Drive Shaft Vibrations Solved Step-by-Step

Yet another edit 07/24/13: This PM I sent makes perfect sense and saves alot of time, but it's the result of pages and pages of learning from this post. The answer you seek may be here in this edit quote. If this doesn't mean a darn thing to you, then, well, read on through these pages.

Quote:
Originally Posted by someguywithaquestion:
Nice explanation---very concise. One thing is a little unclear to me--Are we gauging everything off the transmission flange as it is relatively fixed? So, when I go to measure my angles, I start with the tool on the tranny flange and zero the tool? That being the baseline? When an angle is described as up or down is it up or down from the transmission flange? Thanks for a great post. Unquote.

Response: Good questions! sooo..... yes, everything pretty much starts at the trans / txfr flange. Stick a metal bar against the flange, press the side of your gauge against the bar, and zero out the gauge. This becomes "zero" angle. Aha. Gauge is technically measuring a vertical angle, the up and down angle of that first flange. Then, when you press the top of the gauge against subsequent drive shafts (keeping the gauge in the same orientation is important), you are measuring up or down from the "zero" trans flange. Crawl under there and look at it this way: the trans flange is zero, and the drive shaft obviously drops "down" from the trans flange.

If you have a two piece drive shaft, the two halves of the shaft may drop either down OR up RELATIVE to one another (not to the trans flange now, but to each other): a straight line would have the same angles; the second shaft may drop DOWN steeper than the first shaft; or UP at a shallower angle than the first shaft.

Now we get to that darn pinion at the rear axle. We're now measuring the rear pinion flange, and comparing it to either the trans flange for overall measurements, or more specifically to the second half rear drive shaft component. Most people get success quicker by setting the rear pinion flange just a tad (tenths of a degree) down from the drive shaft, which would be up from the trans flange. If you can follow Osugoose's explanation, he did a nice job of laying it out in theory and practice.

********All these angles depend a ton on your suspension choices and the amount of warp in your drive system, so no one can just give you numbers, but in general: trans flange is zero; drive shaft in as straight a line as possible; rear pinion flange just a tad below straight line created by drive shaft. How much below depends on stiffness of leaf springs: sloppy leafs, lower down (a degree or two); stiffer leafs, closer to zero (a tenth or two).********

+-+-+-+-+-Super quick fix: ignore the trans angle; measure the drive shaft parts and adjust carrier bearing (CB shims) to get everything in as nearly a perfect straight line as possible; measure rear pinion flange and rear drive shaft to adjust rear pinion (leaf spring shims) based on leaf spring stiffness, see above."+-+-+-+-+

end of edit 07/24/13



Edit again: way too many pages and posts to get right to the point for those of us looking for instant answers, but TONS of fantastic experience here shared by all users! Latest advice from several mechanics quite familiar with lifts, all with years of Toyota experience: They ALL say to tilt the rear pinion UP so that it points directly at the second rear-most half of your drive shaft, as perfectly direct as you can get it. For those with angle gauges, zero your gauge on the second half drive shaft, just in front of the pinion (or thereabouts, not crucial), then, using a small flat bar (metal 6" file works great), place flat bar against rear pinion flange and, keeping your gauge at the same orientation as when you measured off the drive shaft, measure the rear pinion flange. You want to read 90deg, indicating that the long line of the drive shaft is perpendicular 90deg to the short line angle of the pinion flange and thus your rear pinion is perfectly pointing physically slightly up and now directly at your rear half shaft. After a lift, this will require you to use leaf spring shims between your axle and leaf springs, usually with the SKINNY END OF THE SHIM WEDGE FORWARD, held down by your u-bolts. Get the shims with slots, not holes, so you only have to loosen your u-bolts enough to slide the shims in and out without losing the orientation of your leaf spring pack centering bolt nicely snugged into that hole in your flat axle bracket. (depending on your lift, the first time you install leaf shims you may need to remove your leaf pack centering bolt and replace it with a longer bolt that usually comes with your new shim kit. Use mega good clamps on your leaf pack to make the job of removing / replacing that bolt easier (think of dropping a loose deck of cards on the ground, leaf springs everywhere really sucks). How big of a shim? Damn good question, read this full thread to answer that one better. Then, the next adjustment is to DROP your carrier bearing. Using your angle gauge, zero on the first half drive shaft, before the carrier bearing, then measure the second half drive shaft. You want to get those two drive shafts as perfectly in line as possible, in other words, your two measurements want to be as close to the same number as possible. After a lift, this will require you to lower your carrier bearing using shims on the two carrier bearing bolts until you get the two measured numbers to match. This will of course mess with your first adjustment back at the rear pinion, but not by too terribly much so usually doesn't matter. The general consensus now is that this arrangement will most quickly fix vibe issues, yet does put a bit more stress on your u-joints over time (decades), and if you're good and take your Toy off-road enough to flex your suspension you'll lube your u-joints nicely and won't have any short or long term problems (come on honey, I HAVE to go to the desert this weekend, I need to lube my drive shaft u-joints to keep my truck safe for taking you out to dinner next week !!!!!! ). And if all this makes absolutely NO sense, just as I was sooooo completely clueless (wtf is a pinion, I thought that was called a differential? what's a flange? ouput shaft? what the fuck is a pre-runner? where's the transfer case? what do you mean you only have 2-wheel drive? huh? etc, when I started this thread, so please read on. By the time you get to the last page and latest posts, this edit will make perfectly crystal clear sense and you too will be a Taco drive line expert!


Edit: read this first post for info, but get the Wixey gauge not the Harbor Freight, and measure off the u-joint flanges themselves not the transfer case or rear differential case. I was wrong, and have better pictures and instructions a few posts down, along with a nice pdf form to print out and drag under the truck with you. Also, it seems if you purchased a complete front and rear lift from the same manufacturer you probably don't have vibes, it's those of us who've mixed and matched that are experiencing hassles. And check out how to loose pin your rear leafs on page four, makes a huge difference. Alohas!

Driveshaft Vibrations Solved Step-by-Step

So I think I finally have this figured out. Driveline vibration is a matter of harmonics, meaning materials vibrating at certain frequencies, like a guitar string. And like a guitar string, when things are “in tune” everything is fine, but when things are “out of tune”, they really suck. Such as a driveline out of tune, for instance. The vibration we’ve all been experiencing is due to the different components of our drive system all vibrating at different frequencies, or doubling up on each other’s frequencies, or in any other way just really sucking. The trick is to tune the driveline components to each other. There is no “do THIS and all is cured” as each of us have different setups. However, the steps you should go through to fix the problem are universal. I'm failing at posting in-line photos, so you'll have to follow along with the attached pictures for clarification. Check this out.

1. Buy yourself an angle finder. I got mine at a local Harbor Freight for around $40. You absolutely cannot, ever, figure this stuff out without one. (photo #1)

2. Measure your current driveshaft angles. You’ll use (4) points to measure from, to get (3) measurement numbers.

a. Zero your angle gauge against the back of the transfer case, up to the right (under the truck facing forward) against that nice flat place with the two holes. (photo #2 and photo #3)

b. Measure your first driveshaft angle by placing the gauge underneath the first driveshaft, keeping clear of any mud, stickers, etc. My gauge is magnetic so I flipped it over and hung it upside down. I messed with it a bit to get it perfectly in line with the driveshaft and perfectly underneath (by perfectly I mean I randomly wiggled it around until it came up with the most consistent number). This is your first measurement of three, write it down somewhere, and represents the angle of the first shaft as it comes out of your transfer case. (photo #4)

c. Take your next measurement underneath the rear (second half) of your driveshaft, after the carrier bearing. I took mine next to the rear differential, again keeping clear of stickers, weights, etc, and wiggling it until I had a consistent reading. This is your second of three measurements, write it down, and represents the angle of your rear half driveshaft as it relates again to the transfer case. (photo #5)

d. For the third and final measurement, you’ll need to re-calibrate your angle gauge. On mine, I left the gauge where it was, hanging by its magnets under the rear driveshaft, and pressed and released the Calibrate button a few times until the gauge, when hanging under the rear driveshaft, read zero. (photo #6) Then locate the nice flat area up against your rear axle housing, next to the rear differential case. Make sure it’s fairly free of mud etc. (photo #7) Then place your gauge (after zero-ing it out on the rear driveshaft) up against this flat part of your rear axle. I found a nice spot just above the molded line (in red) and next to the diff housing bolts (tip of arrow). This is your third and final measurement, write it down also, and represents the angle at which your rear driveshaft comes out of your rear differential. (photo #8)


3. NOW comes the fun.

4. Start with your third and final measurement. Everyone says this should be less than 3degrees, and I agree. When I started, my measurement was 6degrees, so I purchased a set of 4degree shims from ToyTec for $30 (part #RS10473). I could have gone with 3degree shims, or even 2degree shims, but whatever. I didn’t know what I was doing, so I figured go big. Turns out it probably didn’t matter what degree shims I got, as the fine tuning occurs in the carrier bearing anyway. Install pointy end forward, doesn’t matter which side is up or down AS LONG AS BOTH LEAF SHIMS ARE INSTALLED THE SAME WAY. (photo #9) My measurement before shimming was 6degrees, after was 0.1 degrees. How the f*ck you go from 6degrees to almost 0degrees with a 4degree shim I’ll never figure, so in hindsight I should have stuck with the 3degree shims from ToyTec like everyone kept telling me. Again, not a deal breaker.

5. Once your rear leaf shims are installed, it’s time to mess with the carrier bearing. Ideally you want the front half driveshaft angle (your 1st measurement) and your rear half driveshaft angle (your 2nd measurement) to be fairly close to each other. My measurements before were 5.7degrees first half and 7.8degrees second half. After installing an 8mm carrier bearing shim from ToyTec (part #FK29) for around $12, my measurements were 6.9degrees first, 6.7degrees second. Perfect, I thought. Wrong.

6. Now for the secret to this whole mess. Following everyone’s advice, I lined up my driveshaft angles to match each other almost perfectly, 6.9 first, 6.8 second, and 0.2 third. Everything was darn near perfectly in line from transfer case back, and wow did my driveline vibration still suck. WTF I asked. After a few days of messing around, I figured out the whole harmonic thing (back to guitar string crap), and by installing various and sundry different washers, chewing gum, rocks alongside the roadway, a flattened soda can, etc, under the carrier bearing to adjust it up or down, I was finding HUGE differences in vibration. Speed, intensity, etc. Only by messing around with cheap washers from my local hardware store (total of $6 invested) did I come up with the magic combination for my truck of a single 3mm square washer as a carrier bearing drop spacer. (photo #10) There’s no possible way of knowing in advance exactly what combination will work for your truck, but a few bucks worth of washers, a socket wrench, and a few times pulling over roadside to crawl under and add / remove washers made a huge difference in drive-ability and really opened my eyes to how frickin’ impossible that would have been to know in advance. Cheap solution, took about 1/2hr driving around with a pocket full of washers, and my truck screams like a dream. Your setup might require a thicker spacer, in which case there are tons of suppliers available on-line or locally. I wouldn’t recommend a 3/4” thick stack of washers, better to purchase a nice sturdy metal block.



Summary:

• get angle finder
• zero (re-calibrate) angle finder against transfer case
• measure under first half driveshaft for first measured angle
• measure under second half driveshaft for second measured angle
• without moving angle finder, zero (re-calibrate) under second half driveshaft
• measure against rear axle housing, next to rear diff case, for third measured angle
• purchase and install rear leaf shims to get third angle under 3degrees
• purchase and mess with hand full of cheap washers under carrier bearing until:
  • difference between first and second measured angles is close to zero
  • vibrations are gone (magic dude, magic…….)
• finalize carrier bearing shim (get a real one, use washers, whatever)

I know that the U-joints need some semblance of angle offset to keep spinning and keep lubed, so my 5.2 to 6.1 angle between the two halves of the driveshaft are fine. Not too happy the rear diff angle only being 0.1 degrees (again, should have gotten that damn 3degree shim instead of the 4degree), but I figure that’s just more incentive to stomp on it from a dead start (axle wrap), jump it more often (scare the crap out of myself), and load it up with more weight (extra, uh… soda pop for the weekend expeditions…..).

I’m sure your mileage may vary, and I expect some kickback from true mechanics, but I do know this worked on three different rigs I’ve messed with so far, so I hope my experience helps you save some time, money, and tons of frustration.

Alohas!

 

Well done, well written. Excellent post.

Repped. Enjoy the many green boxes.

 

darn, forgot one last photo attachment, summarizes drive shaft angles. thanx to the guy who posted this diagram, helps tons!

 

sub'd

 

What kind of rear leaf pack are you running?? I counted 10 leaf springs. Is that right?

Either way thanks for the write up

 

Looks like deaver

 

Better yet, get rid of the stupid carrier bearing and get a one piece driveshaft made. Why toyota thought it was necessary to use a two piece driveshaft on a truck with such a short wheelbase is beyond me

 

Would this work on a Prerunner as mine has the 2 piece driveshaft?

 

pretty much

 

Maybe Toyota tsb will be just that.

 

Have you considered any variation in the x axis of the carrier bearing?

I used a chalk line to line them up, and then set my pinion angle equal to my t-case and tried to get my carrier bearing u-joint near a 0* angle.

I'm also not sure that measuring off the housing as compared to measuring off the yokes/flanges/ujoints will yield reliable measurements. It could but unless you've compared to see I wouldn't count on it.

 

impressive dedication and unique thinking. awesome write up man! almost makes me wish I had to problem just so I could feel all bad-ass fixing it!

 

is 0.1 degrees at the rear diff in relations to the shaft coming out of it or the transfer case? I know you zeroed the angle finder on the shaft coming out of the diff so it does seem like it's is in relation to the shaft.

 

This is correct. Your pinion and Tcase angles are cancelling. I used a string line to locate my CB.

 

I measured off the yokes though, used shims to rotate the pinion to match the t-case angle and then used the line to line up the carrier bearing joint on the x axis (left to right).


I'm just not certain measuring from the bottom of the t-case or off the axle housing will give correct angle readings.

 

Awesome thread, good job OP, i will be refering back to this in the near future.

 

Yea, I understand, that's why I agreed with your method. I wouldn't use the axle housing either. Should be good, but I don't know. I used the yoke as well. The location indicated by the OP for the Tcase measurement (with the two holes) is good though.

You can use a string tied to the pinion zerk and stretched tight up to the Tcase zerk to align the CB left to right. You just lay directly under the CB and align those center zerks to the string. It's very accurate and simple.

 

Alright, sorry, just clarifying.

Good tips on the zerk though, I made it a lot harder.

You work on class 8s right?

 

Interesting

good thread OP

 

I'm just impressed that you thought to do it. It's usually overlooked.

No, the class 8's must be someone else.