Technical Help please

[vpr]

My nipper’s just acquired a 63 Galaxie 500XL with a 427 and manual box.

The brakes are an issue.

It has the luxury of a servo but drums all round.

On initial braking there’s plenty of assistance and they inspire confidence. HOWEVER, if and when you decide (usually in a panic) you need to brake hard the assistance seem to disappear and it’s as if the servo has stopped working

Any thoughts?

[colin_p]

Stating the obvious; the servo is worn out.

[HD Adam]

Every 50/60's car I've had, I've converted to front discs.

You'll never be happy with drums in modern traffic.

My 69 Rouadrunner currently sports big Willwoods all round.
Absolute night & day difference.





Plenty of bolt on conversions kits available.

Example here

https://leedbrakes.com/p-33751-ford-galaxie-front-...

[spikeyhead]

Whilst the servo is a likely culprit, I'd also check to see if any of the slave cylinders are leaking which would have a similar affect

[vpr]

No leakage on slaves

Appreciate discs will be the answer to better brakes and I think this will be the way to go eventually.

What’s strange is that the servo IS working initially every time.

If it’s the servo, why would it work at all? I thought they either do or don’t think work. No halfway house??

[vpr]

HD Adam said:

Every 50/60's car I've had, I've converted to front discs.

You'll never be happy with drums in modern traffic.

My 69 Rouadrunner currently sports big Willwoods all round.
Absolute night & day difference.





Plenty of bolt on conversions kits available.

Example here

https://leedbrakes.com/p-33751-ford-galaxie-front-...

Thanks for this. Useful.

[Shy Torque]

vpr said:

No leakage on slaves

Appreciate discs will be the answer to better brakes and I think this will be the way to go eventually.

What’s strange is that the servo IS working initially every time.

If it’s the servo, why would it work at all? I thought they either do or don’t think work. No halfway house??

I had a 64 Galaxie with the same problem. Brakes ok on first application, then very little assistance.
Servos run on engine vacuum and performance cams can reduce this considerably - changing to a more sensible cam cured mine. Mine was also converted to discs quite cheaply using Ford parts.

(Separate electric pumps are available to augment vacuum for performance vehicles)

Edited by Shy Torque on Monday 31st May 20:41

[vpr]

Shy Torque said:

vpr said:

No leakage on slaves

Appreciate discs will be the answer to better brakes and I think this will be the way to go eventually.

What’s strange is that the servo IS working initially every time.

If it’s the servo, why would it work at all? I thought they either do or don’t think work. No halfway house??

I had a 64 Galaxie with the same problem. Brakes ok on first application, then very little assistance.
Servos run on engine vacuum and performance cams can reduce this considerably - changing to a more sensible cam cured mine. Mine was also converted to discs quite cheaply using Ford parts.

(Separate electric pumps are available to augment vacuum for performance vehicles)

Edited by Shy Torque on Monday 31st May 20:41

Very interesting, thanks.

[eldar]

I had a 69 mach 1 Mustang. Non servo drums all round, good for one stop from 60mph, then nothing for 20 minutes, hideous. You could get upgraded drums, shoes and master cyls,

But even then, disk conversion was the only sane route in both cost and performance.

[Mike-tf3n0]

Sounds to me like an excellent description of weight exceeding braking capacity = fade! Pedal goes hard, retardation reduces, I remember it well back in the day, solution is discs, drums can never be anywhere near as good.

[HD Adam]

Shy Torque said:

I had a 64 Galaxie with the same problem. Brakes ok on first application, then very little assistance.
Servos run on engine vacuum and performance cams can reduce this considerably - changing to a more sensible cam cured mine. Mine was also converted to discs quite cheaply using Ford parts.

(Separate electric pumps are available to augment vacuum for performance vehicles)

Edited by Shy Torque on Monday 31st May 20:41

Forgot to say, due to the ridiculous cam & 6 pack carbs, I have a servo driven from the PS pump due to lack of vaccum.

[stang65]

vpr said:

My nipper’s just acquired a 63 Galaxie 500XL with a 427 and manual box.

The brakes are an issue.

It has the luxury of a servo but drums all round.

On initial braking there’s plenty of assistance and they inspire confidence. HOWEVER, if and when you decide (usually in a panic) you need to brake hard the assistance seem to disappear and it’s as if the servo has stopped working

Any thoughts?

Do you mean if you hit the pedal hard there's no assistance or on the second pump there's no assistance?

If it's first "hit" then when you say no assistance the pedal remains hard but the brakes don't slow you down? If the pedal still sinks I'd check the master cylinder first. It the pedal remains hard then I'd guess a servo leak.

If it's a second pump that doesn't work then it might be too little engine vacuum or a vacuum leak. Does it have a high lift cam fitted?

Bear in mind that a servo doesn't improve the brakes, it just makes it easier to push the pedal. So when the servo isn't working a good shove should still get the same result. I know it's not ideal if you don't know how hard to shove but it might help diagnose the problem.

[vpr]

So wobbling along the road and when you apply brakes to slow there’s a positive bite but on the same push of the pedal if you suddenly decide, actually I need to stop here, the pedal is hard and there’s no extra baking available unless you stand in it with two feet, wooden pedal with no assistance I think.

[vpr]

Yes indeed

Just tried this.

Popping in into neutral and coasting with revs higher than normally would be when braking (tickover)

And brakes work better.

So obviously once it’s used it’s stored vacuum it doesn’t replenish at tickover.

[aeropilot]

Shy Torque said:

vpr said:

No leakage on slaves

Appreciate discs will be the answer to better brakes and I think this will be the way to go eventually.

What’s strange is that the servo IS working initially every time.

If it’s the servo, why would it work at all? I thought they either do or don’t think work. No halfway house??

I had a 64 Galaxie with the same problem. Brakes ok on first application, then very little assistance.
Servos run on engine vacuum and performance cams can reduce this considerably - changing to a more sensible cam cured mine.

Yep, I wouldn't bet against the culprit being the amount of vacuum.
Is the car an real original Q or R code Galaxie, or is it a made up 427?
If a made up car, likely the servo is setup for a lessor engine?

[matchmaker]

Vacuum leak? A mate of mine had a Mk 2 Jaguar. There was a vacuum storage tank under the front wing. Unbeknown to him it had a pinhole leak. Heavy braking was Ok at first. One the vacuum was depleted you had no servo assistance and the chances of stopping a ton or more of Jag with 4 non-assisted discs was the square root of fk all!

[HD Adam]

Sounds like you need a vacuum tank.

Might be ok & cheaper than a disc conversion.

https://www.summitracing.com/parts/sum-g1464b?seid...

[NMNeil]

On the booster is the check valve, the round black plastic bit.
https://www.startpage.com/av/proxy-image?piurl=htt...
They go bad all the time, so take it out and if you can blow any air at all through the hose connector end, it's bad.
Start there because it's simple and free to check.

[aeropilot]

HD Adam said:

Sounds like you need a vacuum tank.

Might be ok & cheaper than a disc conversion.

https://www.summitracing.com/parts/sum-g1464b?seid...

If the 427 has a radical cam, will probably worthwhile even with a power disc conversion as well

If its a 'real' Q or R code car though and still has drums, its likely it was specced to go drag racing originally, as they only needed to work once at the end of the strip....