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Sharkaholic
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Joined: May 2002
Posts: 5,162
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From: Rochester, WA
So, are you wondering what the stage-3 configuration would be like yet? 
Installing a "T" and check valve as described will make the shift softer, because the transmission will be slipping a more during the shifts. More slipping means more wear and more heat. It's basically like if someone had a 5-speed and was letting the clutch slip during shifts while doing a full throttle run. The modification will also give you a boost leak. Not a modification I'd recommend or do if it were my car.
Installing a "T" and check valve as described will make the shift softer, because the transmission will be slipping a more during the shifts. More slipping means more wear and more heat. It's basically like if someone had a 5-speed and was letting the clutch slip during shifts while doing a full throttle run. The modification will also give you a boost leak. Not a modification I'd recommend or do if it were my car.
The shift from 2nd-3rd @ 12psi boost can certainly create a tremendous amount of pucker factor... I can see the personal desire to enduce some slippage.
Race Car
Joined: Jan 2009
Posts: 4,665
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So, are you wondering what the stage-3 configuration would be like yet?
Installing a "T" and check valve as described will make the shift softer, because the transmission will be slipping a more during the shifts. More slipping means more wear and more heat. It's basically like if someone had a 5-speed and was letting the clutch slip during shifts while doing a full throttle run. The modification will also give you a boost leak. Not a modification I'd recommend or do if it were my car.
Installing a "T" and check valve as described will make the shift softer, because the transmission will be slipping a more during the shifts. More slipping means more wear and more heat. It's basically like if someone had a 5-speed and was letting the clutch slip during shifts while doing a full throttle run. The modification will also give you a boost leak. Not a modification I'd recommend or do if it were my car.
I was having very hard shifts, like chirping tires into 3rd plus I was having the car hit the limiter on the 2-3 shift and couldn't fix it with the bowden cable. It was driving me crazy and I was afraid something was going to break. If I adjusted the modulator valve down to compensate the hard shifts at WOT, the shifts were way to soft at part throttle. I ended up calling Steve Cattaneo and he told me that the Mercedes turbo diesel's with our transmission run this exact setup to bleed off boost to the modulator. He said with boost the modulator will increase the transmission line pressure and cause the issues I was describing. I put this valve in and it fixed everything.
As for the boost leak, it is only a 1/8" port. Compared to what a 5.0 32V engine eats at WOT the amount is probably .001%.
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Joined: Dec 2002
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I'd suggest using synthetic transmission fluid. There will still be increased wear from slipping, but the synthetic fluid is supposed to be able to handle the increased heat better.
Rear tires that aren't quite so sticky can give you some slippage to soften things up during the shift too.
You might be able to imagine what Todd's car is like with 30psi of boost and drag radials. There haven't been any problems with the stock and original automatic transmission that's in that car yet.
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Joined: Aug 2001
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From: Up Nort
He also runs a thicker fluid rated for an allison transmission.
