Jamie Aust

Jamie Aust

Well Known Member
I have been looking all over for one. Every Auto shop I go to doesnt have them with a flat on each end so I can mount them in with a bolt.

I understand that I could just use some #4 awg wire and put the ends on myself, but thats not what I am after. I would like some flex in the lead.

It also doesnt help that I am in Australia :eek:

Any links to where you got yours would be great.

Thanks
 
From my Austin Healey

I've installed this one from AH Spares in UK on my Healey engine.
I don't remember the exact length, but seeing the picture I realize it might be a bit short for your application.
I bet you have a number of Healey specialists in Australia who might be of some help.
Cheers
 
Last edited:
Buy one of the available braided straps, remove the ends, and solder/crimp your own ends on. With a bit of shrink wrap on the joint they will look and work great.
 
Try boat/RV stores for a lot of the strange stuff. I didn't discover them until after I was done building.
 
Thanks,

I now can look at Austin Healey and Mini, around 1955-60s They both used them. So far my local boat and RV shop dont carry them. I also found out via Ebay UK, that have a few types on offer. I will report back when I get some.
 
If there are an amateur radio supply stores in your area give them a try. They have them in various lengths. Used to ground antenna towers.
 
I wouldn't use braided strap. I just replace one on my old Cessna and it was full of green oxidation/corrosion. My mechanic said that was quite common and they don't use them anymore for that reason. If you order the part number for the strap from Van's per their electrical drawing you'll get an insulated cable also. So you can probably just have an auto parts store make you up one. Put some dielectric grease on the bare end before crimping the connectors on.
 
mcattell said:
I wouldn't use braided strap. I just replace one on my old Cessna and it was full of green oxidation/corrosion. My mechanic said that was quite common and they don't use them anymore for that reason. If you order the part number for the strap from Van's per their electrical drawing you'll get an insulated cable also. So you can probably just have an auto parts store make you up one. Put some dielectric grease on the bare end before crimping the connectors on.
Click to expand...


Hi Mark, how old is the cessna, if I can 5 - 10 years out of it before I have to replace them, that would be ok with me. This is untimely as I just received a 100 ft roll of the stuff, from a local ham radio supply group. ( thanks to the member that pointed me in that direction ) only $37 for the roll. I wonder if clear heat shrink would help ? :confused:
 
5 + years

on my ground strap and no evidence of corrosion. I used strap from the ham store with copper terminals on the ends. I clean and inspect at each annual.
YMMV
 
Wire with insulation removed

Just use a large wire, put the lugs on and than remove the insulation. Most wires are vey flexible ones the insulation is removed.

Regards, Tonny.
 
Braid ends

One of the things we have done with braid is to fill the braid with solder for about the last 1/2"-3/4", depending on the braid width, then drill a hole in it for the washer and bolt. If you can get hold of one, use a Belleville spring washer with a flat washer that will serve to maintain pressure on the connection and also to act as a lock washer to keep the bolt from backing out. The best low resistance electrical connection is if you have at least 1000 psi on the joint. Let's say you're using a 3/4" diameter washer; that would be o.44 sq. in. Multiply that by the 1000-1500 lb/in. sq. and that says you would need a washer, or the sum of more than one washer, that would give 440-660 lb of force. These washers are available at McMaster-Carr and are very useful, also, on the prop bolts to maintain FP bolt torque in regions that have a lot of variations in temperature and humidity. To keep the joint from oxidizing, smear petroleum or No-Oxid grease on both sides of the braid, abrade it through the grease with crocus cloth or sandpaper, then assemble the joint without wiping off the grease. The 1000 psi will squeeze out any excess grease and the joint will always be clean and low resistance.
 
How long?

Hi gang.

I'm considering to order a grounding strap as mentioned earlier in this post.
Which length schould I order for a Lyc IO-360?
(engine to battery)

Thanks.
 
Another place to try...

...is the auto junk yards or the parts department for major auto manufacturers. Many autos have a braided strap bonding the hood (bonnet) to the firewall. The intent is to have a wire bond around the hinge attachment and spring assembly that bonds the hood to the auto's firewall.
 
Logic

nucleus said:
What is the logic behind using uninsulated wire for grounds?

Hans
Click to expand...

An uninsulated grounding strap is typically a bridge between chassis parts that might be electrically isolated, such as bridging the gap between the engine and the fuselage which is electrically isolated by the engine mounts. As it is at "ground" or "zero" potential there is no need to insulate it. The fuselage, engine mount, and engine are not insulated, so the "bridge" that connects them need not be. Having said that, there is no reason NOT to use an insulated cable as a grounding strap. I believe braided grounding straps are used because they are so flexible between parts that move (engine to fuselage, car hood to chassis, etc.)

Ideally, there should be zero resistance between the ground of the power source (battery) and the ground of the component using the power. Even a small, almost unmeasurable resistance can cause a loss of power to a component, especially things like starters that draw very high current. The AEROELECTRIC CONNECTION handbook has a great explanantion on this.

Don
 
Try McMaster-Carr

Here's another place that it can be bought in red or black by the foot, although I am not sure if there are any in Australia or what shipping costs would be.

http://www.mcmaster.com/#welding-cable/=844hcl

Red can be used for between the battery contactor and starter contactor.

BTW there is no reason to take the insulation off. My ground is the Van's version of battery cable and has been great for 9 years. I wish I had known about battery cable though. It is much more flexible. I just used a piece to redo the cable from the starter solenoid to the starter and it was much easier to route and clamp.

Ellipse - I'm not sure a Belleville washer works as a lock washer. It seems like it would put pressure up on the nut and would promote the nut working its way up the threads. When I've maintained or designed mechanisms with Belleville washers I've always used a pin instead of a bolt. The pin had a drilled shank and I used a flat washer and cotter pin to hold the assembly together.

Also, how do you convert the force required to get 1000 psi to torque?
 
Bubblehead said:
Ellipse - I'm not sure a Belleville washer works as a lock washer. It seems like it would put pressure up on the nut and would promote the nut working its way up the threads. When I've maintained or designed mechanisms with Belleville washers I've always used a pin instead of a bolt. The pin had a drilled shank and I used a flat washer and cotter pin to hold the assembly together.

Also, how do you convert the force required to get 1000 psi to torque?
Click to expand...

There is a common mis-conception that a lock-washer works by digging-in to the mating surfaces; that is not true. They work by supplying a tension force on the bolt or screw threads to give friction to prevent the threads from getting loose. Basically the same can be said for lock nuts that have fiber, nylon, or distorted openings. It is the friction which keeps the threads from loosening. The same can also be said for using bolt torque; this is just a mechanism to convert from twisting force to bolt tension to supply the needed friction. Torque is not a good way of setting bolt tension, since there are so many variables that affect the conversion from torque to tension. That is why when a precise tension is required they use a bolt that has some sort of indicating mechanism on it.
Once you calculate the clamping force required based upon the area multiplied by 1000-1500 psi, you look at the chart of the clamping force that is listed with the Belleville washers on McMaster-Carr or other supplier catalog pages. For instance with 3/4" braid held by a 3/4" flat washer with a 1/4" hole, the washer area is 0.393 sq in. For 1000 psi, the required clamping force is 393 lb. One #9712K64 1/4" ID X 1/2" OD tightened flat will give 383lb or two #9712K21 1/4" ID X 5/8" OD washers tightened flat will give 455 lb.
I also use a stack of four Belleville washers under each prop bolt; two one way and two the other with no safety wire. Safety wire won't keep a wood prop from coming loose if it shrinks! Belleville washers stacked the same way add their force together, and those stacked the opposite way have the same force but act over twice the distance. If you live in a region with lots of change of temperature and humidity where a wooden prop can shrink or swell and have a wood prop on your plane, you might consider using them. There have been several studies done about this use, the best by deceased Vance Jaqua if you can find it!
 
Last edited:
I'm mostly in agreement with you and am very familiar with load indicating bolts.

The real reason to use Belleville washers is to maintain the load on the bolt (clamping force) with changing conditions like a wooden prop slightly crushing. I still disagree though about their usefulness as a lock washer. They are trying to push the nut up the threads and off the bolt. I'd also point out that using an expensive Belleville when an inexpensive lock washer has proven to work just fine seems like overkill.

I'll study up on lock washers but for now will admit that I believe that lock washers, whether split or toothed, work by increasing the frictional force between the nut and the assembly or flat washer.

The bolt washer nut system is in a static condition and therefore the load between a nut and a washer without a lock washer will be the same as one with a lock washer assuming the same bolt tension. If the load is the same there must be some other mechanism at work to increase friction.

Like I said, I admit I may have bought into an old wives tale first told to me when learning to operate and maintain nuclear power plants and reiterated in engineering school.
 
Lock Washers

Here is what my Machinery's Handbook has to say: "Helical spring lock washers: these washers are used to provide: (1) good bolt tension per unit of applied torque for tight assemblies;..." and "Tooth lock washers: These washers serve to lock fasteners, such as bolts and nuts, to the component parts of an assembly, or increase the friction between the fasteners and the assembly." I would have expected more from this book!
 
Just another data point for braided ground straps. Summit Racing carries a line of straps. Looks like they sell several lengths - 8", 14", 18", and they are less expensive than B&C's.

What would be a good length on an RV-9A from the engine block to the ground tab on the firewall or battery?
 
You must log in or register to reply here.