Before I did the lift job on the Highboy I was noticing that there was a shudder developing when accelerating. I thought I broke some parts when I towed a 30" cedar tree with the truck in 4 low. I assumed (you know what assume does for ya) that it was from pinion angle and worn springs wrapping. Well long story short it wasn't. After the lift job it was still shuddering. In fact it might have been a tad worse. It doesn't show up unless I am at half throttle or above. Now...if I pin the pedal to the wood the shudder goes away. THIS didn't make sense to me at all. Tonight I went searching for this issue and found some interesting things.

I checked the drive lines for worn U-joints...nothing...all were good
I checked the pinion bearings for play...nothing...tight.
I checked the input and output on the t-case....all good.
I checked the splines on the drivelines. I found a minimal amount of rotational play on all of them.
I checked the trans mount..it was slightly weather checked...but still good.

I then moved to the engine mounts. !!!!!!????!!! BOTH of them were freaking falling out! There is a 1/2 inch bolt that goes thru the frame portion of the mount. This bolt would spin by hand in both mounts. Being that this frame mount is slotted it was allowing the engine to torque up and down. CRAPPOLA! So I tightened them up and started the truck.. Now when I rev the engine....it rocks the whole truck around. Makes a difference with the engine is tied to the frame!! I took it for a drive and the shudder is much less. I also found that the transfer case mounts are a tad worn and weather cracked.

Anyone have an opinion on the transfer case movement. I used a large prybar and I can shift the trans case about 1/8 left to right and there is some vertical movement. I am thinking that I need to have that trans case totally tight....what says ya'll? I am assuming that if the transfer case can shift to the side that it will play hell on the u-joints. As for the slip yokes having play...that could make for a little shudder too. I am going to have some new drive lines fabbed up soon with bigger yokes and splines.

By the way....the divorced transfer case used on the highboy.....does it have a chain? I don't know..or is it gears?

Cheers
Bill

 

the transfer case should be a gear driven np205, and im pretty sure the 1/8" moving with the prybar is just the mounts flexing... if everything were completely solid mounted things would break more often from metal fatigue, thats why mounts are rubber

 

hey ford man,
have you considered the clutch.
maybe a warped flywheel or a worn clutch.
just a thought.

 

Cool ...thanks. I was thinking that the aluminum case married transfer cases were the chain drive models. Seemed to me that the old heavy cast iron boxes were gear drive.

I agree about the slight movement issue. I don't think that the little bit of movement is going to make for much shudder. The gear stick for the transfer case does have some vibration when running down the road. That also doesn't surprise me as I suspect that those are some chunky gears in that case.

I would guess that the little bit of shudder that remains is prolly from the worn slip yokes on those puny little drive lines. I am going to pump some really thick sticky grease in them and see if it quiets them down any.

To answer Farm's question: it is an auto tranny not a stick so looking for clutch issues isn't it. And Yeah if it was a clutch that would be a good call...but I am going to spend a while looking for my clutch..heh

Thanks
Bill