Sasqoutch

Have you guys ever ran into trouble from launching and going 100mph at the track in 4wd? Iv never launched in 4wd and am alittle wery of running at high speed while in 4wd.

RunninLean

Drive around the water box then engauge the 4wd stage launch and stay straight. End of the run disengauge 4wd before trying to turn off the track. As long as you dont try to make any sharp turns your fine...

JRD

I launch in 4wd then right after I launch I pop it back into 2wd. My buddy has NUMEROUS 12 sec passes doing the same thing and no problems yet. Still stock transfer case. Trans has obviously been built. This will work as long as you have the manual 4wd and not the electronic.

matego

It has been shown somewhere on here to not kick it out of 4WD while shooting down the track. The synchro inside your t-case may only be partially disengaged and with only a 1/2 bite you could twist or break something. I run 4WD until I make the turn at the end of the track. I usually pop the T-case into neutral to listen for any abnormal noises. I have a ton of runs in the low 13's and some high 12's with no issues yet. (knock on wood )

2007 5.9

I discussed this topic over on CompD, and was told that it does not matter what you do...the T-case will not dis-engage under a load....

BUT, I still kick it out of 4wd at the 60' mark right before I hit the lock-up....

Nsomniac05

I can see how the electronic would not disengage under power, but the NV with the lever....and linkage that runs down into the transfer case.... to the auxilary drive gears..... when you move the levers the gears move. thats like saying if you shift your 6 speed without using the clutch, it won't go out of, or into a gear. as long as nothing grinds, and the lever goes smoothly, then all your gear speeds were close enough to each other that the synchro's would have done little to no work anyways. same applies to the transmission.

2007 5.9

That is exactly why I still kick mine out....others think that it is dumb....but I have timeslips to prove otherwise....took 2 hundreths off my time consistantly....

Nsomniac05

older NV series transmissions and transfer cases didnt even have synchronizers or synchronizer rings. You just have to get engine RPM, trans speed, transfer case speed, and wheel speed as close to each other as possible, before engaging something..... and to disengage, everything is allready going the same speed cause its all connected.

omaharam

Makes the pinion seal leak.

2007 5.9

Why would this be??? My drive shaft spins all the time, even at 100mph....why would high speed cause the seal to leak???

tristan21

I always pop mine out. But who knows. When I break it maybe i'll learn somthin.....nah wont help.

tritont

IMO... it will do nothing for you turning off 4x. As mentioned, it won't disengage anyway under load.

I've got my truck into the 11's. This was done leaving at no more than 15psi of boost and running 4x the whole way. My speed was 112mph. There's no problem in running 4x the whole way.

keeping in mind my truck is 8500lbs on 37's... I'd say this is haulin ! I does take a good amount of hp to do it though

1.6 = 60ft
7.62 = 1/8th
90.7mph @ 1/8th
11.97 = 1/4

matego

You are right about everything being connected but it is rarely going the same speed. Ever try and push your truck in 4WD? You would have to really mess with air pressures and even then when going high speeds there is a lot of tire growth that throws all that out of whack.

I know of 4 different CTD's that I see frequently at the trans and 2 of them have had to replace the pinion seal. I dont know if its something to do with speed and load or even that there is more vibration in 4WD but there is some correlation between racing in 4WD and pinion seals leaking.

tcr

Just an FYI, I broke a billet output shaft doing a boosted 4x4 launch(500ish HP), I see you have a stock output. Be careful.

tritont

I'm thinking pinion seals are going out do to the drive angle of the shaft... not because of launch in 4x. Not all trucks are lifted but, there's still some angle there