IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => Transmissions => Topic started by: Scoobum on December 20 2014, 09:15:11 AM
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What are you guys doing on a rebuild to get more high gear apply pressure?
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Larger boost valve. The stock is a .471. I used a .500 which is a common 700r4 piece. There are also .555 and .570 pieces out there to really jack up the pressure. I have read about a .521 and a .530 but have never seen either for sale. You also need the 700 spring and I did a larger rev boost valve too.
Also setting the clutch up with a tight clearance is highly reccomended. I was told .007 per clutch which works out to .040-.050 for the whole stack. Juggling thicker steels and such can get you there. Some go to a thinner clutch/thinner steel to get more clutches in but I went with the stock count red clutches and thick steels to absorb the heat and a tight clearance to minimise the slip that generates the heat. The red raybestos stage 1 clutches for the direct were one of the things I spent extra on as I didn't want a 2-3 problem. I put Borg warner tans in the rest except the carbon band.
If you have a billet shaft forward drum dual feeding the direct is probably the best way to go.
David Husek or one of the gurus will surely have more info.
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http://realoldspower.prophpbb.com/topic3814.html (http://realoldspower.prophpbb.com/topic3814.html)
This guy has some good pix and advice for how he does one.
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Rich...thanks so much for the info. I have all the billet, hardened parts, 500 boost valve, billet servo and modded governor. I talked to a friend who's building these 200's a couple of weeks ago. Think I'm gonna give him the nod for mine. :)
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http://www.turbobuick.com/forums/threads/dual-feeding-directs-or-modified-direct-drum-with-extra-clutches.237080/ (http://www.turbobuick.com/forums/threads/dual-feeding-directs-or-modified-direct-drum-with-extra-clutches.237080/)
A little back n forth on dual feed.
I didn't do it but have looked at it extensively. If I had an extra coin or two I would have gotten the billet shaft forward drum and done it. "flipping the feed" on the rev and direct is another way but a lot of work when the dual feed is much easier for more force on the clutches.