Time to do Brake system flush
05-11-2003, 03:32 AM
#16
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Guess I've had too many years of DIY brake work and never noticed any brake failures except those due to mechanical failure of some kind.
The ONLY scheduled maintenance my 92 LS400 (90k)has had is oil and filters, it even has the original anti-freeze installed at the factory.
My 01 C4 will get the same treatment.
The ONLY scheduled maintenance my 92 LS400 (90k)has had is oil and filters, it even has the original anti-freeze installed at the factory.
My 01 C4 will get the same treatment.
05-11-2003, 09:49 AM
#17
Technical Specialist
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A couple of things related to this thread:
* There are two varieties of DOT 5 fluids: the silicone-based sort and the so called DOT 5.1 variety. The silicone-based is excellent for long term storage, and for regular use many have found it gives an odd brake pedal feel, so you don't find it in general daily use. It does require a total system flush before using it. The DOT 5.1 fluids are compatible with regular DOT 3 and DOT4 fluids, and do not require a total system flush.
* Stick with what your drivers handbook recommends for brake bleeding intervals. Those with 911's with a hydraulic clutch that shares it's fluid with the brake reservoir will be shocked at how dark brown the fluid comes out from the clutch cylinder during a flush. If you drive on the track, the absolute minimum brake fluid flush is annually, and depending on usage, some of us bleed the brakes before each event. Even if you take your 911 to have someone else flush the brakes per the owners handbook, you're talking an hour labor plus fluid, which I'd suggest is cheap, considering the importance of the brakes.
* While in this area, nobody has mentioned brake hoses. They're good for around 10 years. If your 911 is older than 10 years and you don't know when they were last changed, I'd recommend changing them. What happens is over time they swell internally, impacting the hydraulic pressure to the calipers. I'm not a proponent of stainless-covered teflon/kevlar hoses unless you're going to inspect them regularly and change them more frequently than needed for the rubber hoses. I'm told some of the Porsche racing teams are using rubber hoses, too.
* If you have an older 911, don't use the friend pushing on the brake pedal method of bleeding your brakes, or you'll find yourself installing a new master cylinder. What happens is that the internal master cylinder seals normally move over a fairly short range. Outside of that range, there is corrosion and rougher metal. When you push the pedal to the floor during bleeding, you're pushing the rubber seals over that rough area, typically ripping them or putting cuts in the edges. A pressure bleeder or vacuum bleeder can be bought for $30-$50, or more.
* There are two varieties of DOT 5 fluids: the silicone-based sort and the so called DOT 5.1 variety. The silicone-based is excellent for long term storage, and for regular use many have found it gives an odd brake pedal feel, so you don't find it in general daily use. It does require a total system flush before using it. The DOT 5.1 fluids are compatible with regular DOT 3 and DOT4 fluids, and do not require a total system flush.
* Stick with what your drivers handbook recommends for brake bleeding intervals. Those with 911's with a hydraulic clutch that shares it's fluid with the brake reservoir will be shocked at how dark brown the fluid comes out from the clutch cylinder during a flush. If you drive on the track, the absolute minimum brake fluid flush is annually, and depending on usage, some of us bleed the brakes before each event. Even if you take your 911 to have someone else flush the brakes per the owners handbook, you're talking an hour labor plus fluid, which I'd suggest is cheap, considering the importance of the brakes.
* While in this area, nobody has mentioned brake hoses. They're good for around 10 years. If your 911 is older than 10 years and you don't know when they were last changed, I'd recommend changing them. What happens is over time they swell internally, impacting the hydraulic pressure to the calipers. I'm not a proponent of stainless-covered teflon/kevlar hoses unless you're going to inspect them regularly and change them more frequently than needed for the rubber hoses. I'm told some of the Porsche racing teams are using rubber hoses, too.
* If you have an older 911, don't use the friend pushing on the brake pedal method of bleeding your brakes, or you'll find yourself installing a new master cylinder. What happens is that the internal master cylinder seals normally move over a fairly short range. Outside of that range, there is corrosion and rougher metal. When you push the pedal to the floor during bleeding, you're pushing the rubber seals over that rough area, typically ripping them or putting cuts in the edges. A pressure bleeder or vacuum bleeder can be bought for $30-$50, or more.
05-11-2003, 11:59 AM
#18
</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by willard:
<strong>Guess I've had too many years of DIY brake work and never noticed any brake failures except those due to mechanical failure of some kind.
The ONLY scheduled maintenance my 92 LS400 (90k)has had is oil and filters, it even has the original anti-freeze installed at the factory.
My 01 C4 will get the same treatment.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Good for you, thankfully you will never get passed tech and into any performance driving events.
<strong>Guess I've had too many years of DIY brake work and never noticed any brake failures except those due to mechanical failure of some kind.
The ONLY scheduled maintenance my 92 LS400 (90k)has had is oil and filters, it even has the original anti-freeze installed at the factory.
My 01 C4 will get the same treatment.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">Good for you, thankfully you will never get passed tech and into any performance driving events.
