Brakes 1967

[Michael 427]

I have been fighting this problem for over 1 year, car darts across road when applying brakes, I have installed all new hoses, orginial GM, new brake lines and stainless steel calipers, now the problem is worse, I have used the gravity bleed method no change and also a vacumn bleed system any ideas.



Michael 427

 

[Mikey1]

Hm....have you checked out the master cylinder and the proportoning valve ?

I know, basically this should go in the direction of front/rear balancing.....but looks like it is a combination of effects.

If you have got all new lines and stuff in there can you also please check for the correct diameter of the lines ?

It seems that pressure distribution is not equal.

Did you as well bench bleed your master cylinder after reinstalltion ?

 

[Michael 427]

Mikey1,
No I did not bleed master cylinder, is there a way to determine if the proportioning value is working proper, and yes all the lines are the same diameter, Thanks for the reply.

 

[IH2LOSE]

Sorry it took so long to respond I was thing about your problem.I will assume it disk brakes.I first would properly bleed your brakes.

Is it always a drt to the same side as if the one side always grabs forst of does it dart to one side and then maybee the next time dart to the other?

If it always darts to the same side I will assume the side it is darting to is working correct and the other side may have air/or the pads/caliper is stuck not allow it to self adjust/slide over .

Good luck with it

Also when you did your switch over what type of fluid did you have in the car and what did you put in.

 

[IH2LOSE]

proporting valve problems would give you front to back problems not side to side.

 

[IH2LOSE]

I have installed all new
hoses, orginial GM,
new brake lines
stainless steel calipers,

So whats left
master cylender would not cause darting
proportioning also would not cause it.

brake pads would
a crossed brake line would front and back on same circut?

 

[JohnZ]

67's don't have a proportioning valve (except the very few J-56 Heavy Duty Brake cars) - the device below the master cylinder is a "distribution block", which only separates the front and rear systems and incorporates the warning switch - it does no proportioning at all.

Both front calipers see the same pressure from the master cylinder and distribution block, through one pipe, so your problem is at one wheel; you either have air in one caliper, a stuck piston, a caliper not mounted squarely, a contaminated pad, or a glazed rotor. If it was a master cylinder problem, it would affect BOTH front or rear wheels.

 

[Michael 427]

IH2Lose and JohnZ
Thanks for the input on the brake problem, no I do not have J56 brakes so therefore the porportioning value is not the issue. I will check the caliper to see if it has seated correctly and the possibility of a stuck pistion or a grazed caliper, I wrote this forum last fall with this issue, I'm wondering if any one else has had a similiar problem, now since it has stopped raining in Ohio and I can't drive it.

Thanks again

Michael 427

 

[Michael 427]

IH2Lose,
I used castrol brake fluid it's some where between silcone and dot 4. Corvette restoration shop in Ohio recommend this type with stainless steal brakes, I guess I will look into a brake bleeder system from Motive which was mentioned on this forum.


Michael 427

 

[Michael 427]

IH2Lose and JohnZ
Thanks for the input on the brake problem, no I do not have J56 brakes so therefore the porportioning value is not the issue. I will check the caliper to see if it has seated correctly and the possibility of a stuck pistion or a grazed caliper, I wrote this forum last fall with this issue, I'm wondering if any one else has had a similiar problem, now since it has stopped raining in Ohio and I can't drive it.

Thanks again

Michael 427

 

[IH2LOSE]

I do have a question here if you have a distrubution block and lets say the right rear line (furthest from master) was tied in with the front left caliper(closest) off of the rear circut of the master would that not make the car dart to real hard to the left before the othe calipers coud react??

Have you followed how the lines tie in and wher they go from the block.

The fronts should be with the fronts and rears with the rears isnt that correct?

 

[JohnZ]

Yup - it's impossible to get them cross-connected, and you'd need lots of extra lines and plumbing to do it. One line feeds both fronts (from the block on the frame with two separate lines to the LF and RF calipers), and one line all the way to the rear tee feeds both rear calipers through separate RR and LR hoses and lines.

All the distribution block does is provide a location for the differential pressure warning switch; the front master line goes straight through it to the front block on the frame, and the rear master line goes straight through it to the rear main line. The switch is a spring-centered plunger between the two hydraulic circuits inside the block - if the front or rear system loses pressure, that moves the plunger off center and grounds it, which lights the warning light in the cluster.

 

[Michael 427]

I give up

All new brake lines and hoses and new calipers, all new castings never been on a car, Delco, car still datrs to the right, also to mention new brake pads and no they are not J56 with a portioning value, they right caliper passengers side works fine the left side drivers just skips, system bled with pressure and both calipers have flow. Any help would be appreciated this problem has been going one for 18 months going to give up and let the big sit and drive the Chevelle,

Thanks

Michael 427

 

[JohnZ]

See my response to your other thread.