So,since i purchased my 91 blaze last year its always done this. Overdrive/4th gear kicks in at exactly 52 mph. Soon as it goes below that it downshifts back into 3rd. Ive reset the detent cable a while back and it didnt help. Another issue i notice is when i stomp the gas at 45 mph to make it scoot it'll down shift,rev at 5500 rpm then decide to take off. Not sure if its a severe problem,since its always done it. although i also finished a pan and filter change a month ago which helped smooth the shifts. Do i actually have a problem or is it the nature of the beast? The erratic downshifting etc at 52 just gets annoying,especially when your behind someone going around 55 mph.



Point of the thread :

52 mph shift point erratic when in that area.
5500 rpm when i floor it around 45 mph


No chunks of metal on the pan magnet,just that light grey sludge which is normal.

 

Torque converter lockup is controlled by the ECM. That is adjustable.
Shift points are based off hydraulic line pressure(TV cable signal from throttle linkage) as well as the governor (I have not figured out exactly how yet). If you have low pressure or a valve spool that shifts harder than normal it will require a higher RPM(more fluid pressure) to shift.
How many miles are on the vehicle?

Are you 100% sure you are adjusting the TV cable correctly? I was adjusting mine wrong and transmission operation felt horrible. Even a new rebuild with a shift kit will not feel as good as a TV cable that is adjusted correctly. Not to mention make the transmission prone to failure. Judging by the fact that it's not blown yet would leave me to believe that your adjstment is pretty close though.

 

TZFBIRD is right and I went through a 4l60 a while back and when I put it back in it had the same problem with fourth gear only at 55 or above and it was the governor.

 

Out of curiosity did you have to do a spring/weight rebuild or was it the gear that got stripped? There isn't much that can go wrong with the governor.

 

The way i was told to adjust it was to push the white tab in,and slide the peg all the way in,then get inside the vehicle and press the gas down to the floor till it clicks.

blazer has 200k miles on it. trans shifts pretty good for what its been through. Just the annoying 52 mph overdrive,and the redlining when i floor it at a low rpm.

How can i get that plate off the governor housing? I tried on my old truck i had and never could get it off. I was afraid of damaging the housing.

 

I replaced the springs for the rear end gear ratio in the truck,because the tranny that came with the truck had the wrong governor springs in it.

 

You should be able to tap on it with a hammer and a piece of wood or use a prybar carefully

 

That is fine assuming your pedal moves the throttle to 100%. You can double check it by turning it by hand. That is the correct way to do it though. I did it wrong and lost 3rd+4th the first time I got on it. Which was about 30 miles after I just rebuilt it.