Author Topic: Making Brake cables for a Car.  (Read 14057 times)

Offline ParCan

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Making Brake cables for a Car.
« on: September 05, 2013, 01:21:16 PM »
Hi All

I have a small car with Cable operated drum brakes.
I noticed a cable has frayed so got some new Bowden inner and outer to replace all the cables.
This is the same 2mm OD outer and suitable inner I have used on Motorcycle clutch cables for years.

The original adjusters and nipples were all crimped on. A skilled job requiring specialist equipment which I don't have.

I have soft soldered low stress nipples before now. I have also seen Soft Soldered nipples pull off on things like Motorcycle clutches.
As this is Brakes soft solder is not an option !

Silver solder is the way I decided to go with newly machined Brass Nipples (CZ121 grade) and M6 Threaded Brass rod for the adjusters.

The nipples and adjusters were drilled through 2.1mm (for the 2mm steel cable) and then centre drilled.
Cable was passed through and Mushroomed into the centre drill so they can't pull out.

Cable and nipples/adjusters were well fluxed and warmed to a dull red. Silver solder was applied until it filled the nipple / adjuster and a nice fillet was at the bottom. 
A test was done by cutting one soldered adjuster to make sure it was full of solder all the way through.
It was.
All the flux was thoroughly washed off in hot soapy water or it will corrode the steel.

Installed and adjusted everything then did the foot to the floor test.

Ping and a cable broke right at the bottom of the fillet on one of the nipples.
Obviously not an acceptable situation !

Does silver solder react and weaken steel brake cable ?
Does soldering have another effect on the steel cable ?
Did I get it to hot / not hot enough ?
Any clues and ideas more than welcome.

Thanks
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Offline Lew_Merrick_PE

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Re: Making Brake cables for a Car.
« Reply #1 on: September 05, 2013, 02:15:30 PM »
ParCan -- This is false economy!  The fittings in question are designed to be swaged onto the cable.  Just about any good shipyard or airport mechanic's shop will have the tools needed to swage these parts for you.  My usual approach is to let them sell me the fittings (for about 2X what I could get them for through my sources) and they will generally swage things up for you for a reasonable donation to the coffee & pizza fund (I tossed $10 US into such a kitty last fall to have 8 fittings swaged onto 4 cables).  The fittings ran about $10 each (being fork and clevis types).  Using 3/16 inch (call it 5 mm) cable, the systems tested out to 2400 lbs proof load each.

Offline ParCan

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Re: Making Brake cables for a Car.
« Reply #2 on: September 05, 2013, 02:57:44 PM »
Hi Lew.
I had no intention of doing things that would not work. 2 evenings have gone into setting this group of 3 cables up.

It's obvious silver soldering is not appropriate so will go buy a cable set for the car.

These will be the first cables I have bought in like 30 years and my first failure at making them.
Ether that or Ill find a suitable shop who can put the ends on.

Thanks for your advice.
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Offline awemawson

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Re: Making Brake cables for a Car.
« Reply #3 on: September 05, 2013, 03:34:42 PM »
I'm guessing that heating the cable to silver soldering temperature has softened it. Presumably it would originally have been hard drawn, but the bit by the silver soldering would have been annealed.
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Making Brake cables for a Car.
« Reply #4 on: September 05, 2013, 07:57:30 PM »
The solder also wicks into the cable, and up it forming an irregular hard spot internally that fatigues easily. Swaging actually causes the metal to cold flow into conformance with the outer cable, but does not wick into the cable.
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Offline Anzaniste

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Re: Making Brake cables for a Car.
« Reply #5 on: September 06, 2013, 01:01:17 AM »
http://www.speedycables.com/ offer excellent service.

Silver soldering will have, as awmawson suggests have annealed the wire. Alternatively, if you rapidly cooled the joint you will have embrittled it. Either course of action is fatal to the high carbon cold drawn steel wire that makes up a brake cable.

If you ever have to go down the route of terminating a cable using a non mechanical method then the end of the cable needs to be un ravelled for a very short distance and the resultant "brush" needs to be drawn into a conical cavity which can then be filled with low melting point metal such as soft solder.
With a small diameter cable tinning using a soldering iron rather than a flame is essential(a flame will inevitably anneal the odd single strand here and there)
Typically the depth of the conical cavity needs to be 5 times the cable diameter and the included angle of the cone would be around 15 degrees.
This is an over simplification of what is a method of cable termination that , for safety's sake needs to  be tightly controlled.

As Lew says, got to an expert and pay.
Scrooby, 1 mile south of Gods own County.

Offline ParCan

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Re: Making Brake cables for a Car.
« Reply #6 on: September 06, 2013, 12:21:05 PM »
Message understood :)

New cables are not available so I will go to Speedy Cables and get some custom made.

Looking at the rest of the joints, I can see that they have all thinned so have definitely annealed the steel wire.

Thanks everyone for your help.
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Offline krv3000

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Re: Making Brake cables for a Car.
« Reply #7 on: September 06, 2013, 04:21:53 PM »
hi well as a  ex car nut ther is several ways to do this yes you can soft solder them but you need to mack a taper  in the sleve and a taper pin put the cabel thruw the nipel and put the pin in the midel of the cabel and hamer the pin in ones in then solder up or you can get boddon cabel crimpers larger vershons of wat you use for crimping your electrics on your car with i dont use brass as nipels i gust yous steel the other metherd is to cast the ends on i have seen it dun but have never dun it my self

Offline doubleboost

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Re: Making Brake cables for a Car.
« Reply #8 on: September 06, 2013, 05:21:26 PM »
We used to make up motor cycle brake cables
A large copper iron was used with "tinmans"solder
Soft solder with a high tin content
The same method was used to finish the termination on winding cables in coal mines
Wire rope terminations use a resin now instead of solder

All parking brake cables that I have seen have crimped ends
John

Offline ParCan

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Re: Making Brake cables for a Car.
« Reply #9 on: September 12, 2013, 04:19:27 PM »
5 X 1 KG of Frys tinmans solder arrived today from the Lab at work.
It's stamped 20660 so I think it's the correct stuff.
Cheep solder pot also arrived C/O Ebay.

Need some flux, was planning on Plumbers flux.
The white paste stuff is available cheaply everywhere so that's what I'll go for.
 
Same procedure as before. Put the nipple over the cable.
Un twist the wire for a few mm then clamp the cable and peen the ends into the recess made by the centre drill.
The plan is to dip solder the ends on using the solder pot.

Depending on time I may well attempt a video....
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Offline awemawson

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Re: Making Brake cables for a Car.
« Reply #10 on: September 12, 2013, 04:37:16 PM »
Oh my goodness. Please NEVER drive behind me.
Andrew Mawson
East Sussex

Offline vtsteam

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Re: Making Brake cables for a Car.
« Reply #11 on: September 12, 2013, 09:11:00 PM »
Or near a school.
I love it when a Plan B comes together!
Steve
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Offline dsquire

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Re: Making Brake cables for a Car.
« Reply #12 on: September 12, 2013, 09:38:01 PM »
ParCan

Or near a school.

Oh my goodness. Please NEVER drive behind me.

I'm not saying that this isn't going to be safe but I have to agree with Steve and Andrew. I think that at the very least you should make up a couple of similar cable and fitting joints and test them to be sure that they will not fail. We sure don't want to read about this in the newspaper. Be safe and have fun.  :D :D

Cheers  :beer:

Don
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Never let it rest,
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and your better best

Offline ParCan

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Re: Making Brake cables for a Car.
« Reply #13 on: September 13, 2013, 01:29:04 AM »
Guys: If these aint right they don't go on the car.
If they go on the car they will be adjusted tested and inspected at way beyond emergency braking.

Not even I am stooped enough to compromise on the brakes !

I can not buy these new, they don't exist as new parts any longer.
I could probably source some 2nd user with totally unknown history, no thanks.
The Adjusters are currently crimped on. The nipples are in fact not crimped. They are soldered with soft solder.

Plan B: I put back Frayed cables !
Getting them made is prohibitively expensive. If I have to go that way then it'll have to be.
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Offline DMIOM

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Re: Making Brake cables for a Car.
« Reply #14 on: September 13, 2013, 06:34:20 AM »
...snip...
Need some flux, was planning on Plumbers flux.  The white paste stuff is available cheaply everywhere so that's what I'll go for.
...snip...

ParCan,

I would be wary of the insidious long-term corrosive effects of some fluxes, particularly if there was a chance of some remaining in the interstices between strands of the cable. If such a problem did occur, they might be all right at first but gradually corrode cable where its under stress in the fixture... I'm sorry I can't point you to one that is safe, all I know is some may not be safe...

Offline tekfab

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Re: Making Brake cables for a Car.
« Reply #15 on: September 13, 2013, 07:07:40 AM »
You say "prohibitively" expensive ?  have you tried  a local yacht chandler/Rigging company ? boats use wire rigging from 2mm - 20mm (and bigger) and should be able to do whatever you need. You might need to have a look at their suppliers catalogue to find an end more suitable to your use. I did boat rigging and also architectural wire work and there's an awful lot of fittings available and the cost is not that much, but i suppose it does depend on your means.
What diameter of wire are you using ?

Mike

Offline vtsteam

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Re: Making Brake cables for a Car.
« Reply #16 on: September 13, 2013, 07:44:54 AM »
1.) you need to own a load tester and cycle the cables and understand and prove yield, fatigue etc.
2.) you need to do accelerated aging testing to determine the effect of moisture and vibration on the materials you use and the plumbers flux which will remain in your strands after your "soap and water" removal method.
3.) you might want to find out the actual measured temperature of your solder pot and compare to the tempering temps for the materials you will be using.

Putting a cable into and standing on the brakes a few times isn't "testing".

What happened to, "Ether that or Ill find a suitable shop who can put the ends on."

and, "New cables are not available so I will go to Speedy Cables and get some custom made."

A liability lawsuit could be a lot more expensive than properly swaged cables if word ever got out you'd done this after an accident -- even if the cables didn't break. And i expect when you have your car inspected and when you sell the car you will of course reference your plan here.
I love it when a Plan B comes together!
Steve
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Offline vtsteam

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Re: Making Brake cables for a Car.
« Reply #17 on: September 13, 2013, 08:37:13 AM »
What kind of car is this and what kind of cables? Maybe we can help you solve this availability problem with a little research.
I love it when a Plan B comes together!
Steve
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Offline tekfab

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Re: Making Brake cables for a Car.
« Reply #18 on: September 13, 2013, 08:57:48 AM »
1.) you need to own a load tester and cycle the cables and understand and prove yield, fatigue etc.
2.) you need to do accelerated aging testing to determine the effect of moisture and vibration on the materials you use and the plumbers flux which will remain in your strands after your "soap and water" removal method.
3.) you might want to find out the actual measured temperature of your solder pot and compare to the tempering temps for the materials you will be using.

Putting a cable into and standing on the brakes a few times isn't "testing".

What happened to, "Ether that or Ill find a suitable shop who can put the ends on."

and, "New cables are not available so I will go to Speedy Cables and get some custom made."

A liability lawsuit could be a lot more expensive than properly swaged cables if word ever got out you'd done this after an accident -- even if the cables didn't break. And i expect when you have your car inspected and when you sell the car you will of course reference your plan here.

LMFAO  He's not in the USA where they sue anybody for anything and do you think the original car builder went through all those tests ?  ;-)

Mike

Offline vtsteam

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Re: Making Brake cables for a Car.
« Reply #19 on: September 13, 2013, 09:07:26 AM »
I think the swage fitting, cable supplier, and swage tool manufacturer sure did.
I love it when a Plan B comes together!
Steve
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Offline awemawson

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Re: Making Brake cables for a Car.
« Reply #20 on: September 13, 2013, 09:10:41 AM »
Sadly the litigation culture is spreading to the UK as well.

I cannot believe that it is either sensible, responsible (or legal) to make your brake cables the way that you are suggesting. For a start it will count as a 'modification' as far as your insurers are concerned and will invalidate your insurance.

What is the cost of having them swagged professionally? Contrast that with the human cost that you could cause if your cables give way at the wrong moment. Could you live with the result and still sleep at night?

Just don't do it.
Andrew Mawson
East Sussex

Offline ParCan

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Re: Making Brake cables for a Car.
« Reply #21 on: September 13, 2013, 11:50:35 AM »
Ok OK OK
I give in.
I will try and find someone who can make them locally.

The Car is a 2000 SECMA Q-Pod Fun. It's an early model with the Cast Hubs and Cable Drum brakes all round.
This car was last produced early in 2002. Later ones had Hydrolic Discs.

I have made tens of cables before using Soft Solder and turned (or just a lump of bar sawn off and drilled) nipples.
I have never had a cable that I have made fail. Some in fairly heavy repeat use applications. 
The Copper iron I have used in the past is fairly small, generally used with whatever solder was available, usually electrical solder or plumbers flux and plumbers solder.

The correct solder has been obtained with a temp controlled solder pot.
I have the correct Inner and Outer brand new. The fittings that are good from the old cables can be reused.
I 100% Do not wish to risk My or anyone else's safety on the road.
 
After the 1st attempt which failed miserably, I tried again to source some new ones from the manufacturers in France. They don't have any.
There are none in the UK either. I simply can not buy them.
To get the set made was just over 200 + VAT and Postage which is insane.

I will nip over to Burnham and talk to the boat yards or try a couple of the places around Southend Airport.

I Understand all your concerns, and equally admit to having concerns myself.
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Offline vtsteam

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Re: Making Brake cables for a Car.
« Reply #22 on: September 13, 2013, 12:40:56 PM »
I love it when a Plan B comes together!
Steve
www.sredmond.com

Offline ChadA4MG

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Re: Making Brake cables for a Car.
« Reply #23 on: September 15, 2013, 12:33:43 AM »
That looks like a OHV vehicle sort of the equiv of a Ranger or Rino 4x2. 

Offline tom osselton

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Re: Making Brake cables for a Car.
« Reply #24 on: September 16, 2013, 02:27:47 PM »

Offline ParCan

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Re: Making Brake cables for a Car.
« Reply #25 on: September 18, 2013, 01:12:33 AM »
Yes. They are the UK Dealer.
They have not got any.
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Offline nel2lar

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Re: Making Brake cables for a Car.
« Reply #26 on: December 11, 2013, 10:10:05 PM »
ParCan
Do you by chance a picture of the cable and end? There got to be a mechanical holder that should work. Need some reference to size. Nobody wants to do micro work.
Good Luck
Nelson Collar

Offline Fergus OMore

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Re: Making Brake cables for a Car.
« Reply #27 on: December 12, 2013, 03:46:59 AM »
Get in the car, sir and go up to RAF Duxford and ask for an airframe fitter.