possible drivshaft/tranny clunk/maintenance FAQ?

[semlin]

ok, the two recent posts on drive shaft clunks have great wisdom worthy of a FAQ but they are way too long and disjointed. submitted for your approval is an attempt to consolidate it.

here are a few bits of wisdom distilled from them and other threads (keep in mind I have stolen most of this from others on this board much wiser than me). Others please chime in and see if we can sort it out into a FAQ.

1. first figure out if your clunk occurs during a gear shift or on acceleration/decelleration unrelated to a shift. This helps isolate it to the tranny or the drive train. If you only get it when going in or out of gear when parked it could be either I guess. Also pay attention to where it is coming from. If it is coming from the front or rear axles then a lot of what follows is moot and you might want to just post a thread.

GEAR SHIFT CLUNK

2. if it's a gear shifting issue while driving, especially a clunky downshift when braking at slow speeds, then a throttle cable adjustment is the first step. This is a very easy job described in the FSM at the beginning of the transmission section. This link by randy farnsworth tells you how to do it on the 442 from (93-94) http://www.ih8mud.com/tech/80throttle.php but it is similar on the others. Make sure the cable receiver itself is properly aligned. This is a 1/4 banana job requiring a 12 mm wrench and 2 minutes that can make a surprising difference.

3. Next, check the tranny and transfer case fluids. top up, drain or flush the tranny fluid (using a low pressure flusher that uses the trucks own pump) and replace (you can use synthetic if you want). Top up or drain the gear oil in the transfer case (again synthetic can be used). This will probably not fix a bad clunk but its worth a try and good maintenance.

4. if that doesn't work and you are sure it is a gear shift issue, post a thread and explain the problem. There are complex diagnostic procedures in the FSM for figuring out shifting problems with the tranny. Major problems are rare but there have been issues with solenoids in the 442 that are fairly easy to fix.

ACCELERATION/DECELERATION CLUNK

5. If you get a clunk when you accelerate or brake that is not associated with a gear shift, chances are it is somewhere in the drive shaft.

6. Checking the transfer case oil level and condition is a good start. Occasionally people find ATF in there by mistake. Also check the front and rear axle diff oil levels and top up or change if required. This is also a good time to make sure your diff breathers are not blocked up.

7. next lube the u-joints but do not lube the drive shafts themselves even though there is a zirc to do this. Also check for play in the u-joints yanking the drive shaft at either end hard in all directions. If you can get a wiggle going you should replace the u-joint. The OEM Toyota u-joint is pricey, but much preferable to aftermarket and usually fails only if it has been allowed to run dry. Replacing a u-joint yourself requires dropping the drive shaft and a c-clamp or similar.

8. Lubing in the drive shaft zirc arguably still does not lube the splines that allow the shaft to slide in and out but too much lube in there can cause unacceptable loading and damage to the t-case or diffs. Instead, drop the drive shafts from the diff ends and separate the drive shafts into two parts at the spline (be sure to make match marks before you separate). clean the spline and receiver area for spline (there may be a lot of built up hardened grease in there) and then lube the spline and reassemble. This is a ½ banana job requiring you to undo 8 bolts (although you have to remember to loosen from the bolt side, not the nut, because the nuts are friction locking and can wear out)

9. Check if the drive shafts are in proper "phase". The alignment u-joint arms at either end of the driveshaft should be the same on the rear drive shaft, but at a 90 degree angle on the front drive shaft (e.g., "--" and "--" on the rear, and "[" and "--" on the front). This can apparently cause vibration or other stuff. I just noticed that my front drive shaft was out of phase. It has been for at least 18 months when I had it straightened.

10. next check for play in the u-joints. wiggle them up and down and see iof there is play.

11. still got a problem? Post a thread and describe the symptoms.

[cruiserdan]

Possible wear at the front axle drive flange/stubshaft interface. The flange wears first but in extreme cases the stubshaft (birfield) splines are also worn to a point that replacing just the drive flange will not be enough.

This was partially addressed when the stubshaft was lengthened in April 1994 production but can still be an issue if left un-addressed long enough.

[Safado]

Originally Posted by semlin

9. Check if the drive shafts are in proper "phase". The alignment u-joint arms at either end of the driveshaft should be the same on the rear drive shaft, but at a 90 degree angle on the front drive shaft (e.g., "--" and "--" on the rear, and "[" and "--" on the front). This can apparently cause vibration or other stuff. I just noticed that my front drive shaft was out of phase. It has been for at least 18 months when I had it straightened.

Here's my contribution....for phasing, just refer to this picture and check yours out. Look at how the yokes are oriented. Also, keep in mind that if you have a lifted truck, this will rotate the diffs out of their normal plane and can introduce vibration depencing on how much lift you have.

[nakman]

Good call, Semlin.. I'll help with the bibliography:

-overview of greasing/lubing the driveshafts, followed by a brief discussion of spline orientation can be found here
http://forum.ih8mud.com/80-series-tech/21559-driveline-thump-cunk-when-stopping-starting.html

-An even better discussion of how to properly lubricate your driveshaft, including what you’ll find once it’s taken apart and the risks of over-lubing can be found here: http://forum.ih8mud.com/80-series-tech/20022-updated-warning-greasing-rear-drive-shaft.html

-the “driveline woes” post, 3 full pages of driveshaft discussion glory. Beginning with a lesson on higher education, a discussion of what is “in phase,” some confusion about what is “in phase,” and a fun trick with sockets can be found here
http://forum.ih8mud.com/80-series-tech/22067-driveshaft-woes.html

-Some light is shed on the effort required to properly assemble a U-joint here: http://forum.ih8mud.com/80-series-tech/19836-need-more-help-narrowing-down-vibration.html