Cruiserdrew
On the way there
Sounds like driveshaft to me. Either the angles are wrong or it's out of phase.
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Fresh 4.88 gear install, no I have issues
- Thread starter midfat
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^^^^this^^^^
The driveshafts needed to come off to do the gear install. They were likely separated and put back together incorrectly. Very common.
The driveshafts needed to come off to do the gear install. They were likely separated and put back together incorrectly. Very common.
Wow. I consistantly overestimate the work a professional shop ::should:: put out, and my expectations.
Heaven help the shop that gets stuck with my junk once I'm so old I give up doing my own wrenching.
fyi, this sounds EXACTLY like the problem I'm having with my 4.56 gears. Out of curiosity, do you have any driveline lash?
I have Icon stage 3 as well and have had this problem after the lift. When I step on the gas pedal it was fine and after I let go I would hear/feel the noise/vibration. I pulled my driveshaft initially to confirm. After I confirmed that it was the front driveshaft. I replaced it with a DC driveshaft. Then the noise/vibration went away. Cant comment on the regear part since I am on stock gears and 285's.
- Thread starter
- #26
I dropped it back at the shop this am. After a quick drive at freeway speeds, all were in agreement that something wasn't quite right. Great suggestions on the driveshaft phase. I'll pull that info out of the FSM and drop it at the shop Tuesday morning. Initial thoughts was that perhaps there was a rear axle pinion issue, but like I said, this shop is pretty well respected for gears. That said, they work on a lot more Jeeps and Fords than they do Yotas.
Cruiserdrew
On the way there
The rear pinion angle is a driveshaft issue. If the angle of the flange is not perfectly parallel to the transfer case output flange, the driveshaft will vibrate, often just off throttle. With 4.88s it's spinning faster and so tends to make things more noticeable.
Here is a cheap test. Load 400-500 pounds in the very back, enough to drop the rear several inches. If the vibe improves, it's almost a certainty that your pinion angle is wrong. (lowering the back tends to rotate the pinion down, lifting the truck rotates it up). You can fix the angle issue with adjustable upper control arms.
Here is a cheap test. Load 400-500 pounds in the very back, enough to drop the rear several inches. If the vibe improves, it's almost a certainty that your pinion angle is wrong. (lowering the back tends to rotate the pinion down, lifting the truck rotates it up). You can fix the angle issue with adjustable upper control arms.
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- #28
Just wanted to close this out should anyone crawl this thread in the future. It was indeed the front driveshaft. Pulled the front, locked the center diff and the sound vanished. My guy went ahead and ordered a new double cardan shaft before I could pull the trigger through a local vendor, but the important thing is that we resolved the issue. What threw me was that I've been driving the lifted rig for several months without any issue. It wasn't until the re-gear that these problems manifested. Funny things happen when you ask a lot of tired parts to start working harder and faster. I also went ahead and ordered a set of rear adjustable UCAs to correct the pinion angle. Thanks all for the fast responses and on-point diagnostics.
Okay sorry to highjack and please excause this stupid question. I have a very faint vibration coming from the front end anywhere from 70-80mph. So i was going to take out the front drive shaft and lock the center diff and drive it around and see if that was the problem.
Now this is where i get stupid/lazy. I unbolt the 8 bolts holding the front driveshaft on and i can't get the damn thing to come out. What am I missing? I didn't mess with it to long because it started snowing, I was cold, and didn't think it would be wise to drive the cruiser without the front driveshaft in on snow. But after taking all the bolts out should it just fall out or what am I missing? Very sorry for the very stupid question haha.
There is a raised ring on each end of the shaft that fits into a round hole on each flange. If this fit hasn't been disturbed in a long time they can be tough to get apart.
On the flange side lined up with the u-joint caps there should be a small recess against the flange face. Put a healthy screwdriver or pry bar in there and pull.. it should pop out without a ton of force. Don't keep prying once it pops loose.. the holes of the joint are tight on the studs of the xfer case output flange and if you misalign it too much you'll damage the studs.
On the flange side lined up with the u-joint caps there should be a small recess against the flange face. Put a healthy screwdriver or pry bar in there and pull.. it should pop out without a ton of force. Don't keep prying once it pops loose.. the holes of the joint are tight on the studs of the xfer case output flange and if you misalign it too much you'll damage the studs.
If the drive shaft was out of phase, all you had to do is flip it. Instead of using the witness marks, look at the rust patterns on the flange and match them up. More than likely you don't need the double cardan if it drove fine before gears.
Post #28. Four Responses above yours details the issue and solution
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- #34
Shop had the driveshaft out of phase. It was that simple. But a DC driveshaft was ordered anyway and that's what's on the rig today. Moral of the story, 90* makes all the difference in the wold.