Welder is setup and I'm practicing - check
Under the car and started to clean the metal for the mad dog mount - checkProportioning valve Pressure regulator is in my way to weld in the mount -
I like removing things from the car that are not needed no longer needed i.e. -4 engine mounts, relay board mounts. I read another post from 2009 that some members remove and put a T fitting in it's place. Is this a poor move? The car has an SC front end so the brakes have been upgraded, I assume
I can't believe the factory would have the audacity to place it right in my way knowing full well that this 74 914 would one day turn into a 6
So what are my best options here - relocate further towards the driver side and elongate the main line running down the center tunnel - and replacing the passenger rear with a longer line? Maybe there is just enough main line to get it out of the way. Looks like passenger rear has already been replaced once.
I just want to be where @http://www.914world.com/bbs2/index.php?showuser=24877 is right now
Also, thanks Metric AutoHaus for patching that small hole with a lap weld possibly causing this bracket to not sit flush
Installed a few variations of this mount and don't recall ever moving the proportioning valve. I thought the factory mounted them more to the left side?
There's other mount options, could always use a quick six bar. Some don't like them, but if you don't have a 200+ hp engine, they're fine.
I relocated the stock valve and changed the lines to fit.
I took out the proportioning valve. You don't really need it in a 914. Also depends on how you've upgraded your brakes. My front brakes are stronger than the rear, so I want as much flow to the back as I can get. I still lock up the fronts first .
I have a 75 and installed a T back in 1987 when I installed my first six in my car. Multiple auto crosses and emergency situations where i locked up the fronts and so far no problems. I have had many brake setups with no problems. I am currently running boxster brakes front and back.
Ok, I like what I am hearing. Time to "T" it up..."foooouuurrrrrrrrr" oh wait "sssiiiiixxxxxxx"
Simple version... it increases front bias at higher pedal efforts. So the rear is less likely to lockup in corners on not dry streets.
But so many factors have changed in the past 50 years that it is not really the safety switch it was designed to be.
Just to add to the various approaches: I'd suggest removing the factory proportioning valve (big, heavy, designed for a different braking system than the one you have, etc) and add an aftermarket, adjustable proportioning valve and T-piece. That way, you have all bases covered - adjustable if you want, otherwise set and forget.
I mounted to so it can be adjusted from underneath the car - I seem to have hit a good compromise setting as I don't find myself tweaking it at all.
Yes, that patch on the bottom of the panel will need some attention! Also, careful of weld heat near the loom - melted insulation at that choke point can cause all manner of amusing intermittent electrical problems in your future....
FWIW,
- Tony
I did the same, any thing not needed is gone. I had a T for 20 years of hard driving and stayed with it.
From the brake guru himself: https://www.pmbperformance.com/914-brakes/Late_Pressure_Regulator.html
Repeat after me, "Pressure Regulator" -- "Pressure Regulator"
That's right, this little beast is a pressure regulator, "NOT" a proportioning valve. It proportions "NADA". It is the first anti-lock brake device ever to be installed on a Porsche. Here's the story:
The 914 is a mid-engine automobile. As such, it has amazing handling characteristics... to a point. Once that point is reached, it can bite you like a rabid dog. It's a physics principle called "Polar Moment Inertia". We're all familiar with the childs play toy the "top". Here it is straight out of Mr. Elford's mouth: http://www.amazon.com/Porsche-High-Performance-Driving-Handbook-Elford/dp/0760327548
Porsche knew the issues with rear and mid-engined automobiles so, they installed this pressure regulator in the system to prevent the rear wheels from ever locking up. You see, if you lock your rear wheels in a rear or mid-engine car and your front wheels are anything but straight, you can be that "top" we were talking about and, that's not a fun toy at that time. This pressure regulator senses a panic stop (which it is set and locked at 525psi). Once it sees that pressure on the system, the valve body slides over and activates a microswitch which shuts off pressure to the rear wheels. This is a panic stop mind you, this device flows fluid like a "T" fitting until you need it. That's why we insist that it proportions "Nothing". Once the pressure equalizes in the chamber, it brings the rear calipers back into the circuit. This is "split second" stuff gang, not a leisurely event.
So, yeah, the internet guru's steered you in the wrong direction. You "never" want to replace this regulator in a street car and, you want to make sure it's operating properly otherwise, your rear calipers aren't even working and, that's 30% of your braking power.
Here's what we do; We will completely disassemble the regulator. We will zinc plate the spring housing and the valve housing. We will clean and reseal the valve body using new EPDM seals throughout. We will repaint the freshly plated spring housing and the valve housing. We will zinc plate the mount and the fasteners. We will then reassemble the regulator and reset the pressure switch to 525psi. We will then epoxy the lock nut just like the factory and send you back a perfectly operating pressure regulator that not only makes sure you and your passengers are safe but, it give you back your full braking potential so your 914 stops as good as it did when it was new (and that's still damn good my friends).
If you don't see your model listed here please send us an e-mail at sales@pmbperformance.com or call (855) STOP-101 (855-786-7101). We can usually get what you need within 1-2 business days.
Ah Jeeze - I guess I will think about relocating. I trust Eric when it comes to 914 braking.
Good news is I can continue to clean the metal.
My rear brake pressure regulator is mounted more to the left (driver's side) than what yours shows to be.
I have all the original rust, and then some. I do not believe it has been moved.
Brent thanks for that information. And Eric's top shelf service to our hobby.
Butt, this is only my observation. My 74 1.8 with big bore with cams and webers at many Road America, Blackhawk track days, over 100 autocross, has had a T when I started. A street car, driven to Porland Main PCA Parade, driven to Colorado Spings PCA event...driven all over, PAC events in the Mid-West. All the bad weather, high speed events and never had the back end come around. I would follow PMB but just wanted to give some my experience . Thanks, Mark
Sounds as though the consensus is: relocate the valve
Our /6 conversion has been moved to the back burner for a few months. I had a complex (3 hernias and a diastasis repair mid March), still recovering. I would recommend to make sure the base metal is clean/clean/clean and your welding skills are in order prior to securing the Mad Dog mount. Ours fit like a glove and I am sure it will never come loose.
Best of luck
I adjust my bias valve on the -6 race car nearly every weekend
Depending on grip and weather
I once tracked with the T and no bias valve on a 4.
Went off the track backwards at the end of a straight
Your putting a lot of weight in the rear (150 lbs) with a -6
Changing you balance
I’d want the stock valve on the street
I kept my valve, I cut and welded the mount to clear the valve in the stock location.
Which lines do you need to purchase?
I need to relocate my pressure regulator. I have the bracket I can weld back on, but want to install new lines first.
Can I just buy the two lines and swap sides? one is longer than the other.
Fuzzy picture of Maddog mount:
Attached thumbnail(s)
Thanks @porshetub I reached out to PMB to see if they have a relocate line set. Thinking just buying stock length lines for say an early 914 would be simple?
@http://www.914world.com/bbs2/index.php?showuser=2105 send me a PM, I have the angle, and the 8-12" piece to move them over.
Shea sells an entire SS setup, just need to pick early car to move it over. But if your keeping it steel I have a set just cover shipping.
@http://www.914world.com/bbs2/index.php?showuser=2388 , ordered a line set from PMB. Explained what I did, sent my fuzzy picture. I think I'm good. Guess I'll know when I get the lines.
Not a problem, I have been hauling it around with m for a few days now.
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