parking brake 'worn'

I have the same problem Op has, Prius is used as a delivery vehicle daily. Took it into the dealership and they said the emergency brake cable was stretched and they tightened it up. It was fine for a week after that and then it gradually went back to the condition that it was in before, that of not working as an e brake... My rear brakes were done a year ago and had them inspected again a few months later. Now I've been thinking there's nothing that I can do except have the emergency brake cable replaced. When they tightened it they said they did the best they could but that it was well stretched. Please keep us updated Coyote...

 

I never use B mode. It switches Off regenerative braking, and therefore defeats the purpose of having the hybrid technology. I think this is not the best advice and that many on this forum would agree judging by when this has been mentioned before.

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You are at the apex of an elevation and are about to being the LONG decent, that has a considerable grade/angle of decline.
Pick your poison:

1) Remain in D to Regen. But now you will always be picking-up speed quickly. You now have to frequently apply the brakes with enough pressure, to activate the hydraulic brakes to supplement regen, to slow the car, and maintain a safe speed throughout the decent. Remaining in D and frequent brake application, now runs the risk of overheating the brakes. Heaven forbid you need to make a sudden stop during the decent or near the end of the decent, with HOT brakes. But hey, I achieved a lot of regeneration.

2) Alternate between D and B. When in D, speed will pick-up quickly requiring a quick shift back to B and application of the brakes (regen and hydraulic), to maintain a safe speed. Lower risk of brakes overheating than just remaining in D.

3) Stay in B. Rarely touch the brake pedal b/c you are "engine braking," and not picking up speed quickly during the decent. You infrequently apply the hydraulic brakes. You can always shift back to D, as the grade begins to flatten out. This will be more than enough to recharge the HV Battery to the maximum 80% SOC (full bars on the HV Battery meter), and have cool brakes that are more capable to help with an emergency/panic stop.​

You apparently:
*do not understand down shifting, its application, and usefulness.
*have never driven down a long, steep decent.
*have not read the owners manual.

Fly across the Pond. Rent a Prius. Drive to Las Vegas or San Francisco from Los Angeles. You will find yourself using B. Remain in D and ride the brakes. Alternating D-B-D, not worth it.

 

I would prefer that you stick to describing your own experience rather than describing what you think I do or do not know- which is something you can only make assumptions about and does not really inform the discussion. I do regularly drive down long hills, which may or may not be long by your own U.S. standards, and I take note of the energy monitor and observe when the regen braking stops slowing the car and this is rare in my experience. I think that while Regen braking is working the car.s use of the discs is minimal. I am of course aware of the issue of brake fade, but have never found this an issue on my Gen2. In the UK Prii have disc brakes on the rear which helps. I use cadence braking when necessary to allow the brakes to cool. I would not say that no one should ever use B but I have never needed it and if the view is that it should be used as a matter of course on hills, then let.s agree to differ on this.

Posted via the PriusChat mobile app.

 

Well It supplements regenerative braking rather than turning it off, but B mode is always less fuel efficient than D, and is correctly used to lower overheating of the HV Battery and friction brakes on sustained steep descents. (more than 600 foot vertical drop)

That you never use B makes sense to me, as "Ben Nevis which at 1,343 metres (4,406 ft) is the highest point in the British Isles." You would almost never need B while in the UK.

 

Yes. Lets agree to disagree.

You won't use B to "downshift".
I will use B to "downshift," when needed.​

 

Thank you for the clarification.

 

Cable "stretch" is a bit of a misnomer. A steel cable may stretch a little over its life, but it should not stretch as much as you're describing. What might be happening is a failure of a cable housing or a retainer, or a cable itself may be fraying.

There are actually three cables in the system, as well as a lever sub-assembly and a couple of retainers. Hopefully you get a good enough mechanic to analyze what's broken, rather than just replace everything. The dealer may have just tightened the adjusting nut at the pedal, without inspecting the rest of the system.

You might try a regular brake shop to save some money and maybe even get mechanic who specializes in these systems. No need for a highly paid Prius mechanic to do this. There's nothing new or high tech about parking brake cables on a Prius.

 

yaa

 

You might find a stretch of empty road nearby to do a brake drag test and be sure the rotors are cold at the end. Properly replaced and adjusted Prius brakes should not add resistance to forward motion....

-Chap

 

If it's one corner causing the problem, on one tire, I would think the tire rotation was neglected too.

 

If you find a way to do the drag test yourself (as described in the link in my earlier post), then you have something objective to talk with them about. Otherwise you're just Unreasonable Customer #31.

You should understand that failing the drag test can mean something beyond mere 'adjustment'. Honestly, only the rear drums on your model have any 'adjustment'; disc brakes have precious little to adjust, as long as everything that should move and return easily does so. If it doesn't, it may indicate need for servicing a caliper (the restoring kits aren't expensive, it's a bit of labor if you don't DIY).

Plus, then you have an easy test you can do every now and then just to convince yourself things aren't dragging.

-Chap

 

^ Yes, yes, yes.

It's easy, even with just the supplied scissor jack. You should test wheel spin on both rear corners this way. And it's a good exercise, something everyone should do a dry-run on, to ensure the scissor jack works, before you might actually need it.

I'd suggest to get a pair of wheel chocks and follow the Owner's Manual guidance: on level ground (preferably on a concrete slab, but if that's not possible put a small square of plywood under the jack) securely chock the front wheel diagonally opposite to the rear corner being raised with scissor jack.

Make sure the parking brake is released, and try spinning the raised wheel. It should be near-free spinning. You try applying/releasing the parking brake a few times, see if there's any change.

Then repeat for the other side.

A story:

About a year back I brought in our son's Civic for a brake fluid change, to a Honda dealership. Driving the car a few days later (he was on vacation) I attempted to stop on a yellow light, ended up going across the crosswalk, almost into traffic, the anti-lock braking going off like crazy.

Eventually, I raised the rear (all in one pop, with a floor jack), and had my wife apply the brakes while I spun the rear wheels. One side was completely disabled, not braking at all.

Brought it back to the dealership, with ammo!

 

Would have served them right if you turned in quickly and went right into the showroom . . .

Did they not bleed that side or forget to reconnect something?

 

I'd assume they bled the whole system. They said something in the line likely clogged at that rear brake. I'm inclined to believe them, but really, it's unprofessional (understatement) to return car to the customer in that condition. When I brought it back, and "expressed concern about their workmanship", they bled it twice more, and after the second time test drove it. The latter is paramount I think: to verify everything is ok.

After the first bleeding they'd lost 50% of the bleed caps too, lol.

 

The bigger concern is that having driven the vehicle with the PB applied, the rear bearing may have been overheated causing failure. This is typically evidenced by grease on the shoes or a leaking axle seal, but having drum brakes this condition may not be apparent until disassembly.

Certainly have your shop check for smooth rotation of the hub assembly prior to repair of the brakes themselves.