Reply To: Ransomes motor triple mk 4 brakes seized

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It sounds like the rust has taken hold. On machines that had been laid up for a while we used to have to knock the slide backwards and forwards in the housing, each time getting a little bit more movement until the slide came free. Have you removed the brake pads? If not you may find they are binding inside the housing.

Assuming you’ve removed the pads and the slide still won’t move I would try a couple of things. In these situations I tend to soak the assembly in Brick and Patio Cleaner; this is a weak Sulphuric Acid but it does get the rust moving. The downside to this is that it needs to be handled carefully so you don’t get it on your skin, it gives off hydrogen gas so you need to do it in a well ventilated area and you need to neutralise the acid by soaking in Bicarbonate of Soda afterwards. Despite these precautions I find it very useful and still use the method for de-rusting iron and steel items.

As an alternative you could always light a bonfire and put the assembly in the middle of it. I’ve used this method for large items that would use too much acid; an old oil drum filled with pallet wood usually does the trick. The aim is to heat the whole assembly to an even temperature so that the moisture in the rust is evaporated; the rust is converted to dust and the caliper will come apart easily once it’s cooled down but you must ensure that the whole assembly is heated to a cherry red otherwise you’re wasting your time. The even temperature throughout the metal prevents any distortion, something that you can’t achieve with a blow torch, and leave the caliper to cool down gradually overnight before trying to dismantle it. Plenty of oil is also a good idea.

I found penetrating oil is not much use on these parts as the rust tends to be very deep-seated and there is a great deal of surface area inside the caliper for the rust to take a hold of.

I hope one of these methods will work for you. If all else fails I’ve found that they will put up with quite a bit of hammering!