A Z4 Targa?

[RickyBobby]

Hey RickyBobby, Funny you say this, yes i too was looking at creating some moulds (although a bit higher) to create that speedster look… I was watching Magnum Pi earlier and thought “maybe subconsciously i’m trying to get a 308 look” …

Magnum PI - now your talking.
Anyway I'm just off to comb my chest

 

[ZippyZed4]

Magnum PI - now your talking.
Anyway I'm just off to comb my chest

🥸

 

[Pingu]

I digress

Please do - on a seperate thread . Keep this one for your Targa.

 

[Pingu]

Don’t quote me on this, but i read somewhere the Z4 as you say was designed as a roofless car, so when the coupe was thought of they just simply added the roof… which in all honesty isn’t really structural, I’ve researched so much on this and I have never seen or read of any major differences… as for added weight etc it reports the E85 & E86 are the same weight so i suppose i am adding weight and it will be heavier… it really is a suck it and see job…

I don't think you will have any problems with strength if you base it on the convertible (as you are). The problems come when you cut the roof off a tin-top. Adding a roof to a convertible is just about cosmetics.

I say "just", but you know what I mean .

Looking at the joanna, I think you are the man for the job. The finish will be the challange.

 

[ZippyZed4]

I don't think you will have any problems with strength if you base it on the convertible (as you are). The problems come when you cut the roof off a tin-top. Adding a roof to a convertible is just about cosmetics.

I say "just", but you know what I mean .

Looking at the joanna, I think you are the man for the job. The finish will be the challange.

Thanks Pingu… I think you’re right about the e85 to e86 is more about cosmetics… The Joanna still needs finishing but is based around a digital one i pulled apart to sit in a carcass i made out of scrap wood in the garage

 

[ZippyZed4]

This is the only thing I’m not 100% on… the boot rear bar is a weld on part… I am hoping to brace, cut then add the e86 tailgate bar…any suggestions/knowledge is very welcome… (plus is this

the best way to post it on here or do i need to start a new thread? )

 

[Duncodin]

This is the only thing I’m not 100% on… the boot rear bar is a weld on part… I am hoping to brace, cut then add the e86 tailgate bar…any suggestions/knowledge is very welcome… (plus is th

Oh. I forgot about that bar.

Yes. It's structural.

Personally I wouldn't remove it. I'm sure you're going to make up some custom carpet, trim and roof lining. So cosmetically covering that beam making a cool looking bulkhead/parcel shelf between the boot area and the passenger compartment shouldn't be a problem.

 

[ZippyZed4]

Oh. I forgot about that bar.

View attachment 289127

Yes. It's structural.

Personally I wouldn't remove it. I'm sure you're going to make up some custom carpet, trim and roof lining. So cosmetically covering that beam making a cool looking bulkhead/parcel shelf between the boot area and the passenger compartment shouldn't be a problem.

Exactly what I have been thinking if i find out it’s structural… so even though it’s a part you can purchase, you think it’s best not removed?

 

[ZippyZed4]

 

[ZippyZed4]

Exactly what I have been thinking if i find out it’s structural… so even though it’s a part you can purchase, you think it’s best not removed?

I propped up the tailgate to see what it looked like… note that bar and rollbar hoops tgrough window…

 

[Duncodin]

Exactly what I have been thinking if i find out it’s structural… so even though it’s a part you can purchase, you think it’s best not removed?

Well I'm not a structural engineer so I don't know. But if it's welded I, personally, wouldn't remove it. But that's just me. Others may tell you to do it.

 

[ZippyZed4]

Well I'm not a structural engineer so I don't know. But if it's welded I, personally, wouldn't remove it. But that's just me. Others may tell you to do it.

It does foul the tailgate, this is the biggest issue… I have shown to a vehicle welder guy who seems to think to brace cut and add new part… why did i start this!?

 

[Duncodin]

It does foul the tailgate, this is the biggest issue… I have shown to a vehicle welder guy who seems to think to brace cut and add new part… why did i start this!?

Probably me just being 'old'. In my youth I'd maybe have had that beam out already.

 

[Pingu]

Exactly what I have been thinking if i find out it’s structural… so even though it’s a part you can purchase, you think it’s best not removed?

I think that the torsional stiffness of that bar is replaced by the torsional stiffness of the C pillars, rear crossbeam and roof of the coupe.

You can replace that stiffness in several ways.

1) Leave the convertible's beam in place.
2) Remove the convertible's rear bear and replace it with a suitable strengthening beam (such as a CDS tube - the type used in roll cages)
3) Remove the convertible's rear beam, add the coupe C pillars and rear beam, and test for stiffness. Add more stiffness if required.

 

[IainP]

What Pingu said:
Weld on the rear section, cut out the rear beam. That rear structure has to support the rear hatch, so it’s already structurally significant. I suspect more so than the beam.
If it were me I’d ‘K’ frame it, as Pingu, CDS tube from turret to turret, two more tubes to form a K on its side. Probably box section would be more than adequate, panelled in say carbon, or similar, you could make a feature of it.
For your Targa roof.
You’ll struggle to tension it if you do it as a hood. Make it from fibreglass composite, light, solid and easy to seal. Use hood catches at the front and over centre clips at the rear. An awful lot less hassle. You’re only making one, so use balsa core for the pattern, overlay with glass cloth and diolen. Some strips of reinforcing core on the inside, covered with 2 layers of cloth. Paint, cloth/leather headlining, job done.

 

[Pond]

This is the only thing I’m not 100% on… the boot rear bar is a weld on part… I am hoping to brace, cut then add the e86 tailgate bar…any suggestions/knowledge is very welcome… (plus is thisView attachment 289123View attachment 289125 the best way to post it on here or do i need to start a new thread? )

I would put money on that being a structural piece TBH. It should act as a torsional bar for the upper rear end. Bearing in mind these are RWD, there will be a lot of torsional flex under acceleration. As said above, I am no structural engineer, either but have spent all my working life in mechanical engineering. Not to say I may be wrong!

 

[Pond]

There are 3 ominous letters that could be your enemy with this....IVA or SVA (whichever they are using this week).
If you start altering the structural integrity of a car, our fantastic Government in the form of the DVLA/ VOSA will be all over you like a rash before you can go near a public road with it.
If you haven't already, read up on the IVA/SVA regs before going too deep into this.

The Joanna is fantastic BTW. In a strange way I feel some solidarity with yourself (but I may be a little less mad and gung-ho). I have taught myself many skills over the years, due to being a tight-arse and finding other people just don't do things properly or to my standards TBH.

Good luck and deffo create a new thread in the rebody section, as that is the most pertinent.

 

[Pingu]

Good point about the IVA.

You can avoid that hassle if you leave the rear beam in situ. If you cut it out, you will need an IVA, as you have changed the structure.

Have a read of this...

Vehicle approval

Type approval, individual (IVA), motorcycle single vehicle approval, voluntary approval, certificate of initial fitness, accessibility approval, fees, forms, replacement certificates

www.gov.uk

It will save you a lot of headaches if you read this now, and not in a year's time

 

[RickyBobby]

I guess you'd say this is the other extreme

 

[Mint]

Hi and to the forum from me too in Stafford. Great project, looking forward to the progress thread