Brake Upgrade: Done, but Bugs to Work Out

Scott,

What else have you done to the braking system, other than adding the Baer calipers/rotors up front and the Wilwood rotors on the rear?

Have you eliminated the shuttle valve/distribution block in the front trunk and/or the brake pressure reducing valve in the front brake line?

What are you using for a brake master cylinder?

With the exception of braided flex hoses, everything is original (master/booster/shuttle valve/distribution block). I've tried the "pedal stomp" technique (found in another post) for kicks, though I understand that primarily works for a front/rear imbalance. I'm kinda trying anything at this point.

Scott, I am doing the upgrade on rear as well and was told the Reducing valve MUST be bypassed. If you want to keep original look there is a procedure to remove the internal parts for a free flow/pressure. Also have you checked the weight on the Front Tyre footprint if they are the same? If you have Coilovers it does not take much adjustment to take some weight of a Tyre, especially the right (if you are 220Lbs like me and your car is LHD)
Jan

The light on is because you had a pressure imbalance in the system and it threw open the warning light valve.

This is a mechanical system and you need to reset that valve manually.

The Pantera uses a Mustang unit. It has a plunger that you just push back in, I think on the opposite side of the sender in the brass H fitting. It's been a while since I had to do it so I'd have to look, but it is there. It might be under the sender unit itself. I forget.

If it is under the sender, then you need to take the sender out to reset the plunger.

Just push that in until it clicks and it is rest and the light should go out.

Second, you MUST remove the stock balance valve from the system AND install a manually adjustable valve between the master and the rear brakes.

The Wilwood is the easiest to get and use. It should be set about right out of the box.

You are limiting the rear braking pressure to about 25 to 33 % of the fronts with it.

If you don't install one, it is going to be like using the hand brake and you will lock up the rears every time and the rear end will come around like in the movies were they do 180 degree turns instantly.

You do not want to do that on the street.

Re-balancing the system is the #1 priority and even for re-sellers is the main liability in selling braking systems.

On pad compounds you need to be very very careful.

You do not want race pad compounds on the street. They are designed to work red hot and on a street car are very dangerous.

The most aggressive pad compound that you want is a Porterfield R4S. "S" is for street. The race pad is the R4. That is the pad compound designation and they are available in many pad designs. They are about $140 per axle. So about $280 for a complete set.

I don't know where the yellow pad that you have stands in these formulas but with a race pad on the street you stand a strong chance that the car won't stop at all under normal street conditions because they are not hot enough.

It's nothing to screw around with.

For a novice, go with something like what SAAC Restorations has put together.

Scott did a lot of the hard work on the brakes already to make these a bolt on and go the first time you put them on.

In all fairness to the other vendors, they all virtually have done the same thing and have other systems available too.

The Brembo system by comparison, is very expensive for this car at around $8,000 but really is a NASCAR type of system which not only do you not need, you probably don't even want.

The key here really is that if you add more braking to the rear, you need to add more to the front to keep it balanced.

Those tiny little pads are stock on the rear of the Pantera for a big important reason. The brakes had to be idiot proof and the only way to do that at the time was to under brake the rear.

Scott,

Since your braking imbalance is side-to-side, as opposed to front-to-rear, I suspect you have a maintenance issue rather than a parts selection issue. A piece of "crap" in a brake line can create some serious problems! You could also have multiple problems. A piece of "crap" blocking the left front brake line and a front-to-rear brake imbalance (too much braking at the front) would create the exact problem you're experiencing.

As Jan suggested, it could also be a corner weighting issue but your problem seems to be too severe for that to be the cause. It's also possible that the shuttle valve and pressure reducing valve are incompatible with your new front calipers but that would not explain your side-to-side imbalance.

Are you sure it's your brake pad wear warning light that's on, rather than the emergency brake/shuttle valve warning light? If so, it's a pretty simple circuit, so finding the cause shouldn't be too difficult. I'm not too familiar with this circuit in the Pantera but with many cars, the brake pad warning light illuminates when the circuit is broken as opposed to being completed.

As a general comment, in putting larger than stock calipers on the front of the car only, you've made the front to rear brake balance worse than on a stock Pantera. If you really want to improve the car's braking, you'll need to install larger calipers on the rear as well. At that point, you'll probably require a larger master cylinder, removal of the pressure reducing valve in the front line and the installation of a proportioning valve in the rear line. When it comes to brakes, balance is the single most important factor, so you shouldn't upgrade one end without upgrading the other (IMO).

Call SACC and they'll help you out. Just make sure you know the sizes of the pistons in your new front calipers before you call.

Mahalo for the input, guys!

I'm not too worried about a weight imbalance causing the RF to lock up, as it's happening at a relatively slow speed. I'll check the lines for gunk, and our local speed shop has a Wilwood proportioning valve in stock, so I'll grab that today -- makes sense that with better binders up front, the balance will be off. I understand Baer has a rear system is in the works, but it won't be available for a while.

When I spoke with the folks at EBC, they said the Yellowstuff pads fall into the aggressive street category.

As for the yellow brake pad warning light, I'll just have to trace the wires and look for potential shorts. Since it isn't hooked up to the pads anymore, I could just pull the bulb.

Mahalo -- Scott

Hi Scott- been awhile. Did you repaint the car a darker red or is your avator photo just due to 'Maui Light'?

To trace down your brake problem, pull a pair of caliper bolts and have someone LIGHTLY step on the brake while you watch for piston movement. Do NOT let them push so hard a piston comes all the way out! You can add a block of wood of appropriate size between pairs of pistons to narrow down the piston movements. You will very likely find one piston sticking in its bore. IMHO the most common defect in seldom-used Panteras is varnish on a caliper piston that causes it to stick. This is cheaply fixed by removing all the pistons one at a time for a caliper and scotch-briting all varnish off the nickel-plated pistons. No actual 'rebuild' needed unless there's a leak. Simple & cheap but messy and labor-intensive.

Aloha Jack!

We did a bare-metal resto a few years ago. The stock red's been replaced with a Lexus color: Royal Ruby Pearl Metallic. Ron Haglan,former lead painter for Mike Mayberry, did the job, and added an extra 15-grams of pearl to the mix. It's almost piercing in sunlight, and becomes an incredible dark cherry at night.

And the saga continues...

We pulled the stock shuttle and proportioning valves, blew out all the lines again, checked the Master and Booster (which appear to be working perfectly) and fitted the Wilwood proportioning valve. The Reader's Digest Condensed version: Even with the proportioning valve set fully to the rear (or anywhere for that matter), the fronts lock under moderate pressure (45 - 50 MPH, RF first then LF).

I'm wondering if the imbalance in front/rear caliper size is the culprit (the proportioning valve can't shift enough fluid pressure aft)?

Has anyone else had this issue with the Baer conversion?

On the plus side, I re-coated/bundled the pad warning light wires, and that fixed the idiot light.

The only thing I could add here would be to read the brake pressure at each location with a brake pressure gauge and compare them.
The one I have is from Strange, the people who make the forged rear axles.
Perhaps that would give you some scientific data to give you insight into what is happening?

Scott,
Here's my $0.02 worth: You might check your flex hoses carefully. A friend of mine had one that collapsed internally. Looked fine by visual inspection, but acted sort of like a check valve. Really had us going nuts till we found it. Replaced the hoses and bingo - problem gone. May be worth a look if all else fails. Rodney

The problem is you upgraded the fronts WITHOUT upgrading the rears. Most people do it the other way around.

By upgrading the fronts without upgrading the rears, you have effectively disabled ALL rear braking. This is because the fronts reach lockup before enough pressure is made for the small rears to assist in braking.

Your proportioning valve should be in the front circuit, NOT the rear. Once the brake system is fully upgraded FRONT AND BACK, you would then install a proportioning valve in the rear circuit.

Your side-to-side issue is problem #2. Jack has the right idea for that issue...

Hi Scott,
You're getting some good insights from the team, but one thing I haven't seen discussed is the math. What front brake set up did you go to? What size rotors, what size calipers? Multi piston etc...

Also, you initially mentioned the RF would lock, however in your last post you mentioned "fronts" lock. Please clarify?

Also, please clarify with part number what adjustable prop valve you went with?

Aloha Guys!

Let me address a few posts...

The fluid pressures were checked at all four corners, and with the proportioning valve in neutral (equal front/rear balance) it was pretty equal all the way around.

All the flex hoses are new stainless steel braided, and we've got good fluid flow

The proportioning valve is Wilwood's 260-11179 with brake light switch.

As far as the locking, at 45-50 MPH, under moderate pedal pressure (quick stop, not emergency), the RF locks immediately, and adding a bit more pressure locks the LF. The rears don't lock at all. Under normal driving conditions, using light pressure, the car stops W/O locking.

As for specs, the front calipers are Baer SS4 (4-piston) with 11" vented/drilled/slotted rotors. Rear has stock Girling calipers with Wilwood 11.75" rotors (from Scott at SACC Restorations). Pads are EBC Yellow Stuff (high performance street/strip).

I think Scott's post makes the most sense. I've Godzilla brakes in the front and gnats on the rear, making the balance off by a country mile.

Reduce the hydraulic pressure to the fronts until you can no longer lock them up under any condition but just barely.

Then increase the rear pressure until you can lock up the rears, then back off just a little.

That should balance the system.

In my experiences it usually is the rear that locks up and needs to have the hydraulic pressure reduced, but I'm always learning.

The level that you should be doing this at should not be possible to do this hard enough on the street.

Aloha Doug -- the problem is that the valve is set to full rear, and the fronts still lock

Considering all the work that was done and the diagnostics, I have to agree with Chris and say that the front needs a proportioning valve in addition to the rear.

There is too much pressure going to the fronts. They now have too much bite.

You have to reduce the pressure to them until you can no longer lock them up, or just barely.

You can only do that with an adjustable proportioning valve between them and the master.

Your setup is just going to have a proportioning valve to the front and to the rear.

I don't know why it really should need one but it will give you the ability to completely re-balance the system to your liking.

You have to go with what Chris recommends on this. He is the only one that has done extensive modifications to the Pantera brakes AND is participating in this discussion.

What you are experiencing as far as the front left/right balance issue is possibly what the DT factory experienced in testing the car and the reason they put the balance valve in the plumbing to begin with?

If the front imbalance continues even after you install a proportioning valve, the only logical thing to do after that would be to put it back in the system.

As an added note, the ONLY "production" car I have ever seen that it seemed impossible to lock up the brakes on under any circumstances was the '65 and '66 Shelby GT350.

They added an adjustable Bendix unit to the rear brake line, before the rears.

It actually was one from a Corvette. Don't know what model year, but Bendix gave Shelby their own part number on it.

You could accurately describe this brake system as a mechanical ABS brake system.

Having driven those cars I can tell you that it is virtually impossible to lock up the brakes either in the front or the rear even if you stand on the pedal.

The reason I mention this is it makes precedent in adjusting or designing the brakes in this manor in case someone said, "no, they aren't working right unless you can lock the fronts up".

This post should also stand as a WARNING to the issues ANYONE is going to experience in UPGRADING the brakes on this car. There IS some re-engineering of the system to do and it isn't child's play.


I don't remember what you said about the master cylinder, whether or not you replaced it.

Some masters come with a little rubber check valve that is intended for use with drum brakes. The drum brakes need to be kept on the verge of dragging all of the time and the check valve keeps the fluid from draining back to the master.

The same masters are often used with the disc brakes but you take that valve out of the line to use them with discs since you want the pistons to back off some when you release the pedal.

Your fronts are showing some of those symptoms as well as a sticking piston to one side.

Hi Scott,
OK, so based on what's in discussion....
- you have the wilwood adj prop valve installed (btw I like this piece).
- you dial back the valve so you have fully open (unrestricted) rear brakes, and the fronts are still locking.
- key point here.... you essentially have a prop valve installed for no reason. (seriously... ;-) One typically installs a prop valve to dial back the rear brakes to ensure balance/stability with the rear not locking and therefore passing the front of the car (bad).
- suggestion: only have an inline valve, such as this 260-10922 willwood piece in the front circuit prior to the front circuit T block. Since you already have this one installed, I agree with the above post, just install the in line one between the master and the prop. (that said, recognizing the Gucci one will just be along for the ride.)
- Regarding the front side to side imbalance..this is not unique to the Pantera. I have experienced this with vintage stangs also. I did quite a bit of brake upgrade development work when I had Vintage Venom(now sold), and have seen this ugly beast before. Again, as mentioned previous by Doug, you can put a valve here too to balance the sides, or you can move the T-block to the center with equal lengths of tube to either side in an attempt to remedy it, this can help (keeping all mechanical irregularities of the functional performance of the two sides not considered, such as piston seal roll back, knock back etc etc).

Keep us posted....

Scott,

Rather than installing another proportioning valve in the front line, couldn't you simply connect the one you have now, backwards? That would put the proportioning valve in the front line and leave the rear wide open. Even though your balance would still be way off, at least you could get the fronts to stop locking-up.

As a better alternative, don't wait for Baer to have their rear "kit" available. Just buy a pair of calipers from them that match your front calipers, with the piston sizes they recommend. Then have the appropriate adapter brackets made. You already have upgraded rotors on the rear. I'm sure SACC could help you out with custom adapter brackets. Just have the rear calipers shipped there (to SACC) first. If you're determined to wait for Baer, just buy an interim set of rear calipers. Maybe SACC would have something used that you could sell on eBay later on.

Aloha guys,

Much mahalo for all the great advice. I called Baer Brakes today, and they're going to "look into it." I also learned that a rear brake system for the Pantera isn't gonna happen any time soon. My guess is it might be done by the time I'm using a walker, or that they've scrapped that project altogether.

I spoke with Scott at SACC yesterday, and he laid out what was happening with my current system, logically explained the physics, and how it an be corrected. Now, I'm looking into adding a set of 4-pot Wilwoods to the rear -- it's just a matter of being sure the piston sizes match front-to-rear (Baer to Wilwood). I wish I had done some more research (as does my wife ) , and bought a full system from SACC, which would have averted these problems.