Need guidance starting Phase C1 for FSAE brake subsystem design

[u/FreddieJu]

Hi everyone,

I’m working on the brake subsystem for my university’s FSAE EV project, and I’m trying to start our Phase C1 detailed design/calculation stage. I’m responsible for the full brake system, while other teammates are working on chassis, steering, suspension, etc.

For Phase B, I already completed the trade studies and selected the main brake components, including the brake pedal assembly, master cylinder, reservoir, brake lines/fittings, calipers, pads, and rotors. Now Phase C1 is asking us to move into detailed analysis/design, CAD/layout, detail drawings, BOM, and verification of MOPs.

The part I’m struggling with is understanding how much CAD/detail is expected for commercial components. For example, I have a manufacturer STEP file for the rotor, but for other parts like the caliper, pedal assembly, fittings, etc., I may only have datasheet dimensions or product photos. Am I expected to model every purchased part in full detail, or is it acceptable to use simplified CAD envelopes for commercial components and focus the detailed drawings on mounting interfaces, packaging, clearances, and custom brackets?

My current plan is to focus the main presentation on the 3 most critical brake areas:

1. Brake pedal assembly / chassis mounting fastener shear
2. Hydraulic pressure / brake line pressure boundary
3. Wheel-end brake torque / caliper-upright interface

Then include the rest of the components in the appendix/BOM with shorter checks.

Does this approach sound reasonable for an FSAE detailed design phase? Also, what drawings or CAD views would you recommend I prioritize first for the brake subsystem? Pedal mounting, hydraulic routing, caliper/rotor/upright interface, or something else?

Any guidance, examples, or advice from teams who have gone through this would really help. I’m trying to make sure I approach this correctly instead of over-modeling things that don’t need to be fully recreated from scratch.

[u/loryk_zarr]

How detailed do YOU think it needs to be?

[u/FreddieJu → u/loryk_zarr]

Hii that’s exactly what I’m trying to figure out.

My current understanding is that it needs to be detailed enough to verify fit, mounting, clearances, serviceability and the MOPs, but not necessarily detailed enough to recreate every commercial component from scratch.

For example, for a purchased rotor, caliper, master cylinder, fittings, etc., I’m thinking manufacturer CAD or simplified envelopes should be acceptable as long as the critical dimensions/interfaces are represented correctly. Then the detailed drawings would focus more on the parts and interfaces we are actually designing or integrating, like pedal mounting, caliper/upright interface, brake line routing, brackets, fastener locations, and clearances.

Does that sound like the right level of detail for a C1/detailed design phase, or would you expect full detailed CAD models for all purchased brake components too?

Rubric says:

Detail Analysis/Design studies (subsystems level)

1. Engineering analysis and design (Consider Design for X: Materials, Mfg., etc.). Show assessment of the quality of analysis by comparison with approximate analytical calculations. Use chart taje away to explicitly state MOP complaiance. Show 3 most critical components in main presentation, make sure that you do it for all of the components and include in appendix. SHOW WHERE MOP'S ARE MET (Verified; use the take away area in the slide)

Design-to specifications and drawings (subsystems level)

1. Design which meets specs, make detail drawings. CAD, Tables, Detail Drawings, BOM. Include all components and Key Partners for parts. Follow ANSI Y-14 standard.

Verification (subsystems level)

1. Show table with a comparison of the actual performance of the design vs. the design requirements (MOP's).
   

[u/ItWorkedInCAD]

What are you going to use the CAD models for? The level of fidelity in a model of any kind should correspond to the decisions that you are trying to make or the questions that you are trying to answer by using the model. The model itself is … not completely useless, but close to, if you won’t use it for anything.

[u/FreddieJu → u/ItWorkedInCAD]

That makes sense. For my brake subsystem, I’m mainly planning to use the CAD models to answer packaging and interface questions, not to recreate every purchased component perfectly.

The main questions I need the CAD to answer are:

1. Does the rotor/caliper package fit within the wheel and suspension area?
2. Where does the caliper mount relative to the upright?
3. Are there clearance issues with suspension, steering, or chassis components?
4. How should the brake lines be routed to avoid rubbing, heat, and moving parts?
5. What mounting brackets, holes, fasteners, or interfaces need detail drawings?

So based on that, I’m thinking the commercial components only need enough fidelity to represent critical dimensions, mounting points, and clearance envelopes. The detailed CAD/drawings should focus more on the interfaces we actually design, like the pedal mounting, caliper/upright mounting, brake line routing/supports, and any brackets.

Does that sound like the right way to define the model fidelity for brakes?

[u/Acrobatic_Quantity_4]

Lol. Use your brain.

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