I have a BMW 325 saloon. Since I hd the car there has always been some vibration through the steering wheel as I start to apply the brakes but stops as I increase the pressure on the pedal. I also noticed that often agter making an emergency stop this vibration appears for a while at speeds above 50 MPH. Just recently I have noticed the nearside front wheel is significantly hotter than the offside wheel. I would put this down to the brakes binding but the car does not pull to one side when braking. Performance and fuel economy seem to be OK.
Anyone with any ideas?
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It might just need a balance. Alternatively it could be a badly moulded tyre. I had this problem on one of my cars some years ago and it turned out to be a dodgy tyre. No visual signs unfortunately.
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could be that the brakes are dragging - maybe caliper sticking or pins dragging. you wouldnt always get a significant imbalance in braking.
Is it the wheel/tyre or the disc that gets very hot?
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Just fitted new tyres and balanced last weekend. That is why I noticed the wheel getting hot, I could smell the rubber from the new tyre. Both get hot but I am not sure which gets hot first.
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Had exactly same symptoms on a toyota, it was a small split in the brake piston rubber boot meaning that the top of the piston was slightly rusty and would not push down the last little bit into the bore - although several faults can cause brake binding, so may not be exactly as above.
You need to take calipers off and inspect condition of pads, fluid leakage, rubber seals, caliper guides, disks etc. Also try spinning wheel when car is on axel stands or jacked up, is there more resistance on one wheel compared to the other?. Splits in rubber are often not apparent until you pump the piston slightly further out of the bore (but not too far).
Good test for brake dragging binding is to park on a very slight slope and let brakes off, does car start to roll? Sometimes after wet weather when they are bound on a bit more, the engine will sound like it is straining slightly more, especially up hills.
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Problem is the piston in the caliper does not release after braking. So there is some drag all the time. guess i have to replace th caliper.
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An Indie or good DIYer can strip caliper down - there are refurb kits for many calipers - you may be lucky - new calipers are PRICEY.
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shop around.
I got a new caliper for the Volvo for £70 from PFS. Aftermarket caliper but identical to the original and no surcharge. I thought that the time / hassle of stripping and rebuilding + cost of the rebuild kit made it worth the cash. Same problem boot failed on piston and the piston was manky.
Eurocarparts and gsf will prob do one for the bm at similar cost. Although you may have scored the discs so need to add discs/pads to that.
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OK Thanks. i am going to try and get a part from a breaker and strip down the original to see if I can clean / refurbish. Will let you know.
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Please don't.
It's not worth risking secondhand parts for braking systems. It'll probably come off a car about the same age as yours, and likely to suffer the same failure.
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