4wd Launch To 2wd

NFSGamerUSA · January 4, 2009

I know this is a somewhat common question, but I thought it might make a difference depending on the generation and class. I've also had trouble finding a straight answer. I'm supposed to get my data log tune in from Justin tomorrow and want to know if it's alright to launch in 4WD High in my '98 K1500 (5.7L, 4L60E, NP241). I have the floor-shift transfer case, not the push-button. Now, from what I understand, it's okay to launch in 4WD with such light mods (and that heavily modded diesels have still managed with stock front-ends), but what I want to know is would it be alright to switch out of 4WD after initial acceleration? Most people say (without any real reason that I can find) that if you're going WOT you shouldn't shift the transfer case. However, since the front and rear tires will be moving at the same speed, will it really hurt to disengage the 4WD? Isn't it the same principal as shifting into 4WD on the go? Thanks!

BuckFeverZ · January 4, 2009

From what I understand, you can leave it in 4wd throughout the entire run since you can go any speed in 4 high. Just remember to switch to 2wd before you start turning on dry pavement.

NFSGamerUSA · January 4, 2009

I know I can leave it in 4WD, but I was wondering if it'd be okay to shift out of 4WD while at WOT.

svensk · January 5, 2009

Sorry, I have a push button T-case which can be put back into 2wd with the pedal on the floor, but with the manual t-case do you have to be in neutral to normally engage it to 4hi? If not, I think it should be fine. You can ask Justin as he would know.

NFSGamerUSA · January 5, 2009

Sorry, I have a push button T-case which can be put back into 2wd with the pedal on the floor, but with the manual t-case do you have to be in neutral to normally engage it to 4hi? If not, I think it should be fine. You can ask Justin as he would know.

No, I only have to go through neutral to get to 4WD Low. I already asked Justin and he said he wasn't sure about shifting from 4WD High to 2WD, but that 4WD High launches should be okay.

svensk · January 5, 2009

Sorry, I have a push button T-case which can be put back into 2wd with the pedal on the floor, but with the manual t-case do you have to be in neutral to normally engage it to 4hi? If not, I think it should be fine. You can ask Justin as he would know.

No, I only have to go through neutral to get to 4WD Low. I already asked Justin and he said he wasn't sure about shifting from 4WD High to 2WD, but that 4WD High launches should be okay.

He's worthless!

Spurshot · January 5, 2009

Shifting on the fly is ok, but my recollection of my 98 that had the same setup was that the shifter was so low that you had to bend way down to shift it and there's no shift gate to protect you from going past the 2Hi position right into neutral or worse. I doubt you'll be able to shift under WOT, but I could be wrong, but one slip and it could be a real costly mistake.

NFSGamerUSA · January 5, 2009

Sorry, I have a push button T-case which can be put back into 2wd with the pedal on the floor, but with the manual t-case do you have to be in neutral to normally engage it to 4hi? If not, I think it should be fine. You can ask Justin as he would know.

No, I only have to go through neutral to get to 4WD Low. I already asked Justin and he said he wasn't sure about shifting from 4WD High to 2WD, but that 4WD High launches should be okay.

He's worthless!

dur · January 17, 2009

I know this is a somewhat common question, but I thought it might make a difference depending on the generation and class. I've also had trouble finding a straight answer. I'm supposed to get my data log tune in from Justin tomorrow and want to know if it's alright to launch in 4WD High in my '98 K1500 (5.7L, 4L60E, NP241). I have the floor-shift transfer case, not the push-button. Now, from what I understand, it's okay to launch in 4WD with such light mods (and that heavily modded diesels have still managed with stock front-ends), but what I want to know is would it be alright to switch out of 4WD after initial acceleration? Most people say (without any real reason that I can find) that if you're going WOT you shouldn't shift the transfer case. However, since the front and rear tires will be moving at the same speed, will it really hurt to disengage the 4WD? Isn't it the same principal as shifting into 4WD on the go? Thanks!

Im going to assume your talking about the drag strip.

You wont hurt anything by shifting it into 2wd but its going to stay locked in 4wd untill you lift off the throttle. Your better off leaving it in 4wd untill youve made your pass or launching in 2wd.

Wingnut · January 17, 2009

I'd try it!

Like dur said though...I don't think it'll come out of 4hi until you lift though.

NFSGamerUSA · January 17, 2009

Well, I've done some 4WD launches since then and they worked flawlessly, but I haven't tried switching it into 2WD until after I let off the throttle. Someone as FSC said they've done it many times with no trouble, but if what dur says is true, then he is still in 4WD and just thinks he's in 2WD. However, I have the shift lever and not the push-button 4WD. Shouldn't it go right into 2WD if I shift it into it, unlike push-button where it waits until it's safe to do so?

Spurshot · January 23, 2009

Sounds risky with no protection from going into neuchy. If it won't shift out of 4wd until you lift, you'll probably run quicker in 4wd.

NFSGamerUSA · January 24, 2009

Sounds risky with no protection from going into neuchy. If it won't shift out of 4wd until you lift, you'll probably run quicker in 4wd.

It's pretty notchy, so it'd be hard to shift it too far. I haven't tried shifting from 4WD under heavy throttle, but a guy on FSC says he can shift it into 2WD under throttle and has done it many a time (as I said above). I think I'll just stick to staying in 4WD until I let off, though.

L29er · January 24, 2009

I imagine it will be pretty hard to shift to 2wd as the driven force holding the collar in the T-case might be to hard to overcome, even if you did get the t-case out, the front collar in the diff won`t pop out untill the power comes off.... thats just my guess. I intend to try both 4wd and 2wd launches, we`ll see which works best, even right now in 4wd its hard to go straight...

NFSGamerUSA · January 24, 2009

I imagine it will be pretty hard to shift to 2wd as the driven force holding the collar in the T-case might be to hard to overcome, even if you did get the t-case out, the front collar in the diff won`t pop out untill the power comes off.... thats just my guess. I intend to try both 4wd and 2wd launches, we`ll see which works best, even right now in 4wd its hard to go straight...

Well, you've also got a 454! When I did a few 4WD launches it just goes, and it didn't pull in any direction, at least not enough for me to remember. In 2WD I'd just sit there doing a one wheel peel. I desperately want a G80, that's the one thing I wish my truck had come with that it didn't. Well, I wouldn't mind 3.73 diffs, but I'd rather have a G80 any day.