‘85 911 brake fluid change

[jgurnari]

any benefit or not recommended to using synthetic brake fluid? this is the first time flushing this myself. what is recommended for my 1985 carrera? what do
you like?

how much fluid is needed for a full flush?

thanks!!

[wrxnofx]

I use Pentosin DOT4. One liter should suffice.

[jgurnari]

I see there are few, any specific Pentosin DOT4

[Schulisco]

Basically like on many other cars too. Just one hint: My SC has got a overflow at the brake fluid reservoir going into a rubber hose and finally a steel pipe to drain brake fluid under the car. Don't know if your car this also has. If so, then you have to shut this line with a clamp before. Otherwise you're going to bleed the pipe and not the brake...



Exact amount is unknown, depends on how old and worn your brake fluid is and how much fluid you need to flush the system. The 85 Carrera still has the 915 and cable operated clutch, so no additional brake fluid necessary. I suppose 1 liter / 1 qt should be enough. Outr host made a manual:
https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/49-Bleeding_Brakes/49-Bleeding_Brakes.htm
No videos found yet for the SC & Carreras yet.

I recommend to use a brake power bleeder instead of pumping the fluid with the brake itself. They don't cost that much and the change is an easy job then. ^



Make sure that you also got the right adaptor to connect the bleeder with the reservoir, I got an original from ATE. Works like a dream.



https://www.ate-info.de/de/details/produkte/adapter/bleeding-unit-adapter---20

There may be others available too. I prefer that high quality machined aluminium ones. The china plastic crap is not worth the money.

DOT5 is not recommended for street use. The problem with that: A single drop of water may poisons it and makes it completely unsuable then. Go with DOT4 and replace it regularly every 2 years. DOT 5.1 is also usable for street use as it is also made from glycol and not from silicone as the DOT 5 is.
I personally measure the water content of the brake fluid regurlarly with an electronic brake fluid tester. After three years I'll replace the brake fluid for sure, no matter how high the water content is. Depends on the driving conditions and mileage. Security is not negotionable!

Thomas

[wrxnofx]

Originally Posted by jgurnari

I see there are few, any specific Pentosin DOT4

I know of 2 - "conventional" Pentosin DOT4 and Pentosin DOT4 Low Viscosity (LV).

The first one is fine.

[proporsche]

all you need is one can of dot 4 br.fluid
You can just do it yourself,get a jar-from pickle make a hole on top get clear hose which you attach to the caliber niple and the other end into the jar-where you can just put a little br.fluid so the hose is dipped in it.
Start with right rear after left rear next right front and last is left front.
Open the nipple and pump the pedal about 3-4 times go close the niple and repeat on left ....Alway refill the reservoir after each 3-4 pumping....

It helps if you have your wife or friend to pump but it is easy doable yourself.
No need extra tools and e.t.c. plus quality time with your 911 always counts...
Been doing it like this since ever ......oldtimers way;-)))

Ivan

[jgurnari]

yes i do have the same overflow at the brake fluid reservoir

Originally Posted by Schulisco

Basically like on many other cars too. Just one hint: My SC has got an overflow at the brake fluid reservoir going into a rubber hose and finally a steel pipe to drain brake fluid under the car. Don't know if your car this also has. If so, then you have to shut this line with a clamp before. Otherwise you're going to bleed the pipe and not the brake...



Exact amount is unknown, depends on how old and worn your brake fluid is and how much fluid you need to flush the system. The 85 Carrera still has the 915 and cable operated clutch, so no additional brake fluid necessary. I suppose 1 liter / 1 qt should be enough. Outr host made a manual:
https://www.pelicanparts.com/techarticles/101_Projects_Porsche_911/49-Bleeding_Brakes/49-Bleeding_Brakes.htm
No videos found yet for the SC & Carreras yet.

I recommend to use a brake power bleeder instead of pumping the fluid with the brake itself. They don't cost that much and the change is an easy job then. ^



Make sure that you also got the right adaptor to connect the bleeder with the reservoir, I got an original from ATE. Works like a dream.



https://www.ate-info.de/de/details/produkte/adapter/bleeding-unit-adapter---20

There may be others available too. I prefer that high quality machined aluminium ones. The china plastic crap is not worth the money.

DOT5 is not recommended for street use. The problem with that: A single drop of water may poisons it and makes it completely unsuable then. Go with DOT4 and replace it regularly every 2 years. DOT 5.1 is also usable for street use as it is also made from glycol and not from silicone as the DOT 5 is.
I personally measure the water content of the brake fluid regurlarly with an electronic brake fluid tester. After three years I'll replace the brake fluid for sure, no matter how high the water content is. Depends on the driving conditions and mileage. Security is not negotionable!

Thomas

[jgurnari]

the only retailer I found in NJ that carries this is Oreilly (napa) in NJ.

Originally Posted by wrxnofx

I know of 2 - "conventional" Pentosin DOT4 and Pentosin DOT4 Low Viscosity (LV).

The first one is fine.

[E Sully]

I use Prestone DOT 3 synthetic. I have no need for anything fancier.
Just about all brake fluids are now labeled as synthetic. The only one to avoid is DOT5. Glycol-based brake fluids are DOT3, DOT4, Super DOT4 and DOT5.1. The one to avoid is DOT5. It is silicon-based brake. This does not work well in most situations.
I believe DOT 3 could be a better choice for a daily driver. Dot 3 has a slightly lower boiling point than 4, but is less hygroscopic. Unless you get the brakes really hot, DOT 3 will last longer and absorb less water than the others.

[GH85Carrera]

I have used the ATE Type 200 for 29 years. I change my fluid each and every spring. I still have the original master cylinder and no brake issues.

[Bill Douglas]

Originally Posted by proporsche

It helps if you have your wife...

Save the marriage and get speed bleeders. They are one way valves so you can be the person who pumps the brake pedal and then tightens the bleeder.

[proporsche]

Originally Posted by Bill Douglas

Save the marriage and get speed bleeders. They are one way valves so you can be the person who pumps the brake pedal and then tightens the bleeder.

so funny;-))))
but nice idea..not for me but for next bleed job person;-)

Ivan

[pmax]

The LV stuff, isn't that more suitable for modern ABS systems ?

[stownsen914]

I had a terrible time with speed bleeders. They kept sucking air into the calipers, presumably via the threads. Tossed 'em and went back to regular.

[Funracer]

I used a MIghty Vac. Works great there is a video put online by MV about how to use it for brake bleeding. Very easy to do by yourself. Just add a bit of fluid every couple of minutes to keep the reservoir from going empty.

[HarryD]

Originally Posted by GH85Carrera

I have used the ATE Type 200 for 29 years. I change my fluid each and every spring. I still have the original master cylinder and no brake issues.

My story is the same. I Use a Motive pressure bleeder. Spend more time jacking car and taking wheels on/off than actually bleeding. 1 liter of ATE typ 200 is all I need. Take about 170 ml from each wheel and have some left over.

Same MC as when I got the car 20+ years ago. Replaced the front calipers last year (PMB) because the dust seals looked funny. Brakes were working fine.

I have done 8+ autocrosses since I got the car and in the last 4 years about 8 HPDEs each year. Never boiled fluid or had brake fade with stock ATE M calipers in a 2500 lb car.

[GH85Carrera]

Originally Posted by HarryD

My story is the same. I Use a Motive pressure bleeder. Spend more time jacking car and taking wheels on/off than actually bleeding. 1 liter of ATE typ 200 is all I need. Take about 170 ml from each wheel and have some left over.

Same MC as when I got the car 20+ years ago. Replaced the front calipers last year (PMB) because the dust seals looked funny. Brakes were working fine.

I have done 8+ autocrosses since I got the car and in the last 4 years about 8 HPDEs each year. Never boiled fluid or had brake fade with stock ATE M calipers in a 2500 lb car.

Yep, I have done well over 150 autocrosses, and many track days in my car. Never an issue.



I prefer a vacuum pump. I put my car on my lift, remove all the wheels. I suck the old fluid out of the reservoir, then fill it with fresh fluid. Then start at the right rear, and suck the longest to get the fluid through the system. The left rear, right front, and finally the front left.

Put the wheels on, lower the car all the way, and torque the lugs.

One step I learned long ago, I put my torque wrench on the floor of the driver's seat. Impossible to forget to torque the wheels that way.

[pmax]

Oh, one more thing, surprised no one has mentioned this .... watch the paint ... everywhere.

Don't touch anything painted, try not to, do your best, while there's BF on your hands.

[HarryD]

Originally Posted by GH85Carrera

Yep, I have done well over 150 autocrosses, and many track days in my car. Never an issue.



I prefer a vacuum pump. I put my car on my lift, remove all the wheels. I suck the old fluid out of the reservoir, then fill it with fresh fluid. Then start at the right rear, and suck the longest to get the fluid through the system. The left rear, right front, and finally the front left.

Put the wheels on, lower the car all the way, and torque the lugs.

One step I learned long ago, I put my torque wrench on the floor of the driver's seat. Impossible to forget to torque the wheels that way.

Never liked vacuum bleeding. I Always see bubbles, probably from a bad seal between the hose and the nipple.

Since I do not have a lift, it’s pretty much one wheel at a time.

I hand start the lug nuts, thenuse my air impact wrench to tighten to about 80 ft-lbs and finish with my torque wrench.

[GH85Carrera]

Originally Posted by HarryD

Never liked vacuum bleeding. I Always see bubbles, probably from a bad seal between the hose and the nipple.

Since I do not have a lift, it’s pretty much one wheel at a time.

I hand start the lug nuts, thenuse my air impact wrench to tighten to about 80 ft-lbs and finish with my torque wrench.

I never use an impact on my aluminum lugs. I have a soft socket and remove and tighten them by hand. For my El Camino, yea, the impact gun is handy.

And yea, I drape a fender cover over the left front fender to be 100% sure no brake fluid his the paint. And a small towel around the brake reservoir. And I wash my hands a lot. The bubbles in the line never bother me. It is from the not perfect seal from the hose to the bleeder. Just tighten the bleeder before removing the hose. I have a perfect feel on the pedal.