[hgiv]

When I tap the gas I get a clunk immediately. It isn't totally consistent but it's frequent and reproduceable. Kind of sounds like somebody tapping something lightly with a hammer. I notice it at low speeds if I tap the gas, probably because things are quiet. No noise or vibration during drive or acceleration after the initial sound.

I thought it might be motor mounts but they all look really good. Next guess was the u joint. I'm trying to test it. When I shift to reverse I get a linkage clunk (different) then when I go to neutral and then Drive I get a lesser clunk. I just don't know if that's what I'm looking for or if my results mean anything? Crap clunks.
How else can I test it?

["QUICK-SILVER"]

This a single 'clunk' or a tap tap tap?

Clay

[hgiv]

Originally Posted by "QUICK-SILVER"

This a single 'clunk' or a tap tap tap?

Clay

a single noise each time I tap the gas.

[400 Lemans]

Check your torque converter bolts.

["QUICK-SILVER"]

Originally Posted by hgiv

a single noise each time I tap the gas.

Is it the same in park/neutral as in drive?

Clay

[pfilean]

motor mount?

[vertigto]

Building on what Clay mentioned...tranny mount? I had a 86 TA that made a similar sound when it went.

[hgiv]

Originally Posted by "QUICK-SILVER"

Is it the same in park/neutral as in drive?

Clay

The initial shift out of park is an obvious linkage clunk, but then its different. Also how much play should there be if I grab on to the drive shaft right next to the u joint? My thought would be little or none? The rear side is solid but the front side has quite a bit of play.

["QUICK-SILVER"]

Originally Posted by hgiv

The initial shift out of park is an obvious linkage clunk, but then its different. Also how much play should there be if I grab on to the drive shaft right next to the u joint? My thought would be little or none? The rear side is solid but the front side has quite a bit of play.

Movement between the shaft and yoke says the joint is worn out or it's the wrong joint for the job.

Clay

[Schurkey]

Excess ring/pinion gear lash, or excess play in the spider/side gears, or excess play in the axle shaft splines/side gear splines can also "clunk".

But from the description given, the U-joint is "done".

[steve25]

Agreed, that front joint is shot.

When you drop the driveshaft out make a check of how much rock that front yoke has on the output shaft of the trans.

Slide it back & forth between the ware patterns seen on the yoke from the seal.

I have had a few cases where at the point of engagement between the yoke and the output shaft spend the most time that the yoke rocked around a good amount more then the average amount of play the yoke had elsewhere in its range of travel.

This made for a slight vibration once the new normally tight joint was installed.
The slop that the old joint had nulled out the ware in the yoke it would seem.

[Sirrotica]

If you're having trouble discerning whether a U joint is in the midst of failing, but can't produce any play in the joint, this is how I've had to find bad joints in the past.

Remove the driveshaft, and twist the U joints after removing the shaft from the car to find out if they are binding when swiveled on both axises. Many times you can not find a U joint that is bad by applying pressure with your hand. If the grease has just recently dried out, but the needles havent yet turned to dust, it can be difficult to see any play with it installed in the car. When remove you'll instantly feel the binding as you work the joint both ways.

In troubleshooting customer cars for many years you do sometimes run into some failures that haven't failed badly enough to cause obvious play.

To test a bad motor mount, open the hood and with the car in gear stab the gas with the brakes locked. You'll see the drivers side of the engine lift substantially if the mount is broken. With a stick you'd have to have the car rolling with the hood open, and stab the gas, same reaction, the engine will lift, and slam back down. Dragging the brakes slightly while rolling will help to load the engine further for testing.

From your description, the U joint sounds more probable.

The other points brought up are all possibilities, but these are the most common failures in most vehicles when you're getting a driveline clunk like you describe.

[hgiv]

Upon further inspection is seems like the slip yoke has some play side to side. It seems like the play is more on the tranny side than the u joint side. Although the u joint also looks tired. Again I assume there should be zero side to movement there. New yoke needed? How do I know the transmission isn't damaged?

["QUICK-SILVER"]

Originally Posted by hgiv

Upon further inspection is seems like the slip yoke has some play side to side. It seems like the play is more on the tranny side than the u joint side. Although the u joint also looks tired. Again I assume there should be zero side to movement there. New yoke needed? How do I know the transmission isn't damaged?

Yoke slides through a bushing in the tail shaft housing. The bushing is replaceable.

Clay

[hgiv]

Yeah I'm pretty sure that is my answer. I need to replace the bushing and seal. I'll probably do the u joint too while its all apart.

[Schurkey]

Measure the OD of the slip-yoke in several places--front, middle, rear. Make sure the slip-yoke isn't worn excessively.

[hgiv]

Originally Posted by Schurkey

Measure the OD of the slip-yoke in several places--front, middle, rear. Make sure the slip-yoke isn't worn excessively.

In my experience with this car... everything is excessively worn! Including me!!