Mrchntmarine

Just traded my 3.0 for a TDI and have a towing question the dealer could not answer. Have towed trailers less than 2000 with the old car, but now trying to figure out what actually controls the brakes on a trailer with almost 4000 lbs - would they be controlled through the trailer plug to the back bumper or will I need a separately installed module at the dash?

did a search on this here and there are a lot of posts re:brakes, but nothing that I could find that specifically answers the question. Tks

jim0607

The brake controller is not integrated so you would need to purchase one. The plug on the hitch is simply to control the brake lights on the trailer along with charging the trailer battery (when equipped).

MP4.2+6.0

Back up a step. Most common brakes on your average runabout boat trailer, big jet ski trailer or utility trailer (...if they have any brakes...), camper trailer, etc. are surge, not electric. There is no general electric control for that type of brakes--the trailer connector then only runs the lighting. The only exception is if a reverse signal is used to defeat the surge slave cylinder when you back up.

This common set up means they have a slave master cylinder built into the trailer tongue. The force of the tongue against the vehicle hitch as you slow down then pushes the trailer tongue parts together and puts pressure on the master cylinder inside of it to activate the brakes. The trailer has a whole separate hydraulic system that runs back to the wheels and either drum or disc brakes there. If you ever see a trailer with a boxy looking assembly about a foot long and four our so inches high bolted or welded just behind where you make the ball attachment with the tongue, that's the enclosure for the slave cylinder. If there is no such box, it either has electric brakes, or if a small trailer, likely no brakes.

Yes, there are electrically actuated brakes too, but I have typically run into/seen those either on bigger or older trailers.

From a 5 second Google search, here's a backgrounder blurb on the difference: http://www.redtrailers.com/ShowArticle.asp?id=2

K9 Guy

What type of brakes does the trailer have? If it's surge brakes you won't need any additional equipment. If it's electric brakes then check out these.

http://www.etrailer.com/bc-2014_Audi_Q5.htm

Also make sure you don't exceed the tongue weight of 440 pounds. This weight limit would also include anything you place behind the rear axle.

You might also want to research a weight distribution/sway control hitch.

Yoshimura

Tongue weight rating is only for tongue weigth. Q5 is not compatible with weight distribution hitch.

brutus23079

Merchantmarine, I asked my dealer a similar question. Told them many states require trailer brakes (by law) on trailers over 3000#, and since the Q5 is rated to 4400#, what brake controller did they offer for trailers with electric brakes. They didn't know. They called Audi. Audi didn't have an answer either. Told them that's an epic fail and pressed on without an answer from them. Saw on Clubtouareg that those folks were having the same issue. (Perhaps the Germans rely on surge brakes a lot?) I bought what the T-egs bought, a Tekonsha RF unit. http://www.etrailer.com/Brake-Contro...sha/90250.html Works well although, like the Touareg, I have to do the startup procedure every time I hook up, meaning the controller doesn't retain settings after its unplugged. Not a big deal, just something to be aware of. Using this unit avoids tapping into the Q5's wiring. I have the factory hitch (and more importantly its associated wiring) so everything meshes well together. And with the RF unit, you can switch tow vehicles by just moving the RF Controller to a different vehicle. If anyone has successfully used one of the wired options from etrailer, please let us know. I was just too chicken to try it.

Mrchntmarine

Don't have trailer yet - just doing the leg work anticipating getting a new boat heavier than what I use to have. Hopefully won't have to tow far - if i don't leave it on a lift, maybe 1/4 mile. In that case I won't worry about it. But if we ever have to move it to evacuate for a hurricane, that's another story.

Mrchntmarine

Hey MP4.2 - thanks for the link. Very helpful as that was my next question - what's the difference…
Brutus - pretty weird the manufacturers have no idea about this. Oh well, go figure. Thanks for the info.

MP4.2+6.0

If you do the tongue weight calculation in reverse, the rule of thumb I go by is a properly balanced trailer should have 6-11% of its weight on the tongue to minimize sway but not overload tow vehicle. Since 440 pounds max tongue weight is only in the 10% zone of the towing capacity anyway, the net is if the trailer is properly balanced, you will exceed the total weight tow capacity before you will exceed the tongue capacity.

Many trailers are not well set up weight distribution and tongue wise though--the front end 4x4 pointed up to the sky with the glaring headlights is the classic sign of a bad tow day, and the swaying trailer on the highway when dialed too much the other way is a really bad tow day. You have to know the backgrounder on it and have a trailer axle/spring set up where it is practical to shift the weight centerline. If it's a new purchase, make sure the boat/trailer shop dials it in.

zazzn

Hey all,

I saw that some people had towed cars.. Wouldn't that be exceeding the towing capacity of the Q5? Assuming the trailers are 2210 LBS according to uhal + a car 3000-3800 LBS would push your way 5210 if the car was only 3k. I want to tow my 91 toyota supra to a car meet, but I don't want to rent a truck. The supra is 3534, which would put this at 5744 way above the tow limits of the Q5. Yet I saw a similar car (subaru) posted as being towed in another thread. I'm new to towing and I'm assuming the rating is based on the chassis's ability to tow since I know my Q5 TDI can certainly pull this load without problem.