Currently working on the wiring harness and found a couple wires in desperate need of replacement but they go through this plastic sheathing on the harness. Has anybody replaced wires through this sheathing? Should I just pull the wires out and try and jam them back in? I was also thinking I could just replace the sheathing, because it is 50 years old now, but how would I put new sheathing back on?
Thanks so much

Tie or tape a string to the wire you're replacing. Replace the wire & then tie the string to it. Pull on the string to pull the new wire back through the sheathing. Be careful not to kink the new wire. Electricians do this all the time when replacing wiring in conduit - especially with soft stranded wire. Sometimes a stretched out coat hanger works too if it's long enough. BTDT.

Pulling the new wire thru by attaching it to the old wire may work depending on the lenght of the wire.
They make lube for stringing wires. If it does not work you can cut off the sheath and replace it with shrink tubing. Not original but i think you are going electric so that may not be an issue.

There is no reason not to modernize it. A split loom of your choice and TESA tape for the ends. You are likely going to add wires thru the snorkel at some point.

Gander under the hood of a modern car for reference.

Factory sheathing was originally soft and flexible. Not so much decades later...
you could probably heat it with a hair drier to soften it enough to slide it off in one piece if you think you might want to use it later.

I have some sizes of black PVC tubing (I call it jacketing) that I use in making 914-6 engine harnesses. I don’t have a 914 right now so I can’t measure. Do you know what size you need? I also have large non adhesive heat shrink that might do well for you. With all due respect to Chris, plastic split loom would look out of place on a 914.

For your use-case, you shouldn't really rely on 50+ year old wires, especially if they're hidden inside a casing and you can't inspect them.

At a minimum, i would remove all the casing, replace anything suspect and then re-wrap the harness.

Jeff Bowlsby

If you really want to do wiring to a high standard, I HIGHLY recommend you spend some time looking at the wiring for @tygaboy LS conversion. I’m sure if you PM Chris, he would have excellent advice for you.

Electrical work is around page 192
http://www.914world.com/bbs2/index.php?sho...900&st=3820

The wiring in that project was done to a standard as if it were done by a professional .

The use of Deutche connectors, Kapton tape, and Raychem jacketing is the way to go. This will give you solid reliability and modern connection upgrades over the 60’s vintage connectors you’ll find in a 914.

Thanks everyone! So if I were to replace the PVC tubing itself, how would I thread all the wires back in? typically one would most likely just have a bunch of new wires without the connectors and add them on after everything was threaded through, but if some of my wires still functioned properly and had good strong connectors, I would preferably not want to replace those. How would you thread wires with connectors in? Just the same way as you guys described with the string?

Spend some time on YouTube learning how to de-pin connectors
https://youtu.be/Vt_rAIKPlWA?si=2n7Jm-KKKMoxBn8Q


The ability to de-pin connectors is a game changer and will allow you to run wiring through Raychem sleeve without worrying about fitting the connectors through. After the wiring is pulled through, re-pin the connectors. 914 connectors are very easy to de-pin vs other more modern connectors.

Use of spit convolute and the ability to put it on wiring harnesses without connectors having to be removed is its only redeeming characteristic.

@Superhawk996 - You're too kind! Thanks for the compliments.
@TINKERGINEERING - If there's anything I can help you with, please feel free to message me and we can chat. I think you'll really enjoy the world of electrical stuff!

so the spade ends that go into them will fit through just fine? thats the only thing Im worried about

You may have to remove the spade connectors on the ends but you can re-crimp them easily with a good crimping tool.

There's also no need to cut the connectors off at all, you can undo the factory crimp if needed.

I am currently adding lots of wires to my harness for the MS3Pro ecu. I have been putting them through the tunnel, and up the new snorkel tube to reach into the engine compartment.

I have found that you can use the existing wires, if they are long enough. Just pull one of the existing wires back until a section that was at the far end is inside where you need to start adding wires.

Then get a new, throw away wire, and tape it to the existing wire and pull it through the sleeve. Once it is in there, use it to pull the rest of the wires through the sleeve. The original wire is still in the harness, and you have your new ones pulled through.

Sometimes you have to break it into sections if you want to make it really go though the chassis. I can't pull wires though from the inside of the car and up through the snorkel all in one pass. I have to break that into two pulls, one from the inside to the outside, and one up the snorkel.

Hope that helps.

Clay

Undoing the crimping will usually leave a damaged wire. Usually, but not always. This is poor workmanship.

Crimp, solder, & then cover with shrink tubing. This is how Mercedes does it. Oh & BTW, don't cut any strands. Crimping alone isn't really quality.

You can get bailing wire at lowes/hd. Smaller in diameter than coat hanger and tougher than copper wire. Bend the end over as a hook and tape to the wire. You can't push wire thru but you can pull it easy enough. I've actually broken wire from pulling too hard because it was wrapped around other wires and the friction was too much.

The pins can be staggered to reduce the overall diameter if you are pulling a bunch at a time.

Most OEMs don't solder the connectors. It's debatable why, but if Porsche didn't do it then you don't need to.

Please be careful with this advice as it is a misrepresentation of the approved Mercedes repair procedure.

Crimping alone is standard practice in automotive wiring for new construction of harness.

Yes, there are instances where Mercedes authorizes a solder repair in the field, but they are not done with old fashioned soldering iron, and shrink tubing.

Click to view attachment

I'll add another issue you will have to overcome.

All the previous advice is for the standard automotive wiring that we are all accustomed too.

You will have MUCH higher voltage and amperage for your drive package.

I am well acquainted with standard 12V stuff; I don't have to research methods or tricks.

I would do a DEEP dive into the EV world regarding best practices for your chosen drive package. The EV geeks may have different procedures for the high amperage stuff.

Be careful here! You can hurt yourself if you don't have all of the necessary info.

One of my acquaintances, who is Tesla swapping an MR2, built a pretty serious electric go cart...
It "got away" from him in his shop and did a bunch of damage before they were able to kill it.
Had it been the MR2 folks might have gotten killed.
It was a wiring issue that caused the run-away...

If you haven't joined an EV forum yet that is the single most important thing you need to do IMO.

I've never even looked for an EV forum, so I don't have a good recommendation.

Maybe someone else does.

You need an "experimental" friendly forum.

A bunch of "tinkerers" is exactly what I'd be hunting in your shoes...

@TINKERGINEERING

This is a message I want your father to read!

If one of my children was doing what your daughter is, I'd DEMAND easy to access kill switches, both internal and external on the car.

I like the pull to engage/push to disengage big buttons, similar to the blade drives on lawnmowers.

The dash unit would be centered to allow activation by either passenger or driver.

The outside unit would be EASY to get to and I'd probably have "rescue" arrow pointing to it much like kill switches on track cars.

Imagine a first responder having to deal with the car. Plan accordingly!

I'd make it EASY to take the drive package all the way down.

I wouldn't allow any "test drives" before the "kills" were operational.

Hey there! Daniel here- Frances shared these posts. Yes Great intel and advice all around. Kill points are a great topic. ALA race disconnect style front an back is a good point.
Frances has teamed up and gone thought the LEGACY EV course for the HV side of things. Correct - completely separate system 2/0 3 phase separate control cabeling and BMS setups.
This current process of just getting in a 12v functioning harness is the job. This one has been hacked a bit so replacing strands with fresh ones and crimped solder and heat shrinked is happening. The rubber / pvc tube shrouds cleaned up nice and see to have a few more miles on them. Just the rubber snorkel need replacing it seems. This was a super confusing task months ago and now the confidence is with her and Frances doesnt want me breathing down her neck - exact words HA
So huge thanks to all of you for taking the time to chime in and lend your lessons learned here. truly
Best
Daniel

This is as clear as mud. So what do you recommend for a quality repair? Standard practice? These days standard practice is whatever is the least expensive. And what kind of soldering tool would you use? What I recommended is what Mercedes does. Look at what's in a 300E. I would post some pics if I still had the car. Please prove me wrong. I have an open mind, if I can still find it. Enjoy your evening.

Crimping is standard practice for automotive wiring not due to cost but because it provides a superior connection. A crimped connection is far more robust to the vibration that is ever present in automobiles.

Don’t believe me - take a look at NASA documents or how wiring harness are fabricated at the highest levels of Motorsport such as F1.

Click to view attachment


I don’t want to hijack this thread so please reference this link for more info and the link to the NASA document .
http://www.914world.com/bbs2/index.php?sho...amp;pid=2991842

With respect to Mercedes approved soldering technique: per my previous post, Mercedes recommends a Raychem solder sleeve, not a soldering iron. The reason for this is because the Raychem solder sleeve precisely controls how much solder is applied. This is to minimize the wicking of solder up into the wiring strands and to limit the possibility of thermal damage to insulation via a standard soldering iron.

Note: Mercedes vehicles from 90s (including 300E’s) also used wiring with biodegradable insulation that has a well documented history of premature cracking and massively accelerated, catastrophic deterioration so I wouldn’t necessarily consider everything Mercedes does with their wiring to be a gold standard of any sort.

Francis - this link to video from HP academy is a great video on why crimping is the preferred solution in both production automotive world as well as top level Motorsport.

https://www.hpacademy.com/blog/why-is-solde...ping-tech-talk/


https://www.youtube.com/watch?v=pOTrS6-mNtA?si=juq9mEb0He97_EzH

One more item of note.

For what ever reason when crimping is referred to, most people immediately think of the cheap red, blue, and yellow hardware store connections and low grade $5.00 crimping tool.

These hardware store crimp connectors will work well enough if done well but they are the lowest common denominator type fix that we usually see in the hobby.

When I’m referring to crimping, we are taking about quality crimping tools (which can be had for reasonable prices) and quality, properly sized terminals and butt splices.

Example of better quality butt splice:

Click to view attachment

Or example of Tygaboys work with open barrel butt connectors:
Click to view attachment

Click to view attachment

Francis, decide for yourself which method is best for a specific joint.

Just saying "always solder" or "always crimp" is short sighted IMO.

Soldering takes more skill to do properly and more prep than crimping.

If you have a bunch of wires going into gang plug crimping is better.

Usually crimping works better on new installations.

Crimping is ONLY effective if you use exactly the correct tools, terminals, and nothing goes sideways.

Splicing old stuff together below 16 gauge I'm normally soldering but I have a BUNCH of little things I do that most others don't.

I use more heat than necessary and as little solder as I can. I "spot-weld" my joints in a very short amount of time. I don't have much trouble with wicking.

I use a small drop of solder on the gun tip as my complete load. I'm not adding solder after applying the gun.

I'm under magnification and the solder has to go "chrome like" before I'm happy.
It will "wick" up into the joint if you're doing it right. Takes less than 1 second. Most of the time I'll get a little tiny mushroom cloud from the flux I previously added to the wires. Fans should be used for ventilation.

I don't have problems with "cold" soldered joints.

I fan the individual strands out and apply flux to all then twist them back together and remove the extra flux with a paper towel.

Two pair of hemostats are used as "heat sinks" on either side of my joints.

I quench my joints with a fairly damp cotton dish towel. This happens instantly after the gun is removed. This removes the extra flux that surfaced during the melt phase.

If I'm repairing multiple wires, I stagger my joints as to not have the connections next to each other. If you solder 20 wires at the same point you end up with a big bulge in the harness.

When I'm done there is no increase in resistance and the joint is stronger than the original wire.

All soldered joints are heat shrunk with #2 style shrink. This is the stuff with the glue on the insides and I verify glue "filets" at each end after the shrink.
I use a Gar-tech heat gun (made in Germany!) for all shrinking and I've made a special "tip" for it that forms an almost complete circle. The "shrinking" happens evenly and quickly. Using a lighter is not an option.

I don't have problems with corrosion down the road.

Crimping takes FAR less finesse but requires perfection in the tools and terminals.

Crimping is far easier to achieve nice looking harness, especially if your using brand-new high-end stuff like they do in the video.

Crimped gang plugs CAN be taken apart and re-assembled. This might be a hyper-critical feature to have.

When I'm done with a solder joint it's NEVER coming apart again and should I have to go back in, it has to be chopped out of the circuit, and sometimes replace with a small section of wire with a soldered connection on both ends.


This is the NASA style connection I use for splicing individual wires

https://www.youtube.com/watch?v=uhzXRIj5FaY

That guy would NOT like working for me!
His joint looks like crap.
He took 10 times too long to get it done.
He left a huge amount of exposed wire on either side of the twisted sections.
Mine looks like a 1/8 inch long rolled copper section that is the same size as the OD of the insulation. After the heat shrink is applied you CANNOT tell exactly where the joint is in the shrink.

So, rules are for fools, wise men (and women) use good judgment!

I've been making electrical connections in cars for 40 years. I've paid the price in burns, blood, and having to eat comebacks.

There definitely is a place for soldering in car repairs.

I have not had a failure in a solder repair in 25+ years.

Above 16 gauge I'll use a molex butt splice (as SH shows) and add the solder INTO the tiny open hole in the center. When you see the wires exiting the crimp go chrome, you're done. This takes a bit more time but never more than 3 seconds.

The best "standard" crimpers are made by Thomas & Betts Co out of Elizabeth NJ.
https://www.amazon.com/Thomas-Betts-WT111M-...mp;gad_source=1

I don't know if they are still built in New Jersey. Mine are old and NOT for sale.

And the Molex butt splice SH showed is the seamed style, I prefer seamless.
When using a seamed style, the "tooth" of the crimper HAS to hit exactly on the seam.
You have to bend BOTH sides of the seam in.

Hope this helps.

Thanks so much for looking out for me! I am currently just working on the original car accessories and lights and such in the stock wiring harness, but when I get to the electric components I will be sure to take extra caution and reference more people who are experts in that field!

This is awesome! This is actually really similar to how another on of my mentors told me to create strong connections as well and has been the method I have been using so far! It works really well. Thanks for looking out for me.

Crimp, wick in solder, & then cover with shrink tubing. Crimp & solder!!!

You want to minimize the voltage drop at the connection. Don't cut or nick any strands. I use a thermal insulation stripper to prevent this. Crimping alone does not make for the best current flow IMO. It can splay or put gaps between the strands. The solder that flows into the strands (or gaps) makes for an ideal conductor. If your wire is solid (not stranded) then crimping is "adequate." Mechanical vibration isn't an issue. I mean really, what's going to "pull" on the connection?

Okay. That's it. No more commentary from this old fart. Except... Just because you've been doing something for 50 years doesn't mean you've been doing it correctly.