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I have a powerglide transmission that is behind a KB Olds 526 w/ a PSI roots 14/71 blower in an automatic promod car. It was working fine for all of last year and beginning of this year but now when it goes to shift the rpm spikes while driveshaft drops then it recovers but seems to upset the chassis after that. I was thinking it all started after we raised the pressure on the trans to 275 back in may?? But Im really not sure. I have a psi sensor on trans and the pressure looks crazy! I am not familair with what the psi graph should look like but I would bet its not like this. Highest reading I saw was 304 I think?? I have checked the linkage several times. Had trans out and looked at by the builder. Looked fine but still does it. I have it set to shift at 7600. rpm spikes to 8200. If I raise shift point spike goes higher. I tried shifting at 8200 - it spiked to 8700. Car weighes 2650 1.flat 60ft, 2.79 330' 4.27 @ 171 with this happening. Need help!!
 

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Try tightening the band adjustment 1/2 turn at a time till it goes away.........that usually does it...... you may have bent the band adjuster too.......
 

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Also if you're not using a type F fluid like Redline get some. That will reduce a 1-2 shift flare approx 300rpm if everything is good in the trans.
Any other type oil will allow a slip on the shift,especially with a lot of power behind the trans.
 

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Could be a few things , band settings , servo type,servo return spring, clutch clearance and system pressure. Raising pressure does not normally make the flare shift but it can happen. Could also be a problem in the pressure system causing a slow recovery of pressure after the shift command. Andy also brought up a good note about fluid type , they can be very touchy.


Hutch
 

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The 1st little wiggle on drive shaft before the spike is I believe the shift point. That is 7630 rpm the peak of the spike is 8300. I will try different fluid and also tightening the band 1/2 turn and see if it goes down.
Your log looks like mine after this past weekend. I accidentally bumped my transbrake button in first gear and now it flares before the shift. How did you fix this flare? I'm adjusting my band tonight and checking fluid levels. Just wonder if and how you fixed this.
 

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I have had this same problem for a while , even swapped trans builder to see if he was missing anything. Still have the problem and saw where tightening the band could help. Went from 3 1/2 to 3 on the band adjustment and saw very little if any improvement. How tight can you go before running into problems?
 

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Went to adjust my band last night. Bummed that there is not enough room between the transmission tunnel and the adjuster screw to fit a torque wrench. So I figure I would tighten it 1/2 turn and see if it helps. I went to loosen the jam nut and was surprised it was loose. So I turned it in half a turn and went to tighten the jam nut. Didn't put any pressure on it, didn't hear anything snap or pop, but the end of the adjuster screw just fell off with the jam nut on it. The adjuster screw broke off flush with the case. Since it was flush with the case I couldn't get a jam nut on it. Adjuster screw was to long to come out with the transmission in the car so now the trans is out and a new adjuster screw is installed. Trans is going back in tonight. Not sure why it would have broken off flush with the case.

 

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Wow, that's odd to break there. FYI, drill a small (3/8-1/2") hole in the tunnel directly across from the band bolt. That will allow you to stick a long allen wrench in the band adjuster from inside the car to make regular band adjustments. With a socket on the end you can use your torque wrench too.
 
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