Transmission fluid change

I need to change the fluid and filter in my 1976 corvette.
I called the local stealership and by the time they are done with materials, fluid,
labour, and taxes, it is around $350. They wanted over $80 for a
filter and gasket! Corvette Central - $12.95 or so...
I did some research on the web, and it is pretty straightforward from what I see, aside from the torque converter. Drilling a hole in the torque converter is not advised. The best way (aside from using a special flushing machine) appears to be:
1- remove tranny cover and replace gasket and filter, clean it all up and replace 2- top up fluid 3- remove one end of tranny coolant hose and put it into a bucket 4- start car, run thru gears on tranny, and drain out approx 1 quart 5- shut off car, refill transmission
repeat steps 4- 5 until the fluid coming out is the same colour as what you are pouring in.
In terms of the fluid, mine takes Dextron III. Apparently higher numbers are all compatible with the lower ones. ie I could use Dextron V. Best not to mix though. You get added benefits with the improvements in the newer mixtures if you upgrade. And more by going to a synthetic.
Now - before I proceed, I got this off the web and I am no expert. So does anyone have anything to add to this? Things I should not do? Errors or mis- understandings I may have in this?
TIA.
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No biggie but before I change transmission fluid I stick a strong magnet to the pan for a few trips. All of the critters stuck to it when I remove the pan always amazes me.
I also clamp a steel straight edge in the vise and true up the gasket surface and put very light coat of Indian gasket dope on it to position the gasket. Then put in all bolts to snug it up, then tighten equally all around until they are a bit more than just snug, don't over tighten.
https://www.rockauto.com/catalog/x,carcode,1041051,parttype,8600 Filter kit, $5.97 Fram, with gasket. Check second image for correct fit. Also just for ha ha's while you're under there I would change the vacuum modulator and hose $16.13. Why, because sometimes the o-ring, diaphragm, and/or hose will leak and make your transmission shift funny.
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Couple of good suggestions there for sure - especially the magnet one. Never would have thought of that. I'll check on-line and in my manual for the modulator valve and hose description/picture and where to find said beasts. I already have the gasket and filter in hand from Corvette Central.
Another suggestion someone made was to replace the old gasket and filter after cleaning the pan, refill with fluid, run, and drain to get all of the converter fluid out... then install new gasket and filter and new fluid again.
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well - on the basis of what I have read and inputs, I think I will adopt the drop the pan, drain, clean filter, button it up and fill, run, and drain again, then put on new gasket and filter, and refill. I will probably be too lazy to do it all again next year, so may as well try to do it well this time around. If I can find a big magnet to fix to the pan ahead of time to trap any debris I will do that too, and maybe swap out the modulator valve and the hose while I am at it. Just depends on my time.
The next item to be determined is: do I stick with the current Dexron III or move to something like a synthetic that are supposed to have superior properties?
What's the opinion on that one?
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Bowser wrote:

Stick with the original fluid. It has the right amount of "slipperiness."
-- pj
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..
Yes - thanks. I think I will do exactly that.
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m...
One other maybe dumb question before I tackle this.
When they talk of cycling thru the gears - do they actually mean the wheels must be rotating (ie car off the ramps or rear wheels in the air), or do they simply mean with foot on the brake put it in 1-3 and reverse & park?
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One other maybe dumb question before I tackle this.
When they talk of cycling thru the gears - do they actually mean the wheels must be rotating (ie car off the ramps or rear wheels in the air), or do they simply mean with foot on the brake put it in 1-3 and reverse & park?
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Stationary with you foot on the brake. Not a good idea to run your Corvette through the gears with the rear wheels off the ground unless they are supported as they would be while setting on the ground. When you have a good fluid level take it for a short drive and recheck hot.
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com...
Thanks - I found a video on youtube with some more clues. I am going out to get enough dexron III today to do the job tomorrow since it is supposed to be rainy here.
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s.com...
Just thought I would report in since people here were good enough to lend a hand - thanks!
I went ahead and just drained and changed the fluid, gasket, and the filter in the transmission. I had forgotten that a fair bit of fluid was exchanged when I put the recored radiator and new rad support in a few weeks back. I replaced it all with Dexron III.
The stuff that was in there was a brownish-red color and sort of cloudy. It did not smell of burning though. The filter was relatively clean with only a few bits of debris and no metal filings or anything of that nature at all.
I need to get another bolt just a tad longer as one is not making proper purchase over some of the things it holds in place and there is a cable with an end disconnected that I have to check and see if it is in the service manual. I think it is some sort of safety interlock mechanism - not sure. Somehow over the years and one of the servicing I had it in for, it seems to have been left off. Once I get that done tomorrow, I can roll her off the ramps and properly check the level and try her out.
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Also after driving a week, go under and snug all the pan bolts. That new gasket will lose its initial tension somewhat.
Vito

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