Mustang Owners Club Australia Forum
Technical & General Discussion Area => Tech Torque Pre 1973 => Topic started by: Tulls on September 14, 2022, 11:21:12 am
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Hi all, I need help please. Not sure if it is right or something is wrong......
I have a 65 Coupe 289 auto with power drum brakes. I have now converted the front brakes to power disc using the CSRP SWAP-1 kit. I have just spend the past 3 days bleeding the whole system but can only get a a low brake pedal. The brakes work ok but the pedal is low. Not sure about pedal height as I did not check any of this before I started.
I have a pedal height of about 13cm, with engine on, brakes applied I have a pedal that is 6 cm off the floor. I cannot get them any better.
Is that how they are or is something wrong. I have checked the booster pin spacing and that is set at just about zero space.
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I'm no expert here. But when I got my 65 Fastback its pedal was way too high. As it had an adjustable brake pushrod I was able to wind it in to reduce the pedal height.
Do you have an adjustable pushrod? If so you could wind it out.
https://www.cjponyparts.com/scott-drake-disc-brake-push-rod-set-adjustable-manual-1965-1968/p/A21161DB/ (https://www.cjponyparts.com/scott-drake-disc-brake-push-rod-set-adjustable-manual-1965-1968/p/A21161DB/)
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Also, there can be a difference in the pivot point on the Brake pedal arm. But as you had Power Drum setup you should already have the appropriate pivot point.
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Yes, it has an adjustable push rod. But, I do not know how high the pedal should be. I have no reference of it in any of my books.
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Hey Steve,
I’m not familiar with the kit you’ve fitted.
Did it come with Master Cylinder and Proportioning valve to suit.
If you have fitted a new Master cylinder it is critical to bench bleed them!
Air gets trapped within the Master cylinder.
I had lot of trouble bleeding my Wilwood Master cylinder.
By memory you need about 1mm gap between the pushrod and the plunger.
Cheers Phil.
PS.
Found them , they look awesome for the price!
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I reckon Phil's right that it has air in the system.
Shane's advice about adjusting the pushrod is also on the money but you need to be very gradual with this and only do it once you're sure the system is properly bled. The pushrod needs only very fine adjustment. If you go too far it'll seem fine until you've driven a few k's and the system has heated up as the brakes can effectively lock on. Ask me how I know.
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The push rod adjustment should be that you can still feel where the pedal takes up the slack ie the piston not depressed and small between push rod and piston
Are your rear drums adjusted correctly?
Did you bleed the rears ?
If you still air in the system
What method of bleeding did you use?
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Thanks for all the comments, but I have done them all. I checked the booster pin, bleed the M/C first on the bench. Bled all wheels, I even bled all fitting joints, starting at the M/C.
After I adjusted the foot pedal rod, I now have a pedal height of 155mm. The pedal travels 65mm to a solid pedal, which is then 90mm off the floor. This is all done with the engine off. I have not started the car yet, and know it will go further down when the booster kicks in.
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Hey Steve,
Like Pete said, what bleed method did you use.
It have a cheap eBay Vacuum bleeder, it works very well.
https://www.ebay.com.au/itm/233396961206
A combination of this and the pressure brake bleeders with NRV in a bottle should get all air out of the system if it’s bench bleed properly.
If you still having trouble I’d remove the master cylinder and bench bleed it again (I know it’s a pain) !
The problem is if you have trouble fitting the brake lines quickly and fluid dribbles out in that time.
Brake boosters haven’t evolved much in 50 years? You’d think someone would have designed something better and more reliable by now? Or is it Price?
I had the same problem as you!
All the best, Phil.
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Yes, I have one of those and still having issues.
I have done all I think I can do at home and will take the car to a brake specialist in the next week or so, see if they can pressure bleed it or any other thing..... I will keep you posted.
Very frustrating .........
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Watching - thinking that I’ll have this problem when I finish chasing down all the other ones….
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I have a AH sprite that is a pain to bleed so I use a old cap with a compressed air fitting.
Pressurize with 50 psi and crack a bleeder and away you go
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I have a AH sprite that is a pain to bleed so I use a old cap with a compressed air fitting.
Pressurize with 50 psi and crack a bleeder and away you go
Hey Pete,
That’s a great idea, You’ve got me thinking!
Great idea for those pressed out Master cylinder tops to get a spare top and modify it and a spare rubber gasket with a hole cut in it.
I could just drill and tap 1/8” bsp hole on my Wilwood top, make a temporary rubber gasket and fit a plug after job finished.
There is a breather hole you on the top you could hold a pressure regulated air hose against but that would mean I’d have to get my wife involved.
She hasn’t got the enthusiasm or patience needed.
They really push bench bleeding new or refitted Master cylinders, but if can’t see why you couldn’t fill the master cylinder by very very slowly drip filling the Master cylinder. Allowing the air time to escape, not getting trapped, but there could still be air pockets where only bench bleeding can remove?
Hope everyone reading this have a good think about their situation!
Cheers Phil.
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I have a AH sprite that is a pain to bleed so I use a old cap with a compressed air fitting.
Pressurize with 50 psi and crack a bleeder and away you go
And this works? I tried to bleed my clutch via this method because that's what the Tilton instructions said to do but, if I remember correctly, only about 20 psi. Didn't work at all, actually seemed to introduce more air bubbles into the fluid. Changed tack to a vacuum pump on the bleeder and job done.
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And this works? I tried to bleed my clutch via this method because that's what the Tilton instructions said to do but, if I remember correctly, only about 20 psi. Didn't work at all, actually seemed to introduce more air bubbles into the fluid. Changed tack to a vacuum pump on the bleeder and job done.
Hey Geoff,
I was thinking only 10 psi would be enough.
I have a vacuum pump with the collection bottle like yours I’d imagine.
It worked great on my rear Ford brake calipers, but the Wilwood bleed nipples threads are very sloppy and air sucks through the nipples thread, so you’re really not 100% sure it’s not coming out of the brake line.
So in this case pressure bleeding would be better.
Cheers Phil.
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I notice the CSRP SWAP-1 kit has OE Kelsey-Hayes type 4 piston caliper front disc brakes. A few forum members have had trouble bleeding these in the past. Some old posts might provide some tips/assistance - just an idea
https://forum.mustang.org.au/index.php/topic,27875.0.html
https://forum.mustang.org.au/index.php/topic,35379.msg333730/topicseen.html#msg333730
I have a 65 GT fastback with the original KH calipers. Prop valve recently needing rebuilding so had to bleed the whole system. Mechanic and I probably bled the whole system 3 times before the pedal hardened up. Mechanic was stumped after about an hour. Do you have pig tails in your MC brake lines? Sometimes air gets trapped in the loops which can be tricky to purge.
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FIXED.... :cheers: :lol:
Turns out the Master cylinder was the problem...... The M/C supplied was crap, the primary cups were too far back behind the relief ports causing excessive jetting during application. Fix was to insert a shim between the end piston and clip. Just for note, the under bonnet brake lines supplied are also U/S as one is braided and the other for the rear brakes off the adjustable proportioning valve has a silver soldered nut on the end, again not ADR compliant.
Again, after replacing the non compliant hose lines and fixing the M/C, I now have a good, hight solid pedal that stops perfect.