Clunking noise???

[1981 ss chevy]

My 81 stepside makes a clunking noise when im driving over bumps or when pull into a driveway thats on a slope or a small angle.  It sounds like its under the floor board on the driver side but it varies sometimes.  Its not my exhaust and all the crossmember bolts are tight my shocks are loose.  Anybody got any ideas??

[Layne]

my shocks are loose. ?

That may be it. or is that a typo?

[hotrodpc]

I would want to rule out broken trans mount if I were you.

[Irish_Alley]

also if none of the others check out could be a broken spring

[Lt.Del]

hotrodpc may have hit it.  I used to have a noise when turning sharply.  Come to find out the rubber trans mount insulator was broken and the trans moved when the truck turned suddenly and the driveshaft yoke was hitting the cat converter heat shield.

[Blazin]

If not that I would check the cab mounts.

[1981 ss chevy]

i when the truck is in park on a slope and not running i can rock the truck and it makes that noise too now i noticed, and where are the tranny mounts at??

[Lt.Del]

tranny  mounts are in the crossmember under the tranny...it keeps the tranny in place.  There are only two points that hold the tranny in place, the engine block and the crossmember. There are two rubber insulator things that two 9/16" (or is it 5/8"...dont' remember) bolts bolt into them to keep them still.  The rubber sometimes breaks and it becomes free floating=not good.

[ccz145a]

Mine had that sound when the upper control arm bolts came loose and All the shims fell out.

[1981 ss chevy]

but if it was my tranny mounts wouldnt it only make noise when i was giving it gas or taking off hard? i mean im gonna check them anyway but im just wondering

[Lt.Del]

The way you elaborated on the noise since my original post makes me steer a little away from that. But, it is a very simple check.  Get under the truck and grab hold to the trans tail and try to move it up, down sideways.  You'll know if the mounts are broke.

Check suspension parts as mentioned.  Check shock mounts....the nuts may come loose.  Check exhaust line for knocking. Check engine mounts.  It should be easy to diagnose if you spend a little time on your back.

[1981 ss chevy]

will do i gotta wait til tomorrow its to chilly outside here i need to invest in a heated shop haha but ill check tomorrow and ill let you know thanks

[hotrodpc]

Reason I suggested Trans mount is you said the noise is coming from the floorboard and you know its not exhaust etc. As Sgt says, just get under the truck, and push up on the tail of the trans, or push it to either side. You'll know if its broke. Sometimes its even evident without pusing on it, it will be half off the mount in some cases. If thats not it, then do check your suspension bushings as suggested.

[1981 ss chevy]

i checked the tranny and all suspension its all tight in working order im just stumped now anymore suggestions??

[hotrodpc]

Noises like that will play tricks on you. And you said you are certain its not exhaust pipes? And its a clunk coming from under the truck when you slow down or go over a bump? How about U jonits or carrier bearing if its got a 2 piece driveline?