Squealing sound when towing

[hymer]

Just come back from a couple of weeks touring in France. On the last leg of our journey, a few miles from home, with the car windows down and travelling along local roads with fences/hedges/buildings alongside reflecting the sound of the outfit passing by, I became aware of a squealing noise coming from either the car or van. It was a noise which seemed to be rotational in nature: it increased/decreased in pitch as I speeded up/slowed down. When I touched the brake the noise stopped, only to resume on release of the brake pedal. The character of the noise I can best describe as a high-pitched (at 30-40 mph) metallic scraping sound.

On arriving home, I unhitched and took the towcar for a solo drive - no noise. So the source of the noise had to be on the caravan, my guess being that it was coming from one or other of the wheels or brake drums. Can anyone offer any suggestions as to what might be the cause?

[The caravan is a Hymer Nova, is just over 2 years old, has done 9,000 touring miles and had its 2nd annual service carried out by the Hymer dealer in June this year.]

 

[JohnI.Stephen]

What did the the Hymer dealer say?

 

[hymer]

The dealer has suggested that the jockey wheel (which is within the A-frame) might have been pulled up to a position where it was pressing on the brake rod, thus partially activating the brakes. I'll have to take the van for a run and check this out.

 

[BigRoy]

this can happen if there is a build up of dust or grit on the drums or pads and as you had just done a long journey heat can be a factor to so it might just cure itself.

 

[WatsonJohnG]

I think that you need to get the brake drums off either yourself or a mechanic/dealer.

Seeing if its OK next time could prove inconvenient if it isn't OK and something gets worse

 

[WatsonJohnG]

The dealer has suggested that the jockey wheel (which is within the A-frame) might have been pulled up to a position where it was pressing on the brake rod, thus partially activating the brakes. I'll have to take the van for a run and check this out.

I would have thought that it would prevent movement on and off if it was binding and as you can stop it by lightly applying the brakes it seems an unlikely cause to me.

 

[hymer]

Roy, John, thanks for the advice. I took the van out at the weekend, having first checked that the jockey wheel was clear of the brake rod. The noise was still there, so I will now need to have the wheels/brakes investigated. I'm going to see if a local garage/mechanic would be prepared to look at it, otherwise it's a trip to the dealer in Nottingham.

 

[firesmudge]

Could it be the clutch when under pressure whilst towing it is noisy then when just driving unhitched without the added pressure it is ok ??? just a thought probaly wrong

 

[Lutz]

Could it be the clutch when under pressure whilst towing it is noisy then when just driving unhitched without the added pressure it is ok ??? just a thought probaly wrong

Once the clutch is fully engaged and so long as it's not slipping, it doesn't notice any difference between towing and not towing. No, it's most likely the brake shoes on the caravan rubbing against the drums or gravel or something wedged in between.

 

[hymer]

No, it's not a clutch problem, the noise is coming from the 'van. I suspect it's to do with the brake shoes/drums as Lutz and Big Roy suggest. The dealer will investigate in a couple of weeks time.

 

[Royston]

Mike B,

Just been re-reading your comments

ie when i touch the brake the noise stops ( this is when the caravan is pushing against the towball.)only to resume when you release the brake(this is when the caravan is pulling against the towball)

Have you checked the towball nuts plus the nuts that bolt the towing assy to your car are torqued to there correct torque.

and not moveing when they are under the towing load.This could account for the screaching noise you hear when towing.

Royston

 

[hymer]

Royston, thanks for your suggestion. I will put this to the dealer.

 

[Lutz]

The phenomenon that Royston is describing is more likely to cause a creaking noise than squealing.

 

[hymer]

Just to draw this thread to a conclusion...

I took the van back to the dealer last Friday. As I set out on the journey, it was clear that the noise had disappeared, and there was no evidence of it on the way. At the dealer's I described the problem to the workshop technician who asked if I had done a lot of mountain driving (which I had), as that can cause heavy usage of the caravan brakes, leading to the build up of dust and grit inside the drum and possibly uneven wear on the brake shoes. This results in the squealing noise, but if the dust and grit becomes dislodged then the noise can disappear.

The wheels, brake drums and brake shoes were examined and found to be in good order. They cleaned the dust out the drums and sanded the brake shoes for good measure. So, a straightforward explanation and a simple cure.

 

[Royston]

Mike B

Thanks for returning to the forum, with the answer to your problems, Its information like this that makes the forum a success.

Rroyston

 

[ProfJohnL]

Hello MikeB,

From your description my suspicison would be the brakes. My tame motor mechanic investigate a similr problem on my car, and described brake dust in the drum. I recommend you have teh brakes checked.