Question. In automatic transmissions, how low must the fluid level be before it makes a difference? 1/4 qt. low? 1/2 qt. low?

I added 1/4 to 1/3 of a quart of ATF, and, it seems fine, knock on wood. It had been slipping. The level on the dipstick is now "full".

Thanks
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Director Of Entertainment/ Recreation
Dipstick Street Rod Association
Lower Susquehanna Chapter

I my experiance 1 to 1 1/2 qts. It depends on your trans pans capacity.
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WPoC

Bob i would be looking at the filter and seeing if it might be pulling some air. Check to make sure there are not 2 o rings in place. 1/4 of a quart doesnt sound right.
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"An intelligent man is sometimes forced to be drunk to spend time with his fools."

I have to agree with Mike on this. A fraction of a quart should not make a difference per se.
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Steve "Jack'Stands" Jack

Thanks guys. Good ideas. It's wierd, because it hasn't acted up lately. I'm concerned because it had been slipping. I just want to make a few more shows this year before tearing the car apart. I will look at some of the things that were suggested here. Thanks!
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Director Of Entertainment/ Recreation
Dipstick Street Rod Association
Lower Susquehanna Chapter

If its a G.M. 350 or 400 your referring to and you have no external leaks pull the vacumn line off at the modulator valve and see if transmission fluid drips out of it. If so change out the modulator diaphragm assembly and retest your transmission. One bolt to remove the modulator and you dont have to drain the pan. Try changing oil and filter next.

Is this the original dipstick and tube? If it is an aftermarket,you might want to check the calibration on the stick to be sure it is accurate. In other words,when it says "full" it IS full. Just one of those little things you run into from time to time............
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A wise monkey,never monkey's with another monkey's monkey.

About 15 years ago I had my one and only run in with a blown vacuum modulator valve...It was a '65 Greenbriar Van ( Corvair) and I wondered why I had to keep adding tranny fluid to it about once a month...An old friend of mine that retired from working on trannys told me to change the valve as he had seen it before..The one redeeming feature on tranny fluid in small amounts is that carbon doesn't get a chance to stick to anything!! In fact he suggested an annual engine clean out using tranny fluid in the carb and then letting it sit over night and most all of the carbon gets blown out..problem is that if yur not on good terms with yur neighbors, they'll call the fire department from all the smoke......I found it's much better to run some Marvel Mystery oil thru the motor...works on the air tools too!! lol
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Fred P.