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torn
03-07-2005, 01:14 AM
Hey there,

I have a celica 90 GTS with a manual transmission, and since I had the car for almost a year, I have trouble downshifting into second gear. If I try going from third gear to second gear, and the rpm would be too high in second gear, it grinds and is hard to get in gear or won't go at all!

Let's say I'm at 4k rpm in third gear, and want to downshift in two, the rpm would be about 5.5k, then the gear would be almost impossible to engage and I'll hear a very nasty grind. The rpm needs to be below 2500-3000 rpm for not having any grind at all.

By the way, the grind happens when I try to engage the shifter into second gear position, and when I'm completly pressing the clutch (and the engine rpm is 3k and higher).

So tell me the bad news ... is my second gear synchro dead ? or there's another possibility ?

Thanks! :wiggle:

Dr.Auto
03-08-2005, 01:37 AM
Needs syncros :(

Luis C
03-08-2005, 01:52 AM
Welcome to 5th Gen Synchro 101. Please take a seat and empty your pockets :D J/K

Really, that is normal for 5th Gen Celicas, I'm on my second 5th Gen and eventhough my current car has a S53 gearbox and the NADM has the S52 they still have the tendency to kill the 2nd gear synchro. The only fix is to get a new one.

TRDmkII
03-08-2005, 01:56 AM
yeah, mine does it really bad, i dont' car, when i lose second gear i'll change it...lol.....try to just brake instead of downshifting, that will eliminate the grinding =)

torn
03-08-2005, 04:52 AM
yeah, mine does it really bad, i dont' car, when i lose second gear i'll change it...lol.....try to just brake instead of downshifting, that will eliminate the grinding =)

Hehe that's exactly what I'm doing right now, but I'd really like to downshift sometimes :)

Ok then, I need to change that synchro, how hard it is to do it on my own ? I guess I'd need good documentation (like the BGB manual some guys are recommanding)... I'm pretty confident I could do this, but I would need the right tools.. you guys ever did that yourself ? And while the transmission is open, anything would be a good idea to do at the same time ? Does the second synchro is always the bad one, or the other synchros could break in a short while ? How much are they anyway ? only found at the dealers or they could be found for cheaper (is that a good idea?)...

Anyway, thanks for the help :bigthumbu

Jigglypuff
03-08-2005, 05:06 AM
You're a lot braver than I am. The innards of transmissions intimidate me. Have you tried simply changing the transmission fluid? It won't completely eliminate your grinding (although it may), but it's certainly easier than rebuilding the transmission. A few people, including myself, have used Pennzoil Synchromesh with positive results.

If you do decide to rebuild your tranny, you might want to look into re-gearing 3rd and 4th gear. Well, at least that's what I'd consider. 1st and 2nd are satisfying enough for me, but from 3rd and above it feels weak. Taller gears (or is it shorter gears?) should make acceleration better in those gears.

torn
03-08-2005, 05:23 AM
Well I'm planning to use that transmission with a 3sgte this summer, so I want it to work right :) Putting better fluids could help I guess .. but I want the transmission to be in good shape to handle the extra power anyway, so I might just rebuilt it (what does it mean to do a tranny rebuild anyway ? changing the syncros ?). BTW, I think I have the S-53 transmission, whats the S-52 ?

Oh and I dont want to put shorter gears, they are already too short for my taste :hehe: (although they are fine for the 5SFE normal output). In fact I may put taller gears if possible to increase my max speed with the 3sgte :) But I think getting new synchros would be already good enought hehe

Project5sgtze
03-08-2005, 05:31 AM
thats becuase your fuxoring up your synchro's




swap with an mr2 tranny

Hooligan
03-08-2005, 05:52 AM
Newer, premium gear lube will probably make a huge difference. Even if it doesn't, it's a heck of a lot cheaper than ripping the transmissin apart.

I've had good luck with Redline products, and others like Pennzoil Synchromesh. Either are a good choice (they are actually very similar oils, but they have different additives).

torn
03-08-2005, 05:52 AM
Hey how am I "fuxxoring" my synchro ? I got the car like that.

I googled a bit and lots of people put "Redline Ultralight shockproof" oil and their grinding just disapeared ... I found that a bit magical but maybe this would be a good idea before I rebuilt the transmission anyway.

I checked and the GTS 90 5SFE have an S-53 transmission and Mitchell manual suggests putting ATF-II automatic transmission fluid (althought the transmission is manual). Is that possible ?

Project5sgtze
03-08-2005, 06:29 AM
if you deliberately shift into that gear even tho you feel more pressure than usual or you have to force it to shift... that can screw up your synchros further.

that pressure is becuase the synchros are not lined up and so if you force it you are forcing the synchros into eachother which hurts the teeth on them, hence the grinding...

sgtmayhem4
03-08-2005, 06:32 AM
SYNCHROMESH
/thread

Hooligan
03-08-2005, 06:36 AM
Just so you know, thinner oils will not provide as much protection as thicker oils will, but they will offer easier shifting for both cold and warm conditions. ATF breaks down fairly quickly too when compared to a 75W90 oil or Redline MT-90.

I know it's odd, but some S53 equipped cars had 75W90 recommended, and some had ATF recommended. This topic was discussed throughly, and I mean THOROUGHLY on Celica.net before it was cleared out. The general consensus was that ATF was cheap and worked, but didn't offer as much protection as a 75W90 weight oil/Redline MT-90/Synchromesh.

Personally, I am running MT90. It's a 75W90 weight oil that has friction modifiers to allow the synchros to slip more in the oil and match revs better than a regular 75W90 oil.

Luis C
03-08-2005, 04:10 PM
Beware, something odd happened after I changed the lubricant in my box.
Like I said before, 2nd gear was crunching bad so I also thought that new lubricant would solve the problem... it did, 2nd gear crunching completly dessapeared BUT something worse came up... 3rd and 4th gear begun crunching right after the oil change.

I was like WTF...? I mean, downshifting from 5th to 4th and from 4th to 3rd and everything was perfect but after I changed the lube in the box downshifting down from 5th and down to 3rd is a nightmare... If I don't do it slowly all 3 gears would crunch.

So, as far as I'm concerned the medicine was worse than the illness, although for city driving it was the best solution but not for highway driving or long journeys where 5th-4th-3rd gear use is intensive.

I used Mobil Synthetic Gear Lube 75W90

torn
03-08-2005, 05:27 PM
if you deliberately shift into that gear even tho you feel more pressure than usual or you have to force it to shift... that can screw up your synchros further.


Thanks for the tip, I'll try to avoid as much as possible to make it grind, but sometimes even though I'm doing it slowly and at low rpm it's still grinding.

I even tried double-clutching and I blip most of the time when downshifting (I'm raising the rpm of the engine to match the speed of the tranny) but it still grinds.

torn
03-08-2005, 05:29 PM
Personally, I am running MT90. It's a 75W90 weight oil that has friction modifiers to allow the synchros to slip more in the oil and match revs better than a regular 75W90 oil.

Thanks Hooligan, I think I'm going to buy Redline MT90 like you did. I hope it will be for the better :)

Punisher
03-08-2005, 07:17 PM
I have the same issue.. 2nd and 3rd gear.. 3rd isn't bad.. and I notice if when going into third I push the shifter forward and slightly to the right that it'll go into gear most of the time with out grind.. Now we had a bad snow storm here a few weeks ago and I was driving my celica through some deep snows and I was running 2nd gear hard because it was the best gear for getting through the snow... and after I did that it basically fixed my grinding issue in 2nd! lol.. I used to not be able to shift into 2nd at anything above 20mph with out a grind.. now I can do it at 30mph.. and the other day I did it on a hard stop at 35mph.. So something fixed something because I drove that gear so hard...

Replacing the synchro is a real bitch and all the tools you need to buy... You would probably be better off just buying a good condition junk yard tranny and rebuild the synchro's in that.. atleast you won't have any down time and you can take your time rebuilding that tranny and when the one in your car goes to tranny heaven you have the freshly rebuilt tranny to drop right in.

Punisher
03-08-2005, 07:18 PM
I forgot to ask.. where the hell; is the filler plug on the 90 GTS? (5sfe of course)