Can’t find any answer for trans problem.

chromebumpers

solid fixture here in the forum
Staff member
I’ve been looking for a long time all through the internet, maybe I‘m not describing accurately enough. This is about a 2004 Savana cargo van with all-wheel drive and 5.3 ltr. With 89,000 miles - it has a mild vibration or shudder that occurs pretty much exactly at 47 mph and stops at about 53 to 55 mph. I bought this stuff called Trans Medic in these small Red plastic tubes I was going to pour in with a trans fluid change I’ll be doing soon.
I don’t have a clue what to look at. No OBDII fault codes, Fluid change? Additives? Years ago I upgraded to the new van wheel size of 17” from 16s. The tires are good, what could it be? Is there any GM automatic trans forums?
 

rlphvac

solid fixture here in the forum
LOL makes 2 of us Rich I hate it when things that can't be hard turn into the hardest thing you ever did
 

rlphvac

solid fixture here in the forum
I'm still looking for the post office thing and have the GF and daughter looking out for it
 

Grumpy

The Grumpy Grease Monkey mechanical engineer.
Staff member
sounds like ball joints or bushings wear, the suspension can reach a certain speed rhythmic vibration and it builds/ amplifies until you get above or below the speed it occurs at.
this is rather frequently aggravated with one or more tires marginally out of true round or marginally out of balance or both.
yeah Im sure you checked the tire balance by now:nodding::wondering:
yeah, it might only happen when cruising or accelerating slowly or braking.
 

chromebumpers

solid fixture here in the forum
Staff member
I just rotated the tires, checked the u joints, measured the drive shaft against a laser beam, rotated and measured down the beam to the shaft. All looks good.

It only shudders under power/acceleration.
 
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