Handbrake Issue? "vibrating" On?

July 2, 2015

I've not had my RAV for long, but I've got an extremely annoying issue with it thats proving to be virtually impossible for my mechanic to find :(

It's a 2002, 5 door model and it's not high mileage.

For the past few months, I've occasionally noticed a "vibrating" noise from the back of the car; usually after stopping it has disappeared. Well, I managed to isolate it a few weeks ago - when I noticed smoke coming out from the offside rear wheel well - the disc was hot (as was the alloy wheel). At the time it was identified as a problem with the handbrake shoes in that wheel, as applying the normal brakes didn't change the noise. However, since then the brakes have been stripped, cleaned and serviced top to bottom - but the problem re-appeared. Today it's had the hand brake cables replaced, but yet again ... it's reappeared.

The best way to describe the problem is a rhythmic rumbling / catching noise from the wheel effected; if you slightly apply the handbrake while its doing it there is a change in the noise, so I'm figuring that it is probably something going on here ...

I was wondering if anyone else had encountered something as bizare as this? It's almost as if the handbrake shoes are able to move around inside the housing causing the sticking / noise, but the springs all seem fine (so I'm told). What's even more frustrating is that it doesn't always occur, so it's kind of putting me off driving the car!!

Any advice gratefully received ;)

Andy

July 5, 2015

Hi Andy, I've never worked on the RAV 4 but I've dealt with these brake systems and they're all variations on the same theme.

The symptoms you describe remind me of a drum section of the rear disc that's oval or has damage marks through to the friction surface, possibly caused by hammering on the drum section to get the thing off when the brake is seized. Not saying that your mechanic did this but it may have happened before him. Answer to that would be new discs. Interesting to see that Toyota recommends when you're fitting a replacement disc you select the installation position where the disc has the least runout (see attachment page 3 note 10).

Other things, the brake shoes are held against the back plates under tension by the hold-down springs and anchor pins. They're supposed to be lubricated at the contact points to prevent wear but I've seen these from the factory without any lube on them. If you've got grooves worn in the back plates the shoes can catch in them and not release so they rub on the drum generating heat and problems. Answer is either careful use of a grinder to smooth out wear points or renew back plates (very expensive job). When fitting new shoes it's also important to clean off any rough paint or lining adhesive spew from the shoe contact points before lubricating so that they slide freely. Naturally you must avoid any lube on the friction surface.

I hope your mechanic replaced all the hardware inside the drum ie the return and hold down springs, pins, levers etc and made sure that every moving contact point was lubricated. After 12 years the only place for this stuff is in the bucket.

I assume your mechanic followed the correct procedure in leaving the brake cable slack and adjusting the shoes first. Note that Toyota recommends slackening off the shoe adjuster by 8 clicks after lockup. Most mechanics are loathe to slacken the adjuster off as much as this because you can lose the handbrake bite. They usually prefer to just slacken it off enough to let the disc/drum turn freely.

Best to follow the manufacturers recommendations especially if you're experiencing problems. I don't know about the RAV 4 but with some vehicles if you adjust the brakes under 'no-load' conditions and then carry a heavy load in the vehicle the suspension travel is different and can exert a pull on the hand brake cables.

I hope this helps.

Rav 4 Parking Brake.pdf