4722 replies to this topic

[Nev]

3 beers at lunch time(!!), a bit of fibre-glassing, computer games and a perhaps a mid afternoon nap later...

 

Am beefing up the 8 mounting points for the roof, it's my hope to use tower bolts (like a gate bolts) to fix the roof to the 4 standard roof mounts and also 4 machined bolts to the 4 semi-circular plastic soft-top holes. This should give 8 points of fixing and spread the stress, as well as making the roof a lot faster to put on the car than the cumbersome OEM system.

 

It's great fun using fiber-glass, you can be so "approximate" with it (compared to metal work + welding), just cut the glass by eye, mix the resin and splodge about with a brush. Reminds me of papier-mache craft lessons at primary school.

 

 

Edited by Nev, 27 April 2018 - 01:53 PM.

[SteveA]

Just remember your proper breathing mask, nasty stuff resin when its going off.

[Nev]

Went into the garage again this evening after sobering up and did a bit more glassing. After that I took the F/O/S wheel assembly apart again and hand filed the necessary bevel on the Elise Parts upright to take/mate the FAG hub correctly. The anodising had cracked off in places and obviously the filing that I did exposed raw alu as well, so I gave the exposed parts a thin lick of paint, as this particular alu seems to "bloom" a lot.

 

Edited by Nev, 27 April 2018 - 08:10 PM.

[Nev]

Hmmm, I've just had a devious idea. Rather than tapering/feathering the back of the scoop down to the rest of the roofline, I could leave the scoop open at the rear and install a radiator in the through-hole. This would allow compressed air from the windscreen being rammed down the hole and hitting the radiator with some serious effect. This would be much like a Ford RS200, albeit the x-section of mine would be less.

 

By chance, taking a pickup supply of hot water from the engine would be convenient too, passing it into the cabin and up to the back of the scoop. I could install a bypass valve (to cut the roof water circuit out), such that I could still drive without the hard top on. This would mean fitting the roof would also require pushing 2 hose joins together (inlet and exit out of the rad), which could be easily done by hand with aeroquip fittings.

 

Issues I see is the weight, a small/mid sized rad with water in it would be circa 6 Kg high above the cars roll centre. Also, another mild risk to consider is pipe/joint failure in the cabin, as it could scald me if boiling water escaped. The water pump would have to work slightly hard to lift the water up the extra 50 CM.

 

Apart from anything, the idea appeals to me simply cos nobody has ever done it on a VX and it would be similar to a WW2 fighter plane!

 

Any thoughts anyone?

Edited by Nev, 29 April 2018 - 03:30 PM.

[Nev]

The roof is coming along nicely now. All 4 corners are reinforced and have wooden bosses to fix the tower bolts onto. The 8mm slide bolts lock in tightly to the 4 OEM mounts and appears to be a fair bit more secure than I expected. Putting the roof on/off takes no more time than the soft top.

 

I am currently building up the "wonk" on the front snout with 10 layers of multi-weave. Will fill and sand it tomorrow and maybe cut the end of the scoop off to start re-profiling a taper onto it in order to feather it's line to the roof top.

 

Have investigated the "WW2" air cooled rad in the scoop and abandoned the idea. Firstly I don't have water temp issues if the car is moving anyway and secondly the space is just too small to make a big difference. Lastly, it just adds complexity + delay without enough of a ROI.

 

Edited by Nev, 29 April 2018 - 07:20 PM.

[Nev]

Made a bit more progress on the roof this morning.

 

After cutting the end off the scoop, I made some formers out of balsa wood and bent/laid more balsa over the top. This has now had a couple of layers of glass and will be built up, filled and ground to a smooth curvature. In retrospect foam would have been better, but I'd already bought the balsa wood and didn't want to waste time getting any. Better to crack on.

 

I've also sanded and filled the "wonk" area on the front left top of the scoop a couple of iterations. One more should have to sorted. Lastly I've ground away the front edges of the snout on one side as this was "wonky" too, it should look symmetrical now when viewing the roof straight on.

 

I can't wait for the latest lot of materials to dry so I can get cracking again. Ever so easy and satisfying, more a matter of patience to get it looking bob on, which I probably haven't got!

 

You can see the 4 main slide bolts on the inside of the skin clearly. I will be adding extra glass to on/around these to give extra strength and fillet them a bit.

 

 

 

 

 

Edited by Nev, 30 April 2018 - 09:43 AM.

[jonnyboy]

That looks interesting. What are you now using to hold the shed doors closed? 

[Nev]

Hmm, the angles I chose for the taper aren't quite what I'd like, but it will have to do. A foam core would have been the wiser option as I could have made more complex curves.

 

Getting a good finish on the surface is not easy, patience (a faculty that I have in short supply) and repetition of filling and sanding is the key.

 

Am having to put lots of hardner into the mixes as it's so bloody cold, and don't want the drying cycles to take > 3 hours.

Edited by Nev, 30 April 2018 - 01:20 PM.

[Nev]

What are you now using to hold the shed doors closed? 

 

Your mum.  

Edited by Nev, 30 April 2018 - 01:37 PM.

[jonnyboy]

I guess placing the urn against the door should do it.

[ditonics]

I guess placing the urn against the door should do it.

 

That is all kinds of wrong 

[Nev]

A bit more effort this evening and I put a layer of primer on to see how bad my sanding was; I then got carried away and put a single parse of Halfords' mystery black gloss on it. The finish is terrible, so I will have to sand and fill it a bit more when I can be arsed.

 

I'll give it a trial run drive-around tomorrow, with a safety strap through the entire scoop lashed down to something inside the cabin.

 

The second pic shows how much dust is made, should have reversed poor Nipper out onto the drive whilst working really.

 

 

Edited by Nev, 30 April 2018 - 08:08 PM.

[mbes2]

[Nev]

Getting a bit tired of sanding and painting. Am leaving Nipper parked up on the drive tonight to let the rain give him a clean.

 

Have tried a can of  "Saphire Black" on the roof now to see what the match is like (kindly given to me by a local VX220 owner (Alex)).

[Nev]

Having problems colour matching, I've tried gloss black and the Vauxhall 28U (sapphire black) but neither was a close match. The pic below is the 28U. So I've just been to Halfrauds and bought some other random black cans and will have a squirt with them.
 
Have installed 2 extra bolts (into the front soft-top support bar slots), this will help a lot with stopping the lift and aid spreading the stress, not that I could actually get above 70 leptons to test it with the amount of traffic on the motorways near me. The bolts I've used take 2 seconds each to lock in and are far less intrusive in the cabin than the cumbersome windscreen brace bar and fiddly brackets that required a screw driver if I remember correctly. As a result, I can put the hard top on and off as quickly as the soft-top.

 

Edited by Nev, 02 May 2018 - 02:15 PM.

[siztenboots]

shame there is no practical use for all that negative pressure...

[ditonics]

I'm now totally confused Nev. Where does the scoop actually go?

[Nev]

I'm now totally confused Nev. Where does the scoop actually go?

 

Keep up please Simon!! 

 

It's a dead end at the moment, though if you look carefully down the scoop you might be able to see Joe's mum's backdoor.

 

Phase 2 of the project (if I get round to it) will feed the air down behind the drivers seat, through the firewall, through a lorry air-filter and into the hungry turbo. This will be the hard part of of the project  so I'll need to summon up some will power before starting it. The primary aim is to make the boot available again, with the side benefits of warmer & quieter & waterproof cabin and adds to Nipper's looks.

 

According to my schoolboy physics, 100 MPH air causes 0.17 PSI of pressure, then multiply this up by about 2 due to x-sectional decrease (mouth of scoop vs 4" inlet pipe) and that will be about 0.34 PSI of "free" boost. And as we all know, wind pressure has a square relationship to speed, so things get logarithmically better as you speed up from 100.

 

Edited by Nev, 02 May 2018 - 02:53 PM.

[alexb]

What lorry filter are you using? I had a very detailed look at filters and air boxes for commercial vehicles, but could not find one that flows enough and fits. Issue is that the ones I saw have very large surface areas, but very little inside diameters in comparison. Reason behind that is they have very high dust loading capacity, which makes sense for commercial vehicles doing lots of kilometers (or agricultural or mining equipment for that matter). The design criteria for passenger cars is different. Usually packaging constraints are far more important and filters are changed more frequently. I couldn't find one that had a large enough diameter on the clean side and was small enough to fit. I'm just curious to what you intent to use.

 

Your physics on the ram air scoop are a bit on the optimistic side. And have a look at the Venturi effect with regards to your assumption that the pressure increases due to cross sectional areas decrease. You might be in for a surprise

[ditonics]

Getting it inside will be challenging as the roll bar is in the way of the ideal place. You like a challenge though lol. I think your biggest benefit will be a cooler air flow into the filter than the boot (total guess).