Torsion bar choices

[Kilroy]

Hey all.
I am deciding which torsion bars to use in my Coupe build.
It has Australian suspension and appears to have been set up as, or for, a 6.
The torsion bars are a massive 27mm but have exactly the same splines at both ends as the UK models.
I have both 19mm and 21mm torsion bars on hand and will definitely use either of these rather than risk having uncompliant suspension - as in too harsh riding.
I am in favour of softer springing and firmer damping as being the best arrangement, but I have never tried using the 19mm torsion bars with either 1700 or 1800 engines - being usually equipped with the 21mm from new.

Has anyone got any experience of using the 19mm (1300) bars with the larger and heavier engines.?
The Australian factory shock absorbers seem exactly the same as the UK type, so god knows how they ever controlled a 27mm torsion bar setup....

Cheers.

[MarinaCoupe]

Ken - all UK cars 1.3/1.7/1.8 used the 19mm bars as standard. The 21mm bars were reserved for Commercials and Uprated ‘Police Spec’ cars. The 21mm bars are considered an upgrade over here. A 1.8 saloon on 21mm bars, with front telescopic shocks and front and rear anti-roll bars would be considered the bees knees over here.

The 1.8 engine particularly will understeer the car into corners as the heavy old lump would prefer to travel straight on, the bigger bars help this quite a bit.

[Kilroy]

Thanks Chris.
I thought that the ASB was the thing that cured the understeer.?
At about an inch thick it should also cure haemorrhoids fer gawds sake.

I found that the later 2-leaf rear springs transformed the ride quality in a number of sedans which had previously had more leaves, and in the 575 it was nothing short of a miracle.
Well - excellent info thank you, I shall use the 19mm bars and 2-leaf springs for a start and see what happens.
While I shall be using a B series engine at first, this Coupe will become the home for my ultimate O series build.
You also deserve much credit for how that is going to turn out...

Be good now...

[balmy]

I think 19mm bars are the way to go with firm damping.
I don’t know why people think stiff springs are the way to go on a road car. It’s the damping that matters. 2 leafs rears are more than stiff enough.

[MarinaCoupe]

Overall the thing that improves the Marina front end turn in was the introduction of telescopic front shock absorbers. Set fairly stiffly the allow the car to lean on the outside wheel/tyre as you turn in. Unlike ARBs which only come into play during cornering. The springs and shocks work the car under acceleration and braking in a straight line, a tougher front spring will reduce the nose dip under braking and stiffer rear springs will reduce the squat and axle tramp under acceleration. Some good shocks will then properly damp the recoil on the springs.

Brian Viney over here has been working on his suspension from when he bought his TC Coupe new in 1972, he reckons that the dreaded Marina clutch judder is actually rear axle tramp caused by too soft rear springs. The rear anti-roll bar acts as an anti-tramp bar during straight line acceleration. The the sort of power you are expecting from your engines it’s something else to consider.

[Kilroy]

Balmy - my thoughts too.

Chris - I take your point about the action of the original shock absorbers which resist movement in both directions, but this too will be ameliorated by the use of softer springing, as there will be less total resistance to compression.
I have always noted that the Estate, especially in auto form, is the best handling Marina I have experienced. It is the heaviest, and the auto is a great lump of ballast low down and amidships. With the 7" wheels I could throw those cars around so hard that all manner of other machinery gave up, despite having large power advantages. Perhaps that is a factor - the Marina could get whatever power it had on the ground without losing the plot.
The Coupe on the other hand is extremely light weight, especially in the rear, so I want the softest springs possible and will not use an ASB on the rear, because I do not wish to encourage the rear wheels to lose traction.
Bearing in mind that this will be handling the most power I have ever elicited from a Marina engine(s) in any form I am hoping to consider all of the factors.
I will surely be repositioning a very large battery to the boot and keeping the fuel tank as full as the filler cap can possibly stand...

Time to break out some big guns.
http://www.kilroy.nz/guns.jpg

[MarinaCoupe]

Looking forward to seeing pics of it on the road and reports of its performance and handling.