Just fixed driveline vibration!!!For free!

Thats the same place I measured from. You should only see maybe 3 deg difference bw those two points as the rear end is tilted about 5 deg and the TC angles down about 2 deg for a difference of 3 deg. Thats what I see on mine. But really none of that matters. Its the angles of the shafts attached to those two that were dealing with, and the CB u joint.

 

thanks. so many guides keep saying to measure the rear diff angle. But that leads me to beleive that it is being measured against the TC. What you're saying is that the TC nor the rear diff need to be measured at all.

1)Zero on the TC
2)Measure front shaft
3)Measure rear shaft

That's only 2 measurements. And your 3rd angle (CB) doesn't need to be measured since it's the difference between those first 2 measurements.

Am I correct?

 

I appreciate hearing about success! I've tried to impress on people the need to do this correctly, but I don't think I have reached many. Most want a simple one size fits all answer, and there isn't one. There is no reason for anyone to have a rear end vibration. It is all fixable, and in most cases, very easily. In your case just an 1/8" shim. That is why sloppy measurements, flawed methodology, or random parts swapping rarely ever works. You end up just moving the vibration to different speeds, but you haven't corrected anything really. Oh well, I've explained it as best I can. It's there for whoever wants it.

 

What was interesting is that I first tried a 1/4" spacer- like the ome size, but my best angles came from just half that! The 1/4 " spacer was just as bad as nothing... Droid angle finder app is not the most precise, but it at least gave me a means of comparing what spacing worked best.

 

Answer embedded in bold:

 

Mismatch could be from bent springs or sagging trans mount....really doubt it was bad from factory. Wasn't there a trans mount tsb out there for early 2nd gens?

 

You mean all this time & all the trucks I've re-sprung (with random parts of course) & using 3/4" high spacers to drop the carrier & the fact that everyone of them have rolled out of my garage(usually with 3" + lift) with no vibe issues is just dumbass luck I guess, great write up tho', lots of specs...

 

Yeah, Lots of things can cause the pinion to be out of alignment with TC. That's why the first step is to check it.

I've done some experimenting with my truck and found some interesting things. First off, not every misalignment results in a vibration bad enough that you can feel it. Just because you can't feel it doesn't mean it isn't there. It could still shorten component life and have other adverse effects. Then in some circumstances very small changes can be felt. Much of it depends on whether the misalignment results in a harmonic effect. Harmonics can magnify seemingly small effects. Many factors figure in, but there is one truth. A properly balanced and aligned driveline in good mechanical condition will not vibrate. That is always true. That's where we need to get.

 

can someone tell me what the proper angles are for the TC and the rear diff so I can check to see if one of those is the culprit? I guess zero-ing the angle finder on the frame of the vehicle and then measuring those 2 things would give me something to go by...

there is a 19 degree difference between the 2 so I'm starting to think I have much bigger issues that just driveshaft vibes

 

I'm starting to think that the take off shutter MAY have nothing to do with the drive angles. Especially since some people have said they got it on a new stock truck. But as far as I know I didnt have it before I put the deaver 3 pk on which raised it another 1.5" ove the TSB springs (but maybe it was there just barely cause now I'm looking for it when I take off). My pinion and TC are only 2.5 degrees off and the CB is like 0.7 degrees and I dont get any other vibes whatsoever up to 90mph?? Also as I said before the stock prerunner had the pinion at zero and the CB at 4 deg opposite the trans? I wish I would've taken measurements when it was stock, but I plan on doing a full set of measurements on a stock 4x4 DC as soon as I can.

 

Zeroing on the frame is useless. What I did before I really knew what I was doing was 0 on level then take measurements on everything. It will give you a bunch of reference #'s and you can do the math to get the angles on the U joints. I'll repeat - it showed the TC angled down 2 degrees and the rear end (pinion) tilted up 5 degrees. So if I understand what your saying you should only see 3 degrees difference. Now I think your getting confused because what badger is saying is you need to get the relative angles(on the U joints) from the TC and the Pinion to be the same but opposite from each other. Then if you have the middle or CB u joint close to zero you should be good. Thats it. My problem is I'll need shims on the axel or All pro 3" leaf pack to do that, because I believe if I were to lift it higher in the rear I would see that happen. My theory is if you lift it 3-4" then all you will need is a CB shim because the pinion angle will increase to the point where it will cancel out with the TC output angle.

 

yah but I'm no longer so concerned about the vibes. Now I'm trying to find out if I have a major issue with TC or rear diff. They are 19 degrees apart which could be +10 and -9 but those angles seem kind of huge from what I'm used to reading around here

 

I'm sorry but that's impossible. Maybe you could take pictures showing the readings on the guage on those components. Zero it on one (make sure it shows 0 then move it over to the other and lets see what it says)

 

I will do that tonight.

and then you will tell me my angle finder is broken...

 

Something has gotten confused. If you were off 19 degrees your Ujoint would probably snap the instant you tried to move. That is really huge. Way beyond the operating range of a Ujoint. Pictures would help.

 

When you guys talk about "take off shudder." this sounds an awful lot like axle wrap.. which would be separate unto itself from vibration i would think, just a guess

 

Ok I just measured again> this time i showed the rear end tilted up 4.25 deg and the TC tilted down almost 2.75 deg so now i get only about 1.5 difference. Then I jacked the bed of the truck up 1.5". When I did this the angle off the pinion increased to 4.5 deg. (thats within 1 deg of the TC angle). That proves my theory that if you have close to 3.5" lift you would only need a CB shim to get the CB to near zero and your good. When I brought it back down the pinion angle was 2.75 deg. (over 2 deg difference from the TC). Slightly different #'s than I got before but same result essentially. So a 2 deg shim is what I need.

 

Oh BTW when I lifted my 99 tacoma I had none of these issues. I never needed anything so I never measured anything dumb luck as you put it (doesn't mean it was right just didn't give me any trouble). The 1st gens were much more tolerant, I got to try a 2 deg shim or just fogetaboutit for now and go big down the road. I have the stock UCA's up front so I'm limited there. As my neighbor with the Ford F350 with 8" lift and 40" tires says "Go BIG or go home"

 

I re-measured my angles:

TC shaft: 2.1 down
pinion shaft: 4.8 down

my rear diff is 3.5 higher than the TC. Isn't that strange? Since what I've been reading about hear is that, if anything, you might need to use shims to raise the rear diff to match the angle of the TC. In my case I would have to put the shims in backwards to lower it to match the TC...

 

yes thats what I would have to do as well for the u joint angles to match and cancel each other out, but if I were to make a illustration the #'s be quite a bit different than that? I dont see 19 degrees? So you got it now? How much lift are you running?