Are there SPECIAL hill assist calipers ?

[jonni]

Good day folks.

I have question about my old toyota corolla sedan (2016) E170/E180 1ND-TV (D4-D)

I had to replace damaged rear , screw type caliper on the back left side.
When looking for aftermarket spares it was almost every time noted that they were NOT for hill assist vehicles so i bought OEM caliper from the dealership in Iceland for this "fair" price of 360$. Aftermarket types priced around 120-150$.
Also aftermarket shops carry rebuild kits for calipers without hill assist.

nota bene , had the car for awhile before i realized it had the hill assist.. its activated by pressing the brake pedal hard and then you have two seconds to accelerate after releasing the brake.

So whats the difference between those calipers? what would happen if i just bought two aftermarket calipers and replaced both on the rear axle ?

 

[Audiman]

I don’t know about your Toyota, however typically hill assist uses the abs module to hold line pressure thus holding the brake on and releasing quickly when needed.

 

[twX]

The system would be calibrated to apply enough braking force to hold the vehicle, but perhaps it's a lot less than full braking pressure to help the system quickly disengage, or maybe pressure ramps down gradually. Aftermarket calipers might have a different pressure/braking force relationship and theoretically require different system calibration. Otherwise they may allow the vehicle to roll back a bit too much, or they may apply too much force for too long a period which would contribute to excessive clutch slip or stalling. I suspect that most quality aftermarket calipers would probably work well enough and that it's mostly a liability thing.

I disabled the system on my Subaru since it doesn't disengage quickly enough and I often stall the car when I don't expect the system to be engage on slight inclines.

 

[D60]

The system would be calibrated to apply enough braking force to hold the vehicle, but perhaps it's a lot less than full braking pressure to help the system quickly disengage, or maybe pressure ramps down gradually. Aftermarket calipers might have a different pressure/braking force relationship and theoretically require different system calibration. Otherwise they may allow the vehicle to roll back a bit too much, or they may apply too much force for too long a period which would contribute to excessive clutch slip or stalling. I suspect that most quality aftermarket calipers would probably work well enough and that it's mostly a liability thing.

I disabled the system on my Subaru since it doesn't disengage quickly enough and I often stall the car when I don't expect the system to be engage on slight inclines.

I used to hate it on my '11 F350 but once I got used to knowing it's there and understanding what it is doing I've come to love it -- especially with a trailer behind me.

That said, I see little use for it in a car. I think it makes way more sense in a truck where GCVW can nearly triple at times.

 

[bdcardinal]

My 14 Mustang has it and according to what I have read in the WSM, it uses the ABS module to activate and release the rear calipers.

 

[tcp71]

Off topic, but this exists on the 2022 expedition XL with automatic transmission. We rented one in florida and it holds the truck at a red light without keeping your foot on the brake. once you touch the gas pedal it disengages.

 

[meep]

I had this on a 1990 Subaru, pre-abs. And I’m pretty sure it was on my non-abs 97 legacy as well. I think it was just the a one way valve with release tied to the clutch pedal??

 

[eljefino]

You may have a different piston size for a hill-assist vehicle vs a normal one. The ABS and master cylinder will also be appropriately, differently sized and programmed.

The issue you get is when you start mix and matching brake parts across applications. You bought the right thing by buying the right thing.