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Das Beast: My E30 track / street build

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    Great feedback. Sounds like I picked a winner.
    "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

    1987 E30 3L Turbo Stroker Das Beast
    2002 E39 M5

    Comment


      I have a pretty normal/stock brake setup, but I use the Motive bleeder on my track car. It's fast and easy. Very nice to be able to quickly bleed brakes by yourself.

      RISING EDGE

      Let's drive fast and have fun.

      Comment


        I have been putting off doing my SS lines because of bleeding hassles. Thanks for the info, I'll order one of these bleeders.

        Seems like there are several options, is this right?

        [IMG]https://cimg4.ibsrv.net/gimg/my350z.com-vbulletin/550x225/80-parkerbsig_5096690e71d912ec1addc4a84e99c374685fc03 8.jpg[/IMG

        Comment


          That's the right one for an E30. Motive Products 0100. Confirmed in Amazon reviews. Good tool for $50.

          "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

          1987 E30 3L Turbo Stroker Das Beast
          2002 E39 M5

          Comment


            Originally posted by dvallis View Post
            That's the right one for an E30. Motive Products 0100. Confirmed in Amazon reviews. Good tool for $50.





            I used one of those when i replaced my master cylinder. Didn’t even have to bench bleed it. Made it so easy. Just takes a big jug of fluid to work.


            1989 325is l 1984 euro 320i l 1970 2002 Racecar
            1991 318i 4dr slick top


            Euro spec 320i/Alpina B6 3.5 project(the never ending saga)
            Vintage race car revival (2002 content)
            Mtech 2 turbo restoration
            Brilliantrot slick top "build"

            Comment


              Data logging system is slowing down the brake build. Will be running brake pressure sensors on the data logger, so connections need to be built into the hard lines. Here is my planned setup.

              "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

              1987 E30 3L Turbo Stroker Das Beast
              2002 E39 M5

              Comment


                Back in business. Brake temperature sensors arrived. Here's one spliced into the rear hard line with a T-Block



                Front hard line sensor installed.



                Rob's on vacation so brake bleed down will have to wait. Moving on to the dash. Before .......



                After looking pretty good. The cutout over the steering wheel will be filled with a recessed aluminum panel. Gives the tach and speedo some shade. Also makes them more vertical.



                Here's the view from the cockpit. Gauge plan needs to change. Racing wheel is smaller than the stock wheel, so visibility through it is limited. There's room for a speedo and tach, but that's about it. Trying to see around the wheel to check aux gauges is not a good idea.



                Fortunately, we've got the GS-Dash. It can simultaneously display an RPM bar plus four custom fields. Will set it up as water temperature, oil pressure, fuel pressure and lap time. Should work fine. Also, the dash continuously monitors this data and can set warning lights if thresholds are exceeded. Beats continuously scanning steam gauges. More on all this later.

                "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                1987 E30 3L Turbo Stroker Das Beast
                2002 E39 M5

                Comment


                  Another Brake Extravaganza

                  Finally, today we get BRAKES !!!!!!!!!!!!

                  First, going to need the right brake fluid for track days. If you didn't know, DOT 3,4 and 5.1 brake fluids are hygroscopic, meaning they absorb moisture over time. This characteristic is expressed by the wet boiling point, i.e the point at which brake fluid will boil after absorbing 3.7% moisture. "Out of the bottle" 0% moisture is dry boiling point.

                  On a race track, you're going to get significantly more heat into calipers than on the street. Boiling point become an issue. You can't use stock street brake fluid or .... bad things will happen. Matter of fact, I almost killed myself at Texas Motor Speedway running a 240Z with poorly maintained brakes. That was a behavior changing experience.

                  Here are a selection of brake fluids. You can get Lucas or Prestone at the local car parts store. Notice the low boiling points. I called my local BMW independent mechanic. He carries Pentosin and ATE. Better but not great. The guys that service Ferrari, Lambo, Porsche and such in Austin run a couple of Porsche GT3 Cup cars in the series. They swear by Castrol SRF. Excellent dry boiling point and unbeatable wet boiling point, but $70 per liter. My driving coach only uses Motul RBF-660. In fact, he won't get in the car unless we're running it. :devil: Redline 600 has good specs, but hard to find around Austin.

                  Lucas Oil DOT4 Synthetic 10827 (12 oz) $5.50 476/325
                  Prestone DOT4 AS800Y (12 oz) $4.99 500/311
                  Pentosin DOT 4 Pentosin (5 L) $60.00 506/329
                  ATE DOT 4 Type 200 (5 L) $60.00 536/396
                  Castrol DOT4 Synthetic SRF (1 L) $69.99 590/518
                  Motul DOT4 Synthetic RBF600 ( 500 mL) $20.00 594/421
                  Redline DOT4 Synthetic RL-600 (16 oz) $15.40 600/400
                  Motul DOT4 Synthetic RBF660 (500 mL) $28.00 617/399

                  I scored and found RBF-660 for $20 / 500 ml. Nice!



                  So, how about some brake system math? Let's get wild and do it from first principles. A 1" bore master cylinder has area of 0.785 in2. Exerting 100 lbs of force on the master piston results in 100 lbs / 0.785 in2 or 127 psi.

                  Your brake pedal pivots around a point such that the pedal is on the long end and master is connected to the short end. Long over short is called the pedal ratio. My Tilton pedal box has an adjustable ratio, set to 6:1.

                  So, when we press on the brake pedal with 100 lbs of leg force, it generates 600 lbs on the master piston and 762 psi in the brake lines.

                  Dual masters means that the leg pressure will be divided 50/50 on each one, assuming a centered balance bar.

                  Putting it all together:

                  Force on master: (75 lbs x 6)/2 = 300 lbs
                  Area of master: (5/8/2)^2)*pi = 0.3068 in2
                  Pressure in circuit: 733 psi

                  From the math you can see how a smaller master bore generates more brake line pressure with the same leg force. This translates to a softer pedal feel. Pro drivers recommend 75 to 100 lbs pedal force for lock-up. This in turn depends on tire tread, tire temperature, tire compound, tire profile, wheel diameter, brake pad coefficient of friction, car weight, track temperature, track moisture and car CG. In fact I have a spreadsheet for all of that. :devil: Only way to tell will be real testing. If the pedal feels too soft we will go for bigger masters.

                  Front calipers are 4 piston with 1.65" bore and 2.14 in2 area. Applying 733 psi to each piston will result in 6 K lbs of clamping force. (wow) Rear calipers have smaller 1.25" pistons, resulting in 3.5 K lbs clamping force. Piston sizes were deliberately chosen to pre-bias the brakes front/rear 60/40. Balance bar on the front/rear masters provides further in cockpit adjustment.

                  Onward to the brake bleeding. We're using a motive power bleeder, pushing fluid from the reservoir down to the caliper bleed screw. No need to pump the pedal. Fluid is easily collected at each caliper and reused in the pump.

                  We saved much grief by pressurizing the system with just air before beginning. It was easy to visit each fitting, listen for air leaking and tighten accordingly. No mess. Then the bleeder was filled with fluid and re-pressurized.



                  Bleeder eliminates the whole "open valve, push pedal, close valve" dance. You simply open the bleeder valve and wait until air bubbles are not coming out any more. Bleed from the caliper top screw. This caliper has outer and inner bleed screws. Outer first, then inner.

                  We made the bleeder hose sleeve because the tube kept slipping off the bleeder screw. I can't believe they don't make something that snaps on to the bleeder screw. Need to google this more.



                  Here's a close up of air bleeding from the system.



                  We started with the rear circuit. Wasn't long before the air bubbles were gone and only fluid was coming out of each caliper. However, we were not getting a firm pedal. Remember we have a balance bar? Imagine if the master cylinder in the middle (rear circuit) is fully charged, so the piston is hard to move. Every time you press on the brake pedal, the balance bar will pivot against this piston while the left, uncharged master moves. It feels like a "soft pedal" when in fact you actually have pressure. Once the front (left) circuit is bled down, the other master on the balance bar firms up and both masters respond to the pedal. Deceptive, but easy to understand once you look at it. Re-visiting the rear circuit resulted in perfect pedal feel.

                  Last edited by dvallis; 10-22-2017, 01:31 PM.
                  "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                  1987 E30 3L Turbo Stroker Das Beast
                  2002 E39 M5

                  Comment


                    Back on 4 wheels !

                    Today is a big day. Car is going back on 4 wheels.

                    We did a bit more brake bleeding with the calipers unbolted, rotated vertical and tapping with a rubber hammer. It helped a lot getting rid of bubbles. 1/4" tubing with 0.170" inner diameter grabbed on the bleed screws better.



                    Once the brakes were bled we went around the whole suspension checking and torquing every nut. This is how we did 200 ft-lbs on the wheel hubs. Rob standing on a breaker bar.



                    Did some rudimentary front suspension alignment.



                    Got the rear suspension assembled as well. Note the helper springs.



                    While on the jack stands, rear wheel rubber looked pretty close to the upper spring perch without a spacer.



                    Once the suspension was loaded, perch was nowhere near the rubber. Note we unhooked the sway bars before dropping the car. I read horror stories about sway bar links getting ripped off if they are not adjusted right.



                    So, didn't need these in the rear for now. Might ultimately upgrade the rear rubber to 255 and use them. We're sticking to 245 all the way around as a baseline. Spacers are absolutely required in the front for wheels to clear calipers.



                    Drum roll please ............

                    Back on the ground! Damn that looks good.



                    We're still nose high since the motor and tranny are not in yet.



                    Getting closer to being a race car. Working on wiring harness next.

                    "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                    1987 E30 3L Turbo Stroker Das Beast
                    2002 E39 M5

                    Comment


                      Congratulations! Looks fantastic.


                      Sent from my iPhone using Tapatalk

                      Comment


                        Suspension sensor preview

                        So, if you google "suspension travel sensors" the solutions out there are anywhere from $150 each for linear pots, $250 each for NEMA string pots and upwards of $1000 each for laser based systems.

                        I found these NEMA65 rated string pots on eBay for $50 each. They can measure 15" travel, are highly linear and built for harsh environments. With a bit of cable soldering, I'll turn them into AIM compatible suspension sensors. Nice!

                        "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                        1987 E30 3L Turbo Stroker Das Beast
                        2002 E39 M5

                        Comment


                          Data acquisition

                          Data acquisition is alive. Here's the setup. Box on the left is an EVO4S data acquisition unit, box on the right is a GS-Dash.



                          Gear is already paying for itself. You can see that we have some air in the front brake system. Masters are both 5/8", balance bar is centered, so both pressures should be equal. Time for more bleeding.

                          Using the brake math above, I know it took 77.8 lbs leg force to get 761 psi in the rear circuit. Just about dead-on to the expected value.

                          Last edited by dvallis; 10-22-2017, 01:32 PM.
                          "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                          1987 E30 3L Turbo Stroker Das Beast
                          2002 E39 M5

                          Comment


                            Revisiting the steering linkage

                            I got fed up with the ghetto steering linkage and decided to do it correctly.

                            Bought two E46 lower steerring shafts on eBay for $20 each



                            Will turn them into one of these. See this post

                            "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                            1987 E30 3L Turbo Stroker Das Beast
                            2002 E39 M5

                            Comment


                              Originally posted by dvallis View Post
                              That's the right one for an E30. Motive Products 0100. Confirmed in Amazon reviews. Good tool for $50.


                              Mine is perfect for the BMWs...but after buying the black line accessories to fit my Chevy and Ford, it sucks. The seals would fail at the MC. So ya get it pumped up, walk away to crack the bleeder and poof... an explosion of brake fluid at the reservoir.

                              Starting to rethink mine.
                              Last edited by TimeMachinE30; 10-23-2017, 05:11 PM.
                              ACS S3 Build / Dinan 5 E34

                              Comment


                                We only pressurize to 10 psi. Works fine and no risk of fluid everywhere.
                                "And then we broke the car. Again." Mark Donohue, "The Unfair Advantage"

                                1987 E30 3L Turbo Stroker Das Beast
                                2002 E39 M5

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