4wd Launches

[platinum01]

Went and ran the 1/8th mile last Friday with a bunch of other Powerstrokes. Won both my races one against a 4 door chevy truck and then next one against a ricer. But had to run both of the them down. How are ya'll launching in 4wd? Are you just turning the switch in the cab or are you actually locking in the hubs? 4wd was not working with just the switch in the cab but I didn't lock the hubs in. So I was launching in 2wd and breaking the tires loose off the line and then about 30ft out I was breaking them loose again. After I got past there that new tranny really hooked up. Thanks

 

[Crumm]

Sounds like you either have a vacuum leak on one of the front hub lines or the transfer-case shift motor is bad.

 

[platinum01]

Thanks Crumm for the reply. Do you know were I can find a vacum diagram for the front hubs. Guess if I fix the vacum leak that then it still doesn't work that would mean the T-Case shift motor is bad.

 

[wpfd571]

so what did you run for times?

 

[patrickc]

With the truck not running and the ignition on, cycle the 4wd switch from 2wd to 4hi and you can hear the transfer-case motor shifting. If that turns out be ok next I would check the vacuum lines to make sure they are connected, and see if the vacuum pump on the right inner fender is working properly. If all that turns out chances are one of the front hubs and/or seals (inner seal, or one of the o-rings) are leaking and/or broken. Cheers.

 

[platinum01]

so what did you run for times?

First run was 10.1 but I was sleeping on the light.

Second run was 9.8, but that was still hammering off the light breaking the tires loose getting out of it, getting back in it breaking loose again and then finally hooking up. Going to go back after I fix this problem and see what happens.

 

[platinum01]

With the truck not running and the ignition on, cycle the 4wd switch from 2wd to 4hi and you can hear the transfer-case motor shifting. If that turns out be ok next I would check the vacuum lines to make sure they are connected, and see if the vacuum pump on the right inner fender is working properly. If all that turns out chances are one of the front hubs and/or seals (inner seal, or one of the o-rings) are leaking and/or broken. Cheers.

I'm finishing up cutting my pinch weld covers and then painting them. So I'll install them this weekend and I'll check it then. One other question are you suppose to hear your vacum running? It is really loud when I turn the ignition on and it blows air out the top hole. Maybe that is my problem.

 

[BamaSixGun]

BEWARE of the 4Hi launch. Tranny breakage can occur.

To this day, I am scared to death to even try it again.

 

[DaveBen]

And you can blow the transfer case, I have done that in another vehicle.

Dave

 

[patrickc]

My vacuum pump always ran for a few minutes after start-up then shut off. I'm not sure on the air escaping from the top of the pump.

I had troubles with my 4wd not working properly on my '02. I replaced the inner hubs seals and o-rings twice on both sides (because they were leaking vacuum) and replaced both auto hubs once also. The vacuum pump nor the lines never gave me any troubles though.