Driveline Vibration under load
01-08-2018, 05:06 PM
#1
Junior Member
Thread Starter
Join Date: Jan 2018
Posts: 1
Likes: 0
Received 0 Likes
on
0 Posts
Driveline Vibration under load
Hey all!
I have been the owner of a 1990 F150 2wd with a 4.9 I6 and e4od trans for about two years now. Ever since owning the truck I have noticed a slight vibration coming through the gas pedal and seat when driving above say 45 mph. It comes on mostly when coasting and at very slight throttle but goes away completely when I get on the gas. I have also notice a stronger vibration at low engine rpms when driving up a hill, but when I up down shift, the vibration goes away.
I pulled the rear axle cover and nothing seems out of place. There is a leak coming from the pinion seal and play in the pinion it self.
My inspections point to the pinion seal and bearing being shot but I was wondering if there was anything you all could say about and what the easiest way to tackle this issue would be. Any comment or advice would be appreciated!
Thanks,
Sam
I have been the owner of a 1990 F150 2wd with a 4.9 I6 and e4od trans for about two years now. Ever since owning the truck I have noticed a slight vibration coming through the gas pedal and seat when driving above say 45 mph. It comes on mostly when coasting and at very slight throttle but goes away completely when I get on the gas. I have also notice a stronger vibration at low engine rpms when driving up a hill, but when I up down shift, the vibration goes away.
I pulled the rear axle cover and nothing seems out of place. There is a leak coming from the pinion seal and play in the pinion it self.
My inspections point to the pinion seal and bearing being shot but I was wondering if there was anything you all could say about and what the easiest way to tackle this issue would be. Any comment or advice would be appreciated!
Thanks,
Sam
01-12-2018, 08:59 PM
#3
Member
Join Date: Jan 2018
Location: Memphis, TN, Earth, Milky Way
Posts: 11,256
Received 1,731 Likes
on
1,487 Posts
It's very common for the pinion nut to get loose on these trucks. As a temporary fix, you can remove it, clean all the threads with brake cleaner, let them DRY thoroughly while you clean the seal surface of the pinion flange (the shiny, oily area), apply red threadlocker (per the instructions on its packaging), and reinstall the flange & nut to ~200 lb-ft (yes, it's a LOT, and you need to use a good torque wrench). That should take up the slack in the bearing long enough for you to evaluate the axle, and determine if it needs repair/replacement. Repairing it requires special tools & a LOT of experience, but replacing the entire axle assembly is easier than it sounds (and often cheaper, if you find a good used one at a local JY).
That might take care of the vibration, but there are several other likely sources. Worn U-joints, old/worn/damaged/imbalanced tires, lug nuts torqued improperly (VERY common), contamination on the hub faces, worn suspension bushings, loose front wheel bearings, worn shocks, poor alignment, and (for the gas pedal) fouling of the accelerator cable against the dipstick. Click each of these & read the captions:
(phone app link)
(phone app link)
(phone app link)
(phone app link)
(phone app link)
That might take care of the vibration, but there are several other likely sources. Worn U-joints, old/worn/damaged/imbalanced tires, lug nuts torqued improperly (VERY common), contamination on the hub faces, worn suspension bushings, loose front wheel bearings, worn shocks, poor alignment, and (for the gas pedal) fouling of the accelerator cable against the dipstick. Click each of these & read the captions:
(phone app link)
(phone app link)
(phone app link)
(phone app link)
(phone app link)