Last week John-Joe Vollans started taking you through the fitting of a towbar, this week he gets it finished and even manages the wiring…

My Cars:
1975 Hillman Super Imp
1989 VW Golf GTI 16v
1990 Mercedes-Benz 190D

Last week I finished up by drilling the holes in the rear chassis member and spare wheel well to accept my towbar. The bar is fixed securely to the car by six long bolts and a set of large washers. Despite Mercedes-Benz kindly cutting some holes in the rear body, they didn’t drill them all the way to accept the towbar bolts, but it does certainly make life easier for aligning the drill.

Offering up the towbar by hand proved a challenge, mainly because the thing is pretty substantial and wasn’t easy to manoeuvre. Therefore, life was made infinitely easier by resting the towbar on a trolley jack and wheeling it into position. It could then be lowered and adjusted accordingly. Despite this, it still took three attempts to get it aligned spot-on. After the first two attempts narrowly failed, I realised that the furthest bolt to the front of the car (under the spare wheel well) needs to be aligned first.

With the bar in position, it was just a case of tightening up all the nuts and bolts (the furthest bolt needs a helper to apply pressure to either the bolt from on top or the nut from underneath, as no-one has arms long enough to reach both).

The physical towbar installation was the part I felt confident with, the electrical gubbins that went with it was another matter. My trailer is fitted with a standard light board consisting of brake, turn indicators and running lights. All of these have to be working, along with an audible buzzer for the direction indicators to comply with UK law. After toying with re-using the 12v socket that came with my secondhand towbar, I realised it was beyond repair and so bought a new setup and went about wiring it to the 190’s rear light harness…

A trolley jack is hugely helpful to support the towbar while you locate it in position over the pre-drilled holes.

Sept28-2

The same rearmost bolt emerged from under the car through this pre cut hole that had a grommet over it from the factory. Unfortunately a brake pipe union was in the way and needed to be gently relocated and tightened back up, before the bolt could be mounted correctly.

 Holes drilled and bolts positioned, it’s simply a case of tightening the bolts while a helper holds the top of the bolt with a spanner to resist the bolt simply spinning without tightening. All mounted up with washers in place and nuts tighten to the correct torque, the towbar is supporting its own weight and the jack can be withdrawn.

 With the towbar in place, the job is still only half finished as the all important (and legally required) rear light and audible buzzer needs to be wired up. Thankfully it’s blissfully simple to access the rear electrics on the 190, you don’t even need tools! As the 190 has no complicated bulb monitoring hardware, you can piggy back the appropriate lights with cable lock connections.

Opening the rear light panel, a helpful exposed connector allows you to test each wire in turn with a standard bulb tester as each indicator is turned on, the test light illuminates to indicate current. This identifies the wire for that bulb, which can then be bridged with a lock connector and run to the turn indicator, audible buzzer (required by UK law) and then on to the towbar 12v light connector on the back of the towbar.

With the correct wire identified all you need to do is pin a lock connector between the standard wire and the new cable for the towbar. However, in this case I needed to solder in an additional length of wire to allow enough reach on my towbar loom to connect to a suitable earth. In this case I used the earth point for the electric aerial.

With all the correct cables connected and tested, I made sure they stayed connected by locking the cable connectors with a pair of pliers and then wrapping them tightly in insulating tape. The new loom is in place and working correctly, the final stage is to finish wrapping the cables in insulating tape and securing it behind the rear panel.

All hooked up and ready to tow, it may seem like a lot of work, but fitting a towbar yourself is simpler than you may think and it saved me a lot of money. In total I spent £50 on the towbar, £30 on the new electrics and another £10 on parts such as tape and connectors. The total time spent was about six hours so barring the labour costs, it worked out at just £90, that’s less than a new towbar not to mention the cost of six hours labour!