I have a 89 turbo and I filled up the tranny with an oil that doesn't support syncros. I then started to notice a vibrating sound after a few days. Started with 4th gear now 5th does it too. I drained the old stuff and put royal purple in. Only 2 quarts. Now it still does it after a day..I did it yesterday. Did I mess up my tranny or is it still fixable?

 

Sorry to double post but also could it be my drive shaft? I've searched for wrong oil in tranny vibration but nothing. I've had some weird things go on in past that's similar to a bad drive shaft.

 

Doesn't support syncros?

Vibration like that typically is not a transmission issue. As you suspect, I'd check the driveshaft. If the joints are just a little loose you may only see vibration in higher gears at higher speeds.

 

What do you mean by "doesn't support synchros"? The reason I ask is because some oil doesn't support synchros due to the coefficient of friction, others don't support synchros because they contain sulfur that eats away synchros, and others actually do support synchros but they just don't specifically state so on the bottle.

You didn't fill it completely. See the instructions in the factory service manual, and note that there is a fill hole, an inspection hole, and two drain holes (4 plugs total). Not following instructions can cost you thousands of dollars in stupid mistakes.

If you are not sure what is wrong, you can always take your car to a transmission specialist. Contrary to urban myth, the RX-7 drivetrain is not anything special, so any good transmission mechanic can work on it. This includes the driveshaft.

Bad driveshaft u-joints cause vibration in proportion to the rotational speed of the driveshaft. The vibration gets worse over time, and will eventually get so bad that the car's interior parts will crack. It will never get any better.

 

On the bottle it said for non-synchro transmissions.. and I'm gonna look at the drive shaft today. The first time I filled it the car ran good then vibration started happening.

 

Are you sure the gear oil said "Non-Synchro transmissions" or did the oil say "Non-Hypoid?" Hypoid gears are in most front wheel drive cars and all wheel drive cars. Hypoid refers to the gears for the differential being in the same place as the transmission gears. Either Hypoid or Non-Hypoid gear oil should be fine for a RX7. But if you owned a Honda Civic and you were trying to put a gear oil labeled "For Non-Hypoid transmissions" I would strongly advise against it. As I recall the gears in a Hypoid transmission have some sort of weird grooves in the teeth which makes the pressures between the gears much greater and you need to run a gear oil with additives to resist rapid breakdown of the oil. But the RX7 like I said doesn't have Hypoid gears as far as I know. I hope that helps and I hope you can find your vibration issue.

 

 

Valvoline HP gear oil is actually for the differential so isn't the best thing for the transmission, but it will not cause the problems that you described.

 

So has to be the drive shaft then? Cause last year it made a vibration but it seemed only in 4th gear going up to 40 to 60mph I just thought it was the tranny fluid cause I didn't fill it all the way when I did the engine swap

 

It was the drive shaft front had play.

 

Hey that's Cool to hear you solved it. Good work! I saw the picture. It really says non-synchronized manual transmissions. You just blew my mind. I will be trying to find some Redline Mt-90 for my Diff/Trans fluid change.

 

Yea the guy at AutoZone told me thats what I should get...and something told me that it was the wrong bottle. Never asking them for help anymore...

 

[QUOTE=yammo7013;11756948]Yea the guy at AutoZone told me thats what I should get...QUOTE]

Sell your rx7....

 

Smh. 😑

 

No. Seriously. Never go to Autozone unless you have no other choice, and even then don't take their advice. They're the dark alley discount surgeon of the parts industry. If you don't know more than the guy at the Autozone counter you should be taking your car to a mechanic for everything from tranny swaps to tire rotations.