Sheetmetal 9 inch diff

[irsa76]

Thanks for that. Looks like an epic sway bar.

Looks are deceiving. Probably an easy way to think about it is a beam axle rear suspension on a FWD car, like a Magna wagon, with a diff bolted to the floor pan and the axles driving the wheels.

[ALLMTR]

What about this.
http://www.ebay.com.au/itm/Extreme-f...item4ac32bb034

Ive looked at these before. Theyre double the cost which is starting to get silly especially when I can't see ANY advantage besides looks (subjective)

[ALLMTR]

As I've asked before a few times but never got an answer; why don't more (any?) drag racers use deDion rear ends? Much lighter for unsprung weight and it decouples the torque reaction from the diff.

Neither of those sound like valid reasons, mounting all that looks like a packaging nightmare and your still stuck with shitty weak (comparatively) CV's

[Soopy]

Neither of those sound like valid reasons, mounting all that looks like a packaging nightmare and your still stuck with shitty weak (comparatively) CV's

CVs were going to be my guess as well.

[Supercrown]

Cv joints and the overall complexity would be a pain, but also In a 4 link rear the torque reaction of the diff, combined with the geometry of the links, is used to generate extra traction on launch.

When the Trans brake is released the diff housing tries to rotate backwards, and the geometry of the link bars causes a reaction to that where the diff housing is pushed downwards, driving the tyres into the track, thereby generating a normal force on the tyres that is much greater than caused by the weight of the car alone. This only generates extra traction momentarily, but in a properly set up car, and combined with the overall torque reaction of the whole car against the tyre rotation, that's long enough to get the front wheels up off the deck, at which time the entire weight of the car is then driving the rear tyres into the track.

and as for unsprung weight, as drag strips are so flat it just doesn't matter.

Horses for courses I guess

[Billzilla]

Cv joints and the overall complexity would be a pain, but also In a 4 link rear the torque reaction of the diff, combined with the geometry of the links, is used to generate extra traction on launch.

When the Trans brake is released the diff housing tries to rotate backwards, and the geometry of the link bars causes a reaction to that where the diff housing is pushed downwards, driving the tyres into the track, thereby generating a normal force on the tyres that is much greater than caused by the weight of the car alone. This only generates extra traction momentarily, but in a properly set up car, and combined with the overall torque reaction of the whole car against the tyre rotation, that's long enough to get the front wheels up off the deck, at which time the entire weight of the car is then driving the rear tyres into the track.

You still get exactly the same reaction through the deDion tube as a live axle, but no torque reaction from the tailshaft that tries to lift one tyre up. So better traction.
CV's aren't a problem, use UV joints if you want.

[Supercrown]

Nah, with the centre bolted into the chassis the reaction of the centre to the rotation of the tyres is dissipated into the chassis through the centre mounts. This is why irs cars can rip the rear centre mounts out of the floor, with the pinion then hitting the floor as the centre tries to rotate backwards. in de Dion the big torque tube does not rotate as it is only a carrier, not a reaction member, just like trailing arms don't separate on launch either.

[ALLMTR]

I can't think of one benefit and a shit ton of problems..

[Billzilla]

Not sure what your point is there, but yes I see that the live axle is going to be different to the deDion - ta.

[Supercrown]

if I get a minute at work tomorrow ill throw a couple of diagrams together. If I manage to illustrate the concept well enough you'll see the difference plain as day.

[BigMuz]

You still get exactly the same reaction through the deDion tube as a live axle, but no torque reaction from the tailshaft that tries to lift one tyre up. So better traction.
CV's aren't a problem, use UV joints if you want.

Circuit guys can't comprehend what massive power, short gearing and actual traction mean in terms of how strong diff parts need to be in drag cars. Have a look at strange engineering web site some time.

[Billzilla]

Circuit guys can't comprehend what massive power, short gearing and actual traction mean in terms of how strong diff parts need to be in drag cars. Have a look at strange engineering web site some time.

Ta.
What do the high-power IRS guys use for CV/UV joints?

[Soopy]

Ta.
What do the high-power IRS guys use for CV/UV joints?

God ones, lol. Gforce make some good stuff main problem with IRS is when the car squats the wheels camber in and you end up with fuck all contact patch. So torque and traction arent really a problem at that point as youre blazing the tyres anyway.

[PLAYA]

Doesn't have to camber, just run equal length top and bottom arms

[Soopy]

Doesn't have to camber, just run equal length top and bottom arms

you wouldnt bother. The only reason IRS gets used at all is because its factory. Talking Holden anyway.