Considering Big Brake Mod. What about Master Cyl. Upgrades?

[Merian]

VW engineers designed the system a full load as seen on the spec. placque

but if your engineering degree allows you to design a better system, have at it


agreed - don't buy cheapo rotors or pads[/b]
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[buildyourown]

People often think engineers are infallible and have thought of every scenario and made the best designed system.

Do you think they choose solid small rotors and drums cause that was the best performing system? No, its what fit under 14" wheels and worked adequately and was suitable cost wise.

[Christopher Schimke]

[thummmper]

I have caseys treatment up front--1975 to 1988 jaguar xke four piston calipers with matching 284 mm venters and the 1988 735i bmw rear hubs with unvented rotors and small shoes for ebrake---I just serviced the system, installing centering rings front and pulled the fron calipers off because they were wet. I had worn the system down over 3 years to where I had to pump the pedal 2 or 3 times to stop--so I thought my trw rebuild kit went south, but it turns out the banjo fittings weren't seating---if you are going to pay someone to machine pressure supply fittings on calipers, avoid banjo fittings--they are tedious to machine correctly. the hole gets bored and threaded, but the spot face rarely gets surfaced /milled squarely in 360 degrees, so the little compression washers wont seat completely and you leak--
I was envisioning a jaguar master cylinder, etc. corrected the problem, bled the system and its totally normal now with new pads--no more pumping and pulsing. it takes a vanagon forever to wear down junkyard jag pads. they are so big--the size of cigarette packs

[Butcher]

I would love to see what an engineer would design if the top priority was not the budget. As long as their hands are tied, they are limited on the outcome.

I agree, it would not be a 14" wheel and what ever kind of brakes fit in that space.

On the flip side, I've seen some sad advice and projects on the internet. Some of them the Flintstones stopping method would be shorter.

[IdahoDoug]

As a former product planner for two of the largest auto companies on the planet, I can tell you what the engineers would do for a 1982 vehicle with 90 hp, 14" tires, when brake rotors were more expensive than drums, given the vehicle's GVWR, TUV requirements, NHTSA testing regimens, lawyers, the state of tire development at the time, the legal system, advice from marketing, advice from VW's legal team, advice from the Vanagon platform's overall engineering staff, etc, etc. They'd do pretty much exactly what we have on the Vanagon.

Now, if you told those same engineers the Vanagon was going to be the division's performance image leader (vs the Scirocco or GTI), it was going to come standard with 16" Pirelli PZero 235/45 tires, and all advertising would center around its braking system, you'd get a different system.

I want you all to know I have no desire to quash improvements, etc. But the "bigger brake kit means a safer Vanagon" line simply isn't true. I have been a part of a lot of brake testing and can tell you from actual observation as well as reading written engineering reports by professionals backed by state of the art equipment and decades of professional experience that changes to the brake system emphatically do not uniformly make things better.

If you want a system you can go from stone cold to max braking with no warning and experience a safe, stable, controlled stop - keep your stock system in great maintenance.

I hereby lay out a challenge for any and all takers. My Vanagon will be back on the street in a month or so. At the next sizable Vanagon event I attend, I will publicly notify folks that I will be there and that I am available for a challenge to a brake modified Vanagon. We'll add or subtract weight to get our vehicles the same. We'll have an observer. In a parking lot, we'll chalk out a course. We'll do the stops from 60 dry. We'll wet the surface. We'll throw down some leaves or buy a crate of lettuce to simulate wet leaves. We'll do it with two tires in the grass at the edge of the parking lot. We'll find some gravel. And of course we'll do it with a cone you have to avoid at max braking to see who's rear end comes around.

I will bet money. And you will lose your money if you bet against a stock Vanagon system in good shape. If 10 of you show up, I'll beat more than half of you. That's the way statistics work. Yours are randomly pieced together. Mine is the product of thousands of hours of work.

I am not doing this to be confrontational. For many of you it will be as close as you ever come to an actual instrumented test of a vehicle's dynamic handling and braking systems working in concert to stop a vehicle in an emergency. I suspect there will be lessons learned.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Pcforno]

ID Doug - I will absolutely take you on that bet.
Please let me know when you will be available for me to take your money 😀

Seriously - I think this will be really fun and would love to see the results. Please let's do this! We'll have multiple different folks with different setups and runs to get statistical averages.

Go, go vanagon science!

[nepawesty]

Lives at 5300'. Plays at 10,000'. Coming from all new pads, rotors, calipers, drums, shoes and wheel cylinders (6,000 miles) for the GW BBK. Rears remain stock. Booster is new, stock. Really looking to prevent brake fade rather than increase stopping power. I'll report after a few more miles. Everything seems way better.

[Chainsaw]

[Merian]

uh...no

an extra amount of brake torque will simply skid the tires
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[IdahoDoug]

Cool. This will be fun for all and as stated a great learning experience.

My experience with engineers is actually very good. I find that the quality and "user appropriate" output of an engineering department is often determined by factors OUTSIDE the engineering department. If a company is set up right, the people outside the engineering department consider themselves customers and will hold them accountable for solutions that matched the specifications in spirit, not just matching the specifications by the numbers. The latter is not engineering. When engineers properly see what is being asked and feel entitled to use their talents to make it better, magic happens.

Perhaps because the automotive industry's products are associated with insane liability (vs say a piece of consumer electronics or a sprinkler), the level of engineering and its importance within the company are elevated. So I met a lot of talented people who would stand up at a meeting and say "Hold on - that's just not the direction you need to point my engineering staff. Here's what we think...."

I remember a hilarious episode while developing the late 80's Firebird GTA. We signed off on a special rear hatch that made this fastback body into a notchback with a vertical rear window glass. It was pretty cool and was going to have the performance stuff from the Trans Am and this unique look. Engineering opted for an unusual material for the hatch panel. It wasn't carbon fiber, but some type of enhanced plastic I can't recall. FRP maybe? One of the earlier tests was a rear collision crush and the new hatch panel turned out to be overbuilt. It utterly failed the test as a result, and the potential delay to redesign it weaker was going to blow the schedule, so we dropped the whole concept and the GTA was introduced with a much more conventional look. In slow motion video the car started crushing, the hatch started flexing, the glass blew out, and then suddenly the hatch panel resisted and then tore the entire latch assembly out of the trunk sheetmetal. They made a few halfhearted efforts to weaken it such as hand filing notches for failure points, but it was not to be. They were so embarrassed and I felt bad for them. The material was amazing but it was too strong.

They were a great bunch and tolerated our regular screwups as well. Mine, in particular.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Butcher]

Since this course seems to be set up for smaller brakes, may I suggest a course that would be more suited for a larger brake system. How about a fully loaded 60-0 test down hill, 10x. Not stop, go up hill, then back down again, one continuous test. Certainly a smaller brake system will be challenged on that test.

Any test can be designed to make certain your product shines. Smaller brakes may work better in certain conditions just as larger brakes can be better.

Just so you understand where I come from, I agree, that bigger does not mean it is better, but it certainly does not mean that it's worst either. If your driving habits are flat city speeds, maybe a larger brake system is not for you [and may be worst]. If your Vanagon is fully decked out ready to go camping and you hit the mountains on a regular basis, a well designed larger brake system may be just the ticket.

[fxr]

[IdahoDoug]

While I agree the mountain test with steadily heating brakes would likely show an advantage to a big brake conversion, I would not be interested. My point for years here on Samba has been "modify for long heat buildup and you're giving up instant response in an emergency." I stand by that situation as the brake capacity by far most relevant to people just driving their vans - that they may have unknowingly EXTENDED their emergency stopping 60-0 and 30-0. And they may have unknowingly caused the rears or fronts to lock if the situation also calls for emergency evasive handling under heavy braking. That's a huge problem. It leaves you and your van vulnerable in every day driving to the typical unexpected situation factory brakes are designed to help you with. There's nothing you can do about that random emergency that waits.

By contrast, when you are in the mountains you have the choice of being prudent and putting your flashers on and downshifting to a low gear and ambling on down using a well considered combination of engine braking and service brakes to control your speed. Or you can push it and explore the limits of your brake system's ability to shed heat, throwing prudence and caution to the wind. In addition, getting meaningful testing results for this requires a mountain pass and deliberate brake abuse to bring the vehicles up to brake fade heat levels where one vehicle is unable to slow properly putting Vanagons and people's lives at risk to declare a victory. For argument's sake, I will just give the win to larger systems however.

If folks feel that a win on a steady and amply anticipated mountain pass trumps the risk of longer emergency stops on snow, gravel, crowned secondary roads, wet roads, curves, etc then they can make their decision accordingly.

Doug
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Merian]

Some of you guys should fit the Porsche PCCB (ceramic) brake system. They are real nice and will tolerate a LOT of heat buildup
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[danfromsyr]

I don't have much to add to the brake pissing party
but I do have the BMW caliper/Mercedes vented rotor combo on my 1.8T powered van. and have traveled a fair share of Mtns in the last year on them.

I initially installed the ceramic pads that came with the 1984 bmw 7series 4piston calipers. and while they never faded from heat in my use.
I switched them out for the semi-metallic pad version. for better instant stop grab in a quick jab on the brakes.

by seat of pants engineering, I gained about 30ft stopping distance over the ceramic pads..

and the 1984 mercedes 300d ventillated rotors have kept their cool without issue.

with a 1.8T, 205/65/15 nokians, rear sway bar and loaded it handles mtns roads just fine now.
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[Butcher]

@idahodoug. I really appreciate where you are coming from and I'm glad you make your point on this matter. I truly believe that people when they work on their brakes do not focus on the safety aspect of what they are doing. There are way too many posts about bleeding and overall brake issues. If you do not know the basics of brakes, should you really be working on them, let alone modifying them with components that were never to be installed on a Vanagon.

By focusing on what the big brakes can do [and what they cannot do] will allow people to make their own decision on what's best for them. I just do not believe the issues that you point out are as big as you say.

Just remember, you can make a test that will make a small brake shine, but that does make it right. A fair test will show the pluses and minus's of both options. That is all I ask.

[IdahoDoug]

Butcher,

Thanks - kind words and respectful debate.

I agree I could find a test favoring stock brakes. Ironically, I actually think that most tests would favor stock brakes and only a few tests would favor the larger brakes most have installed. The big brake focus seems to be on larger components, which have their advantage once a vehicle has been on the brake hard and the components are at or near fade levels. Prior to reaching that heat level, its difficult to achieve "better" braking by bolting on stuff you found on a car at the salvage yard.

And a brake engineer will tell you that ultimate fade resistance is probably the LAST aspect you'd work on for a street driven vehicle. Other things like response when cold, when wet, balance, modulation, etc are well before that when human lives and vehicle control in emergency avoidance are at question.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Merian]

Brake torque is not an issue. That leaves heat buildup. (neglecting feel, initial lack of bite from hard "racing" pads, water spinoff, etc.)

Heat buildup will only be an issue on [1] a race course, or [2] a very, very long down grade from a mtn. pass.

[2] is pretty rare - there are a couple of roads out of the Sierras that could qualify (tho my stock '86 Vanagon did NOT have any heat problems on them).

There is one mtn. pass in the PNW that might qualify.

The fix for heat buildup is to duct in air, not to spend huge $$ on a poorly designed big brake kit, esp. when they are not engineered (excepting the SA Vanagons, which IIRC do have different brakes)
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[thatbaldwinlife]

My Small Car kit is better around town and on the mountains. My stock set up was pretty worn and it was not worth almost as much money to bring it up to tip top shape as it was to go with bigger rotors with much higher heat capacity. I am not going to put my flashers on and creep down a mountain when I can use the engine braking with my good brakes.
I'll wait for you at the bottom

nate
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1987 Westy
Insta: @Thatbaldwinlife
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