85NASTYZ28

Help! In addition to having a very fast and very quick 85 Z28, I have a 95 Lumina with a 3.4 DOHC six cylinder engine. When the tranny warms up, it down shifts from OD to third. This usually take about 5-20 minutes and wiil not shift int OD again. It shifts perfectly from 1 to 2 to 3. After it is shut off, It will shift normally again until it warms up. The code reads 740, TCC circuit. If anyone has had experience with a problem, please reply.

Since my last post, I have rebuilt my 383 stroker and had the trans rebuilt with a shift kit and has 3.42 gears with a Auburn (War Eagle) cone posi unit. It has pocket ported S/R tourqer heads and an Extreme Energy 284 camshaft. I donot recommend this cam unless you have a big converter, but, I have a rebuilt converter that has the same part number as an 85 corvett 700r4. It really lopes, but delivers power in spades.

About two weeks I had the extreme pleasure of kicking a 5 spped Mustang's booty, who was using nitrous. later that same night, I kicked the booty of a 78 trans am that has a GS 455 stage 1 cam and heads on it. Smoked both quite convincingly.

4L60bliss

Once that code sets, it will inhibit 4th gear operation.

I have seen to major things cause this to happen. First, the Drive Sprocket Support Bearings on these things suck. They like to fail, and they don't always make noise. It usually tears up the teflon seals causing loss of TCC. If you pull the pan and cut open the filter (de-crimp the edges w/ a pair of dikes and open the center up) and you see metal fragments and/or pieces of GREEN Teflon seal, then sounds like you found the culprit.

If all looks OK, then it may be the other common thing I see, the valvebody. Sonnax makes a kit to repair worn out bores, or you can just replace the valvebody.

Frankly, it could be something stupid like a TCC solenoid, but the first two things I listed are the most common that I see. Good luck.

85NASTYZ28

Thanks very much, I will change the fluid this weekend and inspect the filter. I believe you are correct. I hear a whining that I cannot explan. The car runs strong. The dropping out of od is very very annoying. War Eagle!!

4L60bliss

If you hear a whining noise, and suspect a drive sprocket support, here is how to tell: Start the car and let idle, you should hear it. Now put the car in gear, noise WILL go away. If the noise goes away, regardless of brake torquing or not, but makes noise again as you drive, then it sounds like the drive sprocket support. Pain in the rear to replace, because the bolts that hold it in place are behind the Torque Converter seal. But lets not "jump the gun". Cut open the filter and see what you see.

P.S. your pan gasket is reusable (unless its damaged or isn't stock), so all you need is a filter and 6 qts ATF.

85NASTYZ28

Thanks for the reply. The noise is the power steering pump. It is hard to diagnois a problem by long distance. Right after I received your message, I drove the car for about 5 miles. The transmission shifted perfectly. Let me give you some background. The tranny was rebuilt about 75K miles ago. When I got it back, the shift points for 4th and OD increased from 40 to about 50 mph. There is also a slight shudder sometimes when it goes into OD.
This is the real strange part: When night arrives it shifts correctly most of the time. also, during winter time it shifts very good. If i kick a passing gear, it won't go into OD again until it cools off for a while. My heart wants me to believe that it is a sensor or a switch, I bought the car new in June of '95. I really like it, but I would not buy another with the 3.4 in it. No problem with the engine other than some oil usage, which it has done since day one, about a quart between 3k oil changes. For a small engine, it hums down the road quite well.

Thanks again