Hi all,

So I just purchased a Cusco Tarmac Gear from Mister Two.

I'm very excited about installing it, but unfortunately, I've heard mixed reports about being able to dyno the car with it in, due to the fixed torque split 35:65 F:R causing the dyno to flip out.. Especially hub dynos.

Most internet reports on the matter are hearsay, so I'm interested if anyone has any facts on the matter.

Cheers

ASG couldn't dyno my DCCD (35:65 unpowered) until we could power it back to 50:50.

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[COLOR="Gray"]550Nm off a 2L... Just wish it was in the dak dak...[/COLOR]

when i put mine on the roller dyno at tenagah's ages ago (before i had the dccd controller installed so it was 65:35 split) i mentioned this to johnny, he said it was okay & just changed thew setting on the dyno

might want to just clarify with the guys at asg if this is also the case with thier hub dyno

edit: there you go, kato sneaking the answer in before me

Normally yes as it fixes it permantly 35:65....

Rob is facing the same problems u are

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I'm a jockey kunts...

If this is the case, its not hard to swap back to the viscous centre.. but it would be nice to see if there is a way it could work.

It’s all very confusing because Dynapack claims that the dyno will show the torque split to each individual corner, whilst maintaining equal axle speed (within one rpm) to each corner.. thats the same as driving the car on the road of course.

They even claim that “a four-wheel-drive vehicle can even be switched in and out of four-wheel-drive as you wish on the dyno”.. which is unusual seeing as the dyno flips out when a car has an unequal torque split.

I dunno! I suppose we just have to whack it on there and see

There is a program for the hub dyno that was available for the 996Turbo. I asked when I had mine as the drive setup was similar. 90% rear drive until either traction loss or over a set speed. It can be done, but it might require additional time to set the dyno up accordingly. May be a cost that can be shared between Rob and Yourself.

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www.racewars.com.au

This might be an idea!!

I'll do some of the groundwork from Dynapack and find out whats involved.. and then I'll talk to Sean and find out if he knows anything about it.

The Cusco center diff is completely open isnt it? Just with a 35:65 torque split. So the rear wheels are going to want to go faster than the front on a dyno.

I know with my DCCD box Sean has it locked on the dyno. So the front wheel speed will match the rear wheel speed.

Yeah I always though the hub dynos controlled the wheels at a fixed speed or slowly ramped it up, constantly measuring torque. So if they want to tune some load cells at say 4000rpm, you set the speed and even if you floor it, the wheels won't go any faster and the engine sits at 4000 rpm.

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GOLD PIG STI

Yeah, the Cusco is an open diff.. it has a fixed split and doesn't rely on friction internally (such as a plated or viscous LSD) to vary the torque split front to rear, its all set in the planetary gears.

Everything I've read says you can dyno cars on Dynapacks with varying torque splits front to rear.. it'll even give you power/torque readings for the individual axles!! Also, you can switch 4wd to 2wd and vice versa on the fly and the Dynapack will handle it.

If thats the case, it must be something odd with the Tarmac Gear that the dyno may not be able to compute.

I read the same stuff on the Dynapack Joe.

I'm willing to bet its more to do with it being unknown on a 4WD dyno. They're not going to risk damaging it for a tuning excersise on a 65/35 diff.

Best to get ASG to speak to the Dynapack rep on how to do it.

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[COLOR="Gray"]550Nm off a 2L... Just wish it was in the dak dak...[/COLOR]