jdm svx

[subru92svx]

So the USDM Impreza's automatics have VTD? What years have VTD? I have a lead on a 4.44 impreza 2.5rs transmission for pretty cheap. I was planning on buying it just because I have been wanting to do a 4.44 swap.

[SomethingElse]

Originally Posted by Darren

Shipping containers dont really workout cost effective for cars,

You are paying for cubic space of the whole container and a car only really fills half of the volume so your actually paying to ship air.

how many cars will fit? Ill get one if anyone else wants to get one, or 2..Ever since ive seen the air purification system and the steering wheel controls ive been feenin. not to mention they only produced 7k or so of them.

[Nomake Wan]

Originally Posted by subru92svx

So the USDM Impreza's automatics have VTD? What years have VTD? I have a lead on a 4.44 impreza 2.5rs transmission for pretty cheap. I was planning on buying it just because I have been wanting to do a 4.44 swap.

I remember that we didn't get VTD in the USA until 2001 with the automatic on the WRX... don't know if the RS counts in that or not.

[svxistentialist]

Originally Posted by subru92svx

So the USDM Impreza's automatics have VTD? What years have VTD? I have a lead on a 4.44 impreza 2.5rs transmission for pretty cheap. I was planning on buying it just because I have been wanting to do a 4.44 swap.

The Impreza WRX should have the Full Monty VTD box in any years, but check carefully before buying. I have a US service manual for the 4EAT, and it deals primarily with the rear take-off clutch type, the 90-10 type.

However, if you get a 4.44 from a Forester you are certain to have the VTD transmission. The Forester is meant for light off-road stuff, and always has the good transmission. You will need to install the Forested TCU with the change. It ought to be possible to get one of these cheap at a breakers.

Even in fwd form, the SVX handles very well because of the excellent suspension and chassis.

As Phil says, the JDM cars handle mostly neutral. My first car was JDM. I found it handled well under power, but I was never happy with the amount of power you could push to the back wheels. I found it handled either neutral or understeered. You would notice understeer if you lifted off under very high speed in a tight sweeper.
[Don't bother posting to tell me you are not supposed to do that. . I'm aware of that, I'm describing how the JDM behaves at the limit, K?]

You could make it oversteer in low gears on the loose, but only for a short time until the TCU assigned 50-50 split. On tarmac, it was designed to keep you safe rather than entertained, so neutral is the order of the day.

Anybody wants to play tail out, forget the SVX, it's no drifter. Get a JDM R32 Skyline. The software in them is designed to let you entertain yourself without Big Brother damping down the fun.

Joe

[nonSTOP_service]

I've found that teh SVX's strong point is it's high speed handling. The car was designed to be a touring machine and that's what it seems to do best. I've been using mine to traverse the state, and I gotta say, no matter how hard I push it on those long sweeping corners, it just doesn't complain, it only performs.

Now, on any type of dry tarmac, I agree, you just aren't going to get that tail loose. But I've found if the ground is even a bit slick, it's a whole different ball game.

So far I haven't had any problems getting the car to do exactly what I want. Now it might be due to my experience with an older subaru AWD, but I've found that if you can get the tail end to break loose, the center diff will just keep feeding it power, and you really won't have any problems. Now I suppose if you were used to a RWD you might counter steer too much and cause the car to straighten out. The other key factor, is you can't just expect the tail to whip out, you gotta throw the car nice and hard.

Just a 92 USDM...

[svxistentialist]

I could not disagree with what you said. You have to fling the car to make it slideways. If you have it going sideways, the power [in the VTD one anyway] is split 50-50, so you can keep powering in that general direction on the loose.

My main point was that under no power on tarmac, the chassis at speed will default to understeer and tend to run wide on corners.

This is obviously not how you drive yours, though

Joe

[svxistentialist]

Originally Posted by b3lha

A guy in the UK did that. He had a USDM import and when the transmission failed he put in a UKDM VTD transmission. He said it was a lot of work since you have to swap the whole drivetrain, the TCU and its wiring.

If USDM imprezas have VTD it would probably be easier to get the parts locally than importing them from Japan.

The JDM cars are very neutral in their handling. They just keep on gripping. You have to drive like a nutter to make them understeer or oversteer.

Hey Phil

A "thought" occurs. [very rare event ]

The standard vtd box normally delivers 65% rear and 35% front until traction is lost front or rear, then the computer does its thang and redistributes power to the wheels with better traction.

It must use sensor input to determine when the torque changes are required. What do you think are our chances of dumbing down the vtd box?

What I mean is, if we managed to deny the box signal inputs, and it was to then presume that all is "normal", then I am thinking it would continue to feed out the torque 65-35, no matter what traction prevailed.

This would seem to me to be a bonus for handling an autocrosser, possibly even on tarmac, though of course it would be hoped that the limited slip diffs would give good traction under this format.

What do you think??

Joe

[nonSTOP_service]

I don't think that will quite work. It's a VTD (viscous traction differential) which means it relies more on the viscous couplings than the computer. I could be wrong, but I think some welding would be in order to truly lock the torque split.

[svxistentialist]

Originally Posted by nonSTOP_service

I don't think that will quite work. It's a VTD (viscous traction differential) which means it relies more on the viscous couplings than the computer. I could be wrong, but I think some welding would be in order to truly lock the torque split.

Maybe you are correct. However, it uses two speed signals, one from the front of the box and one from the rear of the box. If the computer sees difference in these signals it presumes slippage and transfers power to the other axle, a relatively simple process.

If it could be fixed that the computer saw the same speed front and rear all the time, then the computer will presume all is normal and dictate the standard split of 65-35 split all the time.

What I am suggesting here is to mirror the front differential speed signal [or split it, whatever it takes] and send this signal to the speed input in the TCU that normally sees the rear axle speed signal. Disconnect the rear axle signal of course and leave it redundant.

I am suggesting that in this mode, as the TCU will be monitoring exact equivalent speeds between the front axle and the rear axle, it will leave the torque split output as "normal", 65-35. Within this normal non slippage range, the viscous couplings will do as you say and assign torque to the left and right wheels as they adjust in use.
[If the vtd works between front and rear rather than side to side, then your prognosis will be correct, of course.]

Still, if the vtd was able to do all that on its own, then what is the point of the front speed signal and the rear speed signal into the TCU at all? The computer would have no control over the torque split selection. This does not seem to make sense. Why have it in place if it is not needed for control purposes?

Is there anybody who thinks this might work?

Joe

[b3lha]

Originally Posted by svxistentialist

Hey Phil

A "thought" occurs. [very rare event ]

The standard vtd box normally delivers 65% rear and 35% front until traction is lost front or rear, then the computer does its thang and redistributes power to the wheels with better traction.

It must use sensor input to determine when the torque changes are required. What do you think are our chances of dumbing down the vtd box?

What I mean is, if we managed to deny the box signal inputs, and it was to then presume that all is "normal", then I am thinking it would continue to feed out the torque 65-35, no matter what traction prevailed.

This would seem to me to be a bonus for handling an autocrosser, possibly even on tarmac, though of course it would be hoped that the limited slip diffs would give good traction under this format.

What do you think??

Joe

If the readings from the sensors are not sensible then the computer uses a pre-programmed default value (and logs an error code). As you said, most likely thats 65:35. It might be possible to play some tricks on the TCU. Remember that timer reset thing I did with the power mode? There are a few other timers in the TCU software that could be abused in the same way but I'm not sure what they do. Unfortunately I haven't had any time to look at the TCU software for the past few weeks.

Could you achieve what you are looking for by simply inserting the diff-lock fuse or wiring it via a switch?

[svxistentialist]

Originally Posted by b3lha

If the readings from the sensors are not sensible then the computer uses a pre-programmed default value (and logs an error code). As you said, most likely thats 65:35. It might be possible to play some tricks on the TCU. Remember that timer reset thing I did with the power mode? There are a few other timers in the TCU software that could be abused in the same way but I'm not sure what they do.

I'm not really following what you are trying to achieve? Could the same thing be achieved by simply inserting the diff-lock fuse or wiring it via a switch?

So far as I know Phil, the diff-lock fuse gives you permanent 50-50 split, so on-power handling with the wheels slipping would be resolutely neutral.

By wiring it to always deliver 65-35, and disable the computer from defaulting to 50-50 under slippage conditions, I would be hoping to retain a rwd handling bias under power and under slippage.

Joe

[b3lha]

Originally Posted by svxistentialist

So far as I know Phil, the diff-lock fuse gives you permanent 50-50 split, so on-power handling with the wheels slipping would be resolutely neutral.

By wiring it to always deliver 65-35, and disable the computer from defaulting to 50-50 under slippage conditions, I would be hoping to retain a rwd handling bias under power and under slippage.

Joe

I'll look into it for you when I have some time.

[svxistentialist]

Thanks Phil

[Nomake Wan]

A note... the Forester VTD (according to the Japanese site I linked earlier) does not have a standard 35/65 split. It's 45/55.

[Nomake Wan]

A thought occurred to me today while sitting in the car... if the VTD cars constantly send power rearward and use an LSD to send power up front... then that means they don't have a FWD fuse, right? Our FWD fuse works because our transmissions send power forward and use a transfer clutch to send power rear... so it just locks out the clutch and prevents power transfer.

But on VTDs...?