I've been searching left and right, I emailed Jacks, Shep and Buschur and asked them the strongest and most reliable setup for straightline big stroked engine. From the responses. They all said just upgrade the center spider's like TRE offers and put in a rear LSD. Torque tube and ring & pinion upgrade if you can afford it. They ignore my question about the Viscous, they said its not a weak point.

I have concluded the EVO so called AWD system is just a front wheel drive car and ONLY if the front starts to slips the VCU or ACD locks the rear but their is a lag in the time it takes. If the rear is not upgraded to a LSD the torque will transfer back to the front. So I can only assume 95% of the straight line driving no torque is transferred to the rear. Right?

So the best setup for stroker's is

1) drag guys tend to do with the VCU it seems to be the consensus but read my question below

2) front diff upgrade to something like a Wavetrac (which keeps the VCU)

3)Rear lsd upgrade

4) t-case ring and pinion upgrade (if you can afford it)

But the center diff (one in the trans) I'm still unsure Quaife or just the TRE diff machining upgrade.

Secondly, I've never driven an EVO, we're doing like a Mirage swap, so I don't know the amount of time it takes to lock the rear once the front starts losing grip with the VCU. But it has to take a few seconds to transfer the torque to the the rear?

Third, why not just spool the VCU or weld it up somehow if the center diff is a LSD type? I just don't see the point of have a Quaife center with a VCU or ACD? the VCU will just fight the Quaife to create the torque split. I just see the VCU as a weak point or just a waste, can someone help here?

 

i dont think u quite researched enough because your words are mixed up.

https://www.evolutionm.net/forums/ev...g-non-acd.html

the "front" diff that people upgrade is in the tcase.
the vcu mates to the housing of the front diff in the tcase, the vcu houses fluid. (acd uses plates)
the evo is essentially a fwd biased car... theoretically.
the "center diff in tranny" is not what you think it is.

 

Oh **** now he got me thinking. I already went with the TRE max lick full built rear diff. I have an 03 so open front diff, I know it us in the transfer case, are you suggesting upgrade the tranny or the transfer case to install the front diff? What is more crucial for straight line racing? Ie what's more likely to fail under heavy launches

 

I know where the frt diff is and where the VCD or ACD is and what it does, I have two ripped apart trannies here, so I know where the center diff is.

So what your saying is the Quaife center doesn't do anything to control the torque bias from the frt diff or rear diff(which channels from the VCU or ACD)?

My wording maybe wrong but I'm sure you know what i'm getting at.

 

Let's leave the transmission itself upgrade alone for this discussion. I'm talking about the center diff, VCD or ACD and the front diff which has to be upgraded to the Wavetrac or something else.

I just think the VCU or ACD is a complete waste if the center diff is controlling the torque bias from front to rear, just weld up the VCU or lock the ACD and let the center diff do its thing.

This is why I think way back GSC Power Division offered a center diff but the price was high because it came with a spool to replace the VCU since its not needed, they should just sell that spool if the center diff (the one in the trans), is upgraded.

http://www.stikiller.com/product.php?productid=16737

https://www.evolutionm.net/forums/ev...ntre-diff.html

 

Edit:

This maybe confusing

2) front diff upgrade to something like a Wavetrac (which keeps the VCU)

should be

2) front diff (the diff inside the tcase coupler which mounts the ring and pinion, ACD or VCU) upgrade to something like a Wavetrac or Quaife

 

If you weld the VCU, you'll essentially have a locked center diff. At that point, you should replace the center diff with a spool and eliminate the VCU and diff all together if you want it light weight. This would probably be a pretty awesome choice for a dedicated drag car actually. It will beat the **** out of the drivetrain just driving around in a parking lot though.

With a torsen diff, the VCU functions like a wheel on the ground. If you removed the VCU, there would be no second load to provide resistance against and the torsen diff wouldn't work. It's not really transferring power through the VCU though, it's just using it to bias the diff.

With a clutch pack LSD, yes, you could effectively remove the VCU and you would have mechanical clutches locking the front and rear together once you replaced the VCU with a lockout setup.

The VCU doesn't have a "delay" really. It is an analog device and the higher the differential speed between input and output, the higher torque it transfers. It's a friction based unit. It provides "instant" torque transfer, but the torque level is not instantly 100%. A rear spring biased EVO with a rear diff upgrade and the torsen front diff handles more like a RWD car then a FWD car in my opinion. My car was tail out under power all the time.

 

I'm lost I know where everything is under the car but I*don't know exactly what you guys are saying when it comes to the transfer of power and what should be upgraded. I was planning on upgraded all 3 components. Rear Diff(complete) transfer case, and transmission. I don't have ACD because I have an 03

 

your exactly right 03white a welded vcu or acd would lock the centre diff as well.

however, if i can somehow remove the splines that couple vcu to the tcase ring gear and front diff, essentially removing the device that integrates the front and rear, obviously you cant remove the vcu since the it supports the ring gear and houses the frt diff but removing the splines so the front diff is spun from the inner torque tube from the centre diff and the outer torque tube to turn the tcase ring gear, its just an idea.

Or I could like to do something crazy like spool the center and weld the vcu. Then add a strong lsd at the back of the car between the propeller shaft from the tcase and the rear pinion shaft so basically it becomes a bmw/audi haldex Awd system so taking those parking lot turns will be easy but i'll have plenty of clutches in the haldex to launch. Heck i could probably pull the rear diff off those big german cars if i could match the evo tcase ratio. 3.43 if i remember correctly.