"thunk" on take-off

[EZdoesit]

Re: \"thunk\" on take-off

I had the exact same thing happening with my truck, I thought it might be the tranny mount, I got under the truck and stuck a big prybar under the tranny to see if the mount was loose and it wouldn't budge, but I couldn't see anything else that could be causing the problem.

I decided to go ahead and replace the tranny mount anyway, when I jacked up the tranny and unbolted the mount I found that the rubber part of the mount had completely seperated from the metal part, I put the new mount in and it the clunk went away. I guess the weight of the tranny was enough to make it look okay without having a load on it, but it was definitely shot.

87 K5 "rusty but trusty"

 

[1986Blazer]

Re: \"thunk\" on take-off

Just to throw my input in....

On my K5 I have a similar problem, I thought about all sorts of solutions then while installing my nerf bars I saw the factory rubber bushings in my leaf springs were cracked and parts were missing. I jacked up the rear by the frame and was able to move the axle a few fractions of an inch forward and back. The problem was the entire rearend slid forward when I came to a stop and it would slid backward when I gave the truck a little bit of gas (a little more gas than slow and normal acceleration). Check the bushings - it may be that simple.

I have not replaced mine, I am waiting for my 4" lift with all new springs.

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So I says to him, I said, "get your own monkey."
1986 K5, 350 GM Crate, 700R4, NP208

 

[muddin4fun]

Re: \"thunk\" on take-off

I would think it's a t-case or tranny mount. Is it like a real heavy sound?

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[Philly87]

Re: \"thunk\" on take-off

I had some clunking noises coming from the rear of my K5 at one point as well. It seemed to do it worse in reverse when I would back it into the driveway. Everything looked O.K. so I decided to check my u-bolts. Come to find out they were loose so I cranked down on em and it stopped the noise. Just something you may want to check. Things tend to loosen up with time.

Philip

 

[Philly87]

Re: \"thunk\" on take-off

I had some clunking noises coming from the rear of my K5 at one point as well. It seemed to do it worse in reverse when I would back it into the driveway. Everything looked O.K. so I decided to check my u-bolts. Come to find out they were loose so I cranked down on em and it stopped the noise. Just something you may want to check. Things tend to loosen up with time.

Philip

 

[MudFrog]

Re: \"thunk\" on take-off

Happened to me and my tranny mount was toast. Replaced it and all was well. What it was is when I started off with decent throttle my transfer case would raise up an inch or so (due to the tranny mount) then slam down on my tcase skid plate. You might want to check that out.

89 K5 Silverado, 4", 33's, 3/4 ton axles
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