Went to the 1/8 mile drags last night. On the way down I discovered that for some reason I was not making full boost. Couldn't see any obvious problems such as hoses or anything. So I decided to run it anyway to see where I was at even with 10lbs less boost. Had TNT on 9, TQ 4, TM default, RP stock with the mp8 cranked. All the runs were pretty close, but the best was an 8.15 leaving at 20psi - that's all it would make at the line. I wasn't too happy with that and was just scratching my head over the boost problem. So I decided I was going to break into the 7s even with less boost. Adjusted the TNT and turned off the shift defuel and set the RP to 3 and turned the mp8 down to about 80%. Pulled up to the line and prestaged. Built to about 25psi and staged. Let her go on the last yellow and it just sat there with the rpms pegged at 3500. Instantly thought I broke a shaft and then thought - wait, I didn't hear or feel anything. Let off the throttle. Gave it a little throttle back and it started to go. Mashed it to the floor and it took off like normal. Then when it tried to shift to third it didn't and just hung at 3500rpm. Got back around to the pits and there was no reverse or neutral. Every gearshift position was a forward gear. Shut it off for a couple minutes and then started it again and now it won't go forward at all. Time for a rebuild.

 

Sorry buddy... seems like things are happening in threes at the track. If I was one, and you are two, who's next?

That hurts...

 

I'll take that third slot. Three passes down the track on Wednesday with no problems, but while driving the truck back home it started to stall against the torque converter at stops and overdrive disappeared. Probably welded it, as the fluid was burnt and the TC seems to be stuck to the input shaft. Hopefully the input shaft splines are intact. This was with the full billet Suncoast Race transmission...

I feel ya on the tranny trouble guys. Such an expensive habit these trucks can be, eh?

 

The track sure is hard on stuff! Tires bite a lot harder on the line than on the street and it likes to break stuff. I have had a vibration since my last trip to the strip and I finally found out what it was Monday. The front U-Joint at the transfer case has about 1/8 rotation twist in the trunnion. It is even the bigger Spicer joint. I am afraid to see how bad the transfer case chain is stretched.

Sorry to hear about your tranny Omaha, hopefully you will only need wear items and no expensive hard parts.

 

I hate to here you are having tranny problems. Better to have them at the strip than out of town somewhere. At least you didn't break any shafts.
I don't like to build more than 15 lbs boost at the line. 14-15 lbs for me is good for low 1.70s-1.69s 60 ft times and low 7.80s-upper 7.70s 1/8. This is with torque management set at #2 mild. Tried #3 moderate but was hard to control boost at the line and once ran a 1.69 60ft 7.78 1/8 ending up with 12.33 1/4. Boost most likely crept up while I was watching the tree go down.

 

That's pretty good with 15psi. You must be running stock size tires.

And you're right about having the problems at the track, because I question if the problem was a direct result of me beating on it. I would think it would break a shaft under power rather than have a clutch problem. We are leaving for vacation on the 4th for 10 days and if it would have gave up 500 miles from home with my camper hooked up.

 

I'm running M/T 285/70R17 Baja ATZs. I run the shift limiter on #1 off all the time. I found I don't look at the lights anyway.

 

BillyRam is right.... I'm on 37's and there's no need for anymore than 10 to 15psi at launch and my times are right there with BillyRam's. I've never seen a need to boost more than that.

 

Yeah, but you also have an extra 150hp or more.

I'm not arguing with you guys on the launch psi, but it is also not what caused whatever my problem is. Too much boost and power on launch breaks shafts.

 

Uh, yeah... I found out the HARD way

 

I broke the input in my NV5600 with the 37"s and SB 3600 SprungDD. It was a perfect shear so at least it didnt break everything else. We have also had trouble out of our other built 48RE in my buddies truck slipping.

 

Ha yea it was either you or me first, I snapped my intermediate shaft when i turned the shift defuel off, won't be messing with that again. Im sure me trying to launch at 35 psi is what did it ha

 

Whoa!! Now that's a BOOSTED launch attempt there.

 

i just got my truck back up and running after a month of being down from a F-ed TC. I hit the lock up, and lost all power to the ground.