0-60 times super slow

[PerpetualSeanX]

So I just recently regeared my truck from 3.73's to 4.56's. I have 93 octane performance custom tune, 35'' tires, gotts mod and the gears, and a 4'' rancho lift.

My times before regearing were 10 seconds flat. After getting the gears, and breaking them in, my first go at really beating on it was 9.1 seconds. That was about a week ago. Today, I couldn't even get the wheels to chirp full throttle and the time has gone up to around 9.6-9.8 seconds.

Something doesn't seem right. With that being said, when I regeared a vibration started to occur around 67MPH, I was told it was probably my torque converter and I never noticed it before because it would have needed to go faster to cause it. Ok. On top of that, occasionally before the gearing I would notice the tranny seemed to be slipping. I'd be flooring it sitting at around 4.7K RPM and not really going any faster until it would kick up a gear. This was very infrequent and I haven't noticed a significant symptom like that again in a while.

Is it possible my tranny is just slipping like mad and I'm losing all my power there? Could it be my torque converter? My tranny just doing normal flat cruising at 45-65 sits at around 155-165 depending on ambient temps (85-95 degrees now). Any insight and help would really be appreciated. I'd like to know if taking it in to get the tranny looked at is worth it.

[907DAVE]

Vibration after a re-gear is probably driveline related. It was there after you added the lift, but the increased driveline speed aggravated it. This simply could be cured with some wedges that correct pinion angle. The angle of the driveling coming out of the transmission needs to be the same as is is going into the rear differential so the u-joint's can work in unison.

Anther thing to note is the front driveline, from the factory the yokes come out of phase. This means they are 90* off from each other - not a problem until you add a lift and change the driveline angles. This vibration will only present itself in 4X4.

For the lack of power I would start with the basics. Check and make sure the MAF sensor is clean, fuel filter is not plugged and air filter condition.

Any codes present?

[PerpetualSeanX]

No codes present at this time. Just changed air filter. I'll check out the MAS sensor. How difficult is it to check out the fuel filter and how will I know if it is or isn't clogged?

No vibrations while using 4x4. The guy I am dealing with that did my gears swears it's the torque converter and not pinion angle. I actually specifically asked him whether it was or wasn't pinion angle when I experienced it and he feels that it's a different kind of vibration. He was actually rather insulted I would question him on it and cited his 20+ years of experience doing gearing and the like. . .

I've been rather frustrated with this whole gearing process and him because it seems in the few short days I've been trying to learn about it, I've learned more about this than he seems to know or is willing to accept. Pinion angle definitely seems to be the issue at this time, or poor backlash setting or preload. . .we'll see what happens when he takes the gears out to replace them cause they also whined when I got them installed, and still do whine. He said he wouldn't replace them until 1000 miles on my first oil change stating Yukon doesn't warranty them until then.

I love my truck too much to see her go through all this stuff. /sigh It's killing me.

[PerpetualSeanX]

On second thought it won't even matter. I'm just going to replace the fuel filter. I've got 74k miles and I doubt if it's ever been changed. I'm also going to clean the throttle body whilst I'm at the maf sensor. Anything else that you can or anyone else can think of that would cause a severe drag on performance?

[907DAVE]

Originally Posted by PerpetualSeanX

Pinion angle definitely seems to be the issue at this time, or poor backlash setting or preload. . .we'll see what happens when he takes the gears out to replace them cause they also whined when I got them installed, and still do whine. He said he wouldn't replace them until 1000 miles on my first oil change stating Yukon doesn't warranty them until then.

Uhh...if they whined they were not setup correctly. Yukon is going to laugh when they hear this.

I doubt this has anything to do with your vibration, but its not right. Its only going to get worse and no amount of setup is going to fix a improperly setup differential after the gears wear incorrectly.

[PerpetualSeanX]

With all due respect, Dave you aren't telling me anything I don't know. Lol That's why I'm so frustrated with the shop. If it isn't right when I bring it back and they install a new set or try and refuse it there will be issues. I'm trying to give them their chance to save face. I really don't like being a jerk. If I'm forced to however I will.

On the issue of power, do you think there are any other issues I could hav causing power loss if after. Clean the Mas and replace the fuel filter along with cleaning the throttle body while I'm at it.

[907DAVE]

I would start with the basics and move on from there, your on the right track.

[cleatus12r]

Back in late '09 from the Mad Doctor himself:

"Oh... and my Expy will beat most of the F-150s in the area. I haven't lost against one yet. The 3.31 gearing actually seems to help the engine produce more torque by increasing load and letting the engine pull harder. I've seen trucks go with shorter gears and actually lose performance because of load loss on the engine. Go figure... "

[PerpetualSeanX]

Man that would be a real ball breaker if that was my issue!

[PerpetualSeanX]

Also thanks a lot for the replies you guys. I love this forum and everyone in it!