I have yet to tear out my carrier and axles, but this is what happend to me last night.

I was driving around testing out the recent shift kit that tends to shift pretty hard even at part throttle. When I let the tranny shift from 2 to 3 without much gas, it shifts so hard that I hear a terribly loud clunk from the rear and the car actually jerks backwards.

The clunk has been getting worse and worse until last night it started to bang/clunk so bad that I decided to take it off the road and check out the rear.

Upon taking out the drive shaft and diff cover I noticed that there is considerable rotational yoke play in the pinion shaft. You can turn the yoke a little bit with out the tires turning at all. And when I turn the yoke I hear SOMETHING hit the housing and make the "clunk" sound I've been hearing.

Is there supposed to be any yoke play rotationally? I know if there is play side to side the bearings are shot. But what could be causing this clunk sound on the housing? Any ideas - thanks.

 

My idea would be, take off the cover and see where the slop is.

I'm betting it's going to be pinion bearings.

In fact, you might find that if you tighten up the pinion nut, you can fix it, at least temporarily. But if the nut is loose, it's a sure sign the bearings are toast; either as the cause of the looseness, or as a result.

 

The shift kit changed the 2-3 shift timing for the worse. The backwards jerk is being caused by being in both 2nd & 3rd at the same time, which locks up the trans. Need to either push off the 2/4 band quicker, or delay the application of the 3/4 clutch packs. I'd try to get the 2/4 band to push off quicker.

RBob.

 

Thanks for the replies everyone.

How would you delay the 2/4 apply? Or for that matter the 3/4 clutches - just increase the clearnace?

 

Don't need to delay the 2/4 band apply, it is already engaged in 2nd. Need to push it off, or dis-engage it, quicker when the 2-3 shift occurs. As for how to do it I'd say that some of the shift kit modifications will be to be backed out or changed. Not knowing what was done I can't make any recommendations.

What is happening is that while the trans is in 2nd the 2/4 band is applied. During the upshift to 3rd the 2/4 band is dis-engaged at the same time the 3/4 clutch packs are applied. The timing of these two events is critical.

If the 2/4 band dis-engages too slowly, or the 3/4 clutches apply too quickly, then a bind-up happens. The loser in this battle will be the 3/4 clutch packs as they self-destruct.

On the other hand, if the 2/4 band dis-engages too quickly, or the 3/4 clutch packs apply too slowly, then the engine RPM flairs up in the middle of the shift. Again, the 3/4 clutch packs self destruct from the slippage and heat.

RBob.

 

Last night I tore the rear apart and found a backlash of .012. So I put another shim in on the left side of the carrier making 0.08 backlash. I also tightened up the pinion nut.

The clunk has gone away although the gears are whining a little bit louder.

Also I moved the TV adjuster a few clicks out so the shifts aren't QUITE as hard at part throttle.

 

I keep having this bang problem -The rear has been apart 2 times now - 0.006 backlash and about 17in-lbs preload with tons of red loctite on the pinion nut - I think it must be what Rbob is suggesting - the 2/4 is not letting off soon enough or the 3/4 is applying too early thanks to the Transgo shift kit.

Could I fix this at least temporarily by removing one or two of the washers in the servo pin? ie making the 2/4 band looser? Or do I need to dive into the tranny and drill/plug some holes in the seperator plate?