Proportioning valve?

Thread view:

Enable EMail Alerts

Start New Thread

Thread rating:

Nate Nagel - 27 Mar 2006 00:42 GMT

All right, I give up on the brakes on my '55 Stude. They are as perfect
as perfect can be mechanically, but I still have a rear lockup issue.
Matter of fact after burnishing them a little with the car on
jackstands, the issue is actually WORSE. Car stops like a big dog in
reverse though :)

Question is this... do those knob style prop valves like wilwood et.
al. sell give zero pressure reduction with the knob all the way out? OR
do they start at some preset pressure drop? REason I ask is I don't
think that I need a whole lot of pressure drop to make this system work
properly, but it's just dangerous the way it is.

nate

(still don't understand why with all factory style components I'm having
this problem...)

Signature

replace "fly" with "com" to reply.
http://home.comcast.net/~njnagel

Reply to this Message

* - 27 Mar 2006 14:21 GMT

Nate Nagel <njnagel@flycast.net> wrote in article
<e078tq0mel@news4.newsguy.com>...

> All right, I give up on the brakes on my '55 Stude. They are as perfect
> as perfect can be mechanically, but I still have a rear lockup issue.
[quoted text clipped - 7 lines]
> think that I need a whole lot of pressure drop to make this system work
> properly, but it's just dangerous the way it is.

1.) It is apparent that you actually DO NOT have things up to snuff
mechanically - "...as perfect as perfect can be." The system worked for how
many years without problem????

2.) The Wilwood valves start out wide open, then begin to limit
pressure......

3.) Disregarding the fact that Studebaker went out of business, they did
have some great engineers - engineers who never saw the need to us a
proportioning valve.

Why do you want to over-engineer engineering that has worked okay for all
these years?

I suspect somebody - somewhere along the line - replaced hydraulic
components believing they had achieved a "form. fit, and function"
replacement when they, in fact, only actually had "fit" covered.

According to my books, the "Early" '55 Stude used 1-1/16" front in
conjunction with 7/8" rear wheel cylinders. The later one used 1" front
with 13/16" rear wheel cylinders.

Now, here's the fun part.....they ALL use the same casting - which means it
is entirely possible to bolt ANY cylinder to ANY location - such as the
larger front wheel cylinders onto the rear brake backing plates......

If you have mix-'n'-mismatched the 1" front with the 7/8" rear wheel
cylinders - or better still - installed 1 or 1-1/16 wheel cylinders on the
rear - you would be getting the very situation you describe.

Even if you have used the same size wheel cylinder all around, there will
be a brake imbalance - biased towards the rear.

Reply to this Message

N8N - 27 Mar 2006 15:48 GMT

> Nate Nagel <njnagel@flycast.net> wrote in article
> <e078tq0mel@news4.newsguy.com>...
[quoted text clipped - 13 lines]
> mechanically - "...as perfect as perfect can be." The system worked for how
> many years without problem????

don't know, the car was a mess when I got it.

> 2.) The Wilwood valves start out wide open, then begin to limit
> pressure......

I'm not sure exactly what that means, could you describe it in terms of
input vs. output pressure, or better yet do you have a graph?

> 3.) Disregarding the fact that Studebaker went out of business, they did
> have some great engineers - engineers who never saw the need to us a
> proportioning valve.
>
> Why do you want to over-engineer engineering that has worked okay for all
> these years?

Because it DOESN'T work OK. I know that a Stude *can* have good brakes
but this one does not. For some reason I am using all the right
components and yet the car is still dangerous to drive. It doesn't
make any sense to me either, I have a '62 hardtop with the exact same
brakes and I don't have this problem with it.

> I suspect somebody - somewhere along the line - replaced hydraulic
> components believing they had achieved a "form. fit, and function"
[quoted text clipped - 11 lines]
> cylinders - or better still - installed 1 or 1-1/16 wheel cylinders on the
> rear - you would be getting the very situation you describe.

Yes I know this. I have the 1-1/16" fronts and the 7/8" rears. All
are new. You can't put the front wheel cylinders on the rear backing
plates BTW, the fittings don't work. But I replaced all shoes, all
wheel cylinders, and all hoses not to mention the master cylinder and
have adjusted, re-adjusted and double- triple- and quadruple checked
everything.

> Even if you have used the same size wheel cylinder all around, there will
> be a brake imbalance - biased towards the rear.

Right. I know this, I have the Stude factory parts books, and believe
me I have checked and double checked everything and everything is
right. The only issue is, I can't really get hard into the brakes
because and even a medium-hard stop, the rear tires are smoking and the
rear end is trying to pass me, and I need to address that.

nate

Reply to this Message

Mike Romain - 27 Mar 2006 15:51 GMT

Could you have air in the lines to the front or maybe in the brake
master cylinder's front section? Was the master ever bench bled? If
you run the master dry when changing brake parts, sometimes you have to
remove it and bench bleed it before it will give even pressure out
again.

Most modern proportioning valves are called combination valves that set
off a red light in the above situation of air in one side of the brake
circuit. You don't have that now.

I am still suspicious about the size of the back shoes. If they are too
big they throw the braking pressures all off. The levering action will
be off and when it comes to lever action, they are pretty fine tuned.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pictures.html?id=2115147590
(More Off Road album links at bottom of the view page)

> All right, I give up on the brakes on my '55 Stude. They are as perfect
> as perfect can be mechanically, but I still have a rear lockup issue.
[quoted text clipped - 16 lines]
> replace "fly" with "com" to reply.
> http://home.comcast.net/~njnagel

Reply to this Message

N8N - 27 Mar 2006 16:19 GMT

> Could you have air in the lines to the front or maybe in the brake
> master cylinder's front section? Was the master ever bench bled? If
> you run the master dry when changing brake parts, sometimes you have to
> remove it and bench bleed it before it will give even pressure out
> again.

I'm still using the stock single circuit master cylinder so even if
there were air trapped in the master it would be affecting both
circuits equally... I really wanted to get everything working well
with the stock setup before I started messing with any modifications.
I have thought about converting to a dual circuit MC but obviously if
I'd thrown that in the mix I'd really be lost now.

> Most modern proportioning valves are called combination valves that set
> off a red light in the above situation of air in one side of the brake
[quoted text clipped - 3 lines]
> big they throw the braking pressures all off. The levering action will
> be off and when it comes to lever action, they are pretty fine tuned.

I hear ya, but at this point I don't see a choice but to throw a prop
valve in there as I don't know anyone that will "arc" the shoes for me,
the only way to get them worn in is to drive the car which I can't
safely do at this time...

nate

Reply to this Message

Steve W. - 28 Mar 2006 00:28 GMT

You could arc them yourself. Get some self adhesive 200 grit sandpaper
and stick it inside the drum. Rotate the drum by hand and use the
parking brake to apply SLIGHT pressure while sanding the shoes. They
will then match the arc of the drums.

Signature

Steve W.

> > Could you have air in the lines to the front or maybe in the brake
> > master cylinder's front section? Was the master ever bench bled? If
[quoted text clipped - 23 lines]
>
> nate

Reply to this Message