Lots and lots of GM trucks used hydro-boost brakes, driven by the power
steering pump. Almost any wrecking yard would have these.
Keep in mind, however, that installing power brakes on an M37 won't
really add to your braking "power" but just reduces pedal effort to
achieve the same braking effect. They make it feel like you have more
effective brakes, even though you typically don't.
If your M37 brakes are properly adjusted according to the sequence in
the manual so that the shoes make even, full-length drum contact, and
the system is properly bled and in good condition, it would surprise me
greatly if you couldn't lock up all four tires on dry pavement.
Do keep in mind that the larger the diameter of the tire, the more pedal
effort will be required to stop the vehicle or lock up the tires. If you
go to a very sticky, extra-large-diameter radial tire, you will have to
push harder on the pedal to achieve the same braking effect as when you
use a stock-diameter tire (stock diameter is about 35").
NOTE: Many (most?) people do not adjust these brakes properly. All four
adjusting points on each wheel are critical, not just the bottom two.
And they must be adjusted in a specific sequence and manner. A
combination of old glazed linings and improperly adjusted brakes will
certainly reduce braking effectiveness. Most brake mechanics don't have
much, if any, experience with these brakes. You might have better luck
at a truck brake shop, but I'd recommend hetting the TM 9-8030 manual,
studying the brakes, and doing a very careful overhaul and adjustment.
Another way to achieve a good adjustment is to get a brake gauge that
measures brake drum ID and brake shoe OD. This allows you to get very
close to the correct adjustment with the drums off, then just do some
minor tweaking after installing the drums. It works best if your drums
have been recently turned, so that there is no lip on the edge of the
drum. When using a brake gauge, you have to check each wheel's shoe
diameter across the center at different angles to assure roundness as
well as proper diameter.
Using a softer lining material might also reduce brake pedal effort. The
softer linings may not last quite as long as hard semi-metallic linings,
but on the other hand, they should be easier on the drums.
The shoes/drums on an M37 are not very wide, but they are quite large in
diameter. To me, the pedal effort required on an M37 doesn't seem much
different than on other non-power-brake vehicles I've owned, although
proper adjustment is more difficult to achieve. I personally think that
the M37 brakes are adequate for an unmodified vehicle carrying allowable
loads.
So, I'd suggest optimizing what you have first, then if you still want
reduced pedal effort, go ahead and look into a possible power brake
installation.
Regards,
Alan
TRice56922@aol.com wrote:
>
> My M37 is normal with so so brakes ....I have been told that a Hydrovac
> appliance is a device that will substantialy add to the braking power of the
> M37.
> Does anyone have experiences with these and where would one purchase a
> Hydrovac unit and at what price?
>
> Tom
>
> 52-M38A1
> 52-M100
> 54-M37
>
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