Okrasa Special

steve wright · Post by **steve wright** » Sat Jan 16, 2010 11:38 am

When we serviced the Special last year it provided a good opportunity to become familiar with the car and chassis in particular. The original builder knew his beans, for example the rear suspension is completely hand crafted and one-off: the VW torsion bars have been done away with and the spaceframe mounts Porsche RSK inspired adjustable coilover springs with long, custom-made trailing arms mounted to the chassis well down to lower the centre of gravity. At the front the VW centre tunnel has been cut and re-welded at an angle to drop the front suspension height, effectively lowering the car without effecting camber, toe, ride height, etc.
[img][img]http://i881.photobucket.com/albums/ac13 ... ingarm.jpg[/img][/img]
[img][img]http://i881.photobucket.com/albums/ac13 ... mehead.jpg[/img][/img]
The front end doesn’t have an anti-roll bar but as they were fitted to VW’s and Porsche in period we can have a play with different ones to improve the handling if required. At the rear I’ll leave things as they are until we test drive the car properly with some shakedown tests on the road and track to judge whether the rear swing axle suspension needs to be tied down better with a period camber compensator bar from Speedwell. The front has also had a few torsion leaves removed to soften the front which was the right thing to do given the car weighs significantly less than the original. This means we can get away with pretty stiff roll bars and dampers if need be, as the springs won’t also be massively stiff, making the car bone jangling and skittish on the road. Obviously the rear is adjustable so we should be able to play around a bit there. Irrespective, it’s great to have something with a bit of adjustability in it and to have the challenge of chassis set up ahead of us. I might regret that last statement when it handles like a pig and we can’t get it to go round a bend! The only concern I have on the suspension is the amount of rust on the springs – does anyone have any views on whether these are good to use or whether I should try and refurbish or replace them?
[img][img]http://i881.photobucket.com/albums/ac13 ... lovers.jpg[/img][/img]
Anyway moving on, the chassis was built utilising the conventional Formula 1 wisdom of day (late 50’s) as used on the Cooper, with their (relatively) heavy tube chassis and it was obviously designed to be strong and rigid without a roof. Adding the roof has increased weight a but as it’s a stressed panel in its own right and has been tied securely into the chassis it should make for a really rigid structure. I must admit I also like the thought of something over my head – I’ve never personally been a fan of open top cars, in the sense of racing one myself. The car doesn’t have a rollbar, but it would be the one concession I would make today, tying something into the equivalent of the b-pillar that is used for the petrol tank/seat support. The side bar is the least pleasing aspect of the chassis design, as it’s not conducive to getting in and out, but it makes the chassis tremendously strong and affords some degree of side impact protection.
[img][img]http://i881.photobucket.com/albums/ac13 ... kofart.jpg[/img][/img]
The underside of the car is almost completely flat, which should clean up airflow under the car. I know I’m not going to be travelling fast enough nor would it be period correct to think about ground effects but it’s lovely to see so much thought put into making the car as clean and slippery through the air on the underside as I hope it will be on top. On the downside the flat floor is typical of Specials of the era in that there are no indentations or curves in the floor, meaning you can’t stand on it, but there are enough supports off the main spine to get in and out effectively.

The one real fly in the ointment is that after servicing the engine we suddenly realised – how do you remove the engine? Two hooks on the crankcase attest to the only design flaw I have so far come across. The roof was put on afterwards and the rear chassis tubes mean it can’t come out beneath or horizontally. So the only way will be to remove the rear screen and lift it out on a hoist or via a pulley in the roof. I spent ages searching for a solution (removable section of spaceframe, etc) but none of the ideas really grabbed me. Besides once you reconcile yourself with the idiosyncrasy then it just means putting in a pulley!
[img][img]http://i881.photobucket.com/albums/ac13 ... engine.jpg[/img][/img]
Next update will be with the 550 Spyder bodywork mocked up. Cheers, Steve

KS · Post by KS » Sat Jan 16, 2010 2:47 pm

I remember asking David Small about the engine installation and he just smiled – 'You'll need to fish it out thrrough the back window' (as you indeed have discovered!). I toyed with making the rear section of the roof so that it could be hinged forward to allow engine access, with a bulkhead behind the driver's head to a) seal off the engine bay and b) add rigidity to the roof pressing. Even doing valve clearances must be fun!

The aluminium paneling is, in fact, aircraft-specification dural sheet bought from aircraft surplus supplies. It is impossible to bend it like ordinary aluminium and makes the whole structure immensely rigid. I don't think you need have any qualms about standing on the floor...

Me? I'd change the springs. Also not sure of the state of the Armstrong adjustables on the back – I know they haven't seized but I wonder if there are any seals left in them?

roy mawbey · Post by **roy mawbey** » Sat Jan 16, 2010 2:59 pm

Steve,

Don't know if you have seen on the 356registry site the thread regarding the manufacture of 550 aluminium bodies by a company in CZ. They make these for around euro 35K. Their work looks really great. I realise what you have to do is something very different to match an existing chassis but you have to smile at their workmanship.

On the 356site on the opening page scroll down to the heading "356 parts and accessories" and then scroll down to the 550 aluminium bodies thread.

Very interesting pages, and pity the company has never been looked at by magazines? Well, I haven't seen coverage before.

By the way I guess the only way to tell with the springs is to find the worst area and very lightly take a file to it. If only a small amount of metal is removed before the rust disapears then if they were mine I would take it they are okay. From the photo a lot of the rust looks surface only?

Roy

911hillclimber · Post by **911hillclimber** » Sat Jan 16, 2010 6:20 pm

New springs are cheap, around £25 each from Demon Tweeks.

I'm looking forward to seeing the body perched on the tub!

Garages are nice and warm now, so we expect rapid progress!!

steve wright · Post by **steve wright** » Sun Jan 17, 2010 8:57 am

thanks for all the comments gents. I think I'll err on the side of caution and replace the springs, especially given they are so cheap. The adjustable shocks I might try to have rebuilt as it's nice to keep as much original as I can. Thanks Keith for the insight on the panelling, that's good to know.

Thanks for the tip on CZ Roy, I've dropped Stepan an email. The craftsmanship there is amazing http://www.356registry.com/forum/viewto ... sc&start=0

Graham not sure how rapid the progress will be - couldn't get to the workshop for the snow last month, but hopefully this month should see some progress

911hillclimber · Post by **911hillclimber** » Sun Jan 17, 2010 12:18 pm

The trouble with putting anything on a public forum is that you end up with an impatient audience!

Rusty springs will break so don't risk it.

I'm interested to see the Ghia roof line merge with the 550 esc body.

Keep going!

Graham.

steve wright · Post by **steve wright** » Sun Jan 17, 2010 12:58 pm

hear you loud and clear on the springs Graham

Part of me put it up on DDK as I knew it would get me into gear! I've been sitting on the project for the past year, so it has been good impetus if I put it out there! my only concern is the bodywork (when I finally get there with the ali work) will not be an instant piece of work!

roy mawbey · Post by **roy mawbey** » Sun Jan 17, 2010 3:20 pm

On reflection you are all correct the springs are best changed. The trouble with me is I try to repair everything like kettle elements etc, etc, etc. My wife thinks I am a little on the tight side and its true I guess

Roy

Will Grant · Post by **Will Grant** » Wed Jan 27, 2010 5:36 pm

This sort of rear would be mighty fine

911hillclimber · Post by **911hillclimber** » Wed Jan 27, 2010 10:16 pm

What a great Ginetta G12!

I wanted one but too ££££££££££ so bought the Lola and spent $$$$$$$$$$$$$$$$$$$$$$$$$$

steve wright · Post by **steve wright** » Sat Jan 30, 2010 11:14 am

wow. i did thin about buttresses like the Dino, etc but wasn't sure how that would work with the exsting roof. that is tiny. not sure i would want to crash in it but i bet it's quick though the wiggly stuff.

Ren · Post by **Ren** » Mon Feb 01, 2010 4:37 pm

How about this back end?

http://strangevehicles.greyfalcon.us/picturesu/d1.jpg

steve wright · Post by **steve wright** » Mon Feb 01, 2010 4:40 pm

Hi Ren, probably too early for my Special. I think (but happy to be corrected by those more knowledgeable) that this was the Rome/Liege/Rome car that was prepared early 1950's? The spaceframe would preclude it as well, as it requires more of a back end life the 550. keep the ideas coming though! Cheers, Steve

MikeB · Post by **MikeB** » Sat Feb 20, 2010 9:58 pm

Reading this with interest, as my dad was the Okrasa agent in Ireland in the 1960s, and competed in suitably modified Beetles.

His "racer" was a split rear window one, that was brought back from Germany by an army officer. My dad built an engine with a 356 crank in it, so it was a bit special for its day

Looking forward to seeing this project develop

steve wright · Post by **steve wright** » Tue Feb 23, 2010 12:06 pm

Hi Mike, interested in your father's exploits. I'm half way through building an Okrasa engine for a '52 split window Beetle with a Porsche 74mm roller bearing crank. It won't be the same car but how's that for coincidence! Cheers, Steve