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Re: Re Re Spitfire rear springs

To: Scott McGibney <mcgibney@sk.sympatico.ca>
Subject: Re: Re Re Spitfire rear springs
From: Odd Hedberg <odd@triumphclub.se>
Date: Sat, 12 Apr 1997 18:32:22 +0200
Cc: triumphs@Autox.Team.Net, odd@triumphclub.se
References: <05948334EB1AF03D*/c=US/admd=ATTmail/prmd=Transam/o=tfs/s=Vincenti/g=Ross/@MHS> <334F62D2.7821@triumphclub.se> <334E8047.2CBA@sk.sympatico.ca>
Scott,
I know it's a great idea - the problem is that all the things 
in the design has to be manufactured, mainly from scratch...  :-(

The bellows are modified from a design made by Dunlop. The Dunlop
bellows had far to big end parts so they had to be changed for a
slimmer design made out of suitable blocks of plastic.

The girder on the other hand was much easier to make... ;-)
It's made up of parts welded together, each of them plasma cut
out of a sheet of steel. Peace of cake...

Then it's just to take the original leaf spring apart, retain 
the two lowest leafs (the ones holding the eye), and then bolt 
it all together with the differential housing and the girder.
Koni shocks at a hard setting is a recommendation...
The regulation of the air pressure can be done in either of three 
ways;

I    Each bellows separate via a standard tyre filler fitting.
     Simple but crude way of regulating/adapting to load variations.

II   Both bellows together via a common fitting as above. Prohibits
     regulation of left/right weight at uneven load. But makes it 
     easier to have a little compressor in the car to facilitate
     ride height adjustment en route...

III  The ultra high tech way: Using a compressor to feed the system 
     - and electronically regulated valves in the feeding lines 
     making sort of an active suspension technology possible... 
     Among other ideas to give an smooth and even ride is the 
     accelerometer approach where a pair of accelerometers senses 
     the movements of the car body longitudinally, and transverse, 
     and then initiate blocking the valves shut, or increasing the 
     bellows air pressure, at the crucial moments... 
     This also facilitates load sensing that increases air pressure 
     if more weight is put in the car, for instance excessive luggage 
     in the rear.

So far the construction has halted att the TypeII solution... 
Lack of fast enough pneumatic valves with electric actuators is 
my way of dodging responsibility for the current stalemate...  ;-)

I hope this explained the design. It's really easy to do if one 
have access to a lathe, a plasma (or cruder: oxy-acetylene) cutter, 
welding etc equipment. The most tricky bit was calculating the 
proper elliptical formula for the girder, and locating the Dunlop
bellows... The rest was mainly just fun...

BFN
Yours
Odd

PS What's an Airstream... ? I've heard of Jetstreams, but they 
   are definitively nothing one tows around behind a car!!! ;-)

> ----------------------------------------------------------
> Scott McGibney wrote:
> Odd
> Great idea. Do you know of a source for said pneumatic springs 
> that will fit (easily)? Sounds like just the setup for those of 
> us with dual duty machines that like to run several degrees of
> negative camber for autox-ing but need a bit more lift for 
> hauling groceries or towing the Airstream.
> Scott Mc
> 
> > ---------------------------------------------------------
> > Odd Hedberg wrote:
> > The trick is to use two pneumatic bellows units, with adjustable
> > air pressure in them, supported downwards on the nr 1 and 2 leafs
> > (who act merely as the upper control arm) and upwards against a
> > T-girder (bolted to the rear axle housing).

-- 
Odd Hedberg
Pomonagatan 4           International liaison secretary,
S-74236 Östhammar       Triumph Club of Sweden
Sweden                 '70 Spitfire Mk3 FD82497LO Signal Red
               E-mail:  odd@triumphclub.se
             Club URL:  http://www2.passagen.se/triumph/
       Home Telephone:  Int+ 46-1731 7131
Geographical Position:  N 60deg15min  E 18deg23min
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