6G Celicas Forums

Alright so I'm driving home from work. I shift it into 3rd and I hear it grind into gear, but it dives perfectly normal in 3rd. Now if I downshift into 3rd then there will be no grinding. Also if I shift really slowly into 3rd then no grinding is heard. The grinding is only heard under quick acceleration and medium to quick shifting. Any idea what could be wrong

Syncros maybe.

That happened to me after changing gear oil. If I downshift too fast, it will grind but after drivng a few thousand miles it went away. I tried shifting slowly till it went away.

yep synchros are starting to go. you could try a different gear oil.

When u say different gear oil do u mean I should go heavier or lighter than the gear oil I have in there now

Not exactly 100% on this, but I believe you should go with a heavier oil. Preferably Mobil1 Synthetic.


-Hope I helped, Ryan.

Maybe try double clutching it instead, that way you dont need syncronizers. Or you could just slip into 3rd without the clutch, just pop the shifter into neutral, raise the rpms to just higher than where it needs to be to shift into the next gear and then try to shift it into gear while letting the rpms bleed off. As soon as the speed of the wheels and the engine match it will slip easily into gear, without the clutch.

how about synchromesh? i know it wont fix the problem but it should help a bit until i can afford new synchros. also does anyone have any idea how much syncros would go for and how hard of a job it could be to replace them?



i actually tried that on my way to work and its a hit or miss. at some points it work and other there was still a slight grind

3rd gear synchro going out is a common issue, and indeed Synchromesh seems to be the fix.

Use Syncromesh... I use Pennzoil Syncromesh and it used to be hard to shift into 3rd quickly, now it goes in just fine.

I had the same problem and this is how my 3rd gear looked. It wasn't terrible but the dog teeth were worn down enough for me to replace it. I also replaced the blocker ring along with it of course.

New 3rd gear...

thanks for the replies everyone. ill give the syncrhomesh a try for now. I just need it to last me till about march next year and thats when ill be in my transmission classes so ill be able to rip it apart and rebuild it

how much did this all cost you and if that from the 5s tranny

Looks like I'm going to have to get some syncromesh for the spring when I do everything to my car lol
It doesn't grind going in when I'm going from 2nd to 3rd, it is a little hard, but say I'm in 5th, take it out of gear for a few seconds, then go to put it into 3rd, it'll grind half the time.

I think i did an entire rebuild for 400 or something, includes bearings for input and output shaft, seals, syncro's 1-4 and 3rd gear

How hard was it to do the rebuild and how long did it take? My 3rd gear syncro is starting to go, but if it's not that hard to do, I might have to attempt a rebuild being that there is over 230k on the transmission now...

All the syncronizers do is match the speed the gears are spinning at to the speed the wheels are moving at. If the clutch is engaged then the engine will spin the gears.
So if you were to double clutch, or if you were to rpm match and slip the transmission into gear without using the clutch then you would totally negate the need for syncronizers. This is because either way you will have used the engine to bring the internals of the transmission to the same rotational speed as the wheels.

For slipping into gear-Because of the design of the teeth on the gears you have to rev the transmission and engine FASTER than the next gear, and then slowly let the rpms drop until it slips into gear. If you were to rev the engine until it hit the correct rpm it wont grab into gear. You must rev it higher first and then drop the rpms to match.

As for double clutching the first thing you need to do is depress the clutch and pop the transmission into neutral, next rev the engine to the approximate rpm it needs to be at in the next gear. With the engine at the desired speed and still in neutral, release the clutch. Now depress it again and quickly and shift into the next gear. Because you dumped the clutch in neutral you forced the transmission to spin at the speed the engine is going which is also the speed of the wheels and the next gear if you were accurate.
Syncronizers are for plebs...



Serious business though, I would never let a tranny grind on me, you never know what disease it may give you.

This post has been edited by Special_Edy: Oct 23, 2012 - 2:57 PM

What I meant is that if I'm driving in 5th and I slow down to take an off ramp on the highway, I sometimes put it in neutral and coast while using the brakes, then I would push the clutch petal, go to shift into 3rd gear, and it would just make this horrible screeching noise (like something hitting against something), but I don't put it into gear. I then put it in 4th gear, shift down into 3rd and it will go in just fine. And mind you this is all with the clutch petal being pushed down.