45mph vibration / noise

Got a vibration / noise that starts around 40mph - mostly when under power (accelerating) - peaks at 45mph, and is mostly not noticeable by 50mph. It's still there if I coast back down through 50 to 40mph, but is less noticeable I think.

It's not an "every revolution" sound - it pulses slower than anything is actually turning. I haven't timed it exactly, but let's say at 45mph it's a "vvvvmp....vvvvmp...vvvvmp" maybe two "vvvvmps" per second.

Two weekends ago I put new Bilstein 5100s all around, with the front set to add about 1.5 inches of lift, and a Deaver add-a-leaf set in the back to raise it about the same.

Then I put in a diff drop kit to lower the front differential an inch to mitigate impact on the axles and boots and all that.

I thought it all went fairly well. A few days / miles later I went under and re-torqued all the nuts and bolts, and all was fine. Then took it in for an alignment. One spec was just very slightly out, and was adjusted. The guy who did the alignment works with 4x4s and lifts and stuff and said everything I had done looked ok to him. In other words, everything should be fine.

I drive it around now a lot with the radio off so I can listen for any problems, and I notice a pulsing vibration and sound that I am pretty sure is new. It could be observational: I'm listening closer now and notice something that has always been there, but I don't think so - and I can pretty clearly hear and feel it with the radio on, too.

The only thing I can think of is that after the drop, the differential is now very close to a frame crossmember, and that it is vibrating there. On my truck the cross member has a flange, so the spacers don't sit tight against the frame. See pic below. I called Toytec and described my drop install, and was assured it's fine.



Here's where the rear of the diff passes above the crossmember behind it:


But it's not touching - there's...an 1/8th-3/16th clearance, and it's all bolted on pretty rock solid.

I don't know what goes on inside the axle CV boots, but I'm worried that something I've done with the lift - even though it's a modest 1.5 inches, is causing the problem in there. I assume there's a reason Bilstein says don't go over 1.1 inches with my model.

I did some searching for "45mph vibration" and see several posts about u-joints... I guess I've changed the angles on that, so maybe caused a problem there? If so, what do I look for?

2003 Tundra SR5 4x4 access cab.

 

Id love to help on this one, if you're feeling a vibration it shouldn't be there and we all know vibrations wear things out. When you have a min give me a quick call and lets go over it.

801.635.4872

 

That is some GREAT customer service right there!!

 

Your diff arm is not fully connected. There should not be a gap between the spacer, top washer and arm.

 

Thanks for the offer - I’ll call when I get a decent break from work.

My 2003 looks different than the image you posted.

The ...flange under my frame, which prevents the spacer from tightening up against it, is solid and welded to the frame. As far as I can tell the OEM washer thing could also. Or possibly have been right against the frame either (but I didn’t think to take a “before” photo for reference).

 

The Toytec diff drop online is an 07+. Did they sell you the correct one?

 

Yes, indeed. I ended up talking to @Coachbuilder1 on the phone for a while, and he was very informative and helpful! Thanks!!

I might double check, but after the convo on the phone I'm going to pull the diff drop anyhow and put that back to stock. I'll report back with my findings.

 

Did ya ever find out?

 

Sorta, but not done yet.

Known things so far:

1) The box from ToyTec does indicate it is for a 00-06 (as well as other models/years) and when I talked to them on the phone and described my setup they said it sounded normal. But...

2) After the conversation with @Coachbuilder1 I removed the diff drop kit anyhow and the 45mph noise did indeed go away. Per his description, I think my CV boots / axles are still within a reasonable angle without the diff drop kit installed, so that's good. I didn't really lift my truck that much to necessitate it.

I haven't reported back yet, as promised, because I'm going to have a Toyota mechanic put it up on his lift and have a look, answer some of my questions, etc. I'd like to know what was causing the vibration, as well as a few other things. For one, the CV boots started leaking grease when I did the lift and diff drop, and haven't stopped.

Anyhow, I'll try to give a more full report after that meeting (next week). I've been a bit busy with other life stuff right now. ;-)

 

Toytec doesn't have your best interest in mind. They don't listen nor care about your problems.

It appears to me that there shouldn't be a gap between the frame and spacer. I would tighten it if possible but don't overtighten; there's no guarantee that's the correct bolt for this install.

 

Grasshopper is in this, as Sensei says, to learn.

 

I was going to suggest that your differential drop was probably unnecessary with the amount of lift, as well as possible carrier bearing drop might be necessary and/or replacement, as well as the U joints. But it looks like coachbuilder took care of you already. He knows his stuff.