2000 F-150 XLT, Flowmaster SIDO Exhaust, K&N FIPK, Transgo shift kit, 4.10 ring & pinion, 5.4 . I recently changed the ring & pinion from 3.55 to 4.10. The low end performance is awesome, the acceleration in all ranges is a marked improvement. However, since the changeout on the big end (over 100mph) a vibration developes and increases until I let off. Twice in a 8 day period the vibration caused the tailshaft housing seal to come out of the transmission. A real mess, easy to fix, but not worth the hassel of having to do it anytime I want to run it out. My thoughts are that the driveshaft is out of balance, due to the faster RPM's of the shaft, due to the changeout. This is only a guess, as I'm not a mechanic. Any input or suggestions would be much appreciated. Thank you very much.

 

Was the vibration present before you changed the ratio? Did you change anything else on the truck when you changed the ratio (such as springs, tires, or body lift)? Do You have a (1) piece or (2) piece driveshaft between diff. and rear of transmission?

If you have a (2) piece driveshaft; there is a possibility that it is out of phase (thus throwing the balance off). Is there evidence that any of the orginal balance weights are now missing from the shaft?

If you still feel vibration is induced by the driveshaft--remove the shaft and take it to a certified Spicer (Dana) driveline rebuilder and have them check the balance at the RPM where you are having the problem. Look in the Yellow Pages under Truck Parts and Service for a Spicer Driveline distributor. Call distributor and ask if they have capability to balance your shaft. Is you shaft aluminum or steel? Be sure to take all u-joint caps with driveline when you have it balanced. I am a (former) Spicer driveline tech.

Also, is pinion seal leaking on the diff.? Do you have any endplay and / or in and out play at the pinion? If so, problem may have orginated at the pinion---CHECK THIS FIRST, before spending money on driveline balance job! Good luck! Gearman.

 

Hey John. You sound like just the guy to talk to. I am assuming you had stock 3.55 gears? How much of a difference did the 4.10 make as far as RPM's are concerned. I have a 2001 SCREW with 5.4, and am looking at 4.10, or 4.56. don't want to rev it too high at 85, but would like to get as much gear as I can.

thanks for the feedback

Kevin

 

ok i got the answer but u arent gonna like it.....i had the same prob with my truck (still have). At about 93 t0 94 mine starts and quits at over 100. Anyway it started right after my gear swap. And after investigating i found that the drivelines are still balanced. It is just that they arent meant to spin that fast and when u do.....what u feel is the driveline actually wobbling. And the only way to fix this is to have a driveline built. Or find one out of an f150 that was built with a low gear if it will fit.. Like out of a HD or a lightning. I dont know what your configuration is so i dont know what will fit but thats where we are both at. I am just living with it. I only get that fast every now and then... an it really slows u down too dont it. I can tell when it starts with my truck is harder to gain speed than when it passes at past 100. Well anyway goodluck i hope u can find a driveline that will work... i cant i have a long bed nothing ford builds with longbed will work with my 4r70w and 410's. goodluck

 

Yeah I had it too after I had my gears done. It began around 80MPH while I was bouncing off the speed limiter.

After checking the usual suspects like U-joints, tailshaft bushing, pinion, and I even tried indexing the drive shaft, I eventually followed a great link to a site that showed a methodical way of indexing and balancing your driveshaft using a hoseclamp of all things!

In my case I was able to eliminate the rumble noise by jacking up the rear of the truck and using the hoseclamp as a weight on the driveshaft. But, I never did eliminate the speed limiter so I dont know if it will still be silent at speeds over 80MPH.

I'll try to find a link to that website or maybe someone will post it.
If you search the subject you'll find a ton of stuff regarding high sped vibrations and driveshaft issues. The bad thing is that the culprit has to be nailed down through process of elimination and even then it could still be a combination of things causing the vibration.

Good luck.