Put 4.10 in my 03 f-150 2wd 4.6L had 3.55. After install and retuned the truck runs great untill 80 mph and the it has a noised and vibration. Every thing checks out ok. The noise and vibration seems to come from the passenger side.

Have had the gears out about 100 time in the last week. What am I missing? This is not the first gear I have done.

 

Did you mark the driveshaft and index it back in properly?

 

Yes, I have an 8.8. I have regeared many. I just put a 4.1 from 3.73 in my L. It is running great!

 

I'm not questioning your experience, I'm a tech myself but it is easy not to mark the d-shaft and reinstall it back properly, just skips your mind. Did you replace ALL the bearings in the rearend?

 

Get the problem solved yet?

 

No the only thing that I can thin is the factory LS is not balanced un like the locker. That is the only diff.

 

what about the drive shaft being unbalanced now that its spinning faster than before you notice it i put 3.73s in my mustang and had the same problem untill i put a new alum d-shaft in same thing with my step bros mustang but he did 3.55s but still had the same problem

 

Did not try the drive shaft, but the noise is comming from the rearend. When the truck is in the air and no load the noise does not start untill 100 mph.
If it is the drive shaft, Its sad that Ford does not put the same quality into all the vehicles they make. My L did not have to the driv shaft replaced after the gear change.

 

Re-phase the driveshaft, turn it 180 degrees and bolt it back in.

 

Have not tryed that. Going to the track, I will know then if any thing eles is wrong.

 

How did it go at the track and did you figure anything out?

 

180 did not work. The track was close because of weather. However' I am going this weekend.

 

w00t

 

OK a little update. I did not get to the track, but the truck did break down.
The seal and bearing in the tail shaft of the tranny started leaking, so they are no good. Put new tail section on and u-joints. Still the truck has a vibration. I have an Alum. drive shaft that came from the factory. Now going to try and look at tranny. Put truck in first and ran up to about 5k rpms and no vibr, did then same in 2nd and no vibr, however, when put into drive and ran up to about 5k rpms the vibra came back. Does this mean tranny going bad?

 

No it sounds speed related, at 5000 in my truck with the 3.55's its at 118-120mph, so you were on a closed course I take it , but sounds more like a tire, wheel, brake rotor problem. Is it possible you overtorqued the rear wheels once everthing went back together? Knocked a wheel weight off?