Rebuilding 6 speed from a 6th gen.
Rebuilding 6 speed from a 6th gen.
Hello.
Anyone have any pointers or tips whilst rebuilding the 6 speed? I have bad bearings in mine, causing a whine. Also, i get a grind in 3rd if i engage the gear very slowly, is this an indicator of a syncro on its way out?
Thanks.
Anyone have any pointers or tips whilst rebuilding the 6 speed? I have bad bearings in mine, causing a whine. Also, i get a grind in 3rd if i engage the gear very slowly, is this an indicator of a syncro on its way out?
Thanks.
Do you currently have an HLSD? If not, then a Spec V may be more attractive for you because they all have it.
Yes, the crunch on your 3rd gear is a sign of synchro wear and is a common problem.
I'm in a similar dilemma and just made my own thread.
This tranny is not at all hard to take apart and a spec v's guts out and put it in a maxima bellhousing. But that assumes you've been inside a tranny before.
Since you have a 2004 Maxima, it has the same final drive gear ratio as the 02-06 Spec V. If you already have an HLSD tranny, you could easily sell the HSLD unit itself to recoup some money.
You could also use a 07+ Altima 6 speed. It has better synchros. It has triple cone synchros on first and second gear and a double cone synchro on 3rd gear. But the downside is a lack of HSLD.
Using your .630 6th gear swapped onto the spec v's shafts wouldn't be hard at all to swap if you have a press.
Another good thing about the spec V tranny is that they're a dime a dozen. Check out car-part.com.
Yes, the crunch on your 3rd gear is a sign of synchro wear and is a common problem.
I'm in a similar dilemma and just made my own thread.
This tranny is not at all hard to take apart and a spec v's guts out and put it in a maxima bellhousing. But that assumes you've been inside a tranny before.
Since you have a 2004 Maxima, it has the same final drive gear ratio as the 02-06 Spec V. If you already have an HLSD tranny, you could easily sell the HSLD unit itself to recoup some money.
You could also use a 07+ Altima 6 speed. It has better synchros. It has triple cone synchros on first and second gear and a double cone synchro on 3rd gear. But the downside is a lack of HSLD.
Using your .630 6th gear swapped onto the spec v's shafts wouldn't be hard at all to swap if you have a press.
Another good thing about the spec V tranny is that they're a dime a dozen. Check out car-part.com.
Do you currently have an HLSD? If not, then a Spec V may be more attractive for you because they all have it.
Yes, the crunch on your 3rd gear is a sign of synchro wear and is a common problem.
I'm in a similar dilemma and just made my own thread.
This tranny is not at all hard to take apart and a spec v's guts out and put it in a maxima bellhousing. But that assumes you've been inside a tranny before.
Since you have a 2004 Maxima, it has the same final drive gear ratio as the 02-06 Spec V. If you already have an HLSD tranny, you could easily sell the HSLD unit itself to recoup some money.
You could also use a 07+ Altima 6 speed. It has better synchros. It has triple cone synchros on first and second gear and a double cone synchro on 3rd gear. But the downside is a lack of HSLD.
Using your .630 6th gear swapped onto the spec v's shafts wouldn't be hard at all to swap if you have a press.
Another good thing about the spec V tranny is that they're a dime a dozen. Check out car-part.com.
Yes, the crunch on your 3rd gear is a sign of synchro wear and is a common problem.
I'm in a similar dilemma and just made my own thread.
This tranny is not at all hard to take apart and a spec v's guts out and put it in a maxima bellhousing. But that assumes you've been inside a tranny before.
Since you have a 2004 Maxima, it has the same final drive gear ratio as the 02-06 Spec V. If you already have an HLSD tranny, you could easily sell the HSLD unit itself to recoup some money.
You could also use a 07+ Altima 6 speed. It has better synchros. It has triple cone synchros on first and second gear and a double cone synchro on 3rd gear. But the downside is a lack of HSLD.
Using your .630 6th gear swapped onto the spec v's shafts wouldn't be hard at all to swap if you have a press.
Another good thing about the spec V tranny is that they're a dime a dozen. Check out car-part.com.
According to the 2004 FSM, page MT-65, there is no double or triple cone synchro on the 3rd gear. Only on 1st and 2nd gear.
Do you currently have an HLSD? If not, then a Spec V may be more attractive for you because they all have it.
Yes, the crunch on your 3rd gear is a sign of synchro wear and is a common problem.
I'm in a similar dilemma and just made my own thread.
This tranny is not at all hard to take apart and a spec v's guts out and put it in a maxima bellhousing. But that assumes you've been inside a tranny before.
Since you have a 2004 Maxima, it has the same final drive gear ratio as the 02-06 Spec V. If you already have an HLSD tranny, you could easily sell the HSLD unit itself to recoup some money.
You could also use a 07+ Altima 6 speed. It has better synchros. It has triple cone synchros on first and second gear and a double cone synchro on 3rd gear. But the downside is a lack of HSLD.
Using your .630 6th gear swapped onto the spec v's shafts wouldn't be hard at all to swap if you have a press.
Another good thing about the spec V tranny is that they're a dime a dozen. Check out car-part.com.
Yes, the crunch on your 3rd gear is a sign of synchro wear and is a common problem.
I'm in a similar dilemma and just made my own thread.
This tranny is not at all hard to take apart and a spec v's guts out and put it in a maxima bellhousing. But that assumes you've been inside a tranny before.
Since you have a 2004 Maxima, it has the same final drive gear ratio as the 02-06 Spec V. If you already have an HLSD tranny, you could easily sell the HSLD unit itself to recoup some money.
You could also use a 07+ Altima 6 speed. It has better synchros. It has triple cone synchros on first and second gear and a double cone synchro on 3rd gear. But the downside is a lack of HSLD.
Using your .630 6th gear swapped onto the spec v's shafts wouldn't be hard at all to swap if you have a press.
Another good thing about the spec V tranny is that they're a dime a dozen. Check out car-part.com.
Not referring to that, im addressing the 3rd gear crunch all 02-03 maxima 6 speeds get along the way as miles pile up, 6th gen maximas trans do not have that issue.
That is what causes the crunch. 3rd gear on the 02-04 trannies has a weak synchro that wears out as the miles pile up. The 2004 6th gen has this issue too. The 2005 and 2006 have an upgraded synchro on 3rd gear. The 2008 Altima has a synchro on 3rd gear that is even better than that because it was still problematic.
first time i did it it took all day, second time took 2 hours. it's not hard, just gotta remember all the steps.
The most annoying aspect of swapping the spec-v guts to the new housing is finding the proper size shims and measuring all the clearances. Some shims take like 4 weeks to come from Nissan.
Which lends credence to the belief that most tranny rebuilders don't give two $hits about actually doing the job right, but to make a quick buck.
i've never worked at a "normal" trans shop but I would not be surprised if they don't reshim transmissions. it takes time and doesn't really gain them anything in the short term. by the time a trans fails from improper shimming it will be out of warranty anyways.
Well i picked up a low mileage maxima trans.
Hopefully it wont sound like dog cut gears in 3rd and above gears. I don't want to venture into a manual gearbox. Ive rebuilt a couple autos, mainly mazdas 626 since they easily overheat and cook inside. Just afraid of the shimming process, but i might rebuild my current one i took off the car.
Once i get some disposable income, i might make a go for it.
Well bummer, gonna pour some amsoil and hope it does not occur. Ever.
Hopefully it wont sound like dog cut gears in 3rd and above gears. I don't want to venture into a manual gearbox. Ive rebuilt a couple autos, mainly mazdas 626 since they easily overheat and cook inside. Just afraid of the shimming process, but i might rebuild my current one i took off the car.
Once i get some disposable income, i might make a go for it.
That is what causes the crunch. 3rd gear on the 02-04 trannies has a weak synchro that wears out as the miles pile up. The 2004 6th gen has this issue too. The 2005 and 2006 have an upgraded synchro on 3rd gear. The 2008 Altima has a synchro on 3rd gear that is even better than that because it was still problematic.
Last edited by L36; May 11, 2012 at 06:48 PM.
I got school all year round.
I find autos much easier to do for some reason, its like legos.
Nonetheless, i might rebuild it since i did get a slight 3rd gear crunch, only occurred if i shifted slowly.
Alright, so new trans is on the car, should have the car on the road tomorrow. Il probably start taking apart the old trans with pics to see how bad the bearing damage was. Also, going to try getting syncors and syncro hub from a altima coupe 6 speed to eliminate the 3rd gear crunch. Should be interesting. Although il need to clean up my garage and make some clean work space.
Also, can anyone fill me in how the shimming process works on these trans?
Youtube is no help.
Also, can anyone fill me in how the shimming process works on these trans?
Youtube is no help.
You want the bearings and shafts to be snug in the case, not flopping around inside the tranny. But you also don't want it so tight that it dramatically increases the load and wear on the bearings. Since there are manufacturing tolerances in the bearings, shafts, the case itself, as well as wear that occurs, you need to dial in the tightness of everything. This is what shimming does.
The easiest way to do all of this is to remove the existing shims and put solder in its place. You then torque down the case which crushes the solder on the end of the input shaft, main shaft, and differential to the exact thickness that makes everything nice and snug. You then remove the case and measure the crushed thickness of the solder. This thickness is the size shim that you need.
Shimming isn't hard if you understand what the point is to it. You have three shafts in a tranny-the input shaft, main shaft, and output shaft (differential). There are bearings at the ends of the shafts.
You want the bearings and shafts to be snug in the case, not flopping around inside the tranny. But you also don't want it so tight that it dramatically increases the load and wear on the bearings. Since there are manufacturing tolerances in the bearings, shafts, the case itself, as well as wear that occurs, you need to dial in the tightness of everything. This is what shimming does.
The easiest way to do all of this is to remove the existing shims and put solder in its place. You then torque down the case which crushes the solder on the end of the input shaft, main shaft, and differential to the exact thickness that makes everything nice and snug. You then remove the case and measure the crushed thickness of the solder. This thickness is the size shim that you need.
You want the bearings and shafts to be snug in the case, not flopping around inside the tranny. But you also don't want it so tight that it dramatically increases the load and wear on the bearings. Since there are manufacturing tolerances in the bearings, shafts, the case itself, as well as wear that occurs, you need to dial in the tightness of everything. This is what shimming does.
The easiest way to do all of this is to remove the existing shims and put solder in its place. You then torque down the case which crushes the solder on the end of the input shaft, main shaft, and differential to the exact thickness that makes everything nice and snug. You then remove the case and measure the crushed thickness of the solder. This thickness is the size shim that you need.
Il give it a go once i get spare time, although my current trans seems really nice. I haven't driven it much, but it shifts so smooth for the period i did.
So pretty much similar to what they guys do on motors when determining the gap between rods and the crank. Only trans edition.
Il give it a go once i get spare time, although my current trans seems really nice. I haven't driven it much, but it shifts so smooth for the period i did.
Il give it a go once i get spare time, although my current trans seems really nice. I haven't driven it much, but it shifts so smooth for the period i did.
Manual trannies use splash lubrication and ball bearings. The races of the bearing need to be snug with the case and with the *****. There's zero clearance, unlike with fluid dynamic bearings.
Using plastigauge to measure clearances in journal bearings and using solder to determine shim size have the same end result-crushing, but for completely opposite purposes. Journal bearings need a specified range of clearance. There should be zero clearance with ball bearings plus a little preload put on them.
Last edited by Weimar Ben; May 19, 2012 at 01:32 AM.
No, it's not really like that at all. With journal (fluid dynamic) bearings as found in the crank pin and the rod, the oil pressure flows through the gap and the metal hydroplanes on the pressurized oil. A hovercraft uses the same principle-the air is blown against the ground, which supports the vehicle. In the case of an engine, it's pressurized oil that supports the moving parts.
Manual trannies use splash lubrication and ball bearings. The races of the bearing need to be snug with the case and with the *****. There's zero clearance, unlike with fluid dynamic bearings.
Using plastigauge to measure clearances in journal bearings and using solder to determine shim size have the same end result-crushing, but for completely opposite purposes. Journal bearings need a specified range of clearance. There should be zero clearance with ball bearings plus a little preload put on them.
Manual trannies use splash lubrication and ball bearings. The races of the bearing need to be snug with the case and with the *****. There's zero clearance, unlike with fluid dynamic bearings.
Using plastigauge to measure clearances in journal bearings and using solder to determine shim size have the same end result-crushing, but for completely opposite purposes. Journal bearings need a specified range of clearance. There should be zero clearance with ball bearings plus a little preload put on them.
Guess i have reading up to do before i attempt anything.
Fluid bearings (which is a bit of a misnomer) need a certain looseness in order for the oil pump to support the load. Older engines have low oil pressure because their clearances have worn down and become loose. A thin film of pressurized oil supports the load. At some point the clearances get so large, the oil pump can no longer provide enough oil pressure to support the load and then metal to metal contact continuously occurs. It's not long after that begins to happen that the engine seizes up or you break a rod.
On the other hand, fluid bearings can theoretically last forever, especially in engines that are never or rarely shut down.
I think is is pretty simple. Ball bearings need to be snug, but not tight. They reduce friction by simply rolling around in a race.
Fluid bearings (which is a bit of a misnomer) need a certain looseness in order for the oil pump to support the load. Older engines have low oil pressure because their clearances have worn down and become loose. A thin film of pressurized oil supports the load. At some point the clearances get so large, the oil pump can no longer provide enough oil pressure to support the load and then metal to metal contact continuously occurs. It's not long after that begins to happen that the engine seizes up or you break a rod.
On the other hand, fluid bearings can theoretically last forever, especially in engines that are never or rarely shut down.
Fluid bearings (which is a bit of a misnomer) need a certain looseness in order for the oil pump to support the load. Older engines have low oil pressure because their clearances have worn down and become loose. A thin film of pressurized oil supports the load. At some point the clearances get so large, the oil pump can no longer provide enough oil pressure to support the load and then metal to metal contact continuously occurs. It's not long after that begins to happen that the engine seizes up or you break a rod.
On the other hand, fluid bearings can theoretically last forever, especially in engines that are never or rarely shut down.
Thanks.
So if you measure 0.79mm, you select a 0.84mm shim.
IMAO, I think it's better to be a little on the loose side. A little bit of slop will cause less of a problem than oversized shims with excessive preload. When torque is applied, it'll load up the bearings and shafts up against the tranny case anyways and in the case of the 6spd tranny, the mainshaft is held in place to the case with a snap ring anyways. I think you could run that without any shim.
IIRC, the FSM basically says to add a little thickness to the shim, like 0.05mm. That's .002."
So if you measure 0.79mm, you select a 0.84mm shim.
IMAO, I think it's better to be a little on the loose side. A little bit of slop will cause less of a problem than oversized shims with excessive preload. When torque is applied, it'll load up the bearings and shafts up against the tranny case anyways and in the case of the 6spd tranny, the mainshaft is held in place to the case with a snap ring anyways. I think you could run that without any shim.
So if you measure 0.79mm, you select a 0.84mm shim.
IMAO, I think it's better to be a little on the loose side. A little bit of slop will cause less of a problem than oversized shims with excessive preload. When torque is applied, it'll load up the bearings and shafts up against the tranny case anyways and in the case of the 6spd tranny, the mainshaft is held in place to the case with a snap ring anyways. I think you could run that without any shim.
Will order a new 3rd gear syncro, hub and pin off the altima coupe to solve my 3rd gear grind. Not sure i need a new hub, but it did grind pretty bad...
no no no no no
Ball bearings require END PLAY. not preload. you preload ball bearings and you are going to wear them out with a quickness. You do your solder crush, and then SUBTRACT whatever the FSM says, not add.
edited for generation specific info:
The input shaft and main shaft in the 6spd maxima transmission have ball bearings that require end play of 0 - 0.06mm. If it's a brand new bearing I would err toward the tighter end of the spectrum, like 0.02mm or so. if it is used i'd go more for 0.04 or so.
Ball bearings require END PLAY. not preload. you preload ball bearings and you are going to wear them out with a quickness. You do your solder crush, and then SUBTRACT whatever the FSM says, not add.
edited for generation specific info:
The input shaft and main shaft in the 6spd maxima transmission have ball bearings that require end play of 0 - 0.06mm. If it's a brand new bearing I would err toward the tighter end of the spectrum, like 0.02mm or so. if it is used i'd go more for 0.04 or so.
no no no no no
Ball bearings require END PLAY. not preload. you preload ball bearings and you are going to wear them out with a quickness. You do your solder crush, and then SUBTRACT whatever the FSM says, not add.
edited for generation specific info:
The input shaft and main shaft in the 6spd maxima transmission have ball bearings that require end play of 0 - 0.06mm. If it's a brand new bearing I would err toward the tighter end of the spectrum, like 0.02mm or so. if it is used i'd go more for 0.04 or so.
Ball bearings require END PLAY. not preload. you preload ball bearings and you are going to wear them out with a quickness. You do your solder crush, and then SUBTRACT whatever the FSM says, not add.
edited for generation specific info:
The input shaft and main shaft in the 6spd maxima transmission have ball bearings that require end play of 0 - 0.06mm. If it's a brand new bearing I would err toward the tighter end of the spectrum, like 0.02mm or so. if it is used i'd go more for 0.04 or so.
"End play: 0 - 0.06 mm (0 - 0.0024 in)
Dimension “P” = “M” + End play
P: Thickness of adjusting shim
M: Distance between mainshaft rear bearing and
transaxle case"
Yes, the FSM is using the verbiage "end play", but if you select a shim that is larger in thickness than the gap between the bearing and case, you are applying a preload to the bearing.
The FSM says NOTHING about subtraction. From MT-47 in the 2003 FSM:
"End play: 0 - 0.06 mm (0 - 0.0024 in)
Dimension “P” = “M” + End play
P: Thickness of adjusting shim
M: Distance between mainshaft rear bearing and
transaxle case"
Yes, the FSM is using the verbiage "end play", but if you select a shim that is larger in thickness than the gap between the bearing and case, you are applying a preload to the bearing.
"End play: 0 - 0.06 mm (0 - 0.0024 in)
Dimension “P” = “M” + End play
P: Thickness of adjusting shim
M: Distance between mainshaft rear bearing and
transaxle case"
Yes, the FSM is using the verbiage "end play", but if you select a shim that is larger in thickness than the gap between the bearing and case, you are applying a preload to the bearing.
Subtraction of 0-0.06mm from the solder thickness when you do the crush is how you come up with the shim thickness required, NOT addition. Either that equation you listed is incorrect, or we are both misunderstanding the meaning of it. I agree with you that equation appears to indicate that you add 0.00-0.06mm to the distance M, but that is not correct, you subtract it. If that equation is from the FSM, it would not be the first time that there has been an FSM error.
To add any significant preload to a ball bearing in a transmission will significantly reduce its lifespan unless you can wear and heat that preload out (as a race application would quickly do, due to thermal expansion of the case and slight bedding in of the bearing). It is wisest to set it up with 0 preload (0 to low end of the range of allowable end play) if it is a race application/hard usage application, or the lower end of the allowable end play if it is a normal street application (depending a little bit on bearing condition and usage/reusage). I have heard of a few builders recommending a tiny (like 0.01mm) bit of preload on a brand new bearing because especially in a race application it will quickly wear that preload into a neutral or slight end play condition as the ***** of the bearing bed in slightly, but that is not what my mentor recommended when i was building race and high performance transmissions for a living).