DIY 993 Beru Silicone Copper "replacement" Ignition Leads

[Traveller]

After 15 years, the original ignition leads on my 1995 993 were starting to show signs of age, physically.

Electrically, they were fine, but the ignition leads had hairline cracks in the insulation where they make tight bends at the valve covers. The heat from the adjacent mufflers accelerates this aging process; the leads within the engine compartment were fine.

At about $500 for a new Beru ignition lead set , I decided to just replace the actual leads and reuse the Beru caps at the distributor caps and spark plugs. Besides, after cleaning up the caps and testing them, they looked like the day they were manufactured.

This DIY is about making up your own set of Beru Silicone Copper Ignition Leads and where to place the cable holders along the lead lengths. Unfortunately, even after all these years, no one had taken the time to post lead lengths or the locations of the ignition lead hold-downs. Charts and diagrams are further down this thread.

TIP: while doing any work, taking digital pics during any DIY might be of help during the reassembly process.

My new Beru Silicone Copper Ignition Leads and original spark plugs caps...



Making your own set of ignition leads vs buying "replacement" leads:
I weighed the costs of making my own set of ignition leads against buying a complete ready-made Beru ignition lead set. Despite the high cost of the Beru crimping tool, I decided on the DIY option. I could have just bought a set of "replacement" ignition leads that are already being sold on a Porsche parts site, but I had doubts as to their quality since they are not made by Beru.

I discussed my intent to make my own set on a thread that someone started on DIY replacement Beru ignition leads. One individual on that forum did everything in his power to discourage me from making my own ignition wires; how I would be wasting lengths of wires trying to perfect my crimping technique and the hours I'll spend determining each wire length which would be difficult because they don't lie flat. Well all that data is right here for others to use.

The crimp shown below is my first crimp and its perfect and identical to the Beru crimps found on the original Porsche/Beru ignition wires I replaced.

A length of Beru 7 mm Silicone Copper Cable with a Beru M3 Terminal installed...


I performed a pull test to verify the integrity of my crimps using the Beru crimper. What failed was the stranded copper wire which "tore" at 58 pounds; the stranded wire had not pulled out of the M3 terminal.


Preparing the cable for a Beru M3 Terminal:
What is important is cutting the insulation square to the cable and not nicking any of the wire strands. The latter will/might cause failure of that strand in time; not the end of the world, but we do expect excellence...in a Porsche.

I made my own jig to do so. Using a tool such as a wire stripper would not provide those results.

With the cable insulation trimmed squarely, it ensures that the cable casing fully sits within the barrel of the M3 terminal. The advantage to cutting the insulation square is that it makes full contact with the end of the M3 terminal when it is slipped on. This provides a bit of extra friction against rotation of the M3 terminal on the cable. Although the crimp does that extremely well, why not take it that extra step.

The next step involves cutting the stranded wire to the correct length; 6.8 mm according to the indication on the Beru crimper.

Start off with a slightly longer section of stranded wire and cut it down a few thou at a time (you need good cutters to do this; your local hardware store will not carry those). If the stranded wire is too long, the M3 terminal will bottom out and spin on the end of the stranded wire and therefore, the end of the insulation will not make contact with the end of the M3 terminal. You want full contact of the insulation with the M3 terminal while also having the full length of the stranded wired within the M3 terminal for crimping purposes. When this condition has been met, you can crimp the M3 terminal; first the end to crimp the stranded wire and then the barrel.




Ignition Lead Length Data & Cap Resistance Specifications:


My "measured" cap resistances were included for information only. Yours will vary slightly.


Beru Ignition Cable Holder Locations:









Ignition lead placement and routing at the dual distributor caps:



Some will argue that the resistors within the caps will fail and that one should replace the whole ignition lead set. Sure they can fail like anything else can fail, even a resistor in the cap of a new ignition lead set. All my caps met the specified values and looked like new after 15 years.

Further information and pics are on my Beru Ignition Cables write-up.

PM me if you have specific questions.

[P-daddy]

Alex
Thanks for the detailed write up. I've followed many of your posts regarding this topic. However Im just too chicken to attempt anything like this. I just did plugs recently and did noticed one wire on driv side lowers had hairline cracks. I think an ign wire DIY is in the near future. Is there another purpose to the wire holders other than to keep the wires somewhat organized? Thanks

[Bill Verburg]

Nice!

[Traveller]

Originally Posted by P-daddy

Alex
Thanks for the detailed write up. I've followed many of your posts regarding this topic. However Im just too chicken to attempt anything like this.

Well I don't know what your level of comfort is. None of it is hard to do, but it can be time consuming depending on how picky you are as to how things are done.

For example, getting to the two center cable hold-downs behind the cooling fan/alternator housing is the most difficult. You can use special screwdrivrs that make the job a bit easier, but even those aren't the solution. Some will take the easy way out, loosen the intake manifold clamps (on a non-Varioram) and pivot the whole assembly up a tad to provide clearance to those screws. Everything else about the installation is easy.

Assembling the cables is a breeze once you have the info, which I've posted.

Although far from necessary, I personally went all out and removed everything above the engine cooling shroud. That gave me the room to work, it gave me the chance to inspect everything (2 clamps holding the main wiring harness needed replacing...the rubber liner had crumbled away) and it gave me the chance to clean everything.

It also gave me a chance to get to know my car a bit better. BTW, after all was re-installed, it started first shot.

Don't let the following pics scare you; going this far wasn't necessary...


The two pair of plastic nut inserts that are hard to acess are shown in the left half of the pic...

Originally Posted by P-daddy

I just did plugs recently and did noticed one wire on driv side lowers had hairline cracks. I think an ign wire DIY is in the near future.

I had those same cracks. Chances are your wires won't misfire even if you drive in the rain, especially if you use the OEM valve covers. I chose to replace mine sooner than later as I like everything to be in tip-top shape on my car.

Originally Posted by P-daddy

Is there another purpose to the wire holders other than to keep the wires somewhat organized?

Organized and held in place. You don't want wiring/cables chafing against anything.

[Arrowhead]

No offense, but that is alot of work and can lead to human error as far as making those 24 conection ends. I would pay the extra money for a complete set and remember the complete set comes harnessed together so not to make mistakes and all the wires are numbered not to mentioned new boots on both ends. I apauld you for taking the time and saving money but.

[Traveller]

Originally Posted by Arrowhead

No offense, but that is alot of work and can lead to human error as far as making those 24 conection ends.

Actually, 28 ends. You forgot the two coil wires.

Originally Posted by Arrowhead

I would pay the extra money for a complete set and remember the complete set comes harnessed together so not to make mistakes and all the wires are numbered not to mentioned new boots on both ends.

That is a right you have. Harnessed or not, the work is the actual installation.

New boots...if I put mine on the shelf next to new ones, I would bet you could not tell the difference.

Originally Posted by Arrowhead

I apauld you for taking the time and saving money but.

The little bit of extra time was worth it knowing they are made properly. As for the money saving part of it, not paying more than I have to for anything allows me to pay cash for things like my Porsche.

[Arrowhead]

I actually should'nt have said anything and I apoligize. You spent alot of time and research and I am sure you did an excellent job with the connections. I am sure it was a great learning experience as well. Most people would not attempt doing what you did and some would have problems in the end.

[Traveller]

Originally Posted by Arrowhead

I actually shouldn't have said anything and I apoligize.

Why, no need to apologize.

Originally Posted by Arrowhead

You spent alot of time and research and I am sure you did an excellent job with the connections. I am sure it was a great learning experience as well.

Provided one has the knowledge, skill and facilities, when you do anything for yourself, the job will always be better done than a store bought product. You also have to care. I consider time spent maintaining my motorcycles and cars as free therapy.

Originally Posted by Arrowhead

Most people would not attempt doing what you did and some would have problems in the end.

Well the internet is a great source of information, but as a co-worker put it, it is also the greatest source of unconfirmed information such as inaccurate information about solutions and products. You'll also come across those who try to discourage you from taking on DIYs.