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Discussion Starter #1
Hi
I drive every day. The gears shift excellently the problem is above 80 mph speed when downshifting there is a blow that is heard from behind.
ABS lamp on
Could it be that this is causing problems in the gearbox?
I connected a fault scanner No faults in the gearbox.
I checked chalk oil has full but is very black
 

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Can I ask a silly question.... why in the world are you downshifting at 80 mph when the RPM would be in the 3500-4K range? This is BEFORE downshifting...
 

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Very black oil, regardless of transmission type, needs you to take action. If the transmission is a manual, you’ll need a fully synthetic GL4 (NOT GL5) fluid such as Redline D4ATF or MTL. If it’s an automatic transmission, you need to determine the manufacturer. If the oil pan has smooth side the transmission was made by GM. It takes Dexron3 or Dexron6. If the oil pan has ribs the transmission was made by ZF, it needs a fluid made by Pentosin. Regardless of which automatic transmission is in the car, the filter needs to be changed after you’ve drained the old fluid.

Be advised that you’ll need to remove the FILL plug first as if you drain the fluid and can’t get the fill plug out you’re screwed.
 

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Can I ask a silly question.... why in the world are you downshifting at 80 mph when the RPM would be in the 3500-4K range? This is BEFORE downshifting...
I was gonna guesstimate that it's the final UP shift, or gearing down for hard braking- at the track?

OP, if it's an automatic, (and guessing it is, since you scanned it)
engine faults can make it shift poorly, too, especially faults that
would cause the trans computer to not know how much torque the engine was
making.

all I got,
t
 
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