HI folks, my 3rd member in my '93 standard cab 22re toyota pickup 4wd was howling, had it fixed at shop (bad bearing, they replaced everything else with what came in overhaul kit as well.) Now getting vibration I didn’t have before, used to be smooth. Now when I let off gas I feel shaking at maybe 20/25+ mph (no vibration when accelerating, at lower speeds anyway for sure), and it's worse at 70+ mph, and at steady speed w/gas then, also now if i let off gas and punch it again it causes a big kick in the pants after a pause as the power hits rear wheels, like it's winding up and kicking all the power wound up at once, pretty sure it used to just ramp up slow, and it just feels off now, out of sync, like an ellipse instead of circle, , like the different parts of powertrain aren’t all in sync / wonky. Shop says they marked driveshaft and put it back the same. They did also bleed rear brakes and add fresh fluid, brakes are better / less pedal travel now. No other changes. Taking it back to shop next week. Any ideas I can share with them to try? I've searched but couldn't find an exact situation where a vibration was caused after differential work that wasn't there before that was then solved. Thank you.

 

My personal recommendation is beforehand write down accurately each symptom, and know how to duplicate it. I also HIGHLY recommend when you drop off the vehicle you take someone from the facility on a test-drive so everyone is in agreement on the issues.
When dropping off the vehicle make sure the repair order is complete and accurate. Date, vin, license plate, mileage, etc.
Also make sure the paperwork clearly states the symptoms you noted; don't have them start writing down speculation at this point.. If during the test-drive with the employee they feel the vibration and start talking about the driveshaft that's fine, but make sure the paperwork just states the vibration. Don't let them put down "check driveshaft". The purpose of the test drive with you and the employee at the drop off appt. isn't to start the diagnostic process, it's simply a way to go ,"There! Feel that(hear that)? That's what I'm talking about!."

 

Thanks, good advice. This shop is actually just a guy I've known a long time and his son so not worried about being ran around about it really, he is saying all he did was pull the wheels and rebuild the 3rd member and that he marked the dshaft so doesn't see how he caused it, but I've been talking to him, I shared some other threads I've since found with some things to look for / examples of others who have had the same problem. It's possible it's something that was there all along but didn't become noticeable till the fixed he did (eg making the brakes better might be causing warped drums to become noticable etc.) I was mainly looking for things to share with him that might save him time troubleshooting. I'll share my notes below I had sent to him in case anyone can improve on them. Thanks much.

notes:

bottom line: didn't have any vibration before, now does, so something done during job caused (or revealed previously unnoticed) problem.

symptoms: no vib at low speed or under load / during acceleration at mid speed / eg 2nd gear high rpm, vibration starts at 25ish+ mph, worst at higher speed / 70+ mph in 4th gear , powertrain feels "off", like power is being delivered in an ellipse instead of a circle, also when letting off gas and then punching it it delivers a big whomp kick in the pants / like it's winding up and kicking out the power all at once where before it would smoothly slowly ramp up

summary of ideas:

* driveshaft / ujoints in phase? see phasing article towards end (try spinning half of the driveshaft 180° as a quick test / possible fix?)
* can drive in 4wd high with driveshaft pulled to confirm not a bad wheel etc.
* something loose? pinion nut etc., grease better / more? ("no load vibration usually from something being loose")
* could it be that bleeding rear brakes and making them grab better allowed untrue wheel drums to cause vib?

Phasing: (full article here http://www.4crawler.com/4x4/CheapTri....shtml#Phasing

Phasing is a term that describes the alignment of the single-cardan joints on opposite ends of the drive shaft. As discussed above, a single-cardan (or u-) joint does not rotate at a constant velocity if the operating angle is non-zero. The drive shaft speeds up and slows down slightly as it rotates due to the nature of the joint. One way to reduce this is to make sure the joints at each end of the drive shaft are aligned properly. If the yokes on each end of the shaft line up with each other, as seen indicated by the light blue line in the figure below:



Then the effect will be that the two joints will tend to cancel out the speed variations from each other. In most 4x4 applications, the drive shaft will have a slip yoke in the middle to allow for changes in length. If the shaft is ever taken apart, it is important to get it re-aligned properly when it is re-assembled. One way to do this is to mark both sides of the slip yoke. However, you should check that the joints really do align properly, don't assume they are. The reason for the phasing is that the speed variation of the joint is related to its operating angle and its angle of rotation. In order to get the most effective cancellation, the joint yokes *must* be aligned exactly with each other and the operating angles must be identical. Any variation in either angle will show up as uncanceled vibration. While unequal operating angles result in a vibration that increases with shaft RPM, phasing problems may be felt at lower RPMs and higher loads, like when accelerating from a stop.

Most driveshafts will have some sort of alignment mark stamped or painted on to indicate the proper orientation of the slip yoke. If there is none, they try lining up the u-joint end caps as close as possible. One trick that can sometimes help with phasing is to spin half of the driveshaft 180° before re-installing it to see if this makes any difference. Often one orientation may balance out better than the other. Once you find the proper alignment, paint a mark on both sides of the slip yoke so that you can get it back together correctly next time.



also from article...

• Vibrations at relatively high speeds are often due to balance problems.
  • These vibrations may come and go as speed increases as you move in and out of resonant frequencies of the drive shaft.
• Vibrations that get worse when transitioning from acceleration to coasting to deceleration, like when you back off the gas over the top of a hill and before you go into full on engine braking, may be due to loose or worn parts, like loose flange bolts, worn or over-extended slip yoke, etc.
  • A slip yoke typically consists of a male and female spline section that allows for the shaft length to change as the suspension moves.
  • The more the splines are pulled apart, the looser the fit will be. At some point, that may allow vibrations to "escape" from the shaft.
  • Lengthening the shaft is one solution or it may be possible to add a drive shaft spacer to extend the shaft.

 

Too much data, it's late and I'm not reading all this..

You've got axle wrap or your guy doesn't have the skills and experience to setup gears, it's not super difficult but it does require some specific tools. The first thing that comes to mind is the pinion lash.

What was includes in your kit they installed?

 

This is the kit
There was one other bearing needed, can't remember which one, I think he said it came in the kit but wasn't quite the right one so he bought a different one.

This is a real shop here, not a shade tree mechanic, he's ASE certified etc., that said I had read beforehand that it was a job that required high skill / preciseness and had asked him beforehand if he knew what he was doing and he said it wasn't his first rodeo so hoping it's not a skill issue.

 

Zip tie a camera to the frame pointing near the pinion end of the shaft, and video a short trip around the block or somewhere you know you've got enough room to reproduce this lurching. I expect you'll see it's shifting/rotating on the wheel axis.