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Porsche Maintenance Tips

Newly Restored Brake Calipers From PMB Performance Make A Huge Difference

My 1976 Porsche 912E is a few years older than I am, and as such it deserves a little rest and relaxation lately. It’s lived a long hard life with a lot of abuse. My goal over the next few posts on the car are to get it back into mechanically tip top condition. The body is perhaps in need of some serious help, but for now that’s going to have to remain untouched. This car has earned its patina, but it doesn’t deserve to have all of this long-term mechanical neglect. It was pulled out of a barn in California about six years ago, sat in a shop untouched for another two years, and I’ve been slowly stringing it along since I got it four years ago. It’s lived too long like this, so we’ll jump into a few refreshing restorative projects.

First on the list is to get the brakes back up to snuff. I did pads and rotors when I got the car, but it’s never really been properly good at stopping since I got the thing. It needs a deeper dive into the system to get rid of a soft pedal and sticky caliper issue. I’ve done what I can do with my shade tree mechanic skills, so I figured it was time to call in the professionals. A quick discussion with my friend Eric Shea at PMB Performance netted me a slot in their lineup of caliper restorations.

The first step was to figure out exactly which calipers I have, because the 912E was built with both « A » type calipers and « M » type calipers. Measuring the gap between mounting ears on the caliper itself will tell you the difference, as they two have different mounts. The ATE A caliper is the wider of the two, as pictured below. If your measurement is less than shown in the below photo, then you have M calipers. This is important, because it will help determine the needed caliper rebuild kit and the correct fitment brake pads. I got a set of Hawk HPS pads for a little more spirited braking performance.

On a nice long Saturday I put the car up on jack stands and removed everything from the car. To keep everything sorted, I bagged and labeled the calipers, pads, and hardware separately. This is shown in the above photo. I then boxed everything up and shipped it on down to PMB for a full treatment.

As you can see from the photos, my car’s calipers have seen better days. They’re dirty, grimy, and have lots of baked on brake dust. It’s time for them to shed their skin.

PMB first strips the calipers down to their component parts before stripping the bare cores down to a clean metal finish.

Then the calipers are re-plated back to their original cadmium coating, while the brake pistons are polished to an anti-friction sheen.

All of the hardware is also properly cleaned and coated. The pistons are installed and fitted with seals and dust boots.

The caliper pistons are then pushed down into their bores.

And the dust boots are c-clipped to the surface of the caliper.

Each caliper is then re-assembled with new caliper half seals to keep them from leaking.

And the hardware is torqued down and marked to as-new spec.

Don’t they look so pretty? Almost too good to install on this scruffy lookin’ old 912E. Having seen the finished product with my own eyes, I can definitively say that this is well worth the $325 per axle price that PMB charges for the service. If I didn’t know any better, I’d say that they had a set of new old stock ATE calipers sitting on the shelf and shipped me those. These look absolutely back to factory, and their customer service is incredible. Well worth $650 for your Porsche and a bit of peace of mind.

The calipers returned to me a couple of weeks after I sent them off. PMB surprised me with a brand new set of pre-bent caliper hard lines, and fresh bleeder screws, which were desperately needed all around. The original pad retaining posts and butterfly spring keepers were all cleaned up and returned, as there are many of these little hardware pieces which are just impossible to find new. Make sure you don’t misplace yours!

It took me about two months between removal and re-installation, which explains the rust on the surface of the rotors.

With a set of fresh ECS Tuning braided stainless soft brake lines and freshly bent hard lines, mixed with the now bone-dry calipers, the system needed quite a lot of brake fluid to re-fill all of the lines. Because the 912E has a brake overflow line I couldn’t use my brake bleeder with the system, so I had to use the old press-and-hold pedal method. It took a few tries to get all of the air out of the lines, but it was still pretty straightforward, and super easy to do thanks to those new bleeder screws.

And now it’s back on four wheels with a fresh ability to stop better than since I’ve had the thing.

Now the tired engine needs a proper rebuild. Let’s go!

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What It’s Like When A 996 Turbo Goes Under the Knife for New Coolant Pipes

Yes, removing the Mezger is that daunting.

The one chink in the Mezger’s armor is its flimsy coolant pipes. For such a bulletproof motor, it seems strange that Porsche just glued the coolant pipes on. Though press-fitted, these coolant lines are known to pop off under high RPM load. Hoovie’s lousy luck meant his first trip to Heartland Motorsports Park was interrupted by his own lines popping off. Fortunately, this did not prompt a spin down the front straight, nor did it cook the motor. It was embarrassing though, and as it turned out, quite pricey to mend.

The Mezger motors that see the track will sustain higher temperatures and loads which are prone to make these lines disengage from the coolant console, and ensuring they stay in place during hard cornering and high revs requires a costly fix. While the cheaper band-aid fix would only set him back a few hundred dollars, the sensible approach costs ten times that. After dropping the engine, the hoses need to be pinned or welded in place, and the especially prudent drivers will replace the problematic OEM plastic elbows with stainless steel units.

The process of removing the engine is more labor intensive than dropping an M96. Turbos, intercoolers, head shields, and all the other forced induction ancillaries take a bit more time and effort. The starter and turbo inlets need to come out too, since they won’t clear the CV axles. With a few minor wiring hurdles cleared, the Mezger can be freed from its cramped confines. However, the process takes Hoovie and Wizard nearly two whole days to complete—which is why he was quoted nearly three large.

If there’s one piece of uplifting news here, it’s that BBi Autosport decided to help by offering to fix the busted water pipe situation. BBi, as well as a host of other Porsche-centric shops, can weld the coolant pipes in place for what should be a permanent fix. If you have any Mezger-powered Porsche, be it a Turbo or a GT3, you can preemptively have this work done, so it doesn’t come apart and leave you stranded without coolant. If you can remove your motor to get the « coolant console » out, as Mr. Hoover has, it’ll help save you a ton of labor.

Now you know. Let his misfortune save you a ton of time and money!

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3 Lighting Mods to Clean Up Your Porsche’s Exterior

While a strong enough will and disregard for appearances can stick LED strips to anything, it is not the way to aesthetic harmony for your Porsche. From the factory Porsche’s aesthetics tend toward distinctive, yet understated. While the brand is not immune to following the trends of the moment (I’m looking at you, side strakes on slantnose 911s), typical Porsche styling strives for a cohesive whole over flashy touches. In recent years lighting mods have changed radically over the last several decades. Previously, owners could move from sealed beams to H7 lamps, or add driving lamps. Today owners can pick from numerous types of emitters, consider lamp color temperature, or even use garish clear lenses and chrome housings. But such is not the Porsche way.

Where the lighting changes made to our project 944 were about as subtle as possible (you can’t even see my headlights when they’re off), EatSleepDrive has opted for a slightly more obvious approach. By delving into the Porsche parts bin he has subtly and effectively updated his 997. The video above provides a useful guide to installing a few common parts on 997s, including the front side markers, taillight assemblies, and license plate lights.

Being 997 specific, these tips don’t work for all Porsche owners, but do provide useful pointers. All of the parts used by EatSleepDrive came from the Porsche parts bin. According to the video the tail lamps carry Porsche part numbers, and are Tequipment accessories in Europe. The side markers are also European-market items, and the license plate lights come from the 997.2.

Light Modifications for Other Porsche Models

Because of Porsche’s often lengthy production cycles, this sort of parts-bin picking can be useful for all Porsche owners. US-market 911s were long afflicted with « sugar scoop » headlamp buckets and sealed beam lights, rather than the glazed H7 lamps used elsewhere in the world. That simple change can not only improve the appearance of your 911, but increase useful light output. By the same token, all of the pop-up headlight cars can be easily switched from sealed beams to H7 lamps.

Even More Choices For Transaxle Owners

For 914/924/944 owners, the quest for increased light output is even easier. Drop-in HID conversions can be used without compromising the look of your Porsche when the lights are off.

Owners of early Boxsters and 996s can use headlights from the 2002-up cars for a cleaner look. Porsche omitted the amber front turn signal from the « fried egg » headlamps following the models’ 2002 refresh. Outside of North America post-2002 cars also used clear front side markers, which are especially clean looking on light-colored cars.

From Porsche’s long history, what lighting modifications do you find most handsome, or most useful? Do they come from the Porsche catalog, or from the aftermarket?

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How Tire Pressure and Inflation Affect Your Porsche’s Performance

For those of us who drive on the street, tire pressure probably doesn’t get a lot of consideration. Porsche includes recommendations in the manual, and frankly, why not use them? Of course, when driving deviates from the daily grind, tire pressures become a lot more important. Whether using your Porsche for a track day, autocross, or road rally, more extreme situations than normal may require deviations from « normal » tire pressures.

The video above from Engineering explained does a good job covering the fundamentals of tire pressure and performance in the dry and in the wet. The video also covers important points such as how temperature affects tire pressure, and how tire pressure can affect tire wear.

991 Tire Pressures

The Modern 911 Perspective

The chart above is from the owner’s manual for 2017 911 Carrera 2 models. Let’s dive in to this chart a little. The 911 is rear engined, and runs a staggered wheel and tire setup, and this drives the tire pressure specification. The high percentage of mass over the rear axle requires greater tire pressure than the fronts for two primary reasons. The first is to carry the load of the rear mounted engine, and the second is to mitigate the oversteer inherent in the layout.

991 Carrera S

Lowering rear tire pressure would increase oversteer, and increasing it further would increase understeer. The opposite tire pressure to understeer/oversteer relationship holds true for the front of the car. In a modern 911, the wheel and tire setup is entirely designed around bringing oversteer in line. In addition to the tire pressure differential, the 911 runs a much wider tire at the rear than at the front(this is true in both RWD and AWD models).

944 Tire Pressure

In my case, this is no longer relevant because I am not running stock sized wheels.

Tire Inflation and Older Porsche Models

Porsche specifies a cold tire inflation number for all models. Into the 1990s, this information was generally on a little yellow tag under the fuel filler door, though it is also in your owner’s manual. These tire pressures are designed to tame the cars’ handling somewhat. In a stock, naturally aspirated 944 with the same size tire at all four corners, this was done by reducing the tire pressure slightly at the front end. Tire Rack has a helpful chart which helps to illustrate how several suspension setup changes, including tire pressure, can affect vehicle handling.

Unlike a 911, a 944’s mass is nearly balanced from front to rear. With equal sized tires at both ends, simply dropping tire pressures at the front will induce some understeer. While this will make the car more docile for inexperienced drivers, it is also easy to counteract simply by raising tire pressures on the front axle. To get the same net effect in a 911 requires both a differential in tire pressure and width. This is part of the reason early 911s have a much more well deserved reputation for tricky handling than later cars. Very early 911s use the same width tires front and rear. As time went on, the rear tires became much wider relative to the fronts, while weight distribution remained approximately the same.

Porsche 356 Technical and Restoration Guide

The Classical Perspective

Fortunately, these truths are pretty much universal. If you look back in the 356 Registry magazine archives(which I have a portion of in their Technical and Restoration Guide), you’ll see the same tire pressure advice. In reference to setting a 356 up for autocross, in Volume 8, Issue No. 3, Bob Napier writes:

« … with this setup I usually run 36PSI in the front and 34(PSI) in the rear. The higher front pressure partially offsets the low speed understeer tendency, and, on a real tight course, I might drop to 33 or 32 in the rear in an attempt to get the rear to come around. »

So whether your Porsche is new or old, monitor your tire pressure for optimal handling!

Resources on Tire Pressure and Setup for your Porsche:

 
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Horse Power vs. Torque: Better Known as Horse Power = Horse Poo

Have you ever wondered about the difference between Horsepower and Torque? These two numbers are probably the most well known specifications in the automotive industry. Yet, I didn’t feel like I really had a solid grasp on the differences. I had some idea of each separately, but I was missing just how they interact.

I started doing some searching on the web and then watching a few videos, but they were either too abstract or blew through a few too many important concepts. So, I went back to the math with the most important insight: Torque is measured, but Horsepower is calculated.

In this video, I go through the history of horsepower while calculating its actual value of 33,000 ft-lb/min. Then I go on to derive the equation that equates horsepower to torque and show just where that constant of « 5252 » actually comes from. You’ll be entertained and hopefully, have a little better understanding of these most important specs.

 
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