i took my F150 into the dealer today to get the rear end fixed because it has this whine at 40mph and i was told that it was normal. i had heard that only the taller gears whine. i only have 3.08s in it! is this true or did they lie to me again?

 

my truck has 3.55 gears and it has whine around 50 mph. i'm still trying to get my driveline thunk fixed and as of yet haven't brought up the whine...

 

the search mode and read on....................

 

the "grind" is gone, but a whine is now present.

3.55 LS can hear the noise at 40-50 when letting off gas. Can also hear it somewhat at 20 on decel.

Dude said he checked the ring/pinion gears for alignment (or whatever it is called???) said it looked perfect..

better than the bearing grind, but still not thrilled.

JT

 

Does the whining increase with speed or is it speed sensitive and only whine at a certain speed range?

If it gets louder the faster you go then it is probably the bearings...

If it is just at a certain speed range then it is probably the gear backlash...

My trucks whines at precisely 40-44 mph and 76-80 mph... I am not worried too much as I am pretty well going to replace the gears anyway...

 

Be really careful. The F150 have a habit of eating rear differentials. My 98 did it at about 85K, but I've heard of much sooner. The problem, so I was told, was that there is only one set of seals between the wheel hub and the pumpkin. The wheel bearings can go and not be heard (mine never made a sound 'til they were all gone). The shavings make their way through the seal and into the differential. You can guess what happens then. Crunch, grind, etc. I don't mean to alarm you, I'm just suggesating that you might want to have the wheel bearing checked. If you catch them in time, no biggy. Good luck.

 

[QUOTE]Originally posted by Randall Phillip "The F150 have a habit of eating rear differentials."

Is there any difference between the 8.8 and the 9.75 concerning this problem?

 

I recently seperated service with my Employer of over 16 years. While at this Co. I would say the ratio of GM 8 1/2" diff's. to Ford 8.8" diff. failures were probably 25 to 1.

From my experience I believe Ford produces the best rear and front axle assemblies in the 1/2 ton class. I have seen many 8.8" & 9" Ford diff's go way past 200,000 miles of service. Rarely, have I ever seen a GM 8 1/2" go past 150,000 miles.

8.8" diff's have extremely large diff. side brg. caps (compared to 8 1/2" GM diff's).

I have never had an opportunity to work on a 9.75"; however, I sold parts for one only one time since 1997.

 

I definately agree with gearman on this!

Ford makes some of the best rearends for everyday and high power usage. Most of the hotrodders I know use a similar formula a SBC, with a Turbo tranny, and a Ford 9" rearend... My own D351 powered 1988 Mustang never had any problems with the 8.8... That is with a 10.56ET @ 133.23 mph... I also had a pretty good 60' on that run but I will have to find the slip as right now I am suffering from CRS... :o

Now the GM 10 bolt is notorius for being a well functioning grenade...

 

when i took my 3.55 L/S in for a bad whine and it was the pinion and carrier bearings gone,the guy at the gear shop said it was rare for fords to go out...mostly GM's is what he saw...lucky me huh?

 

I personally think the 9.75 is a noisy lemon!

After changing most of my bearings, and using the expensive 85w140 oil, it whined worse than ever! (this was put together by a guy who knows his sh#t).

I just replaced my spider and side gears yesterday, and i used 75w90 synthetic mixed with plain old 85w140 in a 2:1 ratio, inital driving says: whine is much better. HMMMMM.


Also i loosened the side bearing caps and retorqued to 70ft/lbs.

I will post again to update on the friggin "whine of death"!

PS: I love the way that ford uses the tiny wheel bearings in these rears.

 

Do you have pics of the replacement job?
Thanks,
UB

 

Sorry, no I did not take any photos. I was doing the job on my cement driveway, battling wind and light snow.....not to mention freezing!

It is a job that any one who can spin a wrench can accomplish.

If you like, I can post my procedure later when I have time.

 

I recently had all the bearings in the rear end replaced. I had a leak in the tranny going up hill & was hearing a wine & a retired ford mechanic said it might be the planitary gears so I had the tranny rebuilt($2150. don't let ford do it!). Well it was the rear end wining & I had all the bearings replaced ($600.), for some reason I had water in the lube. $2750. in 2 weeks hurts. I still hear some pinion noise but I don't sweat it. Always use synthetic in the re & limited slip additive if you have a ls (some say add every 80000 miles)

 

If You have installed a Eaton-Posi or Auburn: do not use synthetic! Use 80W90 or 85W90.

Synthetic lubes are good for extending lube change intervals. Otherwise conventional lubes of appropriate weight & API service ratings are fine.