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thripplewood · 12-05-2005, 08:21 AM

Hello All

I have recently purchased an Airstream in the UK and I cannot get the brakes to work. How can I test the braking systems circiut, and does anywone have a wiring schematics for the brakes. I am told by Larry Metz although it was built as a commericial unit, it design is a 1998 21ft Classic. I have attached a photo for identification purposes.

Regards Thripplewood

markdoane · 12-05-2005, 08:43 AM

Thripplewood,

Welcome to airstreamforums!

There isn't really a schematic. You need a brake controller to go in the cab of the tow vehicle. From there, use at least 12 ga wire, all four brake magnets are wired parallel. Keep the wires equal length from where they branch out to the magnets.

The magnets are not polarized, so one wire from each magnet goes to the brake controller and one goes to earth.

You can check function and wiring by holding a compass near he wheel, the needle will deflect when active.

If you have a 'breakaway' switch it is also wired parallel to the brake controller.

Here's a generic instruction sheet for wiring a brake controller: http://i.b5z.net/i/u/1080235/f/Instruction_Sheet.pdf

dwightdi · 12-05-2005, 08:48 AM

Use this umbilical circuit drawing to find the output terminal on your car plug to measure the voltage at that pin vs ground. It should be 12 volts when the brakes are engaged hard if the brake controller was installed properly. If it not, take the car back to the place they put in the controller.

Link http://www.airforums.com/forum...ams-13217.html

If the voltage is right, plug in the trailer and have someone engage the brake as you listen at each wheel. There should be a klunk noise. If not, there is a problem in the wiring of the trailer. You will have to use a continuity meter to check for positive connection at each brake magnet. Maybe you want to turn it over to an experienced RV mechanic.

nickcrowhurst · 12-05-2005, 08:49 AM

Thripplewood, welcome to the forum! I don't have a scanner to send you a schematic, but the wiring is very simple. The main difficulty is in actually finding the physical location of a wire that might be broken. The brakes operate off 12 volts DC from the tow vehicle battery, unless the breakaway switch has been activated, when the trailer battery takes over. A wire, usually blue, supplies the brakes voltage from the 12 volt distribution centre (center!) below the front window inside the trailer. Near the axle, this wire splits into four parallel circuits, one to each wheel's electromagnet. The frame is used as the earth (ground in the USA).Check with a voltmeter that the tow vehicle electrical connector has 12 volts at the correct pin when the brakes are applied by a helper. Have you ensured that the wires are correctly connected at the umbilical cord receptacles? If not, we can supply pin connection details. Connect the tow vehicle umbilical cord. Check with a voltmeter that there is 12 volts at the distribution panel, and to the (probably) blue wire to the brakes when the brakes are aplled by a helper. If there is, jack up one side of the trailer, disconnect one brake wire at the connector between the wheel and the frame. Install an ammeter ( 0 to 20 amps) between the ends of the wires, and have a helper apply the foot brakes. If I remember correctly, there should be about 3.6 amps. Repeat with all wheels to establish the problem. If there is no current, there may be a broken wire inside the belly pan, or a circuit breaker may be open in the distribution panel. At the distribution panel, an alternative 12 volt supply comes from the trailer battery via the breakaway switch, which is mounted on the trailer A-frame. This switch operates when the trailer breaks away from the tow vehicle in an accident, and an umbilical wire pulls out the actuating rod. This wire is also blue on my trailer. With a good ammeter/voltmeter, you should be able to find the problem. If not, there are plenty of knowledgeable members here who will assist. Good luck.
Nick.

nickcrowhurst · 12-05-2005, 09:09 AM

One way to isolate whether the problem is in the tow vehicle wiring or the trailer wiring is to attempt to use the breakaway circuit to actuate the brakes. Disconnect the umbilical cord between the tow vehicle and trailer. Ensure that the trailer battery is fully charged (12.6 volts after resting overnight after a charge) and connected. Jack up one side of the trailer so the tires (tyres!) are off the ground. Spin the wheels to check they rotate freely. Pull out the breakaway switch, got to the wheels and attempt to rotate them. After a few degrees of rotation, they should lock. Replace the breakaway switch pin immediately, to avoid burning out the electromagnets. If the brakes don't work, you at least have a problem in the trailer electrics. If they do work, the primary suspect is the tow vehicle electrics or the brake wire from the umbilical cord to the 12 volt distribution panel in the trailer.
Nick

thripplewood · 12-05-2005, 10:54 AM

Hello Nick
Your last post is significant as there is a switch fitted to the A frame in line with the breakaway switch. when activated it acts as a sort of handbrake when the trailer is unhitched. Could this have burnt out the magnets in the breaks. also does brake activation rely on movement, because I am testing the brakes whilst the trailer is static.
reggard thripplewood

**Action** · 12-05-2005, 01:23 PM

The electrical part of brake system was not designed for full power apply to the brakes for long durations of time. I do not recall the amount of time that the system can handle, I think it's about 5 minutes.

>>>>>>>>>>>>Action

markdoane · 12-05-2005, 01:33 PM

Quote:

Originally Posted by thripplewood

. . . there is a switch fitted to the A frame in line with the breakaway switch. when activated it acts as a sort of handbrake when the trailer is unhitched. . . .

Thripplewood,

If the switch is in line with the breakaway switch, it is a way to disable the breakaway switch and prevent burning out the brakes.

This is a good idea as sometimes young lads with larceny on their minds will pull the breakaway clip while you are away.

On the other hand if it is parallel (not in line) to the breakaway you could use it as a handbrake.

TomW · 12-05-2005, 04:56 PM

Quote:

Originally Posted by thripplewood

... I have attached a photo for identification purposes.

All those windows!

I will keep your image in mind if I ever order a new Airstream from the factory

Tom

nickcrowhurst · 12-06-2005, 07:52 AM

Thripplewood had PM'd a duplicate of his post to me, and this was my reply:
Re: Braking Problem
Hello there, the switch fitted in series with the breakaway switch was probably added by a later owner to prevent some vandal pulling out the breakaway acttivator rod, applying the brakes for a long period, and burning out the brakes. The breakaway system must NOT be used as a parking brake. This will destroy the electromagnets through overheating, de-temper the axle spindles through over-heating, and rapidly flatten the battery. The 4 magnets will draw about 14.4 amps, and will flatten one battery in perhaps 6 hours. Bad news! Let me know how you get on, and we can talk you through the problems. We live in Calstock, Cornwall, but spend each winter in Florida in our Airstream. Good luck. Nick.

nickcrowhurst · 12-06-2005, 07:57 AM

And a second PM reply from me was:
Re: Braking Problem
I forget to reply about movement of the wheels. As I said in one of the posts to your original thread, you must jack up one side of the trailer, activate the brakes, and attempt to turn a wheel. After a few degrees of movement, the wheels will lock, and stay locked. They do not lock until there has been some movement. If you strip down a wheel you will understand that an actuating lever has to be pulled a short distance before the brakes will activate. Nick

Thripp, we usually use PM's for a discussion off-topic, that will be of no interest to other forum members. Your brake problems will be of great interest, and please let us know the final result. I feel bad about your Manchester weather, AND brakes that don't work! Nick.

thripplewood · 12-09-2005, 08:25 AM

Hello All

As promised heres my update on the braking problem I posted earlier this week. After following Nick's (Crowhurst) advice on how to check if the brakes were working or not I can now report the brakes are working !
Heres what I did:

Jack up the trailer ensuring enough clearance for the wheels to spin freely
Connect the umbilicle cord to tow vehicle
Whilst spinning the wheels have a helper apply the brakes
Continue spinning wheels
If the wheels stop spinning then brakes have been applied, if they dont stop spinning then further tests are required.
If as in my case the wheels did stop spinning even under pressure then the brakes are working.

I'd just like to thank you all for your excellent advice and sharing your knowledge of Airstreams to help me solve this problem.

Just one other question, I realised that if I had to do further tests which involved taking the wheel off, my UK wheelbrace wouldn't fit the wheel nuts, can anyone point me in the direction of a supplier either in the UK or the US who could supply the correct wheelbrace.

One happy Airsreamer signing off for now.

Best regards Thripplewood

3Ms75Argosy · 12-09-2005, 08:41 AM

in the size you need, attached to a long torque wrench will work fine. I don't have a newer unit, so maybe others can tell you about what size to use.

Can you please tell us about your unit? Will you be using it for recreational use, or commercial use? It is quite unusual, and very neat looking!

Can you post pics of the inside?
Marc
Welcome to the boards!

dwightdi · 12-09-2005, 08:51 AM

Unfortunately, we do not have wheel braces in the US so you would confuse the average auto parts clerk for asking for one. Airstreams usually have a 3/4 inch nut on them. I like the X handled variety of lug wrench. Gives you even torque and less likely to slip. You really need to have one on board at all times becuase the aluminum wheels tend to take a set after you install them and you need to check their tightness after the first hundered miles of travel after you have had the wheel off. It is important to do so. Many accidents have happened because the nuts were loose. You should also should have a torque wrench to properly tighten them to the proper amount. Afterwhile, if you use the X handle to get the proper feel of a properly torqued nut, you can do away with the torque wrench step because you know the feel when it is properly tightened.

thripplewood · 12-09-2005, 10:02 AM

Quote:

Originally Posted by 3Ms75Argosy

Can you please tell us about your unit? Will you be using it for recreational use, or commercial use? It is quite unusual, and very neat looking!

Can you post pics of the inside?
Marc
Welcome to the boards!

Hello 3Ms75Argosy
Yes the unit is unusual, I believe it is one of only two ever made by the Airstream factory in Ohio and was originally made as commercial unit which was used as a type of cocktail/food outlet. Also the person that had them made still owns the other identical unit in the US.
There is a sign on the inside wall which says "This establishment is authorised to sell food by the Arkinsas food dept" So I feel its safe to say the unit has spent some time in Arkinsas.
At the moment I'm in the process of stripping out the unit to suit a commercial enterprise which will also sell food on the major rock concerts throughout the UK.
I do have some photos of the inside before I started to strip the interior, would you be interested in seing them. If so 'll resize them and upload them onto the forum.
Regards Thripplewood.

**Action** · 12-09-2005, 11:34 AM

What's a wheel brace?

Would love pics.

Arkansas, hmmmmm isn't there a joke for that? Never mind.

>>>>>>>>>>>>>>>Action

thripplewood · 12-09-2005, 11:42 AM

Hello Action

A wheel brace is a form of wrench for undoing or tightening the wheel nuts on a car or tralier wheel. I dont know what you call it in the US.

Photos of the inside of the Airstream are now posted in my profles photo gallery.

Regards thripplewood

**Action** · 12-09-2005, 11:52 AM

Quote:

Originally Posted by thripplewood

Photos of the inside of the Airstream are now posted in my profles photo gallery.

NICE!

>Action

**azflycaster** · 12-10-2005, 05:59 AM

Quote:

Originally Posted by thripplewood

Hello Action

A wheel brace is a form of wrench for undoing or tightening the wheel nuts on a car or tralier wheel. I dont know what you call it in the US.
Regards thripplewood

Lug wrench

nickcrowhurst · 12-10-2005, 08:19 AM

My Airstream manual lists the torque for alloy wheels at 95 ft lbs. In the UK I would use a 3/4 inch AF deep socket with a 3 inch extension to a ratchet from a 1/2 inch drive socket set for initial fitting and removal, with an extension tube on the ratchet handle if necessary. For final tightening, the same socket and extension can then be fitted into a torque wrench. The folding type wheel brace popular in the USA can be seen and obtained at http://www.machv.com/follugwren.html
It's cheaper at Wal-Mart!
Nick