NP435 vibrates shift lever in 4th gear??

[heel&sole]

I picked up a '68 F-100 4x4 with a 1974 NP435 mated to a Dana 21 T-Case. Shift lever vibrates in 4th gear at any speed (but I haven't had it over 55mph yet). Other than a little whine when in Neutral, the transmission acts normal. Shifts OK, no unusal noises when driving, just the 4th gear shifter vibrating. I have searched this site and other ford and 4x4 sites without finding anyone reporting this problem. Did find some reports of noises/vibrations (but not necessarily with the shift lever) with the NP435 in 3d gear, where the group think was not to worry about it. Does anyone have any experience / opinions on this issue?

Thanks!

[fordman]

how much does it vibrate? it could just be a worn mount or the motor isnt running right and so the motor is shaking also.

[fireguywtc]

mine has always vibrated a little but not enough to annoy me. 4th gear always seem to be a little loser then the others but that could be just me.

[heep70]

Never had any issues with mine. It will vibrate in forth if I am going to slow. take it up above 55mph and see what it does.

[heel&sole]

Thanks for all the advice! I will run it over 55 this weekend and see if it changes at all. Hard to describe how much it vibrates- makes me think it wants to jump out of gear, the shifter shakes more than any other truck I have had. Motor and tranny mounts looked good to me, although sometimes that can be deceptive from just eyeballing it when everything is mated up. Thanks everyone!

[fireguywtc]

Perhaps the problem is not the tranny, but maybe the balance of the drive shaft or a u-joint going out. Those maybe something you wouldn't notice until you get into 4th because you start spinning everything much faster.

[averagef250]

Good chance your D24 input bearings are worn out or you need center driveline U-joints or a new slip. Check your transfercase mounts as well.

Stick trannies never project symptoms greater in direct (4th) than any other gear, the problem is likely speed related and further down in the drivetrain.

Is it loud in the cab of the truck? When D24 bearings get sloppy they make the cab pretty loud at freeway speed.

[willowbilly3]

Get some of thet foam pipe insulation and slide over it, that might quiet it down. I'm sure there is something you can fix but it's an old truck and a little wear here and a little war there makes things a little loose. It might just be the shifter worn in the top of the tower. All you have to do is loosen the shift knob on any of these old trucks and it will rattle like crazy, which shows me the vibration is always there, it just takes something loose to make noise..

[mrtleavitt]

My truck does the exact same thing. '69 F100 swb. I used to have a NP 435 and the 4th gear would cause the shifter to rattle quite a bit. I replaced the tranny to gear up the truck with a freshly rebuilt T19, which is very similar to the NP 435 and it does the exact same thing. The engine is only about 4 years old, brand new drive shaft, u-joint good and centered in the yolks, brand new 3rd member with new gears, all my bearings are good, alignment on, tires have been balanced and re-balanced. I've given up on it! I just rest my hand on the shifter when I cruise on the freeway so it doesn't bother me. I'm thinking my tires may be cupped a bit so I'm eager to get some new ones on and see if that corrects it. Let me know if you find anything else out!

[fordman]

i drove a cabover white one time that had 6th gear messed up in it. some guy jambed the gearshift into gear real hard. so it poped out of gear when it ws driven. we used a bunge cord to hold it into gear on the highway. it was fast to get on and off. so it wasnt a big deal. but it worked the one time i drove it.

[heel&sole]

For those of you who chimed in on this problem or may experience something similar, I just wanted to post a little follow up that I am pretty sure the vibration is coming from the slip yoke. The vibration disappears above @45 mph, so it is only happening from 30-45 in 4th gear. The U-joints seem fairly new, so that is what I am thinking. I am working kind of slow on the truck because it is so cold, but I need to get it down to Raleigh to pass inspection so I can get it titled. I am confident that this problem will not affect my 375 mile round trip down there and back.