Stew Posted March 15, 2008 Posted March 15, 2008 I've got an autotrail chieftain on the al-ko twin rear axle chassis.It's got the drum brakes on the rear and is a 1999. I decided to take it to the coast for the day but halfway there the rear brakes on all 4 rear wheels decided to stick on. Front brakes not affected, and before you all shout "It's the handbrake" this has been checked out fully and its not responsible, its only after the footbrake is applied that the rear wheeks stick on. It appears to be hydraulic pressure related because if I leave it for a while the wheels free off, but if footbrake applied again they stick on. Does anyone have any similar experiences.Is it the brake master cylinder or are there any other brake valves in the system that could be causing the problem? Any advice greatly received. Just as an asside had the vehicle recovered via Brittania recovery services, who were first class, apart from one particular recovery agent who left me waiting for 3 hours and failed to turn up at all, very poor, another agent Fred CAMM the recovery man came and saved the day. First class service.Even Fred the 82 year old owner came out to help his son and convey us home.A marvellous experience all round. Any way thanks for reading... Stew:)
skottle Posted March 15, 2008 Posted March 15, 2008 Hi, Have you checked the brake compensator(probably situated along the rear axle) possibly partially seized.
Stew Posted March 16, 2008 Author Posted March 16, 2008 Have these got one, if so are they on both axles or does one valve control both? Cheers :->
Brian Kirby Posted March 16, 2008 Posted March 16, 2008 Did you actually jack each of the rear wheels to prove all 4 were binding, or are you assuming that to be the case? Also, how do you know the front wasn't binding at the same time. It's just that one would usually need the van up on a hoist to be able to tell with confidence what was, and was not binding. Do the rear drums auto-adjust, or is the adjustment manual? If manual, has anyone (over!) adjusted them recently, causing binding and eventual seizure until they cool down? It could be, if the van has stood idle for some time, especially if the handbrake has been left off, that the drums have rusted and the rust caused binding and overheating. If you are absolutely certain it was only the rear drums then, if your van has a load compensating valve (but surely you'd know that?), suspect that in the first instance. If that is not corroded and is working freely, you'll have to get the drums off and see whether they are corroded from standing idle, or whether the slave cylinders are defective. As you can see, there are a number of possibilities, and until the drums are removed and the brakes carefully inspected, all else is speculation.
Stew Posted March 18, 2008 Author Posted March 18, 2008 Thanks for replies, I've now sorted it after tracing out the brake system all the way back to the master cylinder, then jacking the vehicle up front and rear and testing which wheels lock and don't release.It turned out to be a little inline pressure regulating valve which was allowing the fluid through to apply the rear brakes, but then wouldn't allow the fluid back to release the brakes. Replacing this with a new`one from Al-ko sorted the problem. Cheers anyway. Stew (lol)
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