Kelsey Hayes disc brake trouble

-
Verno

Verno

Active Member
Joined
Jun 17, 2012
Messages
38
Reaction score
15
Location
Victoria
'69 Dart KH disc brake car.
I melted a rotor, caliper seized on. Replaced the following parts and have very little front brake. (All air bled out of brakes)
New MC Raybestos 36412
New KH calipers and pads.
New rotors, bearing and seals
New combo metering valve with built in rear proportioning valve
New flex lines front and rear. Basically I replaced everything except the hard lines and rear brakes. I've bled every bit of air out of the MC and all lines. I can't lock up front brakes. Stops way poorer than before. ??
I have the front small reservoir going to the rear brakes, the larger rear section going to the front. Is this backwards?
 
No.
More braking power to the front is okay.
60/40? Or more.
Maybe @hemi71x may be able to offer a solution.
He does a really good job re building the KH calipers.
I'm thinking a proportioning valve issue.
Joe
 
Is the pedal height good and the car is just a ***** to get stopped? Sometimes, depending on how the rotors are surfaced, you have to go over them with a roloc pad or similar on the end of a cordless drill or cutoff tool and give them a swirl or non directional finish. I've seen it a good bit.
 
Last edited:
Power brakes? or regular manual brakes?
You running a big cam, that produces very little manifold vacuum, if running a big cam?
If power brakes, sounds like you have a defective booster, keeping pressure applied on the pads.
 
The K-H 4 piston calipers went to the single piston in 73 because the KH pistons would get stuck. I had this on my Demon back when I drove it daily.

Your issue - how are the hoses? They have been known to collapse internally, restricting fluid. Even a new hose out of the box. I have bad M/C's out of the box as well.
 
Did you perform the proper break-in procedure with the new pads?

A 69 Dart with factory disks would have had the separate PV in the line going to the rear. The combo w/PV as fitted to later cars with single-pot brakes may not have the same proportioning built in. I installed a Summit adjustable PV when I did a drum-to-disk swap.

But usually the issue is too much rear brake, not not-enough front brake, because the PV affects the rear brakes.
 
Demonic said:
The K-H 4 piston calipers went to the single piston in 73 because the KH pistons would get stuck. I had this on my Demon back when I drove it daily.


Your issue - how are the hoses? They have been known to collapse internally, restricting fluid. Even a new hose out of the box. I have bad M/C's out of the box as well.
Click to expand...
Ditto
 
I think that will have a 1 1/32" bore and will take a bit of leg to lock em up. Get a 15/16" or 7/8" master
and you'll probably be much happier.
Also seating your pads...haul it down reasonably hard from 50 to 30 about 3 times and then 30 to to zero 3 times...they should grab a little better after seating.
 
Joey4speed said:
No.
More braking power to the front is okay.
60/40? Or more.
Maybe @hemi71x may be able to offer a solution.
He does a really good job re building the KH calipers.
I'm thinking a proportioning valve issue.
Joe
Click to expand...
Thanks Joe, that's what I'm thinking too. I'm going to get a pressure gauge set up to see what kind of psi I'm getting to front and rear.
 
Demonic said:
The K-H 4 piston calipers went to the single piston in 73 because the KH pistons would get stuck. I had this on my Demon back when I drove it daily.

Your issue - how are the hoses? They have been known to collapse internally, restricting fluid. Even a new hose out of the box. I have bad M/C's out of the box as well.
Click to expand...
Like I said in my post, everything except the steel lines and rear brakes are new. Thanks for the insight though. I'm going to check the new calipers anyway.
 
RustyRatRod said:
Is the pedal height good and the car is just a ***** to get stopped? Sometimes, depending on how the rotors are surfaced, you have to go over them with a roloc pad or similar on the end of a cordless drill or cutoff tool and give them a swirl or non directional finish. I've seen it a good bit.
Click to expand...
Thanks, I'll give that a try.
 
ir3333 said:
I think that will have a 1 1/32" bore and will take a bit of leg to lock em up. Get a 15/16" or 7/8" master
and you'll probably be much happier.
Also seating your pads...haul it down reasonably hard from 50 to 30 about 3 times and then 30 to to zero 3 times...they should grab a little better after seating.
Click to expand...
Thanks, it stopped great before the caliper siezed on. I replaced everything except the MC and it had very little front brake. MC was old so I replaced it hoping that would help. The new one is the one most recommended here. My pal has the same setup as me without issue. I'm going to get a pressure gauges set up on it and also follow your advice for a smaller bore MC. I'll be able to compare psi on each. Thanks again, Vern.
 
Type of pad lining material and "broken in" can have a GIGANTIC effect.
 
I swithed from drums to Kelsey Hayes discs on my 1969 GTS. I was not happy with the stopping performance. On the advice from member sgbarracuda, I switched to Bendinx SBC11 ceramic pads. Made a big difference for me. Stops like discs should now.
 
You must log in or register to reply here.
-

Back
Top