Hybrid Lego car platform

[chronologically]

Help Needed: Hybrid LEGO Technic Drivetrain with Clutch + Dual Input (Pullback & Motor)

https://imgur.com/gallery/XdUbU8f

 

Hi everyone,

I'm currently working on a hybrid LEGO Technic drivetrain project for a university assignment, and I could use some help/advice with the mechanical layout and power delivery.

Goal:

Build a 4-wheeled vehicle where two different power sources (a pullback/manual axle and an electric motor) can engage a central clutch system to drive the same rear axle.

Key Design Elements So Far:

Rear wheels mounted on a yellow axle

Medium PF motor to power one input

Manual pullback input via a second axle (non-spring based)

LEGO clutch ring + two red clutch gears to switch between inputs

Red 20T bevel gear to drive downward to the wheel axle

Tan 12T bevel gear on the axle for 90° torque transfer

 

What I'm Struggling With:

How to mount the motor securely while keeping it aligned with the left clutch gear

Making sure bevel gears stay meshed without slipping

General layout tips — is my frame too narrow or short?

Any better ways to link the clutch output to the wheels

I’ve got most parts available (PF motor, clutch ring, bevel gears, bushes, Technic beams, etc.) and have built a working 4-wheel frame. Right now I'm finalizing the drivetrain.

Any feedback, images, or build references would be hugely appreciated. I’d love to learn how others have approached something similar — even if it’s not exactly a hybrid.

Thanks in advance!
 

[Aurorasaurus]

14 hours ago, chronologically said:

Making sure bevel gears stay meshed without slipping

If you have this part you can brace a 12t half bevel gear and a 12 full size gear (often black or gray). If it has to be both tan 12t gears you can use this part   and it will work well.

General tips- brace gears whenever you can. Put beams behind the clutch tears and on both sides when you can.

[tseary]

A couple of suggestions:

Minimize the number of idle gears that are turning in pullback mode. I think they will sap the power of the pullback motor. You might achieve this by placing the clutch directly on the output axle.

Perhaps do away with bevel gears entirely. It will be most efficient to use spur gears for everything.

The rectangular frame parts (https://www.bricklink.com/v2/catalog/catalogitem.page?P=39794, https://www.bricklink.com/v2/catalog/catalogitem.page?P=4526, etc.) are good for keeping things square and rigid, if you have some of those.