Brakes: '62 GT Hawk power drum brakes

[rdcompton]

I recently purchased a 62 GT Hawk, 62V16543 and I am having trouble with the braking.

The brakes are well adjusted but not really stopping until a second push on the pedal. I have seen similar posts though I am not certain my symptoms are identical. Since I have never driven one of the C/K cars with HydroVac brakes, I am not sure what to expect. I have also not driven a power drum brake car for maybe twenty-five years though my recollection was a somewhat soft pedal but sensitive braking.

This car, even with the second push feels more like the manual brake '53-'54 C/K cars I had more than forty years ago. It stops well but with a lot of pedal effort. Basicly feels like the boost is not boosting.

I have gone through the shop manual HydroVac troubleshooting procedure. I am not sure how you tell all of the vacuum is gone by pumping the brakes but I pumped half a dozen times or so when called for in the procedure.

On the "pump then hold with the engine off and then starting the engine" procedure I could not discern the pedal falling away as the engine started. Is it possible that I was not sensitive enough or is it really obvious?

Who knows when any neetsfoot oil was last injected in to the HydroVac. The car was stored from '82-'02 and really only passed through a couple of owners since. No work is documented and few if any miles put on the car since '82. Anyway, I will give it a shot of neetsfoot oil today.

Any other insights as to determing the operation of the HydroVac would be helpful. I would be more than happy to replace the HydroVac with one of the newly manufactured units if that is truely the problem.

Thanks for any assistance.

Raymond

[Roscomacaw]

The pedal movement will be easily discernable if the booster's working correctly. Have you bled the system at all?

[SN-60]

To: rdcompton,-------- Check the hose connecting the intake manifold to the hydrovac. Make sure it's not collapsed internally. (I had this happen before)

[(S)]

Welcome to the forum. Be sure there are no leaks, no bad hoses. I think you will re test that booster and find it bad. Your 'second pump' and it stops comment may mean you are stopping without the boosted effect. You can also bleed the brakes, sounds like it needs it anyway. This will confirm all wheels have pressure and there are no bad cylinders or the 3 rubber hoses going to them.

If you run the car and pump the brakes a few times and then turn the car off, you should hear a swoosh sound. The pedal will have slight resistance and get hard as it drops and vaccum is used up.


I went through fits on one car, I did a full brake job and everything was new. The owner before me had the booster redone and the 2 small hoses were never replaced when he said they were. I replaced them, and re-bleed the brakes. Most Studes have 3 rubber brake hoses, the P/B cars like yours has 5.

[SN-60]

Once again, the FIRST thing to check in a situation like this is the vacuum supply hose and manifold fitting. (also the easiest and cheapest!)

[rdcompton]

Thank all. I will recheck the vacuum hose, flex hoses, and bleed the brakes. It would probably be a good idea anyway as the car has spent most of the past thirty years in storage and bleeding to the point of flushing the whole system is not that big of a project. I'll let you know what I find.

[rdcompton]

Thanks for the suggestions. I have bled the brakes, checked the vacuum hose and inspected the flex hoses. Further research led to the 2002 eBay ad and among the "disclosures" was the statement that the booster needed to be rebuilt or replaced. I suspect that is still the case since there is no mention of any work being done since then. When I get the Avanti back on the road I will get one of the new (not rebuilt) HydroVac units from SI.

Thanks again.