I upgraded my clutch to a SMF SBC stage 2 endurance about 5k miles ago after the stock DMF clutch failed. A few weeks ago I killed the 4th gear synchro. It will go in if you double clutch but grinds any other time. The other synchros like to take their good ole time too it seems with this install. car has dpf delete and stage 2 tune. Ive heard these clutches are hard on synchros after doing reading and i was shifting very quickly when the failure occured. Im currently running 85 140 oil since the synchro failure and it seems to help once the tranny has warmed up. I would like to upgrade the synchro if its possible but i dont know that many or any aftermarket tranny parts are available for this car. Id have to research what tranny codes the later year passats are running to see if theres a better compatible synchro available. Anyone know if the jetta or golf trannys will work on the ckra? Ive talked to a few guys that said the passat got a heavier duty tranny for the weight but im thinking jetta or golf trannys are more available and theres probably more aftermarket upgrade parts available for them. Anyone with any knowledge or info on this would be appreciated!
12' Passat 6MT tranny / synchros upgrade
- Thread starter 767wrench
- Start date
JFettig
Vendor
This is problem #1 - why syncros go.
Which clutch kit did you get? Does it have the super heavy flywheel and the "silent" disk?
Rumor has it that a Fluid Damper will help dampen the chatter characteristics but I find it hard to believe that much more than forcing shifts is what is killing syncros.
It doesn't seem to be an issue in the 02M trans from earlier models, I wonder if all the mounts line up for that trans. I believe you have an 02Q trans.
According to my VIN when looked up my transmission is an NGB. Id have to verify that on the transmission itself though. Im not sure if my clutch is the heavy flywheel silent disk or not. I got it from ID parts. http://idparts.com/catalog/product_info.php?products_id=2523.
So after disassembly and some research my tranny is an 02Q with code NGB. 1st gear synchro ring, 3 and 4 synchro rings and synchro hub parts are broken. After researching trying to find why things broke other than aggressive shifting i ran across a thread about gear oils and how G0 52 oils are much thinner than off the shelf 75w90 oils. im trying to figure out the exact viscosity of G052171A2 for my 02Q but could only find oil analysis numbers for some other G0 52 oils on the forum and they were like 6 ish at 100 degrees where my royal purple is at like 16.5. anyone have the answer for viscosity of G052171A2? id rather run something i can buy cheaper off the shelf but i will go back to G052171A2 if i have to. I believe between running thicker oil and harsh shifting with the new smf flywheel it was too much for the synchros. the locking tabs actually broke off of the rings. Id been running royal purple 75w90 for about 25k miles and a smf sb stage 2 clutch for 5k miles
the other gears were slow cause it had to stir up that 85-140
when you get it back together run something like synchromesh type fluid, or honda MTL
They're thin like water, but still have all the good EP additives that keep gears happy.
when you get it back together run something like synchromesh type fluid, or honda MTL
They're thin like water, but still have all the good EP additives that keep gears happy.
Ya I wasnt ever too knowledgeable on how synchros work but am understanding better now. i switched to 85 140 after the damage had already occurred to protect my gears some while i was still driving the car. but even the 75 90 i was running was way too thick apparently! when i initially changed it i ised an amsoil chart for a G052171A2 equivalent and it said 75 90.i had no idea the stock oil was so thin. hopefully ill be able to keep it together this time!
yup
I had the same issue with my ranger
80-90 and -20 degree temperatures meant the only way it'd shift at all was if you idled it in neutral for a half hour and waited for either the churning or the catalytic converter to warm it up enough, or just revmatched best you could while only using the clutch to get going in first.
Fix_Until_Broke
Top Post Dawg
I made one from a Hercules Hook once on my 02J - might still be in there for the last 75k miles? Probably best to get one from another transmission though.
A5INKY
Vendor , w/Business number
^ That makes a lot of sense to me. Goes along somewhat with what Jon Fettig has been saying about this issue but with a plausible cause effect theory to go with it. We need a good SMF strategy since DMFs seem to be hard to make live behind a tuned engine for the long haul.
Perhaps what is needed is a lighter weight properly sprung disc. Maybe it is time for someone to step up with some more exotic materials for that part.
Perhaps what is needed is a lighter weight properly sprung disc. Maybe it is time for someone to step up with some more exotic materials for that part.
Oh right, and the mass of the friction disk is really insignificant when compared to ALL the gears on the mainshaft and countershaft, and the shafts themselves (though they don't count for much as their mass isn't far from the axis of their rotation.
Something you can do that is somewhat easy is to remove gears you don't use often. Always start out in second? Make up a low mass spacer to fit in the place of first. Gears with a large ratio are the most massive, so removing first will make a much larger difference than removing fifth.
This is why light duty transmissions are going more toward being centered around direct rather than having direct as the top gear. Smaller diameter gears are less abusive on synchronizers. Easy enough to make up the difference in the final drive ratio.
Heavy trucks will still always have direct as the cruising gear, as that means there is less power loss through gear mesh. Synchros are expected to be slow, and drivers are somewhat better trained (usually through very expensive experience)
Turning the sides of the gears that are not in contact down to the width of the contact patch, or are rough "as cast or forged" webs is another easy way to reduce rotating mass that the synchronizers have to deal with.
Something you can do that is somewhat easy is to remove gears you don't use often. Always start out in second? Make up a low mass spacer to fit in the place of first. Gears with a large ratio are the most massive, so removing first will make a much larger difference than removing fifth.
This is why light duty transmissions are going more toward being centered around direct rather than having direct as the top gear. Smaller diameter gears are less abusive on synchronizers. Easy enough to make up the difference in the final drive ratio.
Heavy trucks will still always have direct as the cruising gear, as that means there is less power loss through gear mesh. Synchros are expected to be slow, and drivers are somewhat better trained (usually through very expensive experience)
Turning the sides of the gears that are not in contact down to the width of the contact patch, or are rough "as cast or forged" webs is another easy way to reduce rotating mass that the synchronizers have to deal with.
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Got all my parts ordered today! Even the spring and catch pieces for the synchro hub. I got them from ecs tuning. They had everything in stock and for a fraction of the price of the dealer. They saved me a ton since the dealer would only sell me the entire synchro hub for $350.I definitely plan on shifting slower after this! Thanks for all the input everyone!
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VeeDubTDI
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JFettig
Vendor
I agree, I'm not 100% convinced the added inertia is that significant considering everything else on the input shaft but we have covered what the problem really is "bang shifting" as [486] calls it. Always match revs(easy to time) and don't force into gear.
I owned a S4 that the 1st gear syncro was shot, previous owner(a friend) would always downshift too early coming to a stop(put into 1st while rolling in early holding the clutch until left stop) which killed it over time. Treat the trans right and it'll treat you right.
ETA- I'm switching over to SMF within a week or two so I'll report back my experience on the inertia thing.
I owned a S4 that the 1st gear syncro was shot, previous owner(a friend) would always downshift too early coming to a stop(put into 1st while rolling in early holding the clutch until left stop) which killed it over time. Treat the trans right and it'll treat you right.
ETA- I'm switching over to SMF within a week or two so I'll report back my experience on the inertia thing.
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^This is why, despite popular sentiment, I went with a traditional DMF setup on my passat's 01E. I had heard the stories of excessive synchro wear, and chalked them up to the above, plus excessive force on the shift lever - younger crowd "power shifting" and all.
If you have to force the lever into gear, you're doing it wrong. light pressure on the shifter, and wait for the revs to line up. The shifter falls into gear with minimal pressure, even when cold when you do it right.
If you have to force the lever into gear, you're doing it wrong. light pressure on the shifter, and wait for the revs to line up. The shifter falls into gear with minimal pressure, even when cold when you do it right.
Whitbread
Vendor , w/Business number
I call hogwash on clutch disk weight on anything to do with syncro shattering. If youre running a triple disk sled pulling clutch in your 95 Cummins trying to run at the strip, then yes that will noticeably affect shifting speed. But we're not talking about nv4500's here.
$20 says if you look very closely at the broken off drive dogs of the synchro ring, it will show significant wear marks on both sides. This indicates the ring is whipping back and forth causing fatigue impact damage. Yes, hard shifting certainly doesn't help the matter at all and should be avoided, however its not the only problem at work. The strong shaft speed oscillations from firing pulses at low rpms are the killer here. The 02ms and early 02q's use brass synchro rings and they handle the beating just fine and rattle away like midgets with jack hammers in your trans. The newer 02q's use cast steel synchro rings that don't seem to handle the impact at all. 01E's have a similar problem since their input shaft is 2ft long.
My recommendation is to run redline shockproof gear oil (heavy in hot climate, lightweight if in cool climate), and a fluidampr with an smf coversion for the newer 02q's in the CR cars. Be sure to use the heavy flywheel also, not the 17lb one.
$20 says if you look very closely at the broken off drive dogs of the synchro ring, it will show significant wear marks on both sides. This indicates the ring is whipping back and forth causing fatigue impact damage. Yes, hard shifting certainly doesn't help the matter at all and should be avoided, however its not the only problem at work. The strong shaft speed oscillations from firing pulses at low rpms are the killer here. The 02ms and early 02q's use brass synchro rings and they handle the beating just fine and rattle away like midgets with jack hammers in your trans. The newer 02q's use cast steel synchro rings that don't seem to handle the impact at all. 01E's have a similar problem since their input shaft is 2ft long.
My recommendation is to run redline shockproof gear oil (heavy in hot climate, lightweight if in cool climate), and a fluidampr with an smf coversion for the newer 02q's in the CR cars. Be sure to use the heavy flywheel also, not the 17lb one.
yatzee
Top Post Dawg
I also went with a DMF with the 04 wagon after having used various weights of SMF on previous MK4s. The shift quality is like a new car.
I had that in my head once too, just remember that all modern transmissions are constant mesh, and the disengaged gears spin with the input.
I actually don't know about the 6 speed VW transaxle, what with two final drives, but I assume it is consistent with every other transaxle in that regard.
Heh, reminds me of me when I was just learning to drive a manual.
Did that coming off the freeway at 60 or so. You could hear the input bearings SCREAM. Luckily the friction lining didn't blow off the disc, and that clutch is still functional years later. Trans is a little louder though.
VeeDubTDI
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bhtooefr did that in his old naturally aspirated diesel Golf, but he wasn't so lucky and it blew the clutch to pieces. Oops!
Hm. I guess I could see it being set up that way on a transaxle. I'm used to normal longitudinal trannies where the input drives the countershaft and then the idler gears get clutched to the output. meaning the synchros have to spin up/down every single gear in the transmission.
Whitbread
Vendor , w/Business number
I'll let the pics do the talking.
02J syncro ring with 320K on it, last 200k with g60/vr6 smf. Equal polishing, less than .005" deep wear, on both sides of drive dog.
01E syncro ring with 3000 miles on it. 17lb smf, no fluidamper, OE oil. Notice points of contact that drive ring. Easy .040" deep.
Do you know if there is a fluidampr available for a CKRA? I looked on the fluidampr site and couldn't find one. The part number for the jetta and passat harmonic balancers are different also
CharlieT
Veteran Member
My 01E failed 5th gear synchro at ~3000 miles with an SMF. I believe I know of one other 01E with both 5th & 6th failed.
In fact on the 01E the 5th and 6th gear synchros seem to be more failure prone, as they are at the far end of the input shaft.
I think Mr. Whitbread is correct..
Do you know if the brass synchros from early 02Q are compatible for use in a later 02Q or where to find part numbers for an early 02Q? Im not sure of thw weight of my flywheel as it wasnt a choice for the passat with CKRA engine clutch and smf kit
Kawyrider
New member
767wrench. Did you find out if the syncros from the earlier 02qs will work for the newer 02qs and if vw even sells the older style syncros anymore?
adjat84th
Veteran Member
I making an assumption here that the early 02Q still uses brass because it still uses 02M gears. I had sourced 02M synchros to see about swapping into my '15 02Q, and they will not work. The synchro sets lay into the gears differently, so it's a no go.