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nicodemus055
10-19-2005, 10:01 AM
So whenever I try to shift my (manual, obviously) 92 ST with any sort of speed or force I get that awful, gear grinding noise. I'm sort of new to car mechanics, so if anyone could tell me exactly which parts are making that noise I'd appreciate it.

I talked to a couple of people who said that the grinding was caused when you tried to shift to quickly or at a weird angle, and wasn't unique to my older, less sporty car. If that's the case, how do people racing their Celicas or other cars prevent this, especially off the line? Is it harder to grind on shifting in a Porsche, and is that just a function of parts and engineering? I'd like to be able to shift a little bit less gently if at all possible... It's annoying having to push and pull on the shifter so lightly.

Thanks for your help, guys.

embai
10-19-2005, 10:10 AM
i think the syncromesh on your tranny's worn out... some people have try using penzoil syncro oil and i think it works wonders...

AJz
10-19-2005, 11:04 AM
dont shift so fast....hehehe

the 5th gen celicas have shocking syncros. And its very hard to find a good nick one. Basically slow down between shifts, and instead if yanking into 2nd, pushing it down (if that makes sense, basically you wanna push it in rather than grip and rip as they so call it, i find that makes shifting quieter in mine. I am already on my 2nd gearbox by the way, hehehe

Luis C
10-19-2005, 02:37 PM
Worn syncros, your choices are:
1.- Replace them = $$$$
2.- Shift slower = not so sporty
3.- Replace gearbox lube with syncromesh = temp fix until they go *BOOM*
4.- Get another gearbox = you may end up with the same problem in a lesser degree.

Adrian Avgerinos
10-19-2005, 03:08 PM
This may seem like stating the obvious but, have you checked the fluid level? If you have a leak, then you might be low on fluid. This can certainly cause the problems you are experiencing.

If so, drain what's left as you may have metal bits floating around in the fluid. Try re-filling with the recommended 75w90 gear lube. If you live in a part of the country where there is cold weather, you may want to spend the extra money on a synthetic gear lube. Valvoline is a readily accesible brand that makes decent fluid for a good price. I recommend trying this:

http://www.valvoline.com/pages/products/product_detail.asp?product=58

Let us know your progress.

Adrian

caneman
10-20-2005, 04:54 PM
I won't denigrate any of the suggestions given so far, since any one or more of them may be correct. As for grinding being caused by the "angle" of your shift or something, well, if you know how to shift and are coordinating your clutch-shift action, this should not be true. Can we assume that you know how to shift a manual transmission properly (or does this happen in other manual transmission cars that you try to drive?)?

If so, and you don't have worn-out synchronizers, which are the mechanical parts that help the various gears to mesh properly without smashing their little gear teeth together, there may be an inexpensive fix. Before you get all sweaty and nervous about a major, costly rebuild, try this:

As suggested in previous posts, have your lubricant level checked in your transmission. Better yet, unless you know that the lube was changed in the last 40-50,000 miles, just have the dirty old transmission fluid drained, the transmission flushed, and then refilled with the proper lubricant.

Also as suggested, have the drained fluid checked for metallic pieces, which will indicate serious wear going on in there. Assuming the fluid is metallic-bits-free and, if your car is anything like mine, it'll go from grinding gears in second and third while up-shifting or down-shifting to totally silent by just changing the lube.

I also agree on the use of GM Synchromesh, which seems to be a wonder "drug" for sickly transmissions. Since there are different opinions as to the amount of gear lube versus GM Synchromesh to use, check the "search" function here, looking up the word "synchromesh." Read all the discussion posts and then discuss it with your mechanic.

If changing the lube and adding Synchromesh doesn't fix your problem, then you can start thinking/worrying about the much more complicated and costly fixes that may be necessary.

5SFE
10-20-2005, 05:21 PM
I replaced my transmission fluid with Redline and now a couple months later it's grinding between almost every gear on the downshift - Does anyone have a ballpark idea of how much replacing my synchros will run me? and - Would it be more cost effective to just rebuild the whole transmission?

Adrian Avgerinos
10-20-2005, 05:52 PM
I replaced my transmission fluid with Redline and now a couple months later it's grinding between almost every gear on the downshift - Does anyone have a ballpark idea of how much replacing my synchros will run me? and - Would it be more cost effective to just rebuild the whole transmission?

What fluid did you run? What chassis number is your car? You can probably pick up a used transmission for a few hundred bucks, so it may be cheaper to go that route.

5SFE
10-20-2005, 06:37 PM
Just had my mechanic put in redline, not sure exactly what kind.. I have an ST184 with the S53 trans - I got quoted $4,000 to get a brand new transmission and $1400 for a used one.. I'm really curious how much replacing the synchros would cost

Adrian Avgerinos
10-20-2005, 06:47 PM
Just had my mechanic put in redline, not sure exactly what kind.. I have an ST184 with the S53 trans - I got quoted $4,000 to get a brand new transmission and $1400 for a used one.. I'm really curious how much replacing the synchros would cost

Hmm.. unfortunately that's not very useful. If the mechanic put in MT-90, that would be the wrong fluid for that transmission. 75w90ns would be better.

Where the hell did you get a quote for $1400 for a used tranny? You can buy a new one from Toyota for about $1800. :eek:

Start searching here:

http://car-part.com

Punisher
10-20-2005, 07:02 PM
rofl 4G for a new one.. someone really likes giving you one in the stink...

Slider
10-20-2005, 07:11 PM
My car was starting to grind more and more often when trying to downshift into 2nd, finally I couldn't downshift at all into 2nd unless I double clutched. I went out and bought 3 bottles of gm synchromesh. My mechanic drained the old fluid and put in the synchromesh. That was a year ago. And I haven't had a problem with 2nd gear since.

Adrian Avgerinos
10-20-2005, 07:27 PM
My car was starting to grind more and more often when trying to downshift into 2nd, finally I couldn't downshift at all into 2nd unless I double clutched. I went out and bought 3 bottles of gm synchromesh. My mechanic drained the old fluid and put in the synchromesh. That was a year ago. And I haven't had a problem with 2nd gear since.

Partially useful information. How much fluid was in there originally? What kind of fluid was it? How old was the fluid?

Slider
10-20-2005, 08:04 PM
Fluid had to be around 3-4 years old, since that's when the previous owner replaced the clutch. Not sure how much was in there, but I have no leaks that I'm aware off and the mechanic didn't mention anything.

Could I have gotten the same results by just changing out the fluid with regular ATF? Maybe, can't really say. Would've loved to experiment but didn't feel like changing it myself since I don't have anything that would allow me to pour the fluid into that hole.

If you're changing it yourself, I would put the OEM stuff in first, and drive around with that for a week or so. If it doesn't help then go and try synchromesh.

Punisher
10-20-2005, 08:29 PM
Pfftt.. I was having the same issue with second gear.. so I drained fluid... put new valvoline synthetic in.. that didn't do it.. I tried lucas gear oils.. heavy weight the 140w shit.. and i tried the 75w90.. blah blah blah blah blah.. long story short, I found Pennzoil Syncromesh over at autozone.. dropped that shit in.. after driving for a day.. saw no improvement.. the next day I was downshifting into second at 50mph!

caneman
10-20-2005, 09:19 PM
... Would've loved to experiment but didn't feel like changing it myself since I don't have anything that would allow me to pour the fluid into that hole.

Buy a cheap, plastic turkey baster. Use it to inject one baster at a time until it starts running out the filler hole. A baster is also a good tool to remove excess fluid from the brake reservoir when you're collapsing the caliper piston during a brake pad change. Reduce the amount of brake fluid in the reservoir until it doesn't overflow when you compress the piston. :)

Punisher
10-21-2005, 02:48 AM
I use a funnel and some vinyl hose, shove the hose into the filler hole and pour into the funnel

Disco Dan
10-21-2005, 03:04 AM
The trick I used was, to make sure you fill it up when the front is on jacks. Since the filler hole is on the front of the transmission, by keeping the front off the air, you keep the fluid in the transmission away from the filler hole, thus giving you the option to OVERfill it. That did it for me, and I used the penzoil stuff as well. NO sound now, except the occasional thunk and bop because I shift too low or something.

Punisher
10-22-2005, 05:02 AM
The grinding is slightly comin back for me on the cold mornings.. However, I think my drain plug has a leak .. so the fluid might be gettin low.. gonna check that out soon and replace the drain plug and put a copper washer on this time.. lol.

Morwan
10-22-2005, 07:17 AM
A temporary fix would be to learn how to double clutch/rev-match well. I'm not sure what kind of racing you (if any at all), but if you're doing anything that involves actual... Skill (not drag racing), it's better to double clutch anyways.

Articles on double clutching:

http://en.wikipedia.org/wiki/Double_declutch (definition)
http://www.elecdesign.com/Globals/PlanetEE/Content/755.html (how it works)

I'm still in the process of learning, but it'll reduce the wear on your synchromesh, and if you get really good, you won't even need to worry about it. =P

Punisher
10-22-2005, 09:08 AM
I used to double clutch when the 2nd gear syncro was going out.. My motor doesn't have the rev response needed to quickly DC tho.. so it was a pain..

klif01
10-24-2005, 07:22 PM
Are you pushing the clutch all the way to the floor when you shift fast?

5SFE
10-27-2005, 03:58 PM
Well, I don't do much racing - I just drive her hard on back roads and downshift frequently around turns. I can manage to double clutch into every gear except 2nd, even if the revs are dead on. So, which is better, Pennzoil, Valvoline, or GM brand???
I take my car to a mechanic, so should I leave it up to them?

BTW - that quote for 4G's was from Midas/Meineke, some big chain place

Adrian Avgerinos
10-27-2005, 05:16 PM
Well, I don't do much racing - I just drive her hard on back roads and downshift frequently around turns. I can manage to double clutch into every gear except 2nd, even if the revs are dead on. So, which is better, Pennzoil, Valvoline, or GM brand???
I take my car to a mechanic, so should I leave it up to them?

BTW - that quote for 4G's was from Midas/Meineke, some big chain place

Yes.

Better for what?

5SFE
10-27-2005, 05:38 PM
For making my tranny stop going "CRUNCH" every time I downshift...

Adrian Avgerinos
10-27-2005, 07:09 PM
For making my tranny stop going "CRUNCH" every time I downshift...

I guess Pennzoil Synchromesh. It seems to be the holy grail of S53 gear lubes on this board. Considering how cheap fluid is, it can't hurt to try.