down slightly, not half way to the floor. Is this normal with vacuum brakes or am I missing something?

 

[zeus87gn]

My opinion....
The pedal may very well stroke some before the brakes grab. It may be a characteristic of the m/c you installed working with your remaining fcty system and S10 cylinders. The m/c has to create that pressure in the system for you to 'feel the pedal' and it may take an extra bit of pedal stroke to do that. Not a problem, just a new pedal feel.

The important thing is that when the brakes do grab, the pedal is firm at that point. No spongyness allowed. If you have spongyness at that point, you have air.

If I may ask, how much did you pay for those braided lines?
Was it a big deal to get the old ones off?

 

[Dreamcar86]

My opinion....
The pedal may very well stroke some before the brakes grab. It may be a characteristic of the m/c you installed working with your remaining fcty system and S10 cylinders. The m/c has to create that pressure in the system for you to 'feel the pedal' and it may take an extra bit of pedal stroke to do that. Not a problem, just a new pedal feel.

The important thing is that when the brakes do grab, the pedal is firm at that point. No spongyness allowed. If you have spongyness at that point, you have air.

If I may ask, how much did you pay for those braided lines?
Was it a big deal to get the old ones off?

I purchased them from gbodyparts.com for around $90.00 this gives the the two fronts and the one for the rear. As far as getting the 20 year old originals off no problem with a can of liquid wrench 1 hour prior to removal.
When the brakes grab you can tell a difference with the new lines. They feel like they are going to lock up.
BTW, I may need to bench bleed that m/c again. Not sure if I did a good job the first time around and I am told that it is nearly impossible once it is installed to bleed it properly.
Thank you for the feedback.

 

[zeus87gn]

I purchased them from gbodyparts.com for around $90.00 this gives the the two fronts and the one for the rear. As far as getting the 20 year old originals off no problem with a can of liquid wrench 1 hour prior to removal.
When the brakes grab you can tell a difference with the new lines. They feel like they are going to lock up.
BTW, I may need to bench bleed that m/c again. Not sure if I did a good job the first time around and I am told that it is nearly impossible once it is installed to bleed it properly.
Thank you for the feedback.

No problem, I hope I was of some help. Thanks for the info. I may do the lines next year with my typical flushing.

If your brakes feel 'touchy' or 'grabby', you may want to check your adjustment on your rear drums. They can be either too loose or too tight. They have to drag the drum just right. It's something I have learned, but not learned how too explain...yet.

If you bench bled your m/c until there was no air left, you should be good to go.