Rumble on deceleration

[BlazinNewTrails]

Ok, I've searched the archives and I don't see a ready answer to my problem...
I noticed before I installed the 4" lift (truck previously had a 2 1/2" Rancho lift) That when making a sharp right turn, the left front corner(hub or stub?) seemed to make a couple little "pops".
After installing the lift (I left the shims from the 2 1/2" kit under thenew leaf springs) the popping seems to have gone away??? In it's place is a "rumble" in the front left corner (I think) when coasting.
The truck drives great, makes the tiniest vibration while accelerating up to about 20mph then goes away, makes no noise while accelerating, doesn't rattle or sound loose when going over bumps, I've shook that tire while in the air and there is no obvious bearing/ball joint slop...

I know I need to install shims under the rear springs because they haven't been corrected for the lift and the rear driveline has a bit of angle on it, but the front angle looks good.

Help???

 

[Waxer]

Check your frame for cracks near the steering box. Check all 4 sides of the frame (top, bottom, left and right sides) for potential cracks near the gearbox.

Been there done that

 

[4X4HIGH]

Driveline noises can travel. It is my guess that you have a bad angle on the rear shaft that needs to be fixed before you go any further with searching for other things that may be causing your noise and vibration. Usually a 2 1/2" lift won't give any problems but a 4" and larger lift usually will. On a short wheel base vehicle like the blazer it is almost impossible to get the correct pinion angle and u-joint working angle without going to a C/V style driveline.

 

[zakk]

also check the front shackles. mine made a "pop" noise when turning because they were getting spider cracks in them and flexxing /forums/images/graemlins/eek.gif

 

[BlazinNewTrails]

Thanks guys.
I think I'll start with the rear shims because I know that angle looks a little excessive (and shims are cheap!) then I may have to lower the T-case, I hate to do that since getting the T-case off the ground was one of the reasons for raising the rig in the first place.

I appreciate the suggestions guys, time to get greasy!

 

[blazer88k5]

I had the exact same rumble on my 88 after I installed a 4" lift. Drove me crazy!!! After some advice from here I put the t-case spacers, took 20 min by myself and the rumble was gone!

Now I have a question.... what is the "shim" for. I have blocks in the rear..... Do I need shims?? /forums/images/graemlins/1zhelp.gif

Thanks Randy

 

[BlazinNewTrails]

The shims I'm refering to are degree shims. They are placed between the block and axle to tip the pinion up slightly towards the t-case. It helps reduce the angle at the u-joint. They are very cheap (under $10).
If the frame around the steering box looks good, I'll try them before lowering my t-case and see what happens to my noise, if it's still there I'll try lowering the t-case a little too.