2008 RL Brakes (What I sent NHTSA)

[Bogie]

This is an excerpt of what I sent to the NHTSA official handling the brake investigation. I thought I would share it with everyone here for your information:

The Saturn SKY uses a vacuum power assisted brake system, with the primary vacuum pulled from the engine intake. In the 07 Saturn SKY, the brake vacuum is assisted by an auxiliary vacuum pump, which is energized when low vacuum is detected (e.g., during start up before the engine builds the necessary vacuum). Based on discussion and feedback from many 07 SKY owners, I have found this system works very well and no one with an 07 SKY that I talked to has had any problems with their brakes.

The 08 SKY Redline has a hydraulic brake boost feature as part of the Electronic Stability Control (ESC) system. The primary purpose of the ESC is to compensate for oversteer or understeer condition by retarding the throttle and selectively applying the ABS system. The hydraulic boost feature can also be used to compensate for low vacuum in the brake system. I presume the Saturn engineers felt that since the hydraulic boost could compensate for low vacuum situations, the auxiliary vacuum pump was no longer needed. The 08 SKY Redlines do not have an auxiliary vacuum pump. If the vacuum is low, the hydraulic brake boost feature of the ESC is activated for braking purpose.

From personal experience, I have found the hydraulic brake boost is not as responsive as vacuum assisted power brakes. If the vacuum is low, I must press the brake peddle harder in order to stop the car. I also do not stop as quickly as when I have vacuum assist. The only time I experience low vacuum is during the first 20 to 30 seconds after I start the vehicle after it has sat overnight or after it has sat for an extended period of time during the day. If I let the vehicle warm up for 20 or 30 seconds, I have full braking power. I have never completely lost braking ability during this start up period.

On the other hand, there are several owners I've talked to who have experienced little or no braking capability during the startup period. This suggests there may be additional factors at play during startup that either inhibits or decreases the functioning of the hydraulic brake booster. For example, the Owner's Manual indicates the ABS system runs through a diagnostics program shortly after starting the vehicle. This begs the question of how the controlling computer handles the ABS diagnostics check at the same time it is being called upon to apply the brakes to stop the vehicle due to low vacuum at start up.

One of the problems with finding the root of the problem is that I believe the hydraulic boost is controlled by computer and related software. As with any other piece of software, it might work as designed until a unique set of circumstances trigger an unintended state of operation. As I stated above, I have not experienced complete brake failure, but given the number of reported failures, I no longer take any chances. I let my vehicle warm up and I check the brake (I can tell when the vacuum is available) before putting the vehicle in gear.

[shabby]

I saw a post somewhere where gm apperantly stopped this due to complaints and went back to the vacuum pump, not sure if they're going to put the pump back for those that dont have it though.

[Sly Bob]

Originally Posted by shabby

I saw a post somewhere where gm apperantly stopped this due to complaints and went back to the vacuum pump, not sure if they're going to put the pump back for those that dont have it though.

Can anyone confirm this?

[Jaysmith2000]

Originally Posted by Sly Bob

Can anyone confirm this?

Yes please, I'm going to have them put that pump on my '08 Redline....

[shabby]

Its simply a post i saw, cant confirm anything.
Maybe you can check on any new redline arrivals at the dealer if they have the vacuum pump back.

[TINOONIT]

Has anyone heard any "New News" on the brakes issue? Is NHTSA doing anything yet or are they just aware of this problem?????

[sidejam]

For me personally, I don't mind waiting the 20-30 seconds before the engine has vacuum. I just look at my boost gauge and drive off when it's in vacuum. However, I can empathize with others that are not so patient and see this as a problem. If someone is in a rush and in a busy parking lot, I could see this brake issue being a potential accident causing situation...

[lostcause]

Originally Posted by sidejam

I just look at my boost gauge and drive off when it's in vacuum.

[sidejam]

Originally Posted by lostcause

I have and mechanical Autometer vacuum/boost gauge in a dual gauge pod.



Dual gauge pod in!

[1Man1Sky]

Wating 20-30 seconds isn't the issue. Its the initial surprise the first time it happens to you. As well, my father wanted to move my car out of the garage to get in to the attic. He moved it without incident. But, when he went to move back in to the gargae he almost went through my wall.

Its situatiuons like those that are dangerous.