posted on July 07, 2014 11:01
The Road to Speed Week 2014 Part 2: The Progress Continues
Here we are just over a month away from Speed Week 2014. Project 240SX LSR has been under intensive surgery at both Specialty Cars Fabrication and 5523 Motorsports for several months. Asides from the suspension, the entire car has been disassembled including the drivetrain and electrical system leaving us only a few weeks to put humpty dumpty back together again. This time though, more powerful and faster than ever.
When last we left off, 5523 Motorsports was in the midst of revamping the entire electrical system with a custom wiring harness while incorporating an AEM Infinity 8 EMS and AQ-1 data logger. If you remember back to the start of Project 240SX LSR, we literally had finished the previous wiring harness on the salt hours before our first run at Speed Week… and it showed.
Each time we went to pull the center console or gauge cluster, things quickly spiraled into a nightmare filled with stray wires and failing butt connectors. The cluster f*ck residing under the gauge cluster was an appropriate place to start. What used to be made up of over 30 crimped butt connectors, the gauge cluster sub harness has now been consolidated by 5523 Motorsports into one termination with a MIL Spec circular connector.
John Kuchta repeated his magic by making a new center console so that 5523 Motorsports could reconfigure it too with new aircraft style switches. An Innovate Motorsports MTX-D EGT gauge and Wilwood brake knob have also been added.
5523 Motorsports used “spot ties” to harness all of the small wires running off the back of the various switches and gauges. Spot ties are nylon woven, waxed flat braids which are used to bundle wires. Spot ties are very strong, yet has a small footprint and their wax allows knots to be tied very easily. The center console harness was again terminated into a quick disconnect, circular connector.
Tuesday, July 08, 2014 5:36 AM
Wax thread is the industry standard for use in aerospace wiring and telecommunications wiring. Zip ties can easily be pulled too tight and will also chafe wiring insulation over time, which is a real problem in aerospace (high vibrations) and in telecommunications (extremely long service intervals).
Tuesday, July 08, 2014 7:29 AM
Good explanation Dusty, thanks.
Tuesday, July 08, 2014 9:32 AM
It should be noted:
MIL spec doesn't mean better. It always means substantially more expensive, usually more complicated, and (this is the really important part) often misunderstood.
In our case, we chose certain "mil spec" components due to their robust nature, and the inherent "this part CANNOT fail" design. Many of these parts are new "surplus" aircraft parts which are designed to survive similar environments while also not causing aforementioned aircraft to plummet to a messy early retirement!
The above picture shows our firewall connector panel populated with 3 of the 4 circular connectors (notice I called them circular connectors? That's what they are actually called. MIL spec is a military design specification which is bid on and often built by many different vendors.). For frame of referance, these connectors cost between $60-$300 PER HALF. If you get lucky and buy them with terminals, you're doing ok. If not, prepare to shell out anywhere between $0.45-$12 PER TERMINAL!!! The cost to benefit ratio is often hard to justify.... But when you embarrass the hell out of yourself at Bonneville on the starting line, that justification suddenly becomes tangible. Our car was plagued with bad pin fit, goofy grounds, and all around wonky wiring (due entirely to the "oh shit! We wasted the whole off season riding our mountain bikes and forgot about the spaghetti in the passenger foot well!).
A lot of people are accusing us of trying to build a space shuttle for the salt flats. Maybe we've gone a little overboard, but we want to set records, not lay upside down in a hot, broken race car trying to figure out why it won't start!
Tuesday, July 08, 2014 9:35 AM
dusty, on a more practical note, spot tie won't fillet your hands/arms when someone doesn't use flush cuts to trim the end of the zip tie! and zipties also have this weird mating ritual, worse than bunnies even, where they multiply exponentially for no good reason. you install one ziptie, and WHAM! 16 more show up just for good measure!
spot tie is awesome! it's more difficult to work with, but it forces you to audit what you are doing before you do it! not to mention the fact that it looks sweet!
Tuesday, July 08, 2014 9:54 AM
NASA cable lacing:
Tuesday, July 08, 2014 11:09 AM
i've got the NASA wiring technical publication. has all the requirements for harness/cabling, spot tying, terminating, butt connecting, etc. it reads like stereo instructions, but it produces results!
Tuesday, July 08, 2014 11:29 AM
I don't agree that half of the off season was "wasted" on mountain biking. DH MTB (and plenty of craft beer) is how I keep this temple of a body in the pristine shape it's in and my mind fully prepared for the recklessly high speeds of Bonneville.
And don't think you're going to win this debate with that tattoo intimidation crap again. I'm drawing crap all over my arms with a Sharpie as we speak to level out the playing field. How you like them apples Nickie?
Tuesday, July 08, 2014 6:33 PM
Serious porn in this installment. Chuck, I was happy to keep you away from The Zombie Doctor for a day to "waste" time... :)
Tuesday, July 08, 2014 11:46 PM
Amazing, no stone is left unturned here regarding wiring and fittings.
Wednesday, July 09, 2014 5:10 AM
Man, race harnesses have always been one of my favorite topics. The detail that goes into them is insane (often with a price tag to match) but the results of a quality harness are unmatched.
I can't imagine why someone would trash talk a race harness on a race car that happens to run in one of the most corrosive environments on the planet. I pretty much figured that most teams would be running something similar to keep out the corrosion.
Wednesday, July 09, 2014 6:35 AM
Since we are on the topic of wire harnesses, what's the best method of splicing wires? I guess splices are to be avoided but when you are repairing a harness or installing some add on you have to. I normally use solder but solder makes the wire brittle. I don't like butt connectors because the look ugly and sometimes don't crimp properly. I am guessing there are some more high tech methods.
Wednesday, July 09, 2014 12:32 PM
solder BAD!! lol. the "proper" way to do a splice is with an environmental splice. it's a very small (barrel is same OD as wire) barrel which is crimped using some very fancy tool and then has an adhesive lined sleeve which is heat-shrinked to create the environmental part. the "MIL SPEC" environmental spices are super stupid expensive!! there are much cheaper alternatives ($0.05-0.06 per unit as opposed to $4-5 per unit) available through such distributors as Del City. There are also solider sleeves which are better than manually soldering but less desirable to a mechanically crimped connection.
The real issue with soldering is that it's very very difficult to avoid the wicking tendencies of hot copper. Here-in lies the issue... the wire becomes rigid when the solder cools and it is very tough to determine how far the solder has traveled up the wire. in a high vibration environment such as a race car, the portions of wire which have wicked up the solder now become huge stress risers which will vibrate and ultimately fail! this is a bad day! most technical publications regarding proper wiring will list a manual solder joint as a last resort accompanied by additional instructions for lacing the harness on either side of the repair to properly stress-relief the solder joint. a slightly better option is a solder sleeve which has only enough solder in them to complete the job, but require a lot of patience to install properly. the solder usually has a higher melting point than the heat shrink sleeve which encapsulates it. these require lower heat applied for much longer than standard heat shrink tubing. you have to melt the solder completely without scorching the sleeve.
Obviously, you always want to avoid any wire splice, however, especially when making field repairs, it's often unavoidable, particularly when the harness is totally covered in DR-25!
Interestingly enough, in the aerospace world, most harnessing is done with no outer cover... unless required by environment (high heat situations, high abrasion situations). the link that Dusty posted above is a great example of how insane the lacing gets! the harnesses are perfectly round, and are laced approx. every 6 inches. you can see additional lacing which is used for securing the loom to the hardware, as opposed to the lacing which is used for holding the loom together. the specifications that these harnesses are built to is ridiculous! they have to measure the radius of any bend in the wire and make sure it conforms to the maximum allowable bending radius of the particular wire, there are very specific requirements for how a "break-out" should be assembled. the damn manual is 114 pages long! it even describes how much stripped wire should be visible between the sheathing and the terminal being crimped onto the wire.
Wednesday, July 09, 2014 12:32 PM
and chuck, shut up
Wednesday, July 09, 2014 4:13 PM
Thank you for your comprehensive reply! I will look into the environmental splices.
Wednesday, July 09, 2014 4:17 PM
Wasn't aware of Del City either, so thanks for that too.
Thursday, July 10, 2014 11:03 AM
The NASA manual is worth reading if you are going to wire a car. Following it to the letter isn't really needed, but it gives you a REALLY good idea of what is important in building up a solid harness that won't let you down.
FWIW, I've worked in aircraft electronics for 15 years and I would bet 80-90% of failures are related to connections and nothing more. Proper sealing to avoid corrosion in any connection is probably the most important followed closely by proper strain relief. You do not want ANY mechanical movement of the harness transferring into the contacts.
Just a personal opinion here, but I see these DR-25 wrapped automotive harnesses and all I think of is “I hope they got everything right and never want to add anything to the harness...” I’m trying to figure out an affordable alternative to something like the Icore and Glenair convoluted tubing setups. Very nice stuff that can actually be worked on, just crazy high price.
Thursday, July 10, 2014 12:50 PM
mike, we put a lot of thought into possible future changes and/or upgrades and there is actually extra wire already built into the harness (it's just looped back inside the harness.
you are absolutely right about the "i hope they got everything right and never want to add anything to the harness"... it's always a fear!
i also agree 100% about the failure comment - i can only think of maybe 3-4 cases in 20+ years where i've actually found broken wires, and it's always due to improper mid-run crimping and lack of stress relief!
Thursday, July 10, 2014 1:38 PM
Nice on the "future-proofing". Great work that brings out the wiring nerds.
Like was mentioned, "mil-spec" really doesn't mean much in itself. It has started to be thrown around A LOT in the car community though. LOTS of commercial wire is the exact same wire as some of these "mil-spec" wires and it simply doubles or triples the price.
There are some other "mil-spec" wire types that can knock 30% of weight out of the harness due to thinner high-strength insulation. Then there is tin, nickel and silver plated wire options depending on temperature range. High strength copper alloys that can be used in smaller gauge size on low current applications without fear of breaking the wire. The list goes on...
If you know what you are looking for, you can pick up surplus for about the same price as good commercial wire. It definitely takes some searching though and you are going to have a harness of all white wire...
Friday, July 11, 2014 1:13 PM
Did you guys rivet the brake line clips to the chassis? Any worries about corrosion there?
Saturday, July 12, 2014 1:50 PM
Wgo is the pretty girl? :D
Tuesday, July 15, 2014 8:08 PM
@dangermozer which brake line clips specifically are you referring to? we used rivnuts and adel clamps to secure the lines inside, earl's bulkhead fitting to transition to the outside of the car, and the factory retainer to hold the flex line in place.
@Tjonn I think you're referring to Moto IQ contributor Annie Sam. ;)
Wednesday, July 16, 2014 7:45 AM
Why did you put the exhaust back pressure sensor post turbo? All of the useful data will be preturbo.
Monday, July 21, 2014 9:22 AM
@ebturbo... there is a pressure transducer pre and post turbine, some of these pictures were taken before the pre turbine sensor was plumbed.
Saturday, July 26, 2014 2:52 PM
I really the direction this project is going, with all the technology and development in the chassis and engine. I beg of you please don't do an LS swap that would ruin the uniqueness of the car and negate much of the effort in the build in my view. If anything fine tune the aero after this part.
I did have a suggestion for corrosion control. A product called Boeshield T-9 http://boeshield.com/ A number of other teams that run the salt flats seem to like it. We use it in aerospace and I thought you might try that for your uncoated surfaces.
Friday, August 15, 2014 8:37 PM
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