Could this idea work?
Discussion
Hi All
I am new to this forum but have a life long passion for anything with four wheels and an engine. Most of my car projects have been restorations of old Fiats and Lancias but I have dipped my toe into kit cars by building a Toylander for my kids!
Over the years I have aspired to build a kit car, however, there has never been one that ticks all of the boxes in terms of what I would want from living with it day to day (GTM Lybra came close). My solution, develop and build one that does! And if other people like it go into production!
There are limitations to what I can do and would class myself as a hobby mechanic and not an automotive engineer, car designer nor fabricator. So I will need to sub contract out a lot of the work if this is ever going to become a reality.
Before I commit myself to incurring the cost of a structural engineer to design a chassis etc etc I though that I would air my idea on here and see what you guys think and whether I am barking up the wrong tree.
The idea. I have taken my inspiration largely from the work that Smyth Performance has done in the US in converting a Mk4 Golf into a mid engined convertible.
What I am considering is taking a 5 door Mk5 Golf and converting it into a two seater mid engined hard top sports car. This would be done by,
- removing the rear end about 0.25m or so behind the B pillar,
- fabricating a steel frame that will bolt and weld to the B pillar and allow the front suspension, sub frame and engine etc to be mounted were the rear seats would have been.
- Retain the original OEM parts where ever possible to keep the build costs down. (suspension would be upgraded to include coil overs or similar)
- Modify the front hubs that are now at the rear to lock the steering ability
- Retain the dash, front doors, windscreen, interior etc so the the cabin retains an production car feel
- at the front remove all of the bolt on panels and install another sub frame and suspension set up from a donor as the original set up is now in the rear!
Clearly I have over simplified the above stages but this is broadly what I need some feedback on. Could this work and be able to get through the IVA test?
I have sketched out various bodywork designs that would take the form of a GRP front and rear section. Design inspiration from many cars including the Ford RS200, Lotus Elise mk2, Colin McRae R4 and others. But there is no point dreaming about what the concept could look like if the fundamental structural concept doesn't work.
Any comments gratefully received, even if they tell me that I am a basket case for even suggesting such a concept.
Cheers
Dave
I am new to this forum but have a life long passion for anything with four wheels and an engine. Most of my car projects have been restorations of old Fiats and Lancias but I have dipped my toe into kit cars by building a Toylander for my kids!
Over the years I have aspired to build a kit car, however, there has never been one that ticks all of the boxes in terms of what I would want from living with it day to day (GTM Lybra came close). My solution, develop and build one that does! And if other people like it go into production!
There are limitations to what I can do and would class myself as a hobby mechanic and not an automotive engineer, car designer nor fabricator. So I will need to sub contract out a lot of the work if this is ever going to become a reality.
Before I commit myself to incurring the cost of a structural engineer to design a chassis etc etc I though that I would air my idea on here and see what you guys think and whether I am barking up the wrong tree.
The idea. I have taken my inspiration largely from the work that Smyth Performance has done in the US in converting a Mk4 Golf into a mid engined convertible.
What I am considering is taking a 5 door Mk5 Golf and converting it into a two seater mid engined hard top sports car. This would be done by,
- removing the rear end about 0.25m or so behind the B pillar,
- fabricating a steel frame that will bolt and weld to the B pillar and allow the front suspension, sub frame and engine etc to be mounted were the rear seats would have been.
- Retain the original OEM parts where ever possible to keep the build costs down. (suspension would be upgraded to include coil overs or similar)
- Modify the front hubs that are now at the rear to lock the steering ability
- Retain the dash, front doors, windscreen, interior etc so the the cabin retains an production car feel
- at the front remove all of the bolt on panels and install another sub frame and suspension set up from a donor as the original set up is now in the rear!
Clearly I have over simplified the above stages but this is broadly what I need some feedback on. Could this work and be able to get through the IVA test?
I have sketched out various bodywork designs that would take the form of a GRP front and rear section. Design inspiration from many cars including the Ford RS200, Lotus Elise mk2, Colin McRae R4 and others. But there is no point dreaming about what the concept could look like if the fundamental structural concept doesn't work.
Any comments gratefully received, even if they tell me that I am a basket case for even suggesting such a concept.
Cheers
Dave
Plenty of people have build rear and even twin engined Golfs of all flavours. Most of them verge between pretty dire and downright dangerous imo, even the so called "professionally" built ones.
It's not that hard to do, but to do it right so the car handles correctly, and is safe, is time consuming, and if you pay someone else to do it, will be massively expensive!
Google "rear engine golf" or "twin engine golf" to see what i mean....
It's not that hard to do, but to do it right so the car handles correctly, and is safe, is time consuming, and if you pay someone else to do it, will be massively expensive!
Google "rear engine golf" or "twin engine golf" to see what i mean....
Thanks for the responses.
I do take your point about cost if I subcontract out everything. If I can get someone suitably qualified to design the chassis I will at least have a professional indemnity insurance policy to claim on if something goes catastrophically wrong down the line. I will need to brush up on my MIG welding skills to convert the drawings into a prototype.
I have always liked the engineering behind the Z Cars conversions and there is a lot I can learn from what they have done.
My vision is not to create a mid engined car that still looks like a production Golf, instead, I want an original car design that retains a lot of the benefits of its mass produced donor e.g. fit and finish of the cabin, crash protection, tried and tested running gear etc.
Thanks
Dave
I do take your point about cost if I subcontract out everything. If I can get someone suitably qualified to design the chassis I will at least have a professional indemnity insurance policy to claim on if something goes catastrophically wrong down the line. I will need to brush up on my MIG welding skills to convert the drawings into a prototype.
I have always liked the engineering behind the Z Cars conversions and there is a lot I can learn from what they have done.
My vision is not to create a mid engined car that still looks like a production Golf, instead, I want an original car design that retains a lot of the benefits of its mass produced donor e.g. fit and finish of the cabin, crash protection, tried and tested running gear etc.
Thanks
Dave
If the only bit you are keeping is the b pillar to the scuttle then why not go for a whole new chassis (OK keep the doors and windscreen if you want). The bit you are keeping will not be structurally stiff, will just add weight and therefore compromise the handling and the design. I could see the point in doing it your way if you were to retain the full lower floor pan with front suspension/steering etc. as stock, cut a hole in the back seat/boot floor and inset a frame with the engine/rear suspension in it linked to the suspension points front and back and providing roll over protection (but basically a chassis!), chop the roof and replace with a roll bar, fibreglass panels and wings. Leaving so little of the original car just doesn't add any benefit IMO. Which ever way you do it it will need an IVA as you have changed the chassis so much.
Also, for info, the structural bit is possibly Ok to sub out but, it will cost, but not the earth. However, doing the styling, making the buck and then getting the fibreglass moulds taken off that and then probably doing it twice as the first time will not be perfect, is a labourious job (remeber usually charged out at an hourly rate, not fixed price) and so will cost you a packet. Have a look at the Bertini thread on here and see what it has taken someone with the skills to do it and this is just a panel swap without any mechanical or interior changes.
That said, if your heart (and wallet) are prepared for it, then go for it. Good to see some ambition.
Also, for info, the structural bit is possibly Ok to sub out but, it will cost, but not the earth. However, doing the styling, making the buck and then getting the fibreglass moulds taken off that and then probably doing it twice as the first time will not be perfect, is a labourious job (remeber usually charged out at an hourly rate, not fixed price) and so will cost you a packet. Have a look at the Bertini thread on here and see what it has taken someone with the skills to do it and this is just a panel swap without any mechanical or interior changes.
That said, if your heart (and wallet) are prepared for it, then go for it. Good to see some ambition.
So I guess what you're aiming at is something along the lines of this then....
Ginetta G32
As has been said above, really you'll not be saving much by trying to retain the cab section of a modern production car save for the interior styling and finish, though you will save some work on building doors and getting them to fit. A modern car is a monocoque and as such much of what you'll likely cut away will result in you loosing the integrity of the chassis and any 'crash protection' If you want to maintain all that then you'll be keeping the majority of the car and just replacing any bolt on wings.
I don't honestly think the Golf is an ideal starting point for what seems to be your desire for a mid engined sports coupe. It's a car I've considered numerous times too, as there's plenty of them but there's a lot more suitable donors out there. Going mid engined then it's worth considering the MR2 and MGF for the process you are describing.
Ginetta G32
As has been said above, really you'll not be saving much by trying to retain the cab section of a modern production car save for the interior styling and finish, though you will save some work on building doors and getting them to fit. A modern car is a monocoque and as such much of what you'll likely cut away will result in you loosing the integrity of the chassis and any 'crash protection' If you want to maintain all that then you'll be keeping the majority of the car and just replacing any bolt on wings.
I don't honestly think the Golf is an ideal starting point for what seems to be your desire for a mid engined sports coupe. It's a car I've considered numerous times too, as there's plenty of them but there's a lot more suitable donors out there. Going mid engined then it's worth considering the MR2 and MGF for the process you are describing.
ugg10 said:
If the only bit you are keeping is the b pillar to the scuttle then why not go for a whole new chassis (OK keep the doors and windscreen if you want). The bit you are keeping will not be structurally stiff, will just add weight and therefore compromise the handling and the design. I could see the point in doing it your way if you were to retain the full lower floor pan with front suspension/steering etc. as stock, cut a hole in the back seat/boot floor and inset a frame with the engine/rear suspension in it linked to the suspension points front and back and providing roll over protection (but basically a chassis!), chop the roof and replace with a roll bar, fibreglass panels and wings. Leaving so little of the original car just doesn't add any benefit IMO. Which ever way you do it it will need an IVA as you have changed the chassis so much.
Also, for info, the structural bit is possibly Ok to sub out but, it will cost, but not the earth. However, doing the styling, making the buck and then getting the fibreglass moulds taken off that and then probably doing it twice as the first time will not be perfect, is a labourious job (remeber usually charged out at an hourly rate, not fixed price) and so will cost you a packet. Have a look at the Bertini thread on here and see what it has taken someone with the skills to do it and this is just a panel swap without any mechanical or interior changes.
That said, if your heart (and wallet) are prepared for it, then go for it. Good to see some ambition.
Thanks for the points. Also, for info, the structural bit is possibly Ok to sub out but, it will cost, but not the earth. However, doing the styling, making the buck and then getting the fibreglass moulds taken off that and then probably doing it twice as the first time will not be perfect, is a labourious job (remeber usually charged out at an hourly rate, not fixed price) and so will cost you a packet. Have a look at the Bertini thread on here and see what it has taken someone with the skills to do it and this is just a panel swap without any mechanical or interior changes.
That said, if your heart (and wallet) are prepared for it, then go for it. Good to see some ambition.
My plan is to include the steering, inner wings, 'chassis' legs, and front suspension. Therefore, I am hoping that this would result in the front portion of the car retaining its structural integrity. Any additional steelwork at the front would be to support the GRP body work and brace the struts.
Weight is clearly something that needs careful consideration as I don't want to end up with a vehicle that has a lower power weight ratio and a standard road car.
The bodywork does concern me but I was encouraged to read the piece on DNA in this months Complete Kit Car and their service that offers the design and manufacture of new body work for kit cars.
qdos said:
So I guess what you're aiming at is something along the lines of this then....
Ginetta G32
As has been said above, really you'll not be saving much by trying to retain the cab section of a modern production car save for the interior styling and finish, though you will save some work on building doors and getting them to fit. A modern car is a monocoque and as such much of what you'll likely cut away will result in you loosing the integrity of the chassis and any 'crash protection' If you want to maintain all that then you'll be keeping the majority of the car and just replacing any bolt on wings.
I don't honestly think the Golf is an ideal starting point for what seems to be your desire for a mid engined sports coupe. It's a car I've considered numerous times too, as there's plenty of them but there's a lot more suitable donors out there. Going mid engined then it's worth considering the MR2 and MGF for the process you are describing.
The G32 has a cool retro look and a modern twist on that theme is certainly what I have in mind.Ginetta G32
As has been said above, really you'll not be saving much by trying to retain the cab section of a modern production car save for the interior styling and finish, though you will save some work on building doors and getting them to fit. A modern car is a monocoque and as such much of what you'll likely cut away will result in you loosing the integrity of the chassis and any 'crash protection' If you want to maintain all that then you'll be keeping the majority of the car and just replacing any bolt on wings.
I don't honestly think the Golf is an ideal starting point for what seems to be your desire for a mid engined sports coupe. It's a car I've considered numerous times too, as there's plenty of them but there's a lot more suitable donors out there. Going mid engined then it's worth considering the MR2 and MGF for the process you are describing.
The concept of taking a front wheel drive car and making it mid engined is appealing to me rather than taking an existing mid engine configuration and putting a new body on it. But I do need to fully understand what is feasible, safe, reliable, desirable and, most importantly, could be replicated in the form or a kit for a home builder to take on.
Thanks
Dave
Some of my inspiration has come from some of the build development of the Smyth G3F http://www.smythkitcars.com/#!how-it-is-built/c1f2...
Dear God, you would not get me in one of those in a million years !
Looking at the extra metalwork then there will be very little torsional rigidity to that structure. Have a go - get a cardboard box, seal it up with sellotape, grab both end and twist - not much movement - now cut off the top and sides and do the same - welcome to skuttle shake land. Also there is no side impact protection as they have chopped off the B pillar from the roof so this would just collape inward in a T bone accident. The only thing stopping this folding in half is the shape of the sills and the central tunnel.
I'd be interested to see how this would go in an IVA test (which is will have to do as the chassis has been significantly modified, don't let anyone else say it doesn't, see other threads on this subject) noting that this is a US site and they have very different rules and regs regarding car registration ot the UK.
All of the structural integrity of modern cars comes from the complete monocoque and they work by transmitting and dissipating forces thoughout the whole body. Vertical forces end up in the roof, torsional forces are resisted by the combination of the a,b,c pillars, the floorpan and the roof. One of the worst things from a structural rigidity point of view is to remove the roof. This is why convertible versions of saloon cars have 75-100KG of steel added into them to reduce skuttle shake.
Sorry for being a bit alarmist, and other with more knowledge than I please do chip in, but in my opinion the example quoted should not be allowed on the road.
Looking at the extra metalwork then there will be very little torsional rigidity to that structure. Have a go - get a cardboard box, seal it up with sellotape, grab both end and twist - not much movement - now cut off the top and sides and do the same - welcome to skuttle shake land. Also there is no side impact protection as they have chopped off the B pillar from the roof so this would just collape inward in a T bone accident. The only thing stopping this folding in half is the shape of the sills and the central tunnel.
I'd be interested to see how this would go in an IVA test (which is will have to do as the chassis has been significantly modified, don't let anyone else say it doesn't, see other threads on this subject) noting that this is a US site and they have very different rules and regs regarding car registration ot the UK.
All of the structural integrity of modern cars comes from the complete monocoque and they work by transmitting and dissipating forces thoughout the whole body. Vertical forces end up in the roof, torsional forces are resisted by the combination of the a,b,c pillars, the floorpan and the roof. One of the worst things from a structural rigidity point of view is to remove the roof. This is why convertible versions of saloon cars have 75-100KG of steel added into them to reduce skuttle shake.
Sorry for being a bit alarmist, and other with more knowledge than I please do chip in, but in my opinion the example quoted should not be allowed on the road.
Edited by ugg10 on Thursday 16th January 13:13
No problem, may be worth having a look at the work of two of the best kit car designers in the UK IMO over the past two decades - Stu Mills (MEV) and Jeremy Philips (Sylva) - between them they have designed, developed, and sold probably more kit cars than the rest of the industry put together. For a list of their creations have a look at -
www.jpsc.org.uk
mevltd.co.uk/vd/index.htm
Both have successfully taken every day cars as donors and built high quailty, superb handling kit cars. Have a look how they have mounted pretty much standard parts from the MX5 in the Replica, the MGF in the Vectis and the Ford Focus in the Sonic/Rocket. This may give you an idea as to how you may achieve your aim.
Another comment, when doing the structural analysis (by hand of more likely with an FE programme these days) it will be easier working from scratch on a spaceframe chassis with known dimensions and steel material properties than trying to integrate space framce with chunks of complicated geometry presssed steel of unknown steel grades and with unknown boding/welding strengths, this brings in a lot of uncertainties which will result in having to work with greater safety factor than required with a knwon quantity spaceframe. It will also significantly increase the complexity, time and therefore cost of the calcualtions.
www.jpsc.org.uk
mevltd.co.uk/vd/index.htm
Both have successfully taken every day cars as donors and built high quailty, superb handling kit cars. Have a look how they have mounted pretty much standard parts from the MX5 in the Replica, the MGF in the Vectis and the Ford Focus in the Sonic/Rocket. This may give you an idea as to how you may achieve your aim.
Another comment, when doing the structural analysis (by hand of more likely with an FE programme these days) it will be easier working from scratch on a spaceframe chassis with known dimensions and steel material properties than trying to integrate space framce with chunks of complicated geometry presssed steel of unknown steel grades and with unknown boding/welding strengths, this brings in a lot of uncertainties which will result in having to work with greater safety factor than required with a knwon quantity spaceframe. It will also significantly increase the complexity, time and therefore cost of the calcualtions.
It's worth noting that in a modern car, you cannot change anything, even the seats for example, without compromising it's crash performance to some degree. This is because a modern car is not about absolute stiffness but selective stiffness. i.e. it aim to minimise the crash "pulse" transmitted to it's occupants. It does this with both passive and active methods, such as high strength bulkheads, low strength collapsable crash tubes (often "hidden" within the sills etc), deformable seat rails, seat belt pretensioners and load limiters, and a million subtle engineering designs to ensure the air bags (both frontal and side) are both properly and timely deployed, and that the occupants intercept these airbags at the right angle, velocity and moment!
I'd also be absolutely amazed if you will get any engineer to insure their own work in an untested vehicle. Yes, they can design and stress their additional structures using "best practice" but no way are they going to take the liability for that in an untested, low volume vehicle!
Even simple issues are going to cause you a headache. For example, what are you going to do with the fuel tank, and how are you going to validate it's integrity in its new location?
I'd also be absolutely amazed if you will get any engineer to insure their own work in an untested vehicle. Yes, they can design and stress their additional structures using "best practice" but no way are they going to take the liability for that in an untested, low volume vehicle!
Even simple issues are going to cause you a headache. For example, what are you going to do with the fuel tank, and how are you going to validate it's integrity in its new location?
Interetsing idea...
Have a Google for the threads on the RCR (Race Car Replicas) Apex as well:
http://superlitecars.com/apex/
http://www.gt40s.com/forum/rcr-forum-rcr40-slc-p4-...
Have a Google for the threads on the RCR (Race Car Replicas) Apex as well:
http://superlitecars.com/apex/
http://www.gt40s.com/forum/rcr-forum-rcr40-slc-p4-...
dom9 said:
Interetsing idea...
Have a Google for the threads on the RCR (Race Car Replicas) Apex as well:
http://superlitecars.com/apex/
http://www.gt40s.com/forum/rcr-forum-rcr40-slc-p4-...
Cheers dom9. Plenty of bedtime reading!Have a Google for the threads on the RCR (Race Car Replicas) Apex as well:
http://superlitecars.com/apex/
http://www.gt40s.com/forum/rcr-forum-rcr40-slc-p4-...
Some great looking designs there.
AER said:
Your original concept sounds an awful lot like an MGF. They're pretty cheap these days, so that'll save a load on engineering costs... 
One of my main criteria, if I am going to develop a kit that goes into production, is a good supply of donor vehicles for years with a range of engines to suit different customer needs. The MGF does certainly have advantages however might not fulfill this criteria.As an aside, I have a Fiat Barchetta at the moment and was looking at its proportions this morning and it really is a good looking wee thing IMO. Would a modern take on the Barchetta style, front engined with rear drive float anyone's boat? Perhaps as a body conversion for an existing 7 chassis? This isn't something that I am planning to take on but if there is a potential market.....
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