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      05-14-2020, 12:08 PM   #1
RbBugBitMe
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Custom coilovers and stuff

I'm going to document my plan since I seem to have too much time on my hands these days. I will preface this with I am an engineer and I've been designing dampers since 2013 so I'm really good at pretending to know what I'm doing.

I have a habit of designing parts for cars I own and the awesome new2me F30 I recently picked up is no exception. I may make some separate threads to document the other things but for now I'm going to take the cheapest route to a great custom rebuildable coilover system.

Cheap
First I decided not to design and manufacture every single thing, way too expensive and there is no point in reinventing the wheel when it comes to structural bits. I only care about improving the hydraulics. So I shopped around for a cheap rebuildable monotube design that ideally would be easy to get parts for instead of the whole assembly. The best I could come up with is BC's offering which turns out is pretty spectacular for what I'm going to do. Their website lets you buy almost every part of their damper as individual components and their main tube ID finish is more than acceptable.

Ideally I would buy the main tube without everything in it but that is their business' main component, most likely shipped from Taiwan fully assembled so that's never going to happen. That means in the short term I can take the hydraulic assembly and just replace the main piston, the adjuster, and the oil and be happy. Medium term I could swap out the rod guide and floating piston to reduce friction. Long term I could add a remote can for more travel, adjustability, and lower gas pressure for a further reduction in rod force and friction.

I think I have everything I need in the shopping cart at $575.

Rebuildable
I need to make some custom tooling and dyno mounts but BC shocks can be fully disassembled. Perfect.

Specification
BC comes with a single main piston bleed adjuster. It adjusts compression and rebound at the same time which is just flat out unacceptable. The adjuster range and linearity between clicks also leaves me wanting more.

3in/s 16 clicks which is middle of the adjustment range. I'd like to get hysteresis down a bit here.


And of course "dyno tested" out of Taiwan doesn't mean much. There is an issue with the adjuster when its fully closed. Probably too far off on the length of the metering rod but I need to dig in and double check my design length vs. theirs vs. each of the shaft's variation in length.

Force velocity - full stiff 3in/s


Force displacement - full stiff 3in/s


Step 1: Swap out the needle jet for one that checks compression flow so the adjuster only works on rebound bleed. I can design this the opposite way to make it a compression bleed adjuster, perhaps to speed up the tuning process. In order to integrate a dual bleed adjuster I'd need to make a new shock shaft and all the guts which isn't worth it right now. Also, swap out the floating piston cause that's easy.
Progress - Done.



Step 2: A little more difficult. They've integrated the needle and the rod pushing the needle from the external adjuster into one long piece. More investigation is required but it may take machining the ID of the main shaft to get what I want out of the needle diameter and profile.
Progress - Currently measuring critical features and will reuse a needle profile I previously developed.

Step 3: Design a new high flow and double digressive main piston to my liking. RE Suspension sells shims I'll design around. Already have the high flow I just need to tweak for their bore and rod tennon.


Step 4 Buy some hyperco springs, build, install, and tune. Then maybe make the double digressive piston and start looking at integrating a piggyback.

Some other fun bits I'm working on this year are below. I haven't decided yet but I may go full send and change everything to a centerlock style.



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Last edited by RbBugBitMe; 05-14-2020 at 01:35 PM.. Reason: Added dyno graphs
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      05-14-2020, 01:16 PM   #2
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I'm looking forward to seeing how you tune these.

Are Bilsteins too much to start with as a base? They have a catalog you can get a wealth of parts from. Or are you requiring the ability to adjust compression/rebound with a knob?
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      05-14-2020, 01:20 PM   #3
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I am making at least single rebound an compression adjustability a requirement for now. The benefits that come with a remote reservoir are key as well.

I also want to show with a little bit of design experience you can polish a turd.
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Ryan M. PdVMotorsports.com Owner https://www.youtube.com/@pdvmotorsports
2014 EB M-Sport 335i xDrive - PdV/BC custom coilovers, PdV spherical rear shock mounts, PdV big brake kit, MHD Stage 2+
Next up: PdV genuine GTX3582R Gen2 turbo kit, Nostrum HPFP & Stage 2 injectors, PdV PM5 w/ "Veyron" Bosch E5LM

Last edited by RbBugBitMe; 05-14-2020 at 02:14 PM..
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      05-14-2020, 11:08 PM   #4
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Very interesting stuff. Also that rotor hat
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      05-14-2020, 11:33 PM   #5
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Looks awesome! Looking forward to the results and how your setup turns out.
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      05-15-2020, 05:34 AM   #6
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Ycw suspension, an offshoot of mfactory sells many individual parts of their suspension, just another option. actually makes pretty decent stuff.
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      05-15-2020, 06:56 AM   #7
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Thanks ya'll. Side note, I'm thinking the issue in the bad dyno graphs is actually a loose main piston and not a needle valve issue.

Quote:
Originally Posted by mike082802 View Post
Ycw suspension, an offshoot of mfactory sells many individual parts of their suspension, just another option. actually makes pretty decent stuff.
Thanks, never heard of them. They're a bit more expensive than this Taiwan stuff though.
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2014 EB M-Sport 335i xDrive - PdV/BC custom coilovers, PdV spherical rear shock mounts, PdV big brake kit, MHD Stage 2+
Next up: PdV genuine GTX3582R Gen2 turbo kit, Nostrum HPFP & Stage 2 injectors, PdV PM5 w/ "Veyron" Bosch E5LM
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      05-15-2020, 02:15 PM   #8
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Best of luck! I love this community because of projects like this
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      05-15-2020, 02:28 PM   #9
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you can find them for i think 1100 or so through the forums. i picked up a set as a tester for 700$ 4 years ago, dampening was off so i sent them back twice to have them revalved. i actually sent them an Ast damper i had sitting around so they could throw it on the shock dyno and compare and adjust the valving. after that they felt just as good as a friends mcs set up. they are actually ohlins Official Hong Kong/Macau Service Centre) and they have a Roehrig 2VS Shock Dyno. i love what your doing, must be nice to have the access to the shock dyno and the ability/knowledge to build your own dampers.
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      05-15-2020, 04:00 PM   #10
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Quote:
Originally Posted by mike082802 View Post
you can find them for i think 1100 or so through the forums. i picked up a set as a tester for 700$ 4 years ago, dampening was off so i sent them back twice to have them revalved. i actually sent them an Ast damper i had sitting around so they could throw it on the shock dyno and compare and adjust the valving. after that they felt just as good as a friends mcs set up. they are actually ohlins Official Hong Kong/Macau Service Centre) and they have a Roehrig 2VS Shock Dyno. i love what your doing, must be nice to have the access to the shock dyno and the ability/knowledge to build your own dampers.
With the process I'm going through right now its about $550 total for everything I need from BC and then whatever it costs me to mfg. my own parts to finish the set.

You're right, it is nice to have machining, design, simulation, vehicle tuning contacts all over the world as well as my own experience that make a project like this possible. It is with a little regret I'm job hunting outside of the damper world right now but money is money and F1 (and racing in general) wasn't everything I built it up to be as a kid.

I'm hoping I can get this done and still have access to the electromagnetic dyno I do now. I can really turn this into a masters thesis if I want with a dyno like that.
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2014 EB M-Sport 335i xDrive - PdV/BC custom coilovers, PdV spherical rear shock mounts, PdV big brake kit, MHD Stage 2+
Next up: PdV genuine GTX3582R Gen2 turbo kit, Nostrum HPFP & Stage 2 injectors, PdV PM5 w/ "Veyron" Bosch E5LM
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      05-15-2020, 11:49 PM   #11
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Subscribing to this. Awesome stuff.

If it ends up working out, would you try selling the parts you end up making for someone else to follow?
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      05-16-2020, 01:19 AM   #12
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Sign me up as a customer, f32 with edc huehuehue
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      05-20-2020, 09:00 AM   #13
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Pushing ahead with some of the easy stuff to get the layout set up for the rear. Doing this gave me an idea I hadn't thought of yet. I can press out the supplied rubber bushings and install a housing for a spherical bearing so that'll go nicely with spherical upper mounts if I want a little more precise damping.

20mm rod diameter though Just not good, I think the OE is under 14mm. Gets really expensive quick if I want to start swapping rods though.

46mm main bore makes for very simple changes to my existing piston designs so those will be quick work.

Edit: Needle adjuster and both pistons updated.

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2014 EB M-Sport 335i xDrive - PdV/BC custom coilovers, PdV spherical rear shock mounts, PdV big brake kit, MHD Stage 2+
Next up: PdV genuine GTX3582R Gen2 turbo kit, Nostrum HPFP & Stage 2 injectors, PdV PM5 w/ "Veyron" Bosch E5LM

Last edited by RbBugBitMe; 05-28-2020 at 05:05 AM..
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      08-12-2020, 01:10 PM   #14
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any updates on this?
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      08-12-2020, 01:22 PM   #15
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Yes, I just got the funding I needed and started ordering parts. Assembly and Dyno testing is going to be a challenge now with Covid BS but I'll figure it out.
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      08-13-2020, 09:18 PM   #16
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Subscribed. Awesome project. Looking forward to the updates.
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      09-06-2020, 06:38 AM   #17
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any updates?
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      09-06-2020, 01:31 PM   #18
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In a couple weeks, moving to a different state this week so everything is packed up.
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Next up: PdV genuine GTX3582R Gen2 turbo kit, Nostrum HPFP & Stage 2 injectors, PdV PM5 w/ "Veyron" Bosch E5LM
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      09-06-2020, 02:20 PM   #19
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did you decide on spring rates? with your move will you still have access to a shock dyno? good stuff your doing.
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      09-06-2020, 02:28 PM   #20
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Haven't thought about springs yet. Want to calibrate my butt dyno to my calcs when I install and will choose something common first.

I'll still be required to go into the office at least quarterly and I can drive back anytime to get access if I need it. I can also probably get a deal for some time at PRS.
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      09-06-2020, 05:55 PM   #21
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Quote:
Originally Posted by RbBugBitMe View Post
Haven't thought about springs yet. Want to calibrate my butt dyno to my calcs when I install and will choose something common first.

I'll still be required to go into the office at least quarterly and I can drive back anytime to get access if I need it. I can also probably get a deal for some time at PRS.
subscribed. How i've been waiting for you my friend!

I've been autoxing an F30 335 xdrive on BCs for several years now because they offer decent value and they were available and rebuildable. I would love to see how this turns out...These f30s can become handling gems in disguise.

I wasn't to hot on the 6kg/12kg springs that came with the BCs...
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      11-17-2020, 04:54 AM   #22
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any updates?
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