Electric brakes and towing

Am looking at upgrading my horse float and dad mentioned something about a float fitted with these needing to be towed only by a vehicle set up to cater for electric brakes - is this right!

He said its a long time since he's done a lot to do with brakes. the one I currently have are haudraulic and I don't like the way they shunt the vehicle

What kind of car are you towing it with!

Mitsi Challenger

you can fit controllers into the vehicle or use a simpler trailer mounted controller.

So if you want the option to tow with a different vehicle then u should fit it with a trailer mounted controller!

Also. can someone explain overdrive to me! I've always towed with manuals. Dad has just said it should be off all the time when towing, I thought this meant that it dropped it down a gear and so would use more fuel! And as I've always towed with a manual never needed to know about overdrive. I never knew about it even until probably 6 months ago

Leaving overdrive on for the most part makes the fuel economy worse not better, simply because it puts the engine under much more load.Depending on how heavy the float is the trans may not permit O/D operation anyway, or may want to kick down out of it at anything other than cruising at higher speeds on the flat or when any sort of acceleration is needed, or may cycle in and out of O/D, in which case it should be manually locked out with the button.If the vehicle is diesel the economy might not be affected so much but a V6 petrol would definitely use more fuel if the engine is allowed to labour too much.

To clarify, the OD on will give you better economy when not towing and under light loads but worse economywhen you have the vehicle under load or towing.

Ok so for normal driving - OD on ie "normal driving" in my sense

and for towing OD off - so the button on the gear stick IN and "od off" lit on the dash - good to know!

In my mind I always consider something ON when the button is activated and a light on, which is why I think I'm so confused about the OD on/off thing

Electric brakes are, in my mind, a good idea. You say that the existing override setup "shunts" the vehicle. Is it one of those old Hydradisc couplings! If it is it is probablypast it's use by date. They have a hydraulic damper system in them that fails and they are not worth fixing. The new ones have a great big spring in them for a damper and are bomb proof. Might be a lot cheaper to replace the coupling than to fit electric brakes.

Most override couplings have options for spring weight.The couplings are commonly 2.0 or 2.5 tonne ratings.On some the spring tension can be adjusted a bit.
If the trailer is "shunting" the tow vehicle, then the first thing I'd look at is that the brake master cylinder may need adjusting.Set up properly, it should have minimum free play from when the override coupling starts sliding, but must not cause the brakes to bind when the brakes are "off".If there's too much free play, then it'll cause shunting, then a thump as you accelerate again after braking.Should be relatively easy to check and adjust, but you may want to road test it as you make adjustments to make sure you get it right.
If the brakes aren't working very well for some other reason (bad or poorly adjusted callipers/pads/disks etc, or if the master cylinder is too small) then that's going to exacerbate any issues with badly adjusted master cylinder as above.
During a WOF check for a trailer, they'll usually check the brakes by jacking up the braked wheels, turning them by hand, then just seeing if they lock up when someone actuates the brakes via the master cylinder by hand, check to see that they don't bind when the brakes are released, visual check of callipers/disks/hoses etc, and that's it. This doesn't check brake efficiency/adjustment.But there's no easy practical way for a WOF garage to do this, especially given that the trailer is probably unladen when being tested.So, if you're not confident to set up and adjust the brakes, take it to a garage / brake specialist.
If after checking/adjustment the brakes still aren't very efficient, and/or get very hot in normal use you could consider adding a second pair of brakes to the rear set of wheels on a tandem trailer.

Never tow with OD on, unless it's specifically recommended as okay to do so in the car's handbook.
"OD" isn't actually overdrive, it's just a lock up mechanical clutch in the torque converter, not an "extra gear" in the auto gearbox itself.When towing there's more strain on the clutch mechanism, with more slippage as the clutch engages/disengages each time, the OD will probably automatically engage and disengage much more than usual (unnoticed by driver) frequently "hunting", there will be more heat build up, and more wear.Next result can be catastrophic failure of the auto gearbox, and a very large repair bill.I've seen this happen time and time again, usually with people towing caravans or large boats.It really stuffs up people's holidays.

WOW. Somuch info!

"If there's too much free play, then it'll cause shunting, then a thump as you accelerate again after braking." This is exactly what its doing, I knew there was something wrong with the brakes when it came back from getting a WOF. The handbrake bit where you push it forward - instead of there being "squishy resistance" there is nothing. Just pushes into flat nothing. The man said it was fine so I believe him.

No wonder my horse has started being an arse to float >:/

Could be that the brakes crapped out between WOF check and driving it home.Not as unlikely as it sounds.
I presume you'll be getting it fixed, rather than fix it yourself.
Probably the master cylinder stuffed - they're usually cheap to replace for trailers.If the fluid in the reservoir has just dropped so it's been pumping air, then they need to find out why - could be leaking somewhere.The reservoirs are often small, so fluid level can drop quite quickly as the brake pads wear, which is why you need to check the fluid level regularly.The caps on the reservoirs are often a problem - they seem to deteriorate in the sun quite quickly.If parked outside for long periods, you can sit something like a old cup over the top of them, to protect them from the sun.

I'm going to get the father in law to bleed the brakes, see if that helps, have a general look - him and my fiance are crop farmers who maintain their own machinery so they should be able at least to have an initial look and then yes I will get it fixed. Thanks for the info everyone, happy holidays :)

Bleeding them is the first step - see if the master cylinder is still pumping ok.
If not, replacing that and bleeding it again isn't hard.Supercheap/Repco etc sell generic branded ones in blister packs for $40 and up.If there's a leak somewhere, BNT should be able to supply hoses, pipe etc. I saw some "one man" bleed kits for $10 at the local hardware shop - these are handy. You'll need a tool to flare pipe if doing any pipe replacement, preferably a crow's foot style wrench to undo seized brake fittings without munting them.
If you need new callipers, this company make some nice machined alloy (marine anodised if required) dual stainless steel piston callipers, which use holden pads, and fit standard trojan style mounts and disk hubs.
They may need spacing with washers to centre them on the disk, but I like the idea of dual pot callipers for trailers.
http://www.transitengineering.co.nz/