Grinding noise going from neutral to 5th

[opus]

Just got back from our annual trip to Hilton Head Island. During the trip we go through the mountains of Tennessee and North Carolina. I am in the habit of putting the car in neutral while going down the mountains, and then engaging the transmission in fifth gear when we start to go back uphill. This year, when I would try and engage the transmission it would make a shearing/grinding noise when going back into fifth!!! No noise going fourth to fifth, just engaging fifth from neutral. Took it into the dealer, demonstrated the problem. He called Mazda and they said I shouldn't be doing that with the transmission and that I am probably damaging the transmission by doing that!!! Am I off base thinking the transmission should be able to do it, or are they right in saying that the transmission should not be able to do it? Let me know what you think

 

[coyfish]

Putting it in neutral means you will have to ride your breaks which isn't a very good idea. Nor is it the best thing to do to your tranny. Are you rev matching before you put it in gear?? If your not rev matching properly its probably the synchros frowning at you.

 

[opus]

Putting it in neutral means you will have to ride your breaks which isn't a very good idea. Nor is it the best thing to do to your tranny. Are you rev matching before you put it in gear?? If your not rev matching properly its probably the synchros frowning at you.

But isn't that what the synchros are there to do? My wife had a 65 mustang with a 3 speed that had no synchro mesh for 1st gear, so we always had to stop before it would go into 1st but every other gear was fair game.

 

[scottgib]

Bad practice all the way around.
Safety - Brakes can overheat and you cannot accelerate out of the way of a danger. Also, you will definitely have reduced braking capability.
Economy - Using gas to keep the engine turning, and worse if you are using AC.
Transmission - Without rev matching, you are putting a hell of a load on the syncros, and depending on the design of the transmission, it may not be getting lubricated properly with the in-put drive shaft not turning. Remember some cars do not like to be flat towed for a good distance.

 

[dmention7]

Yes, that's what they're there for, but dropping the car in neutral and repeatedly putting it back in gear at highway speed is putting wear on them, beyond what they see in normal driving. The brakes are there to stop the car, but like any friction device, if they are abused they will most definitely wear prematurely.

If you insist on doing this (and it is not a healthy practice), then at least double-clutch when bringing the transmission into gear--rev the motor to or above the expected engagement speed while the transmission is in neutral and the clutch is engaged, then quickly press the clutch, shift into gear, and release the clutch while keeping the engine at speed. This will make sure that all transmission components are moving at roughly the same speed and greatly reduce the amount of wear your synchros see when reengaging 5th gear.

 

[AIMWO4]

You need to rev match if you plan on coasting at more than about 55MPH.

Here is the post from the 3 forum.

 

[opus]

Welllllll ..... now it is doing it if I go from 3rd to 5th. In other words, if I don't go into 4th gear before going into fifth I am getting the grinding/shearing sound. I was accelerating to get on the highway, got up to 60 in 3rd, and went to put it into 5th since I was merged with traffic, and it makes the same sound.

 

[StealthWyvern]

your 5th gear syncro is going out due ot neglect.... yes I said it NEGLECT. A standard transmission was not designed to be used like that!

 

[opus]

your 5th gear syncro is going out due ot neglect.... yes I said it NEGLECT. A standard transmission was not designed to be used like that!

And you base your "neglect" comment on what? Using the theory that putting it into fifth from neutral impacts the transmission tooo dramatically, then what happens when you downshift? Say you are going up the hill and you downshift from 5th to 3rd to get the rpms up? I have 2 saturns that have over 100,000 miles appiece, not a single tranmsission issue. Going with your theory, anybody that ever drives a manual transmission and doesn't rev match is abusing their transmission? The example I provided was something I did very occasionally, and only on downgrades that lasted more than say 4 minutes, it is not a daily practice.

 

[TheMAN]

you're missing the point
there is a GREAT speed difference between your axles and idle speed in your transmission when you're going 65mph... it makes the synchros work very hard, more than what they were designed for... this is considered ABUSE

you haven't presented any rebuttal or logic when you try to argue about downshifting... downshifting from 5th gear to 4th gear at 65mph then 3rd gear as you're slowing down to say 60mph isn't going to put too much stress on the synchros as there is not a great speed difference in between gears... now if you try slam it into 2nd from 5th gear at 60mph, the tranny isn't going to be very happy about it even though there won't be any engine damage... the speed difference is just too great

 

[opus]

Guess I will just have to go to my local transmission shop and have them fix it, and then treat this transmission in a way that no other transmission has ever required me to treat it. I knew the tranny was the weak link in this car when they put the "no tow" requirement on it, just didn't realize how weak. Saturn, Pontiac, and Ford must have made one hell of a transmission in the day because I never had issues.

 

[TheMAN]

no transmission is ever designed to be treated this way... it's just a matter of time when it screws up!

the tranny is plenty strong for lot more power than what your car makes... the "no tow" requirement is there because the brakes and suspension as well as chassis is inadequate to handle the load... the chassis will rip apart and the car will handle dangerously with anything towed... it has NOTHING to do with any mechanical component being "weak"

 

[opus]

My Saturn transmissions went for over 100,000 each without an issue, Ford was for over 140,000, once again, no issues. Mazda transmission, 35,000, major issue. I would say, at least for me, the mazda transmission was the weakest of the batch. On the subject of suspension, already had one shock blow out at 30,000, without ever towing anything, or ever putting anything other than 4 people and some luggage in the vehicle. Have had to have the bushings replaced twice because of squeaking in the winter because they couldn't deal with the cold. So, you are probably right about the suspension not being able to handle even a moderate load or even temperature change for that matter. Saturn wagon could tow 1000 lbs, yet had smaller brakes, less rigid frame, and 30 less hp, never had a shock blowout. Had to replace a set of tires because of the "non-adjustable" rear control arms and the very high negative camber that the factory setting put on the vehicle. Love the design of the 5, love the practicallity of the 5, can't stand the lack of anything holding up on it. I figured they had to cut corners to get this thing in under $20,000, and now I am finding out where the corners were cut.

 

[mazdadude]

Bad practice all the way around.
Safety - Brakes can overheat and you cannot accelerate out of the way of a danger. Also, you will definitely have reduced braking capability.
Economy - Using gas to keep the engine turning, and worse if you are using AC.
Transmission - Without rev matching, you are putting a hell of a load on the syncros, and depending on the design of the transmission, it may not be getting lubricated properly with the in-put drive shaft not turning. Remember some cars do not like to be flat towed for a good distance.

These are all good reasons not to do it. Opus, please give the reason why you are driving the car in this way?

Also, here is another thread with similar experiences...
http://www.mazdas247.com/forum/showthread.php?t=123747021

 

[StealthWyvern]

And you base your "neglect" comment on what? Using the theory that putting it into fifth from neutral impacts the transmission tooo dramatically, then what happens when you downshift? Say you are going up the hill and you downshift from 5th to 3rd to get the rpms up? I have 2 saturns that have over 100,000 miles appiece, not a single tranmsission issue. Going with your theory, anybody that ever drives a manual transmission and doesn't rev match is abusing their transmission? The example I provided was something I did very occasionally, and only on downgrades that lasted more than say 4 minutes, it is not a daily practice.

Down shifting is completly different then up shifting when their is more then likely 2k plus difference in the rpms. I'll just refer you to TheMans post below.

you're missing the point
there is a GREAT speed difference between your axles and idle speed in your transmission when you're going 65mph... it makes the synchros work very hard, more than what they were designed for... this is considered ABUSE

you haven't presented any rebuttal or logic when you try to argue about downshifting... downshifting from 5th gear to 4th gear at 65mph then 3rd gear as you're slowing down to say 60mph isn't going to put too much stress on the synchros as there is not a great speed difference in between gears... now if you try slam it into 2nd from 5th gear at 60mph, the tranny isn't going to be very happy about it even though there won't be any engine damage... the speed difference is just too great

WOW that is a very tame response coming from you! I have nothign else to add to your post!

 

[opus]

These are all good reasons not to do it. Opus, please give the reason why you are driving the car in this way?

Also, here is another thread with similar experiences...
http://www.mazdas247.com/forum/showthread.php?t=123747021

You guys keep listing this thread, to convince me, and I keep reading it and find out that Mazda did indeed replace his 5th gear synchros!!

Then I read the postings from Frink in this post:

http://www.msprotege.com/forum/showthread.php?t=123668944&highlight=grinding+in+5th+gearng

He also got his synchros replaced....

I am no longer arguing, you guys know waaaaayyyyyy more about manual transmissions then I will ever know!!! (stooges) I'm accepting that.... admitting my ignorance.... and generally just glad that "theman" did not tear me a new one

On the flip side, I get to see 2 other guys get theirs fixed, even though they did the same thing I did. That tends to chew on a guy, and make him wake up at 4:58 in the morning and get online to try and clear his head.

Now..... does anyone know what it should cost to either A. get 5th gear synchros replaced... or B. get a new 5 spd transmission???

 

[wmzda5]

My Saturn transmissions went for over 100,000 each without an issue, Ford was for over 140,000, once again, no issues. Mazda transmission, 35,000, major issue. I would say, at least for me, the mazda transmission was the weakest of the batch. On the subject of suspension, already had one shock blow out at 30,000, without ever towing anything, or ever putting anything other than 4 people and some luggage in the vehicle. Have had to have the bushings replaced twice because of squeaking in the winter because they couldn't deal with the cold. So, you are probably right about the suspension not being able to handle even a moderate load or even temperature change for that matter. Saturn wagon could tow 1000 lbs, yet had smaller brakes, less rigid frame, and 30 less hp, never had a shock blowout. Had to replace a set of tires because of the "non-adjustable" rear control arms and the very high negative camber that the factory setting put on the vehicle. Love the design of the 5, love the practicallity of the 5, can't stand the lack of anything holding up on it. I figured they had to cut corners to get this thing in under $20,000, and now I am finding out where the corners were cut.

Sell it. Your need is not for a 5. Besides you're not comparing apple to apple, saturn, and chev is not mazda. And ford might be mazda but might not be the same tranny design. I don't have this kind of problem and I don't hear this from any other poster. to me downshifting from 5th to 3rd is not normal unless you are going on the apex of a hill on 5th until the rpm is really low, the reason for downshifting lower than 4th. Maybe that's another interlock of the MZ5 just like you cant shift from 5th to R directly. My $0.02

 

[mazdadude]

The reason I posted the link to the other thread was that it was a similar experience, the dealer rectified the problem, and it also contained some good diagrams and explanations of why the tranny does not like the N-5 shift.

I never like to think of any of the disagreements in point of view as arguing, but rather as discussions that can sometimes get heated. (dark) After all most of us here are pretty passionate about cars in one way or another.(hump)

Suprisingly I have seen several Mazda5 transmissions on ebay...(eek2)

Is your Mazda5 still under warranty? If so, I would try another dealer.

Also, I reread but did not see if you revved the motor to get it to the approximate RPM before trying to engage 5th? Or were you going from N-5 without revmatching? I am still wanting to know why you like to do this, or what purpose it serves you to do it?

 

[opus]

The reason I posted the link to the other thread was that it was a similar experience, the dealer rectified the problem, and it also contained some good diagrams and explanations of why the tranny does not like the N-5 shift.

I never like to think of any of the disagreements in point of view as arguing, but rather as discussions that can sometimes get heated. (dark) After all most of us here are pretty passionate about cars in one way or another.(hump)

You're right. I used a poor choice of words(doh)

Suprisingly I have seen several Mazda5 transmissions on ebay...(eek2)

Is your Mazda5 still under warranty? If so, I would try another dealer.

Yes, and that is why I am frustrated, I am not one to stick others with messes that I create, I just never had this mess from doing the same thing with other cars.

Also, I reread but did not see if you revved the motor to get it to the approximate RPM before trying to engage 5th? Or were you going from N-5 without revmatching?

No, I was not revmatching I had heard of revmatching on a down shift, just never thought to do it when going straight from neutral into a gear. My understanding of revmatch was that it was a performance driving strategy to get the best use of the engines RPMs and keep it in the torque band, I never thought of it having any benefit for the transmission.

I am still wanting to know why you like to do this, or what purpose it serves you to do it?

It is just a habit that I have had ever since I can remember. The car feels as though it is less restricted by the drag from the transmission and can utilize the downward inertia more efficently. I only do this on really steep mountains, like in Tennessee. My father always chewed on my ass if I kept the clutch in too often or for too long, like at lights. He always told me that unless I was using the engine to pull me forward, or backwards, just leave the car in neutral. Have done this for 25 years, yeah I am old, and have never had a problem till now. (shrug)

 

[mazdadude]

LOL, I hear you on the free-rolling feeling of a coasting car. I used to live in an area where I could coast from the top of my driveway, down and up varying hills, and at one point slowing almost to a stop on the crest of the big hill before gravity would get me going once again. I could do this all the way to the nearest gas station several miles away without ever putting the car into gear unless I had accidentally scrubbed too much speed off on one of the corners, or I had a low tire pressure.

I have tried the N-5 shift on nearly all of my other Mazda's from 1980-2003. I found that without revmatching, it is nearly impossible to do the N-5 shift without a nasty sound. I can not say for sure, but your previous experiences doing this on other cars sucessfully might be due to differences in tolerances, design, the angle of the gear cut or depth, etc., etc..

I would vote to try it again, but this time try revmatching the engine to the approx RPM and see how it feels then.

Out of curiosity, do you revmatch as you downshift when you are slowing to a stop?(drive2)