Friction tape or what for repairing wiring harness?

[Stanley]

I remember reading somewhere that friction tape is bad. Datsun left me stranded. It had been intermittently hard to start. Then yesterday it died on the road. It would start and idle OK, engine would rev fine, then it would die, tach dropping instantly to zero, no sputtering. Lights OK, cranks well, was running great at 4000 rpm. So I'm pretty sure problem is corrosion or an open between the ignition switch and the distributor. So I'm going to have to check out the wiring in that area. I'll probably have to replace some wiring and connectors, which means removing the old material that covers the wires. I want to replace all that wiring from the coil to the distributor - it looks really beat-up. So if I don't wrap it with friction tape, then what ?

Also, regarding that big ceramic resistor by the coil: does it's connection to the inner fender provide a necessary ground connection ? Because it looks loose.

[gwri8]

Here's what I've been using lately for stuff like that when I can't use heat shrink tubing. 

https://www.amazon.com/X-Treme-Tape-TPE-X36ZLB-Silicone-Triangular/dp/B00HWROLIG/ref=pd_yo_rr_bia_t_5?_encoding=UTF8&psc=1&refRID=HRDDD61QMTE67TQ4SC9F

 

[Namerow]

For the pragmatist, there’s not really a reason anymore to wrap a bundle of wires with tape.  Just go to your local hardware store and buy some of that split, corrugated plastic sheathing.  The ‘woven plastic’ sleeve is another contemporary alternative to tape.  Re-taping a wiring harness with tape is for purists only.  Decide which camp you belong to and proceed accordingly.

Adhesive-backed electrical tape doesn't really belong in the engine compartment of a car.  Sure, it'll look good after you've finished.  And it will probably continue to look good for a few months afterwards.  Over time, though, it's said that the temps under the hood will cause the adhesive to begin to weep out of the seams, after which the harness becomes a grime magnet and a gooey mess (won't be easy to clean either, I expect).  In hotter climates, this may even be a problem for the under-dash wiring harness. 

I recommend that you look into using 'loom tape'.

‘Loom tape’ is just wider-than-normal pvc electrical tape that uses no adhesive.  Back ‘in the day’, this is what vehicle manufacturers (including Nissan) used.  Loom tape is more expensive than high-end electrical tape, but it’s still relatively inexpensive in the grand scheme of ‘things automotive’.  I bought mine from a muscle car restoration parts supplier located north of Toronto.  You should have no difficulty finding a comparable supplier in your own area.  A 100’ roll sells for about US$13.00.  Find vendors by searching on, ‘automotive loom tape’.

Loom tape is typically 1.25” wide.  Other commonly-available widths are ¾” and 1”.  The loom tape that Nissan used on the S30 appears to be metric-spec -- on my 70 Z’s Engine Harness, it measures as 30mm wide (1.18”).  That’s only 5% narrower than 1.25” tape, so they’re essentially the same.  Metric-spec loom tape is available from vendors in the UK, apparently sold only in a maximum width of 25mm.  Also offered are 15mm and 9mm widths.

Loom tape is typically wrapped with a 50% overlap.  To create this, the tape needs to be wrapped at about 30 degrees off perpendicular.  Or, at least, that’s a good guide for getting started.  After that, you can just adjust on the fly so that you get and maintain the 50% overlap.

  The S30’s Engine Harness measures about 0.70” in diameter at its fattest part (i.e. about 2.2” in circumference).  When I stripped my 70 Z's engine harness (damaged and also covered with paint overspray) , I found that Nissan used the equivalent of 22 wraps per foot over the fat part of the Engine Harness.  Long story short, that means that a 100-ft roll of 1-1/4’’-width loom tape will be good for the equivalent of 26 ft. of the fat part of the Engine Harness.  Of course, the S30’s Engine Harness only runs at its fattest diameter for about 2 feet.  Conclusion:  A 50-ft roll should be all you need.  A 100-ft roll will leave you with lots left over for other places.  For the skinny parts of the harness, I laid a 6-ft length of tape out on my workbench and then slit it down the middle with a razor to create two lengths 5/8" wide.

Wrapping with loom tape is a two-handed affair.  You cannot wrap the tape around the harness using just one hand!  You have to pass the tape roll from one hand to the other on every single wrap, while also maintaining a bit of tension during the transfer (warning:  over-tensioning the tape serves no useful purpose and may, in fact, cause problems).  No amount of words can explain the actual wrapping process, but it’s not rocket science either and you’ll quickly figure out your own routine.  Probably impossible to do with the harness still in the car, though.

Tape all of the branches of the harness first.  Start about 3" from the 'device end' of the branch, wrapping towards the end.  When you get there, turn around and wrap back towards the harness trunk.  When you get to the trunk, do a couple of figure 8's, then wrap down the trunk for about 3".  Cut off the tape, and use a bit of regular electrical tape to hold down the loose end (you'll be wrapping over top of this when you're doing the main trunk).  Do all the branches first.  Then finish up by wrapping the main trunk.  I recommend starting at the firewall end and working towards the front of the car.  Once again, use figure 8's at each of the branch junctions.  When you get to the skinny part of trunk that goes across the front of the car, switch over to the 5/8" wide tape.

There's a very elegant technique for finishing a wrap.  It involves pulling the loose end of the tape back under the end of the wrap.  Too complicated to explain here (although I found it easy to perform after a couple of practice attempts).  Most people, I think, just tie off the loose end.  If you do all of this properly, you should only have one end where you need to tie things off.  I think you'll be pleased with the results.  Bonus of using loom tape:  If you make a mistake, just unwrap the tape and try it again.

Good luck!

[Captain Obvious]

I bought a couple rolls of the no adhesive loom tape for when I redid my engine bay harness. I used Elliott Tape EE 201. It worked really well, but there were a couple things I did notice.

First, I tried to purchase something that had the same gloss (or lack of gloss) as the original stock wrap. But even though I tried to duplicate the original finish, the stuff I ended up with is glossier than the original wrapping tape. And it's more than just "new and clean"... It's glossier. Not a huge amount, but if I was judging the car for originality, it would catch my attention and I would ding it for that.

Second, I've come to the conclusion that the original wrap DID have some kind of adhesive on it. Not the thick rubbery smeary adhesive on the ubiquitous 3M 33+ electrical tape, but I really think there was something there. That said, the non-adhesive loom tape that I used seems to stick to itself quite well and isn't going anywhere despite the fact that there's no adhesive.

I have only had it on there for one year (or was it two?) so I can't provide any longevity info.

If someone turns up a source for the "real" stuff, I'd be interested in a roll or two.

[Mikes Z car]

  Right after I got my 240 the ignition didn't want to let the car run (as I discovered) so I unplugged and replugged in the connectors on the coil and ballast resistor several times which did help by scraping through corrosion.  I also carefully very slightly squeezed together both sides of the female spade connectors on the end closest to the wires so they would grip better. 

  That fixed that, the only time the car didn't get me home I was a block from my house because, well, if truth were known I ran the thing out of gas.  Some of the new gas cans have safety spring loaded nozzles and I could not make gas go in the car.  So I poured gas into a glass jar a quart at a time so I could get enough gas in the tank to drive a block.  

[sweatybetty]

the ballast resistor does not need to be grounded. loose is ok

[Stanley]

That loom tape sounds pretty good. I'm only doing the coil to distributor harness part for now, keeping the job small since I'm busy with other stuff. Would like to replace any wires that carry some amps like the lights though, in the future - don't trust 40 year old rubber insulation. But for now, the new part will intersect a larger existing harness, so if it matches the look of the old harness that's a plus but not a big deal, main thing for looks is getting it wrapped neatly.

Found my DVM yesterday and tossed a bunch of junk from my truck during the search, so that was good. I used to have a basic auto electrical manual, Haynes I think, that would make the trouble-shooting easy, but it got moldy and I guess I tossed it. Would go get another one but my car won't run. The truck has no wipers and it's raining.

[Stanley]

Don't have to worry about matching the rest of the harness, it's not stock, just  regular electrical tape, starting to come apart.  Anything will be an improvement (famous last words).

Ballast resistor was shot. 50 ohms resistance is bad, right?. Came with the PS20 coil. Maybe too much vibration.

[Captain Obvious]

I wrapped my entire engine bay harness (from under the dash to the coil and both headlight stubs), and I used just over one roll. Point is...  I've got some left over from my work, and you're happy to give it a try. Use what you need and send the rest back? If you're just doing some stuff over by the coil, you won't need much.

Elliot EE 201. LMK if you're interested.

[zed2]

Consider 3M™ Wire Harness Tape 5078, Black, 1.0 mm

http://solutions.3m.com/wps/portal/3M/en_US/3M_Automotive/OEMs/Product_Center/~/3M-Wire-Harness-Tape-5078-Black-1-0-mm?N=4607+3292658863&rt=rud

or

Non-Adhesive Harness Tape

http://www.wiringharness.com/harnesstape.htm

Keith

[Captain Obvious]

zed2,

I don't think the first tape you listed is a good choice. It doesn't appear that it's for wrapping harnesses... It appears it's for attaching already wrapped harnesses in place so they don't flop around. It uses the very sticky acrylic adhesive like they use on foam mounting tape:

Recommended Applications

• Bonding of cellular urethane, polystyrene and polypropylene parts
• Securing wire harnesses to headliners
• Bonding impact relaxation pads to door panels
• Attaching interior trim

The second choice might be OK, but tough to tell since there's no real info on the product. As a matter of fact, if you take a look at the pics of the rolls, you can see that they even peeled the cardboard off the inside of the spools so you can't see the manufacturers name and part numbers and figure out who it's from. All you know is that it's impossible to find except through them, and it's 100% correct for all years 1955 to Present.   Marketing...

[Stanley]

Thanks, looks like I'm getting some Elliott 277, like C.O. I will probably have a bunch left over, though I'm redoing more of the harness than the original plan.

Also found this at wirecare. https://www.wirecare.com/category/braided-sleeving/split-tube-wraps

The F6 woven wrap looks pretty good. Probably a lot better than what you'd find at the auto parts store for about the same price, and easier than wrapping it.