Towball problem

[Christech]

The van has been in storage since last July and on checking the detachable towball this week, I've found that it has had some rusty areas. I've got rid of the rust but there is slight pitting in the towball where the rust was.

I'd appreciate some advice as to what's the best thing to use to get rid of the pitting - I'm assuming that it would take ages using emery paper!

Many thanks

Chris

 

[Gagakev]

Chris for the sake of less then £20.00 (assuming it's the normal alko type) I would replace the towball altogether.
If you "grind" down to get rid of the pits my assumption would be that the ball would no longer be
the perfect shape. Will give you piece of mind as well.

 

[WoodlandsCamper]

I've seen new towballs with pits in them, so does an odd pit or two matter?

As it is a detachable ball a replacement could be quite expensive. Could you have kept it at home in the dry?

 

[Christech]

It was kept in the garage but I can only assume that it wasn't dried out before storage.
Could be an expensive mistake as it's a Volco XC90 detachable towball. hmy:

 

[WoodlandsCamper]

Does your caravan have a stabilized hitch or not? If stabilized (with 2 pads) then they only rub on the sides of the ball - where are the pits? If non-stabilized then the grease will fill the pits in any case.

 

[Christech]

The pits are mainly to one side unfortunately.

 

[JTQ]

The pits if only on the ball itself and unless massive will almost certainly not effect the towball's strength, nor the stabiliser's friction to much of an extent, but could to the wear on the stabiliser's friction pads.
Pitting in the shank area under the ball would be of more concern, but even there needs to be quite marked.
A photo would help give a more considered opinion but from what I sense is being said, that they are no more than could be addressed with emery cloth, then I would use it but keep an eye on the stabiliser's "wear" indicator. The replacement pads if subsequently needed will only cost sub £30 and are a 10 minute easy DIY replacement task.
I would definitely not be attacking it with any vigour using emery cloth, you have correctly taken off the surface rust, I would leave it at that.

 

[otherclive]

I had a problem once on a car that I bought. I used Belzona which is an epoxide compound used extensively in the marine industry for repairs to castings and bearing surfaces. But these days two part epoxy compounds are readily available at DIY and automotive outlets. They come under various names but you just cut a slice and its like a soft putty which you mix by rubbing it in your hands. Then apply to the towball and after 10-20 minutes its easy to sand smooth. It will then have no effect on the stabiliser performance but will prevent friction pad wear and dirt pick up.

 

[ProfJohnL]

I had a problem once on a car that I bought. I used Belzona which is an epoxide compound used extensively in the marine industry for repairs to castings and bearing surfaces. But these days two part epoxy compounds are readily available at DIY and automotive outlets. They come under various names but you just cut a slice and its like a soft putty which you mix by rubbing it in your hands. Then apply to the towball and after 10-20 minutes its easy to sand smooth. It will then have no effect on the stabiliser performance but will prevent friction pad wear and dirt pick up.

Hello Clive,
I'm very concerned with your suggestion of using an epoxy compound to repair pitting on the surface of the tow ball. The conditions and function of the surface are very different to bearing shells, and whilst the properties of some epoxies may be compatible with the function you describe, I think its very uncertain they will be suitable for a tow ball used as part of a friction stabiliser.

Stabilisers rely on the very high sheer strength of the tow ball surface to resist the motion of the friction pads. The pads whist may have the appearance of being smooth, actually have very very fine abrasive properties. If the tow balls were not so hard and strong they would wear away quite quickly.

The characteristic of the epoxy you describe where the cured compound can be shaped by common abrasives gives a clue to it poor sheer strength. The action of a friction pad in a stabiliser will be like an abrasive to the epoxy. The secondary effect is the dust from epoxy compounds is usually very fine and is rather like talcum powder. Talc acts like a lubricant which is contrary to the required function of a stabiliser.

I cannot recommend common epoxies for this repair.

In practice I don't think the pitting is likely to be a major problem unless it is significantly reducing the surface integrity and reducing the nominal diameter of the ball, and consequently I don't think any remedial action is necessary, It does make sense to protect the ball form future rusting, but do ensure any protective coatings are removed thoroughly before use.

 

[otherclive]

Well John I used an epoxide compound to repair significant corrosion pitting on the drum brake of a ships crane which had brake shoes analogous to the stabiliser-tow ball situation. It was agreed by the DNV surveyor as a permanent repair subject to periodic inspection. The OP describes minor pitting which without a picture and location cannot be fully understood, but if left it could itself harbour dust which would wear the pads. So perhaps best to just fork out for a new tow ball. Even a detachable one doesn't cost the earth.

 

[starlightdj]

Hi
I have an XC90 with detachable tow ball, but must admit I leave it attached to the car most of the time.

It has a small cover on it but even so when I remove it there is always some sign of surface rust.

I usually give it a quick rub down with fine emery paper then wipe it over to clean any muck off.

It always has some very slight pitting to it, but nothing that has ever caused a problem.

Like others have said as long as there is no major deformity to the shape, I wouldn't think you have any issues.
Cheers
John

 

[Christech]

Thanks for your replies folks.

Having spoken to a caravanner who is also an engineer, it seems that the state of the towball is borderline, so for safety's sake I've bitten the bullet and bought a replacement.

Just goes to show - you need to keep an eye out and make sure that your towball is kept free from rust!

 

[emmerson]

As some of the other members have suggested, i think this is a storm in a teacup!
The towball is a solid lump of 50mm diameter steel. It would need some pretty severe pitting to make it unsafe, more I think than would be possible in a normal lifetime (of the ball, that is).

 

[MichaelE]

Agreed , "slight pitting" is what has been said , i wouldn't change a tow ball for that

 

[colin-yorkshire]

hi all,
here at last (long story) but still cannot get to grips with the Gravatar icon thingy. will leave that while later I think.
anyway to the topic. I think Clive's suggestion is a good one if one is really bothered about a bit of pitting, and with respect to the Prof, one can get a little carried away with the abrasion technicalities unless one remembers that it is a pit one is filling and not a large area of wear,
a pit is just that a small deep indentation, seeing as the edge of the pit and the surrounding area is steel it is most unlikely that given the surface area of the pads in relation to the pits they would ever grind away the epoxy resin,
personally I don't think a bit of pitting is any thing to worry about hmy: my old ball's got a few pits in it but still works without a problem

 

[xtrailman]

Its the diameter of the ball that's important, it's wear, a few pits are of no importance.
My last alko ball was 14 years old with virtually no wear on it. Yes I bought a calliper to test it.

My latest one, a detachable, came with black paint, I ignored the advise to remove the paint and let the alko pads do that for me, and cleaned the pads afterwards.