Can't remove the driveshaft, all the fluid will come out of the tcase that is still being spun by the tranny. Can't remove the rear axles because the fluid will leak out of the diff that is still being spun by the driveshaft.

Even if you did take those parts out any ways, the viscous coupling would simply unload to the rear drive train. Or if you left the front axle cups in place to hold the fluid in the tcase and trans, the viscous coupling would unload to the front drivetrain. No matter what you do, the viscous coupling will unload to the unloaded side of the drive train. All 4 tires needed to be loaded equally, or the VC will simply not spin the part load by the dyno when the other parts have zero load. Also, the evo does not have a 50/50 torque bias in the AWD drive system.

This is a fruitless and expensive idea to simply put the car on a 2wd dyno. Find an AWD dyno, or sack up and find a secluded road to road tune it..

 

the viscous coupler is another word for LSD. works the same way. the VC is attached to center diff to control slip between front two axle and rear two axles. the dsm trans had easy access to the VC in the trans. the VC can be welded so the center diff is locked. or you can weld the center diff itself. or buy VC eliminator which simply acts like a welded VC.

the VC in evo4-8 only came in the non-ACD cars. the VC and center diff are not in the trans like DSM. it resides in the tcase. the VC is integral part of center diff housing. not separate like in DSM trans. The ACD cases dont have a VC. they have a clutch pack that has oil pressure fed to the plates by the ACD pump which is controlled by ACD computer. same thing needs to be done here. weld center diff, weld VC or weld clutch pack in ACD case. welding VC could be reversable. the other methods are not. none of the DSM stuff is inter-changable with EVO stuff.

lots of ways to skin a cat. but to run a 4wd car in 2wd mode the center diff must somehow be locked.

 

I have two 9 t-cases - one stock, one shep stage 3 w/a wavetrac. You're telling me that I need to weld the ACD clutch pack(s) to force it to RWD? I'm a little bit confused about what would happen - or would it simply be an instance of I'd weld the pack(s) and then leave an axle stub in the front or rear and be good to go? I'm not 100% behind your statement, but I like that we're flowing some ideas around now.

Is there any sort of factory "default" that if there is no power to the ACD controller or pump that it will force the car to do this naturally? That's kind of the cheat that exists in VWs and some other cars with electronic center diff control. Effectively, pull a fuse and the transfer case doesn't engage part of the system.

For everyone who says street tune - can you please understand that my intent is to do strict comparative analysis across multiple turbos. Additionally, I don't want to spend thousands of dollars renting a dyno whenever I have one available. If I can't use his dyno then it'll be a loss for the community as I would otherwise report my results here.

 

I don't believe so; The way I understand it, the transfer case is permanently engaged.

 

1 I think I have bad clutch pack parts I could weld and send you. then you would need to install the welded pack in your good tcase. this odesnt force car to RWD. it forces to AWD. you still have to drop driveshaft and plug output seal (easy) . you would have to install this tcase every time you want to dyno. this is easiest scenario for dynoing in 2wd. i dont have time to explain why all the other options are more complicated.

2 there is no default that locks the clutch pack. only different degrees of slip are available. gravel, tarmac, and snow setting are just different levels of slip of clutch pack.

3. agreed its infinitely easier to use on road tuning with 'virtual dyno". just as acurate as real dyno if not more so if the operator knows how to keep conditions consistent. sooo much easier it makes this thread stupid hard to get answers because "no one" dynos these cars in 2wd anymore.

 

Here's thinking outside the box....

Help your friend to buy an AWD Dyno?

 

Haha, I think it's about $40k to do the conversion and add the second box. That is outside of the EvoM box though! haha

 

If you have a bad clutch pack to sell me I'd be game in trying it out! I have a tig and/or mig available - or if you have something I'm happy to throw you a few bucks for your time as well.

As I had mentioned, I have a good, stock (36k miles) Evo 9 t-case as well as a Shep Stg3 t-case. My instinct is to use the stock t-case and the welded clutch pack? Then I'd drop the driveshaft and seal (big rubber stopper and some duct tape? haha, but seriously...) the tail of the t-case off?

That t-case would stay on the car until my testing was done and then the Shep Stg 3 would go on permanently. The car has been at my buddy's shop nearly a month now and will reside there until he and I are done getting the data we're looking for.

 

good luck dynoing 700 WHP evo on just one axle... big bills waiting to happen...

 

Why? Aren't there plenty of 2wd cars making 700 whp in the world? The transmission sees all 700 whp one way or another, the t-case sees all 700 whp one way or another... the axles are the only things that may only see their portion (which still may be 70% at times). Why would they fail on a dyno? It's not doing burnouts or launches.

Seems awfully closed minded IMO.

 

frankly speaking, I do not see the economies here..

I'd rather pay a dyno hour than pull the Tcase to put in another one with a blocked central clutch pack.
Otherwise you are right in a way, gearbox is the same, although the front driveshafts will bear twice the load.. hope they can take it...

And on the dyno you will probably just tune full throttle....

 

You know it would be far cheaper and less time consuming to pay the dyno fee than it would be to figure out/buy parts to make the car 2wd just for some dyno passes.

 

True, true, true, true

 

Dyno time is probably $100-150/hr. I'm not nearly good enough to properly tune and adjust for three different turbos (58-68mm, JB, BB) in just 2-3 hours. That doesn't even contemplate trying to properly maximize spool up with adjustments to the timing, AFRs, Mivec, etc... in that time either.

It's really not that fast to test several turbos. Max power is pretty easy, but I'm trying to determine streetability/curve... and I can have free dyno time at my buddy's.

It seems to be falling on a lot of deaf ears here. Hopefully the one or two people who are hearing me properly will help me figure this out...