Drive Train Noisy When Coasting

[RonMele]

So I've declared my 66 road-ready and we've taken it on a few short drives... It's been 15 years since this truck went more than 5mph around the yard (no brakes) but she drives nice...

Here's the issue: Under power (accelerating or at constant speed) the drive train sounds as it should. On coasting, though, it whines pretty loud. We cannot figure out if it is a vibration getting amplified through the body or what...it's not a grinding sound but a pretty distinct and loud whine or growl. Fluids are fresh and full. (I am reading the service manual and will check the various nuts and bolts for proper torque next time I'm working on it...)

Any other ideas, hints or clues?

Thanks
Ron

[unibody madness]

If it sat for a very long time your diff gears could have rusted causing the whine.. not sure if a good cleanout and new gear oil will help,or if a new gear set is needed.

[HiBoy63]

If it has 2 piece driveshaft it may be the center carrier bearing.

[Hunter's 64]

x2 on ring gear and pinion . Cant vibrate under load but, under a coasting situation it loosens up and vibrates.


Danny

[jkimbrel65]

Could be the rear tranny shaft.Had that in my 66 with the 3 spd

Mike

[RonMele]

Thanks Guys..

We did replace the pinion gear at the beginning of this project. The truck also sat for about 15 years (other than a few moments of driving about 3 mph from the garage to the front lawn and back) so rust could be the problem.

I'll suggest these things to my Able Bodied Auto Assistant (brother...he's owned Ford trucks since we were kids!)

If any of you are in northern Connecticut this weekend...I'll have my truck at the Simsbury Airport Fly-in and Car Show on Sunday and Marks Auto Parts on Monday evening. (I am brand new to the car show bit and/but am very excited to show this truck off a bit. I bought it from my nephew..he got it because my Dad (his grandpa) had one like it when I was a kid...my newphew never got far "fixing it up" so I decided to buy it, restore it, and will it back to him...trying to create a family heirloom of sorts.

Anyway, thanks for the tips!

Ron

[R Pope]

When you say you replaced the pinion, do you mean the ring and pinion set, or just the pinion? If you put a different pinion on the old ring gear, that's the source of the whine.

[64 f100]

Could be any number of problems First, I would check the rearend by chocking the front wheels, front and back side. Put the truck in neutral, crawl under the truck, and check rear end slack by turning drive shaft back and forth then grab the yoke and puh up and down to see if there is play in the bearings. After that I would check play up and down motion on the yoke coming out of the transmission. Once you've done that, check to see if you have any grease coming out of the rearend onto the backing plates, if so then you may have bad axle bearings. Jack up the rear axle enough to get the tire off the ground, take a prybar and slip it between the ground and the bottom of the tire, again pry up and down and see if it has bearing play. If it does then you need new bearings , at least on that side. These are all simple checks and ones that should be done. It's a fact that after setting for years and things have drawn moisture then rust may have ruined the bearings. Usually, shopws up after being driven after having been set. Once the rust has been run off , then you have pits where the rust was. Wheel bearings need special attention, because you can loose and axle if things get to loose.

Rich