Bernardd Posted October 11, 2004 Share Posted October 11, 2004 Any of you tranny guys know enough about valve bodies to help out in trying to make a jatco auto into a full manual valve body (doesn't have to be full manual). I've found two company's in Australia that make 'em so I know it's possible. I need to make the 2-3 shift quicker. The engine revs up 500-1000 rpms during the 2-3 shift. Lower the boost and it shifts fine. Bernard Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted October 11, 2004 Share Posted October 11, 2004 The flare with added boost (added power) is due to clutch or band slippage. This slipping creates gobs of heat, which burns said clutches/band and a rebuild is soon needed. A shift kit may help by engaging the clutches more rapidly, thus not letting things slip as long, but if you are on the edge of not having enough clamping force to contain the power that your engine is developing, it is only a band-aid. Raising the line pressure can help alleviate the problem (some shift kits include mods to do this), as can physical modification of the transmission to include more clutches, bigger servos etc. for greater holding power. I'd seriously suggest finding a solution immediately--- slippage kills trannys .... Chances are that you already knew this stuff, but just in case... and sorry, I don't know the specific mods that your Jatco needs. I've been researching 200R-4's. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted October 11, 2004 Author Share Posted October 11, 2004 So far there is no indication that the oil has overheated after 4000 km's. The line pressure has been bumped up and some of the holes for the shift valves have been enlarged. I've also got a 17k lb rv trans cooler on it. The two places in Australia that make the valve mody into a full manual require or suggest that a larger servo piston be installed. I'll have to look into that. Bernard Quote Link to comment Share on other sites More sharing options...
A. G. Olphart Posted October 12, 2004 Share Posted October 12, 2004 Evidently your application isn't quite as critical as the 200R-4; the guys on http://www.turbobuick.com report that one good run with the tv cable maladjusted can kill a trans. However, those are approx. 3800 pound cars running 10-11 second quarters. Some even break into the 9's-- Here's a quote from one fellows sig: "Stage 1 3.8 engine w/GT76Q 9.98 at 140.18 With a 1.60 60 FT 10.80 at 131 on street tune" Good luck in your quest. Quote Link to comment Share on other sites More sharing options...
Bernardd Posted October 19, 2004 Author Share Posted October 19, 2004 I've found some trans shops in Australia that have made the jatco tranny withstand 500hp at the wheels. Full manual valve bodies as well as trans brake valve bodies are available along with the upgraded components needed inside. Websearch for Keas will get you to the website. I'll be removing the tranny in the next couple of weeks to see what is needed. Bernard Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted October 19, 2004 Share Posted October 19, 2004 Either hope that 240Z Turbo sees this post and chime in or contact him directly. He was running a modified JATCO down to 11.1, I believe, and would have gone quicker except for some convertor problems. He switched to a P-Glide and went 10.60s 1st time out. I am sure he will have good JATCO feedback for you from his experience. Quote Link to comment Share on other sites More sharing options...
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