01 elantra trans synchros?

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    This isn't something I'm going to attack myself, I'm more curious about difficulty and price.
My 01 elantra stickshift is having trans issues. When downshifting
into 1st or 2nd gear I get serious grinding. It doesn't happen when accelerating from a stop and/or shifting 1->2, or in any other gears. People tell me my syncros are going, and while I understand the concept of synchronizing the gear speed as they mesh, the actual mechanics of it (or actually fixing it) are well beyond me.
It's going to go to a shop, but my question then is, how hard is this? I have a bad feeling that the trans will have to be removed and some serious internal work will be required, but I'm also a natural pessimist. Any thoughts as to the difficulty?
I probably ought to get this done soon. Learning to float gears and estimating proper rpms isn't coming to me quickly enough.
Thanks Ben
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Richard Dreyfuss wrote:

Unfortunately, your friends are correct. The 2 > 1 shift will almost always grind if you're not at a dead stop, but if the 3 > 2 shift is grinding, the synchronizers are probably worn.

Replacing the synchronizers requires a transmission rebuild, which will likely cost $1000-$1500, most of which is labor.
If you're downshifting and engine braking, stop doing it. As you're learning, brake pads are a lot cheaper than transmission rebuilds, so it makes sense to use the brakes to stop the car, rather than wearing out the transmission by engine braking.

That's up to you, as it's more of an inconvenience than a major problem. It's not likely to cause a more serious failure, though it would probably be a good idea to change the transmission oil in order to remove as much of the wear particles as possible. I strongly suggest using a good synthetic transmission oil like Redline MT-90. Regardless, you MUST use a GL-4 oil ONLY, as Hyundai transmissions require it! DO NOT let anyone put GL-5 or "universal" oil in your transmission, as it will cause premature synchronizer wear.
Modifying your driving habits is an easy and inexpensive workaround for the issue you're having and it will allow you to put off the rebuild nearly indefinitely. If you continue driving in the same manner, you'll quickly wear out rebuilt synchronizers too, making a rebuild largely a waste of money.

Generally, all it takes is a well-timed blip of the throttle, which is something you develop by feel. Still, I would recommend getting out of the downshifting habit. If you're determined to keep doing it, learn to double-clutch.
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I'm really surprised to see this Brian. Cars have been fully sychronized for decades, so it really surprises me that there are not synchros between 1,2. I havent' owned a manual transmission for several years now, so I don't doubt that there are trannys on the market that behave differently than what I was last used to, but man - that's a step backwards.

For any particular car this may be dead nut truth, but as a principle of manual transmissions, I'd have to disagree. I have always downshifted every single manual tranny I ever owned, with no ill effects. No premature wear, etc.

Ah - the good old days, huh? Remember when you had no choice - you had to do this? Most modern manuals (qualified by the ones I've experienced) with decent synchro's don't require a blip anymore, unless you're coming down from way too high. In that case, it is questionable whether the downshift should even be taking place at that speed/rpm. I have not double clutched a manual in so long that I don't remember the last vehicle that I had to do it in - other than a fire truck.
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Mike Marlow wrote:

The difference in RPM is greater between the lower gears so the synchros have to work a lot harder, however, my Sonata goes into first OK if you are going less than 10 MPH or so. I always blip the throttle on down shifts as well which helps.

Same here. This is the way standard shift is meant to be driven. It is a good idea to blip the throttle on down shifts though to help synchronize the speeds a little. I don't double-clutch my cars as I did when I was driving OTR, but blipping the throttle helps and is easy.

Blipping the throttle isn't necessarily required, but it is very good technique.
Matt
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Mike Marlow wrote:

There are probably 1-2 synchros, but every car I've owned (I've never owned an automatic) has had a tendency to grind during 2>1 shifts if the car is moving. The Elantra definitely does. If you're moving at anything more than a crawl, downshifting to first is unnecessary and pointless, so I rarely do it.

Consider yourself lucky. Downshifting without RPM matching does wear the synchros and engine braking wears the gears. Whether it's enough to cause a problem over the typical life of a given transmission is debatable. FWIW, I used to drive my cars hard, heel and toe downshifting all the time and it never caused a problem (sadly, Hyundai pedal placement is lousy for this). However, Hyundai transmissions are prone to synchronizer wear (as I learned with my first one), so I don't downshift/engine brake in the Elantra.

While that may be true, it doesn't mean it's good technique or that RPM matching is not a MUCH better technique. It dramatically improves the smoothness of downshifts while reducing wear on the clutch and transmission. For that matter, if you match RPMs well, you don't even need the clutch for upshifts OR downshifts. Again, this is not something I do any longer, but I experimented with it years ago, so I know it's possible. When you get it right, it's pretty amazing, when you don't it sounds horrible!

True, but it depends on how aggressively you're driving. For example, when braking hard into a low speed corner requires pretty dramatic downshifting if you're planning on exiting said corner in a hurry.

I've never had a vehicle that required it, except for downshifting when the synchros were worn.
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Brian Nystrom wrote:

My Sonata needs first below about 10 MPH. It is really gutless at low RPM and doesn't pull away in second as my previous cars have done. It seems to have almost no torque below 1500 RPM, unlike my pickup that will pull literally down to idle.

Sure it causes some wear, but if you change your oil regularly this wear is almost imperceptible. And the wear on the gears is on the other side of the teeth which are seldom used so you are wearing a part that otherwise sees no wear and in any event gets far less wear than the drive side of the gear teeth.
If Hyundai's are prone to synchro wear, it is due to poor materials or design.
Matt
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Those were pretty much my thoughts Matt. There is really no "consider yourself lucky" about it - transmissions in general have no problems with upshifts or downshifts. It causes no premature, or excess wear and tear. Transmissions and engines are always out of synch in terms of rpm's whenever a shift occurs - whether that is upshifting or downshifting. That's the whole purpose and reason behind a synchro. I wondered about the Hyundai transmissions based on what had been posted. If indeed, they do not suffer shifting well, then that's a design issue. Brian's historical comments seem to suggest this as well.
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Mike Marlow wrote:

While gear wear may be small enough not to pose a problem over the life of a transmission, that's not true of synchronizers, which do wear if a transmission is shifted without matching rpms. The sloppier the shifts, the more wear and tear.

I beg to differ, Mike. If you match RPMs, there is no significant difference, which is why you can shift without using the clutch if you match revs accurately. Granted, not many people do it or can, but like any other skill, you can develop it with practice.

That may well be true, but it's irrelevant to whether one should go easy on the synchros or not, since the empirical evidence suggests that they are prone to wear. We can complain about it - and we should - but it won't change the need to adjust our driving styles to suit.
Some of the reported problems are undoubtedly due to people changing the oil and using the wrong type. Hyundai transmissions require GL-4 oil, which is not commonly available at auto parts chain stores and department stores. Using the commonly available GL-5 oils or those labled "universal" will cause premature synchro wear in a Hyundai tranny.
Older Hyundai transmissions were also prone to bearing wear, but I don't know if that's true for the current ones.
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True, but only to a point. Wear is going to occur in any tranny, but when the wear does not affect the tranny over its useful life, then that amount of wear is neglible. That's what I'm talking about. Upshifting and downshifting just don't wear out syncros prematurely. I've consistently driven vehicles over 200,000 without having to replace syncros. I'm sure they were worn, but who cares? They were no more worn than anything else on the vehicle at that point.

Consider the normal shift process. Accelerate, simultaneously take your foot off the gas and press in the clutch. From that point on the engine rpm's do not match the speed of the tranny. That's why we have syncros. Agreed, you can match them and I've done that millions of times, but in normal driving, 99% of the population just does not do that, and the manual tranny is no worse off for it.

This is the only point I would strenuously challenge Brian. I disagree that there is empiracal evidence of excessive wear to the syncros. I do agree they are a wear item, but that's life. They don't wear out in tens of thousands of miles. Like I said, I've driven them hundreds of thousands of miles. There does come a point where worrying about wear just isn't worth the worry. The rest of the car is going to be junk at the point where you do enough damage to the syncros simply by downshifting.
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Mike Marlow wrote:

I agree. Using engine braking to help save brake wear makes a measurable savings on brake pads and shoes while incurring an immeasurable amount of wear on the clutch and transmission. I've never, ever worn out either a clutch or a transmission and I've driven standard shift for 30 years up to and including OTR rigs.
My standard shift cars get nearly double the brake pad life of my automatic vehicles so I know the savings there are real. Since I've never replaced either a clutch or a transmission, the cost there is zero for downshifting and using engine braking.
Matt
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Mike Marlow wrote:

How many Hyundais have you owned? Hyundai transmissions ARE prone to synchro wear. The sychros in my Excel's transmission only lasted about 30K miles before grinding in 1>2 and 2>3 shifts became common. The rebuilt transmission suffered the same fate, so it wasn't a fluke. I've been driving standard transmissions for over 30 years and this was the first car I ever had a synchro problem with. If you follow the any of the Elantra sites, you'll hear plenty of tales of worn out clutches and synchros. Do whatever you want with your car, but you may not like the end result.
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My mistake Brian - I had lost track of the fact that you were talking specifically about Hyundai synchros and thought you were talking about manual tranny's in general.
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Mike Marlow wrote:

No, not at all. In general, you're correct, synchro wear is not a big issue. It does seem to be with Hyundai transmissions. FWIW, I was also told this by the guy who rebuilt mine.
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You don't practice on your own car. Yo do that stuff on rentals or cars at work. When I was 17, I used to deliver groceries in a '58 Chevy Sedan Delivery (windowless station wagon) and got to practice all sorts of shifting techniques, braking in snow and ice, other things I'd never want to do in my own vehicle.

I wonder how many people under about 50 know what you are talking about. Ed
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I suppose I didn't explain properly. I don't tend to downshift for braking purposes, I just meant when shifting down from a higher gear, such as dropping down into 2nd gear after turning a corner or after slowing for a traffic obstacle.
I've never been a huge fan of engine braking (except on steep hills such as in colorado, but I've never been there with this car). I always figured that there was extra clutch wear (engaging it extra times every time you decelerate), and I can do brakes many times over for the cost of what I'd have to pay someone else to replace my clutch. That's the theory anyway.
Ben
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Richard Dreyfuss wrote:

Proper shifting causes almost zero clutch wear.
Matt
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Matt Whiting wrote:

True, but it's common to slip the clutch when downshifting for the purposes of engine braking, in order to avoid sudden deceleration and the jerkiness it can cause, particularly in low gears. That does wear the clutch considerably. I assume that's what he's referring to.
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Brian Nystrom wrote:

That is poor technique and not proper shifting. Poor technique causes problems in many areas, not just shifting! :-)
Matt
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I strongly suspect that a great deal more clutch slipping happens while taking off than happens while downshifting. I would not put clutch slippage while downshifting into a category of concern.
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Richard Dreyfuss wrote:

OK. If that's the case, your synchros are probably worn.

Sounds good to me.
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