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grinding in 3rd gear 05 sti


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23 replies to this topic

#1 jbo_05sti

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Posted 10 December 2005 - 03:40 PM

My second and third gear are grinding on my o5 sti. i only have 20k on the transmission. Third grinds at low and high rpm, second only at high rpm. Does it sound like my syncros? I am supposed to be getting it dyno tuned next week Posted Image. Can they still work on it with the grind?

#2 grossgary

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Posted 10 December 2005 - 03:51 PM

is it still under warranty? have the transmission replaced.
sounds like synchro's, but that sure is early.

#3 jbo_05sti

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Posted 10 December 2005 - 04:00 PM

I don't think I still have a warranty. I have a 3 in. turbo-back exhaust, gt spec header, and intake. They have denied me warranty work in the past..... So I would have to replace the whole transmission? they cant work on just the syncros? Would my drivetrain still be under warranty since my mods are powertrain?

#4 grossgary

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Posted 10 December 2005 - 05:03 PM

i don't know what happens with warranty and modifying engines....depends on the contracts you sign when you buy i suppose.

synchro's are likely replaceable, but i'd find a used trans for $500 before i spent that kind of money to open up the trans.

i'm not familiar with these newer transmissions, so maybe the clutch adjustment or something else is to blame? i'm not saying i'm right, but i'd start sourcing something to replace it just in case.

#5 nipper

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Posted 10 December 2005 - 05:54 PM

Well if you did anything to dramatically boost HP, you have voided your driveline warrenty. Synchros are replacable, but you have to rebuild the tranny to do it.
They should be able to dyno test as long as its not poping out of gear, just double clutch, but yes check your clutch adjustment
Out of curiosity ... how much estimated HP is the car now? If you double clutch the tranny you can drive the car indefanitly with bad synchros, just do a oil change in the tranny to get all those brass peices out of the tranny.

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#6 jbo_05sti

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Posted 10 December 2005 - 06:35 PM

What exactly do you mean by double clucting? I am guessing the car is at about 360hp with the mods. I was planning on getting an ecutec reflash,front mount intercooler, cold air intake, and fuel pump this next week but now I am not so sure. If I am gonna have to spend my money on a new transmission I definately will have to wait on the hp upgrade. Should I take it to the dealership or an independent mechanic? Where can I find good used parts for subies?

#7 subarubrat

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Posted 10 December 2005 - 07:15 PM

"synchro's are likely replaceable, but i'd find a used trans for $500 before i spent that kind of money to open up the trans."

Unfortunatly you need to add another zero to that cost estimate......


That does sound like synchros but almost certainly not due to the increased HP. That is a pretty mild warm up for that car. Unlike the 5MT the 6MT has proven to have a huge margin for increased HP. That tranny would have likely failed under normal use and I would strongly suspect a faulty part or assembly problem. Your problem is that it isn't what you know it is what you can prove. Check out the Magnusson Moss Warranty act of 1975. http://www.ftc.gov/b...m#Magnuson-Moss

In short it provides a number of consumer and business protections when it comes to warranties. The one relevant to you is that a company cannot deny your warranty due to use of aftermarket parts or consumables. By law they have to prove that the part caused the failure. IE if your AC compressor fails they can't deny your warranty because you had an aftermarket muffler or wheels. However they do it all the time and even if you are making a reasonable claim and show them a copy of the law they will often go ahead and deny it anyway. Most people will not pursue litigation to recover a repair that costs less than the legal process. Given that reality and that you have already taken it in modified and that is a matter of record you are in a tight spot. If you have the skills I would say pull the tranny and deal with it. If not buy a 6MT, sell yours honestly (someone will want it) and chalk it up as a lesson learned.

#8 NoahDL88

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Posted 10 December 2005 - 07:16 PM

The minute you put any aftermarket go fast bits on your subie, the powertrain warranty is voided. Some dealers may work with you if you have built up a rapport with them, but i wouldn't count on it.

When you rebuild your tranny, as you are gonna have to pay for it yourself, i'd get some RA gears or some MRT gears, there are a whole bunch of distributors for high strength gears, check the "unibombers manifesto" on Nasioc, he's got a good write up on the available gearsets that will work in your application.

#9 scrap487

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Posted 10 December 2005 - 07:19 PM

double clutching is what you had to do before syncros were invented. pretty much the theory of it is to get the input shaft spinning at the right speed to get the gears on the output shaft to match the speed of the(forget what its called... think that the shift fork attaches to that locks the gears in with the outputshaft...). double clutching will also make your syncros last quite a bit longer, and slam shifting will tear your transmission up in a couple days(shifting without fulling disengaging clutch, or even disengaging at all). if your driving habits are really nice and easy on the car, something is probably wrong with your clutch thats causing it to not fully disengage, I would check to see if it is adjusted correctly to start off with.

anyways, if you dont know how to double clutch, when down shifting, pretty much what you do is you disengage the clutch to bring it out of gear, then engage it when in neutral and then rev the engine so the input shaft is spinning at the right speed, and then with it at the right speed you disengage the clutch and put it in to gear, it should slide right into gear VERY easily, and then engage the clutch and you're good to go. when up shifting its the same, except its not quite as needed as the inputshaft will slow down normally and be closer to the right speed when you put it in gear.

#10 jbo_05sti

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Posted 10 December 2005 - 07:23 PM

so what would rebuilding the transmission entail? new gearsets and what else?

#11 scrap487

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Posted 10 December 2005 - 07:32 PM

so would would rebuilding the transmission entail? new gearsets and what else?


depends on what is wrong... might only need a couple syncros, I wouldnt worry about gears unless they are worn and/or have broken teath. if you have to pull stuff off I'd put in some new bearings on whatever you have off, other than that maybe new seals. if your gonna bother replacing most of the guts in the transmission, it'd probably be way more worth your time to just replace the whole unit.

#12 jbo_05sti

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Posted 10 December 2005 - 07:52 PM

What exactly do the syncros do? Is there an individual syncros for each gear? Is that someting that I have to go would have to go through the dealership to get fixed, or can I buy the parts and have an independent mechanic put them on?

#13 nipper

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Posted 10 December 2005 - 08:42 PM

http://en.wikipedia....rd_transmission
http://www.wisegeek....e-clutching.htm

this explains everything.
If your going to bump up the engine power as much as you have, you really need to know how the transmission works.

PLEASE tell me that you also beefed up the brakes.



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#14 jbo_05sti

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Posted 10 December 2005 - 08:57 PM

ummm....... no. it comes with factory brembo brakes. Are those not sufficient?And the car has not really hasnt been beefed up that much. We are talking about 3 bolt on parts. From what I have read the factory 6 speed tranny is supposed to be able to support a significant hp increase. I have seen so many sti's on the internet with 400+ whp running on stock trannies. I just don't get why it is always my car that has to mess up. The motor had to be replaced at 7k, tgv valve went out at 15k, it started leaking oil out the valve cover at 18k, and now my 3rd gear is shot at 20k. I think it is just not meant for me to enjoy my subie!

#15 subarubrat

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Posted 10 December 2005 - 09:25 PM

Due to the press fit parts needing precise alignment you are probably better off swapping the tranny as a whole. Someone with the skills and tools to replace the synchros will buy your tranny, granted at a discount. The STI tranny has proven to handle greatly increased power 400~500Hp is an everyday thing. I am putting down 463. Again, I think your tranny would have failed at stock HP and it seems like you just have a defective one assuming driving habits are appropriate. And as the other fellow said earlier driving habbits are critical and underestimated. My Gen1 2.5 RS was putting down just over 300Hp and it was 165 stock. That 5MT had a reputation for loosing second with HP much over 240. Mine was sold at 150k miles with a perfectly functioning tranny. Not shock loading the gears is more important than their overall loading under power.

#16 BlueTrain

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Posted 10 December 2005 - 09:27 PM

http://en.wikipedia....rd_transmission
http://www.wisegeek....e-clutching.htm

this explains everything.
If your going to bump up the engine power as much as you have, you really need to know how the transmission works.

PLEASE tell me that you also beefed up the brakes.



nipper


:clap:

#17 jbo_05sti

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Posted 10 December 2005 - 09:35 PM

Please Define Appropriate Driving Habits

#18 DerFahrer

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Posted 10 December 2005 - 09:43 PM

Not slamming gears around like a rabid orangutang...

I find it really hard for synchros on an STi transmission to go out any other way. Every gear in the STi transmission has double-cone synchronizers except 2nd, which has triple-cone synchronizers. It would take some serious abuse to wear those out in 20k miles...

#19 jbo_05sti

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Posted 10 December 2005 - 10:00 PM

Well, I dont throw my gears around. I know how to drive. And I am not some immature kid that gets on it everywhere I go. Don't get me wrong, I have taken it to the local track a few times, but I dont throw my gears around like a monkey. The way I see it, the sti is a performance car, so why can't you take it out every once in a while? thanks for the input. this is a great site.

#20 scrap487

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Posted 10 December 2005 - 10:11 PM

check the clutch rump roast'y, check the gear oil, both the level of it and the quality of what comes out, if the oil is murky, speckly, has tiny little metal flakes, appears gray in color or otherwise does not look like normal new gear oil, something is definately wrong. also if there is a bunch of metal shavings on the magnet.

As far as driving goes, learn how to double clutch, especially when at higher speeds/rpms, it will save you ALOT of wear and tear on the transmission and clutch. also shifting at high rpms, especially without double clutching, will cause parts to wear much faster.

#21 BlueTrain

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Posted 10 December 2005 - 10:30 PM

http://nasioc.com/

you'll probably learn quite a bit more abour your vehicle on Nasioc. maybe even some other folks with the same tranny issues..

#22 subarubrat

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Posted 10 December 2005 - 10:41 PM

"I have taken it to the local track a few times, but I dont throw my gears around like a monkey. The way I see it, the sti is a performance car, so why can't you take it out every once in a while? thanks for the input. this is a great site."

Agreed. The driveline should stand up to the use that the car is marketed for. This was a chief complaint with the WRX's 5MT. And for the most part the STIs tranny has excelled at this. Again, your car seems to be an exception to the norm. Mitsubishi is a huge offender in this area. They are leaving EVO owners holding the bag on even the most legitimate failures. They have a history of doing that on prior non-performance cars too. Subaru denied allot of 2nd gear failures with the WRX when the truth is that the tranny was not as strong as it should have been.

#23 scrap487

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Posted 11 December 2005 - 12:23 AM

yeah... well he's had a lot of problems for only 20k... driving habits or his car was made out of all the throw away 2nds...

#24 Setright

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Posted 11 December 2005 - 04:52 AM

Wait!

Before you get too worked up, try draining the gear oil and refilling with some Valvoline Synpower 75W-90. This oil has stopped many gearboxes grinding.

The 6MT not only has strong synchro' rings, but the gear teeth are twice as wide as those in the 5MT.


Driving habits: If you often brake hard from high speed to a sharp corner and simultaneously force the stick into a lower gear like 2nd or 3rd coming 5th or 6th, you will kill the syncrho rings pretty quick. Under those circumstances, you MUST double de-clutch and match the revs.




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