~Stingray

Hey Guys,

I spoke to the original owner of the 1980 vette and he said that he never changed the tranny fluild. I have had it since 2011 and have not changed it, I think it is time, just to be safe.

I have never done this before so a detailed step-by-step would be helpful and all tips and suggestions are welcome. Tools needed, parts to get, jack up on side of the car so it pours out better, etc. I did a search but all I saw was for newer corvettes and discussions about using ATF or not.

And should I do the diff at the same time or separately?

Thanks.

Alan 71

Hi S,
What year is your car?
Do you have the Chassis Service Manual for it?
In the 71 CSM in the Transmission Section there's a 10 step guide to Draining and Refilling the Transmission'. It section 7-45.
The guide for doing the job begins with; "Raise car on a hoist or place it on jack stands…." and ending with " check fluid level with selector lever in park, engine running, and vehicle on a level surface".
It also lists the parts that need to be replaced… o-ring, filter, pan gasket, and amount of fluid.
Good Luck!
Regards,
Alan

~Stingray

1980. I have a factory service manual. Not sure what distinguishes a chassis manual from just a regular one.

Alan 71

Hi S,
It appears the early manuals used at the dealerships were called Chassis Service Manuals, and the later manuals were called Shop Manuals.
Is this what you have?
Have you looked carefully through the automatic transmission section for the instructions on changing the transmission fluid?
Regards,
Alan

~Stingray

I will have to look at what I have again. I don't recognize that cover.
Mine is a manual by the way.

Mr D.

Here is a link

https://www.corvetteforum.com/forums...id-change.html

~Stingray

I did read through this earlier. But I wanted to make sure there wasn't something different to worry about for the manual. I know there is no torque converter so a flush is not needed.

Mr D.

there is no torque converter ?

jlpskydive

By this do you mean it has a clutch and you change gears with your right hand?? If you do, you do not have any transmission fluid in the car you have gear oil and it's pretty simple to change that. You might be looking in the wrong part of the book at this point. FYI

jlpskydive

If it's a 5 or 4 speed manual car, it's TOTALLY different and you need to look at a different section of the book. Now with that being said some 4 and 5 speed cars use ATF in the gear box, but I don't think yours is one of them.

mark79,80

I also have a 1980 with a 4 speed. The transmission takes 80-90 weight gear oil. It is very simple to change:

Raise the car up so that it is level.
Un-screw the drain plug on the lower side of the transmission to drain the fluid.
Reinstall the drain plug.
Remove the fill plug.
Fill with gear oil until it reaches the bottom of the fill plug opening.
Replace the fill plug.

~Stingray

I thought that was an auto thing. Am I mistaken?

~Stingray

Its a 4 speed.

jlpskydive

That's good news and see Mark's post above, really a simple procedure with the 4 speed.

Alan 71

Hi,
I was thinking... automatic transmission because aft was mentioned in the first post.
The service information for the 4-speed indicates SAE 80 gear lube.
Regards,
Alan

~Stingray

Sorry to have confused you. I was reading online that many people put ATF in a manual. And even some companies to it today. So I wasn't sure if it applied today, well, back then rather.

Mr D.

Oh crap we been following along as if this was a Auto trans.

Changing the gear lube out in a 4-Speed is just hitting the easy button. Pull the fill plug than the drain plug and refill with approved gear lube.

I would not use AFT in a Corvette manual transmission.

ZZZZZZ

As Mark 78 79 said. I would just add to have the car as level as possible. Because the gear oil will not be to the desired level if the front is jacked up in the air when you fill it.

gguillot

Hi Stingray,

I changed mine recently in my '72. Here's what I did:

1. Run the car for a while to get tranny oil nice and warm.
2. Jack it up in the front and rear enough to get under there with some tools and a drain pan.
3. I removed both the fill plug and the drain plug with a good quality, large crescent wrench - an open ended 9/16 wrench will also work (did on mine, anyway) but you'll need a large tool with some leverage to get those plugs loose.
4. Let all of the old oil drain out of the tranny case - give it some time.
5. Clean off your drain and fill plugs and reinstall the drain plug and snug it down.
6. I purchased Sta-Lube 80-90w GL4 gear oil (2 qts) from Napa for my tranny. https://www.napaonline.com/en/p/SLRSL24229 Also, I had to call ahead and get them to get two quarts from the warehouse for me to pick up. They only had the gallon jug in the store, and I didn't need that much.
7. You'll need some method to pump the gear oil up into the tranny fill hole - Napa sells a cheap little siphon pump you can use - I had one on hand already, so I don't know the part number. Just ask the counter guy.
8. Pump the oil into the tranny until it starts to run out of the fill hole. It will take about a quart and a half.
9. Snug down both fill and drain plugs.
10. Wipe everything down, remove the car off the jackstands.
11. Have a nice cold beverage.

7T1vette

What he said... Only thing I would suggest is that you install a good quality synthetic gear oil, instead of organic stuff. The gearbox is a bunch of working gears/bushings/bearing/shafts/etc. The better lube those 'sliding' parts have, the longer it will last. Synthetic lube is SOOOooo much better than the regular stuff, you just shouldn't put the stuff specified in a 40 year-old manual in it.