# how bad is it to grind gears?



## Banditt007 (Oct 23, 2002)

While i dont grind gears often at all occasionally i do. TOnight i ground second pretty good, i beleive it to be a combination of new shoes (on my feet not the car) and a new shift knob i installed b/c everything feels completly different. 
Everytime i grind a gear i cringe and think about it for like 3 days and feel really bad about it and feel like i took sooo much life off the tranny.

Anyway, back when my car had much less miles on it 3rd gear i used to grind a good bit even shifting really slow at high rpm, a bunchof us had it, and w/ milage it seems the whole tranny loosens up alot shifts great and no more problems w/ 3rd gear.
Anyway i most always let the syncros do the work and shift easy and usually waiting for the syncros puts me right around the rpm for the next gear when it slides in. Even when racing i'm not one to start pounding through gears. I always am very easy on the tranny, double clutching downshifts/rev matching ect. But very rarely i get too pumped up and and will bang a gear and most times thats not a problem but it will grind others. _So i'm not looking on advice on how to not grind, i know its my fault when it does happen and know how to avoid it. I'm asking what kind of damage happens when you do grind_.

But what i'd like to know is the following
-When you ocassionally grind gears how much damage is it doing, and when you crack open the tranny is it like DAM those gears are really beat up or what?
-Do our tranny's have any magnets inside them to minimize metal floating around in the fluid and further damaging parts in the tranny?
-If the tranny does in fact need a new gear or syncro is that super labor intensive, and can you get individual parts for our trannys?
-Like how much does your average gear or syncro cost on these things/work to put them in.
also if anyone knows the thread size/pitch of the fill and drain plugs that would be helpful i want to track down some plugs that are magnetic.

_Modified by Banditt007 at 2:04 AM 6-30-2005_


_Modified by Banditt007 at 2:05 AM 6-30-2005_


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## AlecGTI (Aug 22, 2003)

If it's only occasional it's not really that big of a deal. The synchros wear anyway doing their job.
Mostly what's wearing when you grind is the synchros. You do grind the gears themselves too, but the synchros much more. The synchros are made of brass, and thus are much softer than the steel gears, and thus wear much easier. Unfortunately, since the synchros are brass, a magnet doesn't help pick up the flakes; though it will help with small flakes from the gears.
Individual parts are available as far as I know.
Rebuilding a manual tranny is usually pretty much an all or nothing deal. The labor is pretty much the same whether you're replacing one synchro ring or all of them. The only difference is parts cost. That's why many take the opportunity to change gear ratios, install an LSD, etc.
Again, a magnetic plug will only help a bit. Most of the particles created with normal wear are brass.


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## Jcr1982 (Jul 18, 2002)

*Re: (AlecGTI)*


_Quote, originally posted by *AlecGTI* »_If it's only occasional it's not really that big of a deal. The synchros wear anyway doing their job.
Mostly what's wearing when you grind is the synchros. You do grind the gears themselves too, but the synchros much more. The synchros are made of brass, and thus are much softer than the steel gears, and thus wear much easier. Unfortunately, since the synchros are brass, a magnet doesn't help pick up the flakes; though it will help with small flakes from the gears.
Individual parts are available as far as I know.
Rebuilding a manual tranny is usually pretty much an all or nothing deal. The labor is pretty much the same whether you're replacing one synchro ring or all of them. The only difference is parts cost. That's why many take the opportunity to change gear ratios, install an LSD, etc.
Again, a magnetic plug will only help a bit. Most of the particles created with normal wear are brass.

Yeah thats all right on point. http://****************.com/smile/emthup.gif


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## 2002gtibluvr6 (Oct 5, 2002)

*Re: (Jcr1982)*

there is no official rebuild kit from VW for this tranny. trust me in my little adventure they were gonna just rebuild it but there were no parts available for the 6 speeds.
you never will actually hear a gear grind, all the gears are spinning all the time, what grind is the synchros trying to mesh the gears together.
as you know its not good to grind but its not like extremely detrimental, in think on the tranny that just went out in my car the gear ground maybe 10 times in the 18k miles i had it, like 7 of those were other people driving the car. 
its reall yhard to say how bad it is persay and put a number on it or something. also synchros arent the only things that go out in trannys, ive seen a couple six speeds *personally not mine but other peopls in service* for differential shims going bad. basically the part that keeps the differential in place and in line with everything fails and things start rattling like crazy. ive enver actually seen a broken gear in the 6speed i doubt you will ever see it


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## BigBlockBug (Oct 7, 2003)

*Re: (AlecGTI)*


_Quote, originally posted by *AlecGTI* »_ You do grind the gears themselves too.

To clarify you do not grind or damage the gears as in the 1st 2nd or 3rd speed gears, all you are grinding are the teeth or "gears" on the blocker rings. all of the gears 1st through 6th, (sometimes but mostly not including reverse, based upon the design) are always engaged with each other, always... there are two shafts in the trans that these gears ride on and the driven gears ride on the output shaft, all the blocker rings and synchros do is lock the given gears rotation to the shaft it is connected to, rather then letting it freewheel. When you are in 3rd gear the 3rd gear is locked to the shaft its housed on, and all the other gears, while engaged, are freewheeling on their respective shafts.
The only transmissins that do disengage contact between driven gears are the old 3 speeds, where double clutching is necessary to shift.
The gears that ride in our transmissions between pilot shaft and output shaft are all helical cut gears, meaning they cannot be engaged and disenegaged due to the mesh design of the gears. this feature adds strength to the gears and trans. hence why constant engagement is necassary. Ill see if I can find a pic....


_Modified by BigBlockBug at 10:55 AM 6-30-2005_


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## BigBlockBug (Oct 7, 2003)

*Re: (BigBlockBug)*









The *spur gear *is the simplest design used in manual transmissions and transaxles.
-Its main advantage is that its teeth are cut straight so it can slide in and out of contact with other gears 
-Its main disadvantage is that it is noisy during operation. The spur gear whines at high speed 
-If a spur gear is found in a manual transmission/transaxle, it is usually only used for reverse gear 








*Helical gears* are the most common types of gears used in manual transmissions and transaxles. These gears are cut at an angle to the gear’s axis of rotation. This allows two or more teeth to be in full contact at all times during operation. 
-The main advantages are that helical gears operate much more quietly and are much stronger than spur gears 
-The main disadvantage is that they cannot slide in and out of contact with their adjoining gears. Since this is the case, another common name for helical gears is constant-mesh gears 
-Helical gears are used for all forward speed gears, and in some cases, reverse 

As explained in the Gears section, *all forward-driving gears in modern transmissions are helical gears*. This makes them quiet and gives them additional strength. However, because the teeth of helical gears are angled, they cannot be slid into and out of engagement with each other. 
For this reason, the speed gears are not directly splined to the shaft upon which they ride. Their inner diameter is smooth, allowing them to rotate freely on the shaft. 
When the gear needs to be connected to the shaft, the synchronizer sleeve moves over and engages the clutching teeth on the side of the gear. 
-This locks the synchronizer sleeve to the speed gear 
-The synchronizer sleeve inner diameter has internal teeth that slide along the external teeth of the synchronizer hub outer diameter 
-The synchronizer hub is splined to the shaft's inner diameter 

Synchronizing Gear and Shaft Speed 
Another function of the synchronizer is to make the speed of the speed gears match that of the shaft before the gear is locked to the shaft. This must be done since the rotating speed of the gear is different than the speed of the shaft. If the speed of the gear and shaft weren’t the same before the synchronizer sleeve engaged the gear’s clutching teeth, both the sleeve and the clutching teeth could be damaged. 
Synchronizing Gear and Shaft Speed 
When a gear is selected, the shift fork forces the synchronizer sleeve toward the speed gear. 
A blocking ring, which has a cone-shaped inner surface, is pushed into contact with the cone-shaped shoulder of the speed gear. As the synchronizer sleeve continues to move, it compresses the inserts against the retaining springs. As it moves further, the sleeve splines mate with teeth on the blocking ring. Friction between the blocking ring and gear shoulder causes the gear, which is rotating freely on the shaft, to speed up or slow down to the same speed of the synchronizer. The blocking ring prevents the sleeve’s splines from engaging the gear’s clutching teeth until they are all rotating at the same speed. 
When the blocking ring, which is connected to the synchronizer, and the speed gear teeth are lined up, the synchronizer sleeve can slide over the gear’s clutching teeth, locking the gear to the shaft. As this happens, the compressed inserts move into a notch on the inner diameter of the sleeve. This helps hold the sleeve in place.









The driven Gear ^ #3 normally will freewheel on the shaft #4, untill the grooves in the synchro #2 match up to the teeth on the blocking ring ( just to the left of the driven gear #3) this action locks the driven gear to the output shaft and the chosen gear is now the gear the transmission is operating in.
Thats the best pic i could find, all the rest are Flash files and I cand pull them off the page.



_Modified by BigBlockBug at 11:23 AM 6-30-2005_


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## AlecGTI (Aug 22, 2003)

I meant the clutching teeth on each speed gear. Those do wear with the blocker rings, just much less since they're steel and not brass.


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## BigBlockBug (Oct 7, 2003)

*Re: (AlecGTI)*

I knew you knew what you were talking about, just clarifying for the readers







I knew they would have seen "gear" and assumed.
then I got out of hand with the info, found alot on one of my old web based training programs from class.


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## Banditt007 (Oct 23, 2002)

*Re: (BigBlockBug)*

def good info all, this thread blew up quick.


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## BigBlockBug (Oct 7, 2003)

*Re: (Banditt007)*

this is what these forums are for http://****************.com/smile/emthup.gif


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## MeiK (Mar 18, 2005)

*Re: (BigBlockBug)*

Wonderfully informative chaps! I'm glad my tranny is'nt quite doomed yet.







Yet.


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## 2002gtibluvr6 (Oct 5, 2002)

*Re: (MeiK)*

like i said there is more parts in your tranny to worry about then synchros. . . never be so sure your tranny is safe from destruction, it can happen in any car at any time you just never know


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## BigBlockBug (Oct 7, 2003)

*Re: (2002gtibluvr6)*

after having about 14 manual trans overhauls under my belt now, I need to reiterate the importance of taking your hand off the shifter while driving, dont leave it there, and dont hold on to it in 2nd gear going around corners for leverage, this one usually seems to be the worst
The forks that ride down in the synchro get worn down from this force holding it into the synchro, once it wears down it has to travel that much further to enage gears, and will help cause missed shifts and grinding gears.
Just my public service announcement for the day


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## jeremyc74 (Dec 30, 2004)

*Re: (BigBlockBug)*


_Quote, originally posted by *BigBlockBug* »_after having about 14 manual trans overhauls under my belt now, I need to reiterate the importance of taking your hand off the shifter while driving, dont leave it there, and dont hold on to it in 2nd gear going around corners for leverage, this one usually seems to be the worst
The forks that ride down in the synchro get worn down from this force holding it into the synchro, once it wears down it has to travel that much further to enage gears, and will help cause missed shifts and grinding gears.
Just my public service announcement for the day









Are those 14 all on VWs? Or differant makes? 
I've done one VW, a couple of other manuals and one automatic. I hated the VW, because of all the odd tools I had to buy (it was a Scirocco tranny), but the autos were the worst. It's so hard to tell what's actually going on in there.
BTW, good advice about taking your hand off the shifter. http://****************.com/smile/emthup.gif


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## BigBlockBug (Oct 7, 2003)

*Re: (jeremyc74)*

good majority were Fords, had a couple chryslers and 1 VW. I feel your pain on the VW though I made no money off that one because i had to "rent" the tools i needed from the resident veteran tranny tech.


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## oldspice (Jul 21, 2003)

*Re: (BigBlockBug)*

i need some advice on what to do because i grind quite often.. probably 3 or more times a week, and its not me.. i swear...atleast not any more.. i gorilla shifted a bit in the past. like a year ago, but now i have like 25000 miles on and occasionally when i shift into either 2nd or third.. usually when the car has been driven for more than 30 min, i'll get a grind, but the clutch is all the way in, and i purposely try not to grind, like i'll be trying to downshift from 3rd to 2nd. and i'll match rmps and it'll still just make a little grind while i'm going into gear.. i dont' know what to do... i was planning on just trying to argue it under warrentee when i get closer to 36000... any ideas.. i'm sure its just my synchros but any advice?


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## BigBlockBug (Oct 7, 2003)

*Re: (oldspice)*

its your synchros, from exerting more pressure while shifting then you should have in the past you have worn the cones in the brass down to far and they arent generating enough friction anymore to match speed to the blocking rings. not to mention after all the grinding the blocking rings and synchros im sure are rounded off.
you need a ttrans overhaul plain and simple. A temporary stop gap solution might be swapping fluid to redline MT-90. It has a better friction modifier and might prolong its life a bit more.


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## 2002gtibluvr6 (Oct 5, 2002)

*Re: (BigBlockBug)*

kraftwerks is a good company if your looking to rebuild a VW tranny. thats basically their whole purpose of exsistance is to rebuild custom/stock trannys for VW's
ive heard nothing but good things about them, and considering the tranny i have in my car right now was built by them and i love it id definatly recommend them.
they can rebuild stock setup or they can re-gear it however you want, put a diff in there theres a bunch they can do.


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## kungfoojesus (Jan 10, 2005)

What kind of range have you all seen for the cost of tranny rebuilds? Just a ballpark estimate for a basic, stock rebuild. I'm only at 9,000 miles but would like to know for informative purposes.


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## oldspice (Jul 21, 2003)

*Re: (kungfoojesus)*

yeah,, and would replacing syncros be on warantee at all?


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## Banditt007 (Oct 23, 2002)

*Re: (oldspice)*

i had the same problem, oldspice. Only when the car and tranny were hot, like you said after driving 30 minutes or more, especially when really racing on it. Even w/ the clutch to the floor and granny shifting into third i'd get a grind. Now at 45k miles there is no grind unless you are shifting like an idiot, it was one of those things that 'cured itself' Happened for like 5k miles then went away.


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## oldspice (Jul 21, 2003)

*Re: (Banditt007)*

see it kind of goes away on its own for me too, but i think its just because i'm subconsiously trying to avoid it and not shifting normal... so i took it in and now i'm getting a new 2nd gear, 2nd gear synchro, 3rd gear and 3rd gear synchro all under warantee


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## Schwagger (Jun 4, 2003)

*Re: (BigBlockBug)*


_Quote, originally posted by *BigBlockBug* »_after having about 14 manual trans overhauls under my belt now, I need to reiterate the importance of taking your hand off the shifter while driving, dont leave it there, and dont hold on to it in 2nd gear going around corners for leverage, this one usually seems to be the worst
The forks that ride down in the synchro get worn down from this force holding it into the synchro, once it wears down it has to travel that much further to enage gears, and will help cause missed shifts and grinding gears.
Just my public service announcement for the day









ahhh crap . I always have my hand on the stick, but I never put pressure on it.. Guess I will have to stop doing that. 

Nice write up on the gears.. very interesting.


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