So when I'm driving and I let off the gas and then gas it again there is a noticeable thud, like the driveline is picking up the slack. I'm not sure how to explain it better than this but hopefully you guys know what I mean.

What is worn out that causes this thudding when going from coasting to gassing?

88' 302 4x4, single cab, short bed.

 

Could be bad u joints.

 

Say you reverse out of a parking spot then put it in drive and go do you hear it?

 

Automatic or Manual ?

Grab a hold of the driveshaft close to the rear differential and give a few good yanks on it , Watch for the pinion flange/yoke to move , I'm thinking Pinion bearing , I would suspect a constant high speed vibration if it were u-joints

 

Could be u joints, but i had that same thudish clunking noise and it turned out to be my rear end went to crap

 

Its an automatic. Its mainly just giving it gas from a coast. All I can say is it feels like picking up slack, like somethings loose.


Tonight I'll check the driveshaft near the rear diff and see if there's movement.

I'm trying to work out all of the "weak spots" before I go into trying to get more power out of it or put a lift on it. I literally just picked this truck up in SW Virginia and drove it all the way home to MD. I changed the spark plugs last night, what a pain! Next up is the throttle position sensor tonight. I had a CEL pop up on drive back. Code 63, throttle position sensor low voltage...

 

Even if there is no wiggle at the Pinion flange the bearing could still be ok but the Ring and Pinion gears may be worn , especially if there's no delay or clunk noise when going from Park to Drive , I had that god aweful noise but didn't get to it before it ate the Pinion and bearing out , at 140,000 miles I just replaced the whole rearend and did the brakes and axle seals on the replacement before it went under the truck.

 

Maybe I should think about changing gear ratios sooner and this issue could be taken care of...

On that note, If I'm planning on eventually running around a 33" tire, what ratio should i switch to? If I'm opening up the rear-end, I'll definitely freshen up some other stuff too. I need to do some research...

 

I changed out that throttle position sensor today and It made a huge difference. Starts nicely and doesn't die when the throttle is lightly pressed. Drivability is money now (compared to before).

I think the issue is just driveline slop so I'm wondering the best way to tighten things up?

 

Tighten the u joints