Drivetrain Vibrations

[01001010]

Originally Posted by 01001010

So I've changed my RotoFlex to a Genuine one from DAP. While doing the job, I went ahead and lubed everything that had a grease nipple on it. The low speed vibes have been gone for a while now. But ever since I changed the rotoflex, ive had really pulsating vibes between 65 and 75 mph.

When doing the job, I couldn't find a comfortable enough position in order to torque and read the wrench. Because of this, I tightened them more than I was suppose to. Could over-tightened bolts be the culprit to the pulsating?

Since I'm on vacation, I decided to start working on the truck today (tomorrow there will be more dirty action).

I found the culprit of the vibes! ONE Loose STUB axle bolt on my rear right. This has been loose since the brake job!!! ANd I never noticed!

I took the wheel off and checked that the caliper bolts were tight, inspected the drive shaft at the Diff end, and as I was taking my head out of the wheel well, I get a top view of the stub axle flange and there it was, sticking out like a Jousting lance over a horse's shoulder, ONE bolt was halfway out!

I removed the bolt, inspected it, then removed the stub axle ot make sure of the condition of the teeth; all was perfect! I put the stub axle on and tighten all bolts to spec! I go on a test drive and WHAT YO DOU KNOW!!...Pulsating gone! Amazing what ONE! stinkin bolt can cause!

While this solves alot I still have a tiny prob...not sure if its a prob but its definately annoying.

When I'm accelerating or when im coasting to a stop, the rear of my truck sounds like a bike when you're not pedaling, moreso when I'm coasting to a stop. This has also been goin on since the RotoFlex swap.

[John C]

You might have snapped the crosspin inside the rear diff, just a thought.

[01001010]

Oh man! not good! Will a snapped crosspin still allow the diff to function atleast moderately?

I have been drouling over those Detroits and GBR/RT shafts for a while now

Hmm..I'll see if I can lift the truck now, put it in drive and see where the noise is commin from exactly.

Thanks for the prompt response John!

[SCSL]

As a side note, your initial post on this thread was the best job of describing various squeaks & vibes that I've yet seen on a board

[01001010]

Originally Posted by SCSL

As a side note, your initial post on this thread was the best job of describing various squeaks & vibes that I've yet seen on a board

LOL!!!... Thanks!

[John C]

JC, I've had two crosspins blow up on me. The first one lasted a few months: the pin broke but the spider gears stayed in place. The second one only lasted a few weeks. When the second one broke (my wife was driving the Disco) I had to lock the CDL and drive it home.

I'm not a big fan of diff lockers so I might just go the 4 pin route. While I'm at it I'll go to 4.11 gears.

Right now I'm running a stock diff and haven't broken the pin yet, might be because I am running the Simex tires and I don't have to "push" the truck so hard. Let's see what happens.

Try this, drain the oil from the rear diff, see if there are any shavings.... stick your finger into the drain hole and see if parts of the pin are sitting at the bottom of the diff.

The only other way of checking your rear diff is by removing it. A propshaft tool comes in handy for this type of work.

Good luck.

[01001010]

John, under what circumstances did the pins break on you? How did it happen?

[pickuprover]

Originally Posted by 01001010

While this solves alot I still have a tiny prob...not sure if its a prob but its definately annoying.

When I'm accelerating or when im coasting to a stop, the rear of my truck sounds like a bike when you're not pedaling, moreso when I'm coasting to a stop. This has also been goin on since the RotoFlex swap.

Not sure about the Disco rear axle.. but it does sound a little like when the pinion nut that holds the flange on and loads the bearings in a salsbury comes loose.... just a thought... check to see if you have any play latteraly where the drive shaft and diff meet.. once again, I am a series guy, but if the disco axle is anything like a salisbury, then I would check out that as well....

[John C]

Both times they broke after doing some rocky trails. At the moment I had 285/75/16 BFG ATs with HD rear axles (GB). I have a feeling the heavier tires and the HD axles might have contributed to the breakage. I have some pics of the busted pins somewhere on my PC. As soon as I find them I'll post them.

[01001010]

Thanks John! Hmm...I have slightly larger than stock MTs and stock axles that I've abused the hek out of in muddy situations and now with those vibrations I was having from the Stub Axle...it all seems to be falling into place.

[01001010]

Originally Posted by pickuprover

Not sure about the Disco rear axle.. but it does sound a little like when the pinion nut that holds the flange on and loads the bearings in a salsbury comes loose.... just a thought... check to see if you have any play latteraly where the drive shaft and diff meet.. once again, I am a series guy, but if the disco axle is anything like a salisbury, then I would check out that as well....

I just mentioned it in the RRC thread and thought I should update this thread as well for archive purposes...

Pickup, turns out you were the warmest! It was one of the bolts that holds the rotoflex to the diff flange. I guess I didnt tighten it enough and it came loose. It actually scretched out and due to the extra play it allowed for itself and the shaft, managed to wear out the metal on the flange itself. I'll post some pics of the bolt later and of teh flanage when I replace it.

Luckily and unfortunately, it wasnt my differential (I was really excited about getting that Detroit and GRB axles in there)

[01001010]

Here is the bolt after being loose for about 4 or 5 months. (please, no name calling...lol...I know I should have taken care of it earlier)...

Lesson learned.

[01001010]

And here is the damaged flange...

[01001010]

Ok, so I changed out my rotoflex, damaged flange, new bolts BUT I'm still getting a TINY TINY pulsating upwards of 30mph and fades away at around 70. I think it may be my tires since they are just now at about 50% tread. Since these are still my first EVER set of MTs, it could just be that I'm not used to the ride now that they are wearin out. But I can now make it to 100mph without having the truck feel like its about to fall apart.

[01001010]

Im thinkin its still something in the driveline...when I let my foot off the skinny, it feels smooth..back on, its pulsating again. Im boggled.