Sway and Torsion Bars

[Storm_X]

I would just like to know what cars came out with, (what) sizing front and rear sway bars and torsion bars


GTV  1.8  2.0
GTV6
Alfetta  ""  ""
Giulietta ""  ""
75
90


Thanks Chris

[Duk]

The 3 litre V6 75s came out with:
22.8mm TBs
24mm front anti roll bar.
21mm rear anti roll bar.

I think you'll find that all of the short TB V6's were 22.8mm

[Storm_X]

Thanks for the info, i am buying some upgraded parts for my Giulietta. I know the TB of the 75 90 and late gtv6 wont fit but i just want to compare  sizes.

The sizing i am getting is

Front 27.25
Rear 21
TB 28.7

[Duk]

Thanks for the info, i am buying some upgraded parts for my Giulietta. I know the TB of the 75 90 and late gtv6 wont fit but i just want to compare  sizes.

The sizing i am getting is

Front 27.25
Rear 21
TB 28.7

You'll be having a very big increase in the stiffness of the suspension with those TB's and front AR bar.

[Storm_X]

i thought just my konis where nice and stiff, but the stiffer the better.

[Cool Jesus]

Responses are a little thin on my restoration thread, so thought I'd chime in here and add some info to the thread.

Anyhow, cleaning up the torsion bars on my 1976 Alfetta GT, I can't seem to distinguish any markings on either of them. They are 989mm long, and 23mm dia (~0.90 - 0.91"). Both bars appear to be painted blue. There are neither coloured markings in the first 100mm from each end of either bar nor the "L, R, D or S" markings at the rear ends.

So, my question is why is there a separation as to left and right for the bars? Are they manufactured to resist torsional forces in that particular direction better than the other?

Sway bars are; (not exact due to grime, but very close)
Front sway bar – 0.720" (18.3mm)
Rear sway bar – 0.800" (20.32mm)

I also came across these figures in my files which were posted on a forum;

GTV6 Early model:

Stock bar:
Rate - 96lbs/in    Diameter - 23.5mm      Length - 989mm

Sport Bar:
Rate - 134lb/in    Diameter - 25.4mm       Length - 989mm

SS Bar:
Rate - 179lb/in    Diameter - 27.3mm       Length - 989mm

GTV6 Late and Milano:

Stock bar:
Rate - 93lbs/in    Diameter - 22.8mm       Length - 932mm

Sport:
Rate - 143lbs/in    Diameter - 25.4mm       Length – 932mm

SS:
Rate - 191lbs/in    Diameter - 27.3mm       Length – 932mm

[Storm_X]

Any one here run 30 mm TBs ?

[aggie57]

Long time ago - best riding GT/GTV I ever owned.  Serious.  Key is the damper valving. 

[Simon Aarons]

Any one here run 30 mm TBs ?

30's are excellent on the track and a smooth road. The rest of the time is spent avoiding pot holes! I think they're too stiff for the road. If anyone is after (short) 30's i'm happy to do a swap for some 28's!

[Storm_X]

There is another guy who wants to swap 28s for his 30s and I'm unsure if I want stiffer

[aggie57]

Any one here run 30 mm TBs ?

30's are excellent on the track and a smooth road. The rest of the time is spent avoiding pot holes! I think they're too stiff for the road. If anyone is after (short) 30's i'm happy to do a swap for some 28's!

Nah - good for both. 

[Midda Samid]

I'll get in on this..

I have another thread trying to swap my 30's for 28's..

30's are great.. in the dry.. the ride is firm, but not bone jarring.. If they functioned better in the wet, I would keep them.. their biggest issue for road use is weight transfer on damp or wet roads.. you just can't get weight onto the front to get decent brake force into the tyres.. (well, the tyres I am using..) I am sure someone somewhere is getting their brakeforce through the tyres or there wouldn't be a market for 30mm bars..

I have revalved koni's and 180lb rear springs, 24mm rear sway and 22 front sway.. front roll centre extended ball joints too.. It steers very well.. It's a little oversteery which is perfect(for me).. I had it too low in the front for a long time and it was horrible.. wallowy and unsure.. ride height is a little rear down now and it is much better.

StormX, you say you are running a 27mm sway bar up front with the 28mm bars?.. I think you'll find you'll have serious understeer issues with a sway bar that big.. 28mm bars are pretty firm to start with.. You'll struggle to shift weight to your outside wheel and you'll push over the tyre.. and your rear sway is a tad light.. That's just my 2 cents worth though. What rear springs are you running?

[aggie57]

What tyres are you using?  It'd be a real shame to go through all that only to find its the Tyres all along.

[Evan Bottcher]

.. their biggest issue for road use is weight transfer on damp or wet roads.. you just can't get weight onto the front to get decent brake force into the tyres.. (well, the tyres I am using..)

I'm a bit dumb when it comes to suspension.  This is the first time I've heard someone describe lack of weight transfer as a downside of stiff springs, can you explain more?  I'd have thought weight transfer would mostly relate to roll centre?

[Duk]

.. their biggest issue for road use is weight transfer on damp or wet roads.. you just can't get weight onto the front to get decent brake force into the tyres.. (well, the tyres I am using..)

I'm a bit dumb when it comes to suspension.  This is the first time I've heard someone describe lack of weight transfer as a downside of stiff springs, can you explain more?  I'd have thought weight transfer would mostly relate to roll centre?

Weight transfer is a function of wheel base and track width dimensions. All things being equal, if the car was longer, it would dive less under braking. If it was wider, it would roll less during cornering (that's wheel base longer and track width wider). Tho more weight will transfer as the car moves around, in the same way as holding a rectangular container with liquid in it and you lower 1 corner, more weight will transfer onto that corner.
Roll centre height weight transfer only happens with lateral load (cornering) not longitudinal load (accelerating and braking).
If someone is having trouble with weight transfer during braking, simply use more braking force at the rear.
It's a common misinterpretation that in the wet, the car requires less rear brake bias, but it actually requires more rear brake bias (obviously within reason and assuming your car isn't some nose heavy front wheel drive).
Take even more advantage of the added weight over the rear wheel and get them to do more braking work. The rear brakes suck, so you will probably be looking at a rear brake upgrade to get the job done decently.

Incidentally, a few guys on here are saying that 30mm TB are fine on the street, by my calculations based on a full bodied 75 with approximately 350kgs over 1 of the front wheels (700kgs total at the front), that gives a natural frequency of the front suspension of 2.13Hz! That is dedicated track car (you know, PROPERLY DESIGNED, WELDED IN ROLL CAGE and slick tyres!!!) stiff for the heavier 75 and bonkers stiff for a lighter Alfetta type car.
And after seeing the photos that Sheldon posted showing cracks in his chassis (using 32mm bars), that says straight up, that the chassis is doing lots and lots of flexing!