I'll be replacing the rubber brake lines and flushing the brake fluid in my '97 840. I've been searching and I'm a little confused by the use of Pentosin in the brake system. As I understand the Pentosin is power steering fluid (or do they also make a brake fluid?). Brake fluid is also used in the brake system. I'm partial to the ATE Gold/Super Blue flavors that I use in my other cars, can the ATE be used in the 840? It would be nice if I don't have to have multiple brands around.

If Power Steering fluid is used in the system does it need to be flushed too? Where is it flushed from?

I use the Motive Pressure Bleeder for my other cars, anticipate using that on the 840 too.

The '97 840 I bought was delayed in delivery to me by the weather in the NE this week. I had hoped to have the car here for a few weeks and get all this done before I go on a 2k mi. road trip but my maint. window is being cut short due to the delay. I would like to have everything ready so I can go to work on it as soon as it gets here, don't want to wait on parts. If I have to wait until after the road trip I will but I'd rather get it done before. All help appreciated.

Pentosin is for the brake booster and the brake bomb. As for brake fluids I used ATE Super Blue for my 97 840 as I used it for Autocross. I currently use Motul 600 for my 860. I used to alternate between Ate Blue and Motul as this way I could tell if the flush is complete by the color change.

I have also used a pressure bleeder system in the past with good results.

Pentosin is for the brake booster and the brake bomb. As for brake fluids I used ATE Super Blue for my 97 840 as I used it for Autocross. I currently use Motul 600 for my 860. I used to alternate between Ate Blue and Motul as this way I could tell if the flush is complete by the color change.

I have also used a pressure bleeder system in the past with good results.
OK, now I just have to understand how the brake booster and the brake bomb function with respect to the main brake hydraulics.

I know where the brake bomb is because I found the procedure to change it on E31faq.com and that's where I noticed the use of Pentosin PS fluid in the brake system. That's what triggered my initial inquiry.

It sounds like I can ignore the Pentosin side of the system and just flush the brake fluid side. Thanks

It sounds like I can ignore the Pentosin side of the system and just flush the brake fluid side. Thanks

Yup! Until you get the Brake booster leak which is just a matter of time and involves a lot of work for a $0.79 part.

The car only has 54k miles so it shouldn't need a lot of work (did I just say that out loud?) but things like 10 YO rubber brake lines I do intend to replace promptly and brake fluid I'd replace no matter how recently it's been done. I do it every year on my 993.

I replaced my brake lines with Teflon Coated Stainless steel braided brake lines. It improved the brake pedal feel and should last a long time. I have a spare set I can sell to you or you can buy a set from Race Parts Wholesale (http://www.racerpartswholesale.com/goodbrake3.htm).

Thanks for the offer Ahmed. I've put SS (coated) brake lines on my last 3 cars but I plan to use the stock rubber(?) ones on the 840. Never had a problem w/ the SS lines just don't feel I'll need them in this application. This is a GT car for me and won't be spending time on the track (at least I don't think so right now).

The SS brake lines do take some of the Springy feel out of the pedal though.

I don't track mine but did the SS brake lines for a better pedal feel.

Of course you stop noticing the difference in about 10 minutes of driving.

I suppose that someday I need to drive a dead stock 840 just to remind myself that mine isn't ordinary anymore (that is if you could accuse any 8 series of being ordinary):)

Thanks for the SS info, maybe for next years flush I'll upgrade to SS lines. I'm hoping that replacing 10 YO rubber w/ new rubber will be sufficient for now. I've got several other upgrades on the short list to get done promptly but making sure the brakes are working their best is always a priority.

Holy Crap! Just sucked out the old brake fluid out of the master cyl res. (turkey baster method) and I've seen worse fluid but not by much. It's going to be a 2 qt. flush on this car for sure.

Flushed the brake system today. The stuff that was in there sure didn't look like brake fluid anymore. I'll be doing it again in a few weeks just to flush out whatever may break free. I'll also be going to the stainless lines too.

Good job. Sounds like the brake fluid was very old and being hygroscopic started to soak water and the water started accumulating the contaminants. Yes, it will be a good idea to flush it again in a month or so.

Ahmed, do you still have those stainless lines available? I have no problem ordering through the link but if you have some you want to unload PM me.

Bill...They have been spoken for now locally. Really sorry. They are the same thing as the ones from the link.

Not a problem, have credit card, can order.