Chris Kouba
Supporter
I couldn't agree more. I think this is the most epic project/thread on this forum.
Homemade CFRP mid engine sports car
- Thread starter Paul Bristo
- Start date
I couldn't agree more. I think this is the most epic project/thread on this forum.
Feb update, been working on the some of the rear chassis parts. Three out of the four rear wishbones are done - more on those later, and finished the rear cross-members that the rear dampers mount to. These are wet layup cfrp with a high temperature resistant resin, again I used a 3d printed core to hold the metal insert tubes around the bolts in the right place, I find using 3d printed cores works really well. The layup is mostly UD, with some 45deg layers in there too. I'm aiming to get the rear wishbones done and on next month, then dig the door moulds out of the shed and move onto door making
gap between rear bodywork and springs and rear structure is SLIM .. might need some adjustment later
gap between rear bodywork and springs and rear structure is SLIM .. might need some adjustment later
Hi Paul
As usual very neat work !!!
Some question regarding this part ; did you thought that dampers will introduce loads not only at the angle they will have when fit to the wishbone but there will be also a residual load ( and apreciable in term of amount!!) pushing down the middle part of this crossmember .... Do you intend in the future to add some vertical braces to take account of this load ????
Hope in my "poor english terms" I have explain clearly my idea about this .....
As usual very neat work !!!
Some question regarding this part ; did you thought that dampers will introduce loads not only at the angle they will have when fit to the wishbone but there will be also a residual load ( and apreciable in term of amount!!) pushing down the middle part of this crossmember .... Do you intend in the future to add some vertical braces to take account of this load ????
Hope in my "poor english terms" I have explain clearly my idea about this .....
Hi Michel, the dampers are very close to horizontal, there is some downward load but calcs show the crossmembers should be fine for bending
I've been working on the rear wishbones as they are small enough to bag up and take indoors to cure in this cold weather, finished them all now. Thankfully they all fitted to the tub OK, making parts by hand always makes me worry about tolerances.
In other work i've been busy designing the details of the door frame for hinge and gas strut attachments (doors are next). Unfortunately i've discovered there's a been a design error with the tub, not enough clearance for the rear springs, so going to need to fix that so will set me back a few weeks
I've been working on the rear wishbones as they are small enough to bag up and take indoors to cure in this cold weather, finished them all now. Thankfully they all fitted to the tub OK, making parts by hand always makes me worry about tolerances.
In other work i've been busy designing the details of the door frame for hinge and gas strut attachments (doors are next). Unfortunately i've discovered there's a been a design error with the tub, not enough clearance for the rear springs, so going to need to fix that so will set me back a few weeks
Finished off the fix for the unfortunate spring/body clash. A cut out with a carbon capping piece over the top. I also modified the cross-members to move the inboard damper attachments closer the centre of the car. All done now, phew.
Next job .. doors. I managed to fish the door moulds out from the back of the shed and have assembled them. I have designed a 3d printed core that will form the door frame and hold the inserts for the gas struts at the correct places, over the coming weeks i will make these frames and begin to lay up the material into the door moulds.
Next job .. doors. I managed to fish the door moulds out from the back of the shed and have assembled them. I have designed a 3d printed core that will form the door frame and hold the inserts for the gas struts at the correct places, over the coming weeks i will make these frames and begin to lay up the material into the door moulds.
progress update .. been busy having fun with doors ! I've moulded both doors and today did a first test fit on the car with the LH one. So far so good. Not tried to properly align it yet, but expect some challenges with gaps and flushness !
One both sides are on and aligned I will next sort out the sealing (lower half of the sealpath not thought through yet). Then come up with a latch setup, UK IVA says for gullwing style doors a slide bolt system is required, so need to design that. Then once all thats clear i'll make some kind of inner panel with handles and what not.
One both sides are on and aligned I will next sort out the sealing (lower half of the sealpath not thought through yet). Then come up with a latch setup, UK IVA says for gullwing style doors a slide bolt system is required, so need to design that. Then once all thats clear i'll make some kind of inner panel with handles and what not.
Still tinkering with doors, the LH one is nearing completion now
Sealing;
I fitted a flange around the door aperture for the seal. Once in place I 3d printed some little clips that clip onto the flange and mark out the exact offset i need for the seal to make contact with the door panel. Then I carefully glued some cardboard onto the door inner at this offset, then i hand laid some plies of CFRP over that cardboard. Now I should have the right seal gap and the door is nice and stiff.
handles and latches;
I wanted to have concealed flush door handles (the ones where to push on one end to pop the handle out to pull). I cut out the rectangular portion of the door outer, and then designed the mechnanism. Once designed i 3d printed a mock up of the mech, and once happy i 3d printed a mould to make the handle housing. I added a spigot to attach a drain hose for any water it collects. I'm quite happy with the end result, a nice stiff spring provides a good 'push' feel to deploy the handle, and a cable to the latch works well. The door striker is a bolt through a CFRP bracket. Still need to finish the interior handle.
gas struts;
I have the gas struts fitted and now the door now stands open by itself ! this is great news as i no longer need to work under a ladder that props it open. I needed to make some carefully shaped brackets that the body side ends of the gas strut would attach to. I 3d printed some proto parts to check they fit, and then i decided to mould the real parts from chopped carbon fibre. I used this process below and it was pretty easy and worked pretty well;
1) 3d print the mould, avoid small features that might break off under the pressure. I use PLA and then coat it heavily and PVA mould release.
2) chop A LOT of carbon fibre. you need loads of this, i must have spent an hour just cutting CF into cups. I had a big box full of offcut and loose strands from earlier works. I chopped the fibre to lengths of about an inch.
3) paint the mould with resin and stuff the fibre in, then add more resin, then more fibre. repeat until full. You want to have a high ratio of fibre to resin to really mash the fibres in tight. I made a selection of different sized wooden sticks to push the wet fibrous mess into the mould nice and tightly.
4) clamp the top of the mould down, i used nuts and bolts in holes made into the mould. I made sure to overfill the mould so that when its closed up there's good compression to fill all the cavity.
5) demould, rework and areas that need it, sand and laquer the parts, drill and tap any features. I threaded in some helicoils for bolted joints and added some epoxy while winding them in.
Sealing;
I fitted a flange around the door aperture for the seal. Once in place I 3d printed some little clips that clip onto the flange and mark out the exact offset i need for the seal to make contact with the door panel. Then I carefully glued some cardboard onto the door inner at this offset, then i hand laid some plies of CFRP over that cardboard. Now I should have the right seal gap and the door is nice and stiff.
handles and latches;
I wanted to have concealed flush door handles (the ones where to push on one end to pop the handle out to pull). I cut out the rectangular portion of the door outer, and then designed the mechnanism. Once designed i 3d printed a mock up of the mech, and once happy i 3d printed a mould to make the handle housing. I added a spigot to attach a drain hose for any water it collects. I'm quite happy with the end result, a nice stiff spring provides a good 'push' feel to deploy the handle, and a cable to the latch works well. The door striker is a bolt through a CFRP bracket. Still need to finish the interior handle.
gas struts;
I have the gas struts fitted and now the door now stands open by itself ! this is great news as i no longer need to work under a ladder that props it open. I needed to make some carefully shaped brackets that the body side ends of the gas strut would attach to. I 3d printed some proto parts to check they fit, and then i decided to mould the real parts from chopped carbon fibre. I used this process below and it was pretty easy and worked pretty well;
1) 3d print the mould, avoid small features that might break off under the pressure. I use PLA and then coat it heavily and PVA mould release.
2) chop A LOT of carbon fibre. you need loads of this, i must have spent an hour just cutting CF into cups. I had a big box full of offcut and loose strands from earlier works. I chopped the fibre to lengths of about an inch.
3) paint the mould with resin and stuff the fibre in, then add more resin, then more fibre. repeat until full. You want to have a high ratio of fibre to resin to really mash the fibres in tight. I made a selection of different sized wooden sticks to push the wet fibrous mess into the mould nice and tightly.
4) clamp the top of the mould down, i used nuts and bolts in holes made into the mould. I made sure to overfill the mould so that when its closed up there's good compression to fill all the cavity.
5) demould, rework and areas that need it, sand and laquer the parts, drill and tap any features. I threaded in some helicoils for bolted joints and added some epoxy while winding them in.
Attachments
Nicely done Paul.
Regards Brian
Regards Brian
Davidmgbv8
Supporter
really nice parts
Ian Anderson
Lifetime Supporter
Looks impressive
How close to your head will those gas struts be. When seated and the door closed?
There has been a lot of discussion on here about roll bars and other protrusions that could cause head injury
How close to your head will those gas struts be. When seated and the door closed?
There has been a lot of discussion on here about roll bars and other protrusions that could cause head injury
Thanks Ian, the gas strut mostly sits between the windscreen surround structure the door frame section (next to the seal bulb), it doesn't really protrude much below these for head to strike .. but having said that there's not a lot of general head space between head and roof which has always been a concern.
Have been mostly working on the door inners over the last couple of months;
step 1 - build up the required sections with cardboard. hot glue gun works well for this, as does having several carboard boxes of beer, then wet lay carbon/epoxy composite over this, taking care to add extra layers where any bolted fixings will be. Then sand it all back, paint on a thin layer of resin and fine sand then polish. This was also a chance to smarten up the door frame a bit.
step 2 - make the door inner trim parts. I made a door grab handle from carbon over a 3d printed core, in a 3d printed mould. I made the grab handle quite large because closing the door from inside the car is reasonably difficult, but it does not protrude further into the cabin than the sill when closed.
I made some internal door release/lock switches. One lever unlatches the latch, the other will pull up/down a slide bolt to lock the door from inside (there is a UK IVA req for gull wing doors to lock using a slide bolt for some reason). The levers are solid carbon made from chopped fibre like i have used elsewhere and explained before, they sit in bearings inside a 3d printed housing. I decided to spray the housing white to add a bit of contrast, however i'm not 100% sold on this and may repaint them later.
I added a drain hose from the exterior door handle recess as this will collect water, it runs to a hole on the lower surface of the door.
Also I fixed in some cable sheath for the latch unlocking cables to run through, attached to the door via some 3d printed hardware and clips.
I may or may not make a door card panel to cover the visible door interior parts (i guess i'll need something even if temporary for the IVA), or i might leave open, or maybe install some kind of bungee/cargo net so i can use the upper cavity area for storage
Next step .. repeat it all again for the RH door ! this time around should be quicker and i've already made the RH side trim & hardware parts. My goal was to finish all door work in 2023 but i suspect i will miss this.
Some photos with it back on the car;
Have been mostly working on the door inners over the last couple of months;
step 1 - build up the required sections with cardboard. hot glue gun works well for this, as does having several carboard boxes of beer
, then wet lay carbon/epoxy composite over this, taking care to add extra layers where any bolted fixings will be. Then sand it all back, paint on a thin layer of resin and fine sand then polish. This was also a chance to smarten up the door frame a bit.step 2 - make the door inner trim parts. I made a door grab handle from carbon over a 3d printed core, in a 3d printed mould. I made the grab handle quite large because closing the door from inside the car is reasonably difficult, but it does not protrude further into the cabin than the sill when closed.
I made some internal door release/lock switches. One lever unlatches the latch, the other will pull up/down a slide bolt to lock the door from inside (there is a UK IVA req for gull wing doors to lock using a slide bolt for some reason). The levers are solid carbon made from chopped fibre like i have used elsewhere and explained before, they sit in bearings inside a 3d printed housing. I decided to spray the housing white to add a bit of contrast, however i'm not 100% sold on this and may repaint them later.
I added a drain hose from the exterior door handle recess as this will collect water, it runs to a hole on the lower surface of the door.
Also I fixed in some cable sheath for the latch unlocking cables to run through, attached to the door via some 3d printed hardware and clips.
I may or may not make a door card panel to cover the visible door interior parts (i guess i'll need something even if temporary for the IVA), or i might leave open, or maybe install some kind of bungee/cargo net so i can use the upper cavity area for storage
Next step .. repeat it all again for the RH door ! this time around should be quicker and i've already made the RH side trim & hardware parts. My goal was to finish all door work in 2023 but i suspect i will miss this.
Some photos with it back on the car;
Chris Kouba
Supporter
Paul,
This endeavour is heroic!! Fantastic looking work, I get more impressed with every post. Great job!
This endeavour is heroic!! Fantastic looking work, I get more impressed with every post. Great job!
Well my goal for 2023 was to get some doors on and i just made it ! I even had a spare couple of weeks to get the front bodywork on as well
The doors are pretty well set now, just need to build up some material in a few places on the door inner flange to make a tight contact to the seal. Since you last saw them i've also had to redesign the latches, I had previously had them horizontal and they had a lot of free play when latched, so i've rotated them to be more perpendicular to the door opening arc and now they're much more stable when latched. At some point i need to take the doors off again though as i need to trim the ends of the rod end bearings that make the hinges, annoying i forgot this step last time they were off.
The front bodywork rear edge needs trimming to the correct line, once i've done that i'll take it off and mould some reinforcement on the inner surface with foam and wet layup CF. The fit to the doors is awful - the front body is about 10mm too narrow in Y, i'll have to rework this at some point but i'll wait until i know exactly where the tyres end up before deciding how to do it.
As for 2024 .. not sure yet, I want to finish of the composite moulding stages so maybe the seats and IP next, i also want to finish the suspension off so maybe brakes and uprights. Front lights and wipers strategy worry me still so maybe those too. I'm still on the fence regarding engine options .. still dreaming
The doors are pretty well set now, just need to build up some material in a few places on the door inner flange to make a tight contact to the seal. Since you last saw them i've also had to redesign the latches, I had previously had them horizontal and they had a lot of free play when latched, so i've rotated them to be more perpendicular to the door opening arc and now they're much more stable when latched. At some point i need to take the doors off again though as i need to trim the ends of the rod end bearings that make the hinges, annoying i forgot this step last time they were off.
The front bodywork rear edge needs trimming to the correct line, once i've done that i'll take it off and mould some reinforcement on the inner surface with foam and wet layup CF. The fit to the doors is awful - the front body is about 10mm too narrow in Y, i'll have to rework this at some point but i'll wait until i know exactly where the tyres end up before deciding how to do it.
As for 2024 .. not sure yet, I want to finish of the composite moulding stages so maybe the seats and IP next, i also want to finish the suspension off so maybe brakes and uprights. Front lights and wipers strategy worry me still so maybe those too. I'm still on the fence regarding engine options .. still dreaming
regarding engine, what type of length and width do you have to work with?
Thinking something like a VW W12(Or Bentley version), Mercedes M120 or maybe the odd 1GZ-FE?
W12 being the shortest of them all, but also the widest.
Digging what you are doing here btw
Thinking something like a VW W12(Or Bentley version), Mercedes M120 or maybe the odd 1GZ-FE?
W12 being the shortest of them all, but also the widest.
Digging what you are doing here btw
Thanks for the words of support guys
i have been reading Alexanders VW W12 thread with fascination .. and recently watched someone on youtube restore an M120 V12 which got me dreaming. I'm wary of being caught out by any changes in UK IVA rules (given this is going to be a slow build) so trying to be patient
I have >1050mm between rear axle and rear bulkhead so i think (hope) there's a decent length to play with, even more if i scavenge from the space reserved for the fuel system. Available width varies somewhat.
i have been reading Alexanders VW W12 thread with fascination .. and recently watched someone on youtube restore an M120 V12 which got me dreaming. I'm wary of being caught out by any changes in UK IVA rules (given this is going to be a slow build) so trying to be patient
I have >1050mm between rear axle and rear bulkhead so i think (hope) there's a decent length to play with, even more if i scavenge from the space reserved for the fuel system. Available width varies somewhat.
Davidmgbv8
Supporter
Does Audi make some kick ass diesel overthere? Anyone else on a bad ass diesel sports car?
That sounds like more or less the same space i will have in my future project, meaning that all the mentioned options will fit, even though some of them will rub your back more or less because of the tight fit.
update on progress into 2024 .. it didn't start very well, with Covid followed by Pneumonia i basically lost all of January
I'm better now and I've been working on two things, designing the suspension uprights and building the seats. For the seats i need to make my own because off the shelf ones won't fit, and also because why make things easy ..
I've been building a pattern of the seat from wood/cardboard/plaster/body-filler. Nearly done now, then will take a glass fibre mould, then will make some CFRP seats via vacuum infusion. The seats will be fixed to the body, i intend to use adjustable pedals rather than adjustable seats.
I'm better now and I've been working on two things, designing the suspension uprights and building the seats. For the seats i need to make my own because off the shelf ones won't fit, and also because why make things easy ..
I've been building a pattern of the seat from wood/cardboard/plaster/body-filler. Nearly done now, then will take a glass fibre mould, then will make some CFRP seats via vacuum infusion. The seats will be fixed to the body, i intend to use adjustable pedals rather than adjustable seats.
