romashkaman

[WIP] 42110 MOD by Romashkaman

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Hello all!

I know, there already exists a topic about 42110 MODs. But, considering I plan to rebuild the whole car (except exterior) - it really would be better to separate my posts in a new topic (I agree with @Nazgarot).

So, for now, I just copy what I posted in 42110 - Land Rover Defender - MODs and Improvements.

The actual progress is:

- completed front part of the frame (it's stiff enough even without any other part of the body attached):

48930261731_e794b57c45.jpg

- McPherson suspension and front differential module mounts on that frame and is easily detachable (also McPherson struts include new cv-joints from 42099):

48930261886_e83645c5c3.jpg

- front suspension is built with caster and KPI angles:

48929721358_57550d472a.jpg   48930262426_efc1336201.jpg

- engine is built from 4 PF XL-motors coupled together (output gear ratio is 20:36), also it's equipped with one-way clutch (it's built years ago by @nicjasno):

48930262111_edcd3e05ba.jpg    48930446992_79cfa236d7.jpg

- given that drive shaft of the engine has half-stud offset in vertical direction, here is an "offset remover":

48930447472_0dba0d9336.jpg   48930262011_bfb80d49d4.jpg

All modules assembled look like this:

48930447602_a3cdb6c279.jpg   48930447707_499b102e5d.jpg

And, of course, a video of the short test:

 

This module has some little issues (at first, I need to improve stiffness of the suspension's struts - under load they bend a little bit inward, but it doesn't affect all the process of a drive), but it has a really stiff frame and it's a good start point.

You can find more photos on Flickr.

About the question why I decided to use XL-motors:

XL-s have the biggest torque among all Lego motors (according to the @Philo's page). Buggy-motor has higher rpms, but lower torque (and it's much more expensive and bigger than XL). It's not good choice for heavy vehicles. L-motors are more compact, but, again, if you compare torque/rpm ratio among all of the motors - XLs are the best imho. I tested this setup (4 XLs) two years ago at local fest:

 

This model hadn't any gearbox and was pretty heavy. But, as you can see, the car accelerated easily, than acceleration stopped and speed was constant - only because of low max RPMs of the XLs. Theese motors have very good potential even without gearbox. L-motors are too weak for such acceleration of heavy models. Considering I plan to add a gearbox to this rebuilt Defender - it has to be fast and powerfull))

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Interesting mod.

Few suggestions:

1. The ungeared CV joints and differentials will be the first thing to fail at any slight offroading or braking. Use planetary hubs instead.

2. Why are you using a one-way clutch? A proper drivetrain should be able to survive braking and reversing forces too.

3. Those axle-assembled shock absorbers will eventually slide apart and cause the collapse of the whole suspension.

 

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Thanks for the attention!

1. Tests will show, but my previous model (unfinished -  black Mustang from the video) was built with old cv-joints and I didn't notice any failures. I don't like that front wheels hold on driven axles only, without any hubs, but... For now, I don't see a way to avoid the use of new hubs from 42099 other than this concept.

For now, even when wheel holds only on one axle, the backlash is much less than in case of use of every other Lego hub.

2. 4 XL-motors coupled together + gearbox = it stops everything)) I wanted model to be able to do some free ride after motors disabled.

3. 

47 minutes ago, romashkaman said:

This module has some little issues (at first, I need to improve stiffness of the suspension's struts - under load they bend a little bit inward, but it doesn't affect all the process of a drive)

 

40 minutes ago, Zerobricks said:

Those axle-assembled shock absorbers will eventually slide apart

I know there is some work to be done, but I doubt struts will slide apart. It doesn't happen even without load (because of spring unclenches, for example), but when the car is on the ground - load tries to compress the strut via frame and spring (it causes that little strut's bending I mentioned before). I can imagine strut's scattering only in case of very fast spring's unclenching.

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4 minutes ago, romashkaman said:

I know there is some work to be done, but I doubt struts will slide apart. It doesn't happen even without load (because of spring unclenches, for example), but when the car is on the ground - load tries to compress the strut via frame and spring (it causes that little strut's bending I mentioned before). I can imagine strut's scattering only in case of very fast spring's unclenching.

That would depend on whether you have limiters for downward travel on the lower arm. If not it could be a problem in off-road situations when one front wheel is spinning freely in the air and there is a lot of torsion forced working on the suspension. With a limiter for downward travel on the lower suspension arm there is no possibility of this.

This was a problem on some old Chevrolet Corvettes, where the rear axle could collapse under the car in sharp turns because the only thing limiting downwards travel was the shock absorber...

-ED-

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1 minute ago, Nazgarot said:

That would depend on whether you have limiters for downward travel on the lower arm. If not it could be a problem in off-road situations when one front wheel is spinning freely in the air and there is a lot of torsion forced working on the suspension. With a limiter for downward travel on the lower suspension arm there is no possibility of this.

This was a problem on some old Chevrolet Corvettes, where the rear axle could collapse under the car in sharp turns because the only thing limiting downwards travel was the shock absorber...

-ED-

That is very good idea! Thanks! Will try to implement it.

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