Reverse Trike

[cRiPpLe_rOoStEr]

Originally Posted by Christ

Rear hub from a mid sized 90's GM, has caliper with cable lock attachment point on it. Just take the while rear spindle from a donor car.

If could get 3 of these calipers, wouldn't be so bad to make an all-mechanical brake assembly, without hydraulics and vacuum booster...

[Christ]

Originally Posted by cRiPpLe_rOoStEr

If could get 3 of these calipers, wouldn't be so bad to make an all-mechanical brake assembly, without hydraulics and vacuum booster...

Not legal in most states in the US if it's to be registered as a car. Also, many states have laws (I imagine, haven't checked into it directly) against modifying existing brake systems as part of their inspection process to system-types not originally installed (subbing hydraulic for mechanical).

The idea would be to drop the MC size by 1/8th inch (unless moving from drum brakes in the rear) and add the rear fluid master cylinder, then hook a cable to lock it for an emergency brake.

However, in most states, 3 wheelers are registered (can be) as motorcycles and are therefore only subject to the motorcycle inspection procedure. Ergo, they don't actually need an emergency brake or parking brake system and needn't account for brake failure with redundancy systems, leaving him the opportunity to use whatever brake system works adequately for his purposes.

The GM suggestion was just that, and only because it affords a disc brake with hydraulic and mechanical capability, including the disk and a wheel hub with a fairly common 5-lug bolt pattern for which wheels can be sourced from literally 100's of vehicles spanning half a century or better.

[freebeard]

Once you settle on those parts, the really interesting imagineering begins. You could do worse than start here:

Zero Cost Modelling of SpaceFrames

[HydroJim]

So I've been doing some design work and this is what I've come up with:

I wish I had some CAD education, but I guess that's what college will be for

On a side note, I've been researching Megasquirt standalone ECU's and I will definitely be building one for this car. It should allow for lean burn close to Honda lean burn levels.

[freebeard]

I see now where your question is coming from. It looks like you're going back from four wheels to a tricycle.


Variable wheelbase is all the rage. MIT and Toyota do it.

Put a horizontal hinge, kind of like a motorcycle framehead, at the gray dot. The subframe would be a parallelogram 4-bar linkage with coil-over-shock[s], and a positive stop at the front and back.

I haven't thought out the telescoping bodywork yet.

[NeilBlanchard]

I think making a 4 wheeled car into a trike would be a big problem -- the wheel geometry is just too unstable. If you want to make major modifications, go for a narrowed rear track; similar to what Dave Cloud did to a Metro to turn it into the Dolphin.

[HydroJim]

There are a lot of videos on youtube with a lot of reverse trikes and they seems pretty stable to me. The worst thing I can do is not try it. If things don't work out, it won't be too hard to cut the wheel off and put 2 in it's place. I'm sure it won't handle nearly as well and there will be rear traction problems, but there is nothing wrong with taking corners slowly.

[groundflyer]

Originally Posted by NeilBlanchard

I think making a 4 wheeled car into a trike would be a big problem -- the wheel geometry is just too unstable. If you want to make major modifications, go for a narrowed rear track; similar to what Dave Cloud did to a Metro to turn it into the Dolphin.

the wheel geometry is just too unstable. How ? I already have a project reverse trike crx and that this is solid.. rolls with ease also.

What you don't want is a front wheel trike race

https://www.youtube.com/watch?v=KGULcLUr0I4

[freebeard]

the wheel geometry is just too unstable

At the limit, a nose-heavy four wheel car wants to become a three-wheeler anyway.


With 66/33 weight distribution and the suspension sorted out, the rear wheel should swing out and track behind the outside front wheel. A longer wheelbase helps, but creates problems parking, that why I suggested the variable wheelbase. I don't expect you to try it, it's just a thought experiment.

The biggest problem I see is the lower rear corner of the door window glass when it is rolled down into the door. That is the constraint on plan taper in the lower body.

[HydroJim]

variable wheel base is cool, but definitely beyond the scope of my project which is basically a $5000, 100 mpg car. I'm going to be looking for a metro and will be doing a project very similar to groundflyer's so hopefully anything he finds out will help me to learn. After all, that's what it's all about.