Thread: How will brass shim last on towbar

Philip, as you know the brass is much softer and will wear out fairly quick, some lube may prolong the life of the shim, but if I was you I would drill the hole bigger to take a steel bush and press that into the tongue with the I.D. to suit your shouldered bolt, lubed with some Moly grease it should take care of the slop, local machine shop could turn up sleeve for you, Regards Frank.

Tank, the wear is on the flat surfaces of the towbar tongue and hitch tongue which wear only from turning the car left and right.

Another answer would be to turn down the shoulder of the bolt by 50 thou, or machine the tongue flat and the towbar tongue flat, then machine the shoulder to suit.

It's not smart to lubricate these areas as the grease gets full of dirt/sand on dirt roads and turns into grinding compound. Up until now I have used Lanolin Grease but even that quickly turns into grinding compound.

I can get a new assembly for about $75, but I am just hoping to prolong the life of the current one.

From what you have said - I gather the wear is from two sliding plates with a bolt lossley pinning them in location?
The bolt (in shear) is taking the load, and the wear is the result of sliding friction?

The brass shims will give some lubrication but will wear pretty quickly I would think?
Would the design be significantly compromised if you were to space the two sliding plates by 5mm or so? If not, could you insert some PTFE or some such that would give dry lubrication to the sliding joint. There are some amazing 'plastics' available these days that would I am sure do the job.

S

The brass shims will give some lubrication but will wear pretty quickly I would think?
Would the design be significantly compromised if you were to space the two sliding plates by 5mm or so?

The design calls for about 0.3 -0.5 MM gap which is enabled by the fixing bolt having a shoulder which is bigger than the towball fixing hole of the height of the hitch tongue plus the 0.5MM. The problem is that that gap has opened up through wear. This allows the hitch tongue to flop up and down a bit, which is amplified by the distance to the nylon bush of about 150MM, so that it flops 5MM at the connection to the trailer.
I am going away next weekend and will trial the shims. It is tight now.
Regards Philip A

I used to buy 3mm thick teflon (PTFE) sheet to cut out washers to reline the strut tops in P76 front suspensions. I machined solid rod for the vertical bushes. It is quite easy to work with and seems to hold up well. About the only common substance that will attack it is R12 refrigerant and that is just about all gone.

Can't say I've ever seen one....

How different is it to a Treg hitch??

Brass will wear if not tear if it's got that much movement. Brass is generally used as a shim where there is no movement against it ie under some form of pressure.

Brass is used in lock mechanisms because it is self lubricating. PTFE is good slippery stuff but I think it would be softer than brass and would be subject to gauging by grit as much if not more than the brass.

You have got nothing to lose by trying your brass shim.

Originally Posted by PhilipA

I have a Brisbane Axles and Trailer Components 3500Kg Off Road Hitch which has now towed the 700KG loaded camper over 10KK on corrugations and double that on road.
The design is like an ORAC with a tongue that swivels for side to side movement on a shouldered bolt in the towbar tongue which goes where the towball usually sits. It has a horizontal nylon bush for up/down which a pin goes through.

Any materials experts care to comment?
Regards Philip A

Hi,
Any chance of a photo?
Can't get my head around what you have.
Cheers