Grinding in third gear., Mainly when down shifting. Options

[Box]

Those transmissions were also designed to run on Synchromesh, where as these were not. It's like saying, "Well a lot of Borg Warner transmissions in Fords used ATF, so I guess that's just dandy in anything else I deem fit." A lot of older Honda transmissions used straight up 5W-30 motor oil. What works for one doesn't work for all.

I've had SynchroMesh only for a year without issue.

There have been DSM's use straight Synchromesh and their transmissions turn into slurry. Then again you're talking cheap gearboxes anyway, so if you're in that desperate of a situation to remedy it then I guess anything is worth a shot.

The trick to rpm matching is to force pop the shifter into neutral and then apply force to shift it into the next gear. Let off the throttle and allow the rpms to slowly drop. As soon as the rpm of the motor hits the speed of that gear, it will kick into the gear, without the clutch. Due to the shape of the gear teeth, it only works if the motor is loosing rpm, so if you downshift you have to first rev the engine in neutral and then apply shifter pressure as the rpms fall (since you are shifting to a lower gear with higher rpm).
Probably best to practice with 3rd to 4th or 4th to 5th until you get smooth at it, they are more forgiving than 3rd or 2nd. Like I said slowly drop the rpms, you dont want to totally lift your foot of the throttle.

Even if you are using the clutch you should still develop a feeling for the rpm matching. With the clutch I just know how LONG to lift my foot off the throttle and when to release the clutch pedal to hit the rpms perfectly.

I probably do half my shifts in the car without the clutch and 100% of my shifting on my motorcycle without the clutch, its much smoother.

Floating the gears really comes in handy with left foot braking, which is your BFF in a FWD car.

[Special_Edy]

You could try double clutching on top of rpm matching too. This would totally negate the need for synchronizers.

[Box]

Just float them, screw double clutching through eighteen gears. Or five in this instance anyway.

[VavAlephVav]

And yet when I called Toyota to ask what was the recommended fluid for the transmission, expecting them to have their own special stuff, I didn't get any better of an answer he said "uh... 80/90 I think"
I had thought they would have a specific recommendation but they didn't. Other info I've seen says that the new gl-5 oil is too slippery for the synchronizers to grip right, and you should always used the gl-4 in a manual.

[Box]

The thing with GL-5 is that it's corrosive to the brass synchronizers used in a lot of transmissions, GL-4 is yellow metal safe. Has to do with the added sulphur from the pressure additives. Transmissions with carbon synchronizers use GL-5.

This post has been edited by Box: Jul 17, 2014 - 3:37 PM

[TClifton91]

Finally got around to changing my transmission oil, I used full synchromesh as recommended by prime performance. WOW! What an improvement over that black sludge I drained out. No more grinding in third, or any gear for that matter it's so smooth now. Amazing how something as simple as changing trans oil can make such a big difference. And perfect timing too, have a new 7gc short shifter on the way in the mail right now . I hope it's as good as what I've read, I set my expectations pretty high

[Box]

For the $20 or so I spent on mine it was worthwhile. Just play with it for a minute once done to reacquaint yourself and you should be good to go.