DIY mid engined car

[s91]

First post here after lurking for a long time, had a bit of a silly idea for a project car and there are some clever people on PH so here goes.

Would it be possible to create a mid engined RWD car, by using the entire drivetrain/suspension/subframe assembly from a front wheel drive car, if you were to unbolt the upper suspension mounts, exhaust pipe, wiring loom, lower subframe and so on, then lift the body out of the way so you are left with all of the running gear and sticking that into the rear of another car after removing it's original engine and drivetrain and cutting out the boot floor, relocating the fuel tank, and fitting a roll cage to allow for mounting points? Of course there are loads of other issues such as the handbrake, making the wheels fixed rather than steered, gearbox linkages etc...

Other than the obvious issues it seems a relatively straight forward idea because you've already got all of the main mechanical parts which are known to work together, you're just mounting them in a different place. Lets say the engine/drivetrain/suspension you were fitting comes from a car with double wishbone suspension and the geometry was fully adjustable, with some trial and error would you be able to make a car that works properly in terms of handling/driveability?

[Escy]

Toyota did all the hard work with the MR2, better off getting that as a base and modifying from there in my opinion.

[Equus]

Yes; numerous mid-engined kit cars use this approach - often with fixed tie rods replacing the steering rack arms, to fix everything in the 'straight ahead' position.

There are complications with roll axis, spring rates and weight transfer, to make it handle right, though.

[Arnold Cunningham]

I think Rover did it with the MGF/TF too - front subframe w/ fixed tie rods.

[jhonn]

Anything is possible, if you're prepared to spend enough time, money and effort on it; I wouldn't think the mechanical work would be straightforward as the rear of the car wouldn't be designed for the mounting and subsequent loads. You could probably lash something up but making it driveable (and safe), as well as looking right would be quite a task.

You would need access to lots of tools, materials and the right skills.

However, if you do decide to go ahead, remember to start a thread on it here!

[anonymous-user]

Remember, that cutting any cut into the body of a unitary body car, or similar structural chassis member means that car must be re-certified before it can be re-licensed under the Individual Vehicle Approval (IVA) scheme, and may then have to have a Q plate as a result.

[kambites]

You could certainly use all of the "active" components with a custom space frame providing pick-up points of identical dimensions to the donor. Whether you could actually use the entire front half of the monocoque, I don't know.

Obviously with the former approach, how much benefit you get out of it depends on how many of the donor's hardpoints are mounted on removable subframes and how many are welded straight to the monocoque.

[mdw]

Bit like a GTM K3. 2 metro front ends.

[gazza285]

Have a look here...

https://www.kimini.com/

[Flying Phil]

I did this with an Alfa Romeo Sprint. The front 4 cylinder boxer engine and gearbox was removed and the front subframe/inner wings/engine and gearbox of an Alfa Romeo 164 3 litre V6 were put into the back. There was a thread of the entire build on the Alfa Owner website and elsewhere - ref "Sprint 6C".

[anonymous-user]

Flying Phil said:

I did this with an Alfa Romeo Sprint. The front 4 cylinder boxer engine and gearbox was removed and the front subframe/inner wings/engine and gearbox of an Alfa Romeo 164 3 litre V6 were put into the back. There was a thread of the entire build on the Alfa Owner website and elsewhere - ref "Sprint 6C".

very nice found the retro rides thread. how do you get air to the engine?

[Flying Phil]

Thanks Sprucegoose
Air to the engine from underneath and out through the louvred tailgate. 164 Radiator in the front with electric fan plus standard Sprint interior heater/fan.

[anonymous-user]

very nice, surprised you have never done a readers thread on here i know a lot would be interested, is looks a very interesting car.

[rodericb]

Someone in the US did this with a DC2 Integra. Moved the drive train back into the boot. Now if you want to talk about Alfasud Sprints, an Australia company converted a few to mid-engine but they did use a longitudinally mounted V8 and gearbox. https://www.google.com.au/search?q=giocattolo&...

https://en.wikipedia.org/wiki/Giocattolo

[s91]

Those who have already done it - how do cars like this tend to handle? Once you've played with the suspension settings do they drive "properly" or are they usually a bit silly as they are generally built in a garage by a man with some spanners as opposed to a team of engineers?

[Fastpedeller]

If you want to go this route with a kit car, and you want it to really handle, then you can't go wrong with a Sylva Vectis or J17.

[s91]

I'm not overly bothered about building the ultimate handling machine so to speak, although of course that would be nice, aslong as it isn't dangerous. I'm expecting a car with a fairly short wheelbase and rear wheel drive and mid mounted engine to be a bit more of a challenge than the front engined front wheel drive cars that I've been used to.

Edited by s91 on Friday 22 September 19:43

[Codswallop]

Escy said:

Toyota did all the hard work with the MR2, better off getting that as a base and modifying from there in my opinion.

Definitely this!

Mk3 MR2 is one of the lightest and best handling modern roadsters, all of the body panels are just bolted on so you can plonk any bodywork you want onto it, and they're great value. Loads of engine swap options including well documented Camry V6 swaps (as used in the Evora).

[Equus]

s91 said:

Those who have already done it - how do cars like this tend to handle? Once you've played with the suspension settings do they drive "properly" or are they usually a bit silly as they are generally built in a garage by a man with some spanners as opposed to a team of engineers?

Surprisingly well, seems to be the answer (especially when you're aware of how much trouble Lotus had taming the fundamentally similar Elise).

The problem is that if you use 'front' subframes and suspension arrangements at both ends, you inevitably end up with the roll centres in the same place front and rear, and therefore a horizontal roll axis. This effectively takes one of the main 'tools' for tuning basic handling balance out of your control.

None the less, cars like the GTM (both the original Coupe, which used two Mini front subframes, and the Rossa/K3, which used Metro subframes) handled quite tidily.

FWIIW, the Sylva J15 mentioned above doesn't use the subframe approach, though the 'budget' version, the Vectis, does (MGF).

Note that contrary to received wisdom, cars like the MGF and MR2 don't use identical subframes and suspension geometry front and rear, so their approach is not quite the same (ie. front & rear roll centre heights differ, to give an inclined roll axis).

[anonymous-user]

s91 said:

Those who have already done it - how do cars like this tend to handle? Once you've played with the suspension settings do they drive "properly" or are they usually a bit silly as they are generally built in a garage by a man with some spanners as opposed to a team of engineers?

The key, is to get the engine / transmission as LOW as possible across the back. The FWD suspension kinematics won't be ideal, because they will be set for power on dynamic toe (ie oversteer!) when you use them at the back, but make sure you have a low powertrain CofG, stiff mountings (enigne mounts and subframes etc) and spend a bit of time playing with the tracking etc (castor/camber/toe/offset) and you can do a reasonable job in your shed. The two hurdles tend to be:

1) What to do with the steering rack. If you replace it, make very very sure you are not introducing ANY bumpsteer

2) The gear shift. Getting a link to the back of the trans, now facing out the back of the car, and away from the gearstick way up front can introduce a pretty un-inspiring gear change.....


i built a rear mid transverse engine Volvo 480 way back in 1996 (eek, that's 21 years ago!!) but i didn't use fwd suspension in order to avoid some of those issues.