reasembling my transmission but its stuck in 4th gear
#1
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Thread Starter
reasembling my transmission but its stuck in 4th gear
got my transmission all apart and now I'm putting it back together, its a turbo s4 transmission. I have the lunchbox put back together (all the gears inside the central casing) but for some reason something is binding the input shaft to the output shaft and it isn't the shifter sleeve. when I put the sleeve in 4th everything spins but if I take it out of gear and then slide it into another gear it acts like its in 2 gears at once but its not, and I cant move the input shaft independently from the output shaft even when all the shifter sleeve are in the neutral position.
so what could it be? I know i probably didn't put something back together right but I want to know what it is before I start pulling those bearings back out.
so what could it be? I know i probably didn't put something back together right but I want to know what it is before I start pulling those bearings back out.
#2
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on the M box when you put the input shaft bearing on it can jam the 4th gear synchro, not bad to pop it apart, maybe this is you?
#3
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Thread Starter
#4
Senior Member
4th is direct drive, so you should have the input shaft locked to the output shaft, and the countershaft rotating according to the input shaft. If everything is spinning ok in 4th, that means 1st and 2nd aren't binding or engaged. It also means that your front bearings should still be at an ok depth (input shaft and countershaft teeth would start eating each other if not). I agree with j9fd3s that you likely have a problem with the bearing that goes inside the back of the input shaft. If that is bound, you will only have a direct drive scenario because the input and output shafts can't move independently. Load that sucker with grease prior to assembly.
#5
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Thread Starter
4th is direct drive, so you should have the input shaft locked to the output shaft, and the countershaft rotating according to the input shaft. If everything is spinning ok in 4th, that means 1st and 2nd aren't binding or engaged. It also means that your front bearings should still be at an ok depth (input shaft and countershaft teeth would start eating each other if not). I agree with j9fd3s that you likely have a problem with the bearing that goes inside the back of the input shaft. If that is bound, you will only have a direct drive scenario because the input and output shafts can't move independently. Load that sucker with grease prior to assembly.
#6
Senior Member
There is another point to consider as well. Can you spin the 4th gear synchro freely when the 4th gear forks aren't engaged? If it does not spin, it could be that the input and output shafts are too close to each other and may need shimmed to space them apart correctly. If the 4th gear synchro can spin freely, then the problem is with alignment, or that intermediate bearing.
#7
Senior Member
Thread Starter
There is another point to consider as well. Can you spin the 4th gear synchro freely when the 4th gear forks aren't engaged? If it does not spin, it could be that the input and output shafts are too close to each other and may need shimmed to space them apart correctly. If the 4th gear synchro can spin freely, then the problem is with alignment, or that intermediate bearing.
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#9
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Edit: lubed up the synchro and pulled the input shaft away from the output shaft a bit and it finally budged. the counter shaft gear that meshes with the one on the input shaft isn't meshing right but I think that's because I don't have that bearing installed yet because if I hold it in place with my finger on that end it cooperates. thanks for the help
Last edited by Paulc19; 01-17-22 at 04:53 PM.
#10
Senior Member
Fantastic! Sounds like you'll need to spend some extra care on shimming. Its not a fun crunchy noise when the input and countershaft aren't depthed correctly and it was your first transmission rebuild and you were so proud of it and you just showed your wife...
Let us know if you need anything.
Let us know if you need anything.
#11
Senior Member
Thread Starter
Fantastic! Sounds like you'll need to spend some extra care on shimming. Its not a fun crunchy noise when the input and countershaft aren't depthed correctly and it was your first transmission rebuild and you were so proud of it and you just showed your wife...
Let us know if you need anything.
Let us know if you need anything.
#12
Senior Member
Couple things here.
1. Did you keep the C-washers near the rear mainshaft bearing separated into front and rear sets when you disassembled? The manual says they can be different thicknesses.
2. Are you re-using your mainshaft and countershaft bearings? If not, you will need to tolerance and shim the transmission to within that tolerance or the sucker will be either too sloppy and break, or be locked up. There are shims that go either above or below the great big snap ring (that you used the puller on), for the input shaft and counter shaft front bearings. For the output shaft, make sure the C washers are correct (or if they're the same size, don't worry about them) and there is a thrust washer that goes in between the output shaft bearing and the 1-2 gear pack. This sets the correct tolerance for the output shaft. There is also another thrust washer on the other side of the bearing and the whole shaft is squeezed down by the nut on the end.
How far did you take this thing apart? What parts are different? Let's start with that and we can get you going. Nothings broke yet!!!!!
1. Did you keep the C-washers near the rear mainshaft bearing separated into front and rear sets when you disassembled? The manual says they can be different thicknesses.
2. Are you re-using your mainshaft and countershaft bearings? If not, you will need to tolerance and shim the transmission to within that tolerance or the sucker will be either too sloppy and break, or be locked up. There are shims that go either above or below the great big snap ring (that you used the puller on), for the input shaft and counter shaft front bearings. For the output shaft, make sure the C washers are correct (or if they're the same size, don't worry about them) and there is a thrust washer that goes in between the output shaft bearing and the 1-2 gear pack. This sets the correct tolerance for the output shaft. There is also another thrust washer on the other side of the bearing and the whole shaft is squeezed down by the nut on the end.
How far did you take this thing apart? What parts are different? Let's start with that and we can get you going. Nothings broke yet!!!!!
#13
Senior Member
Thread Starter
Couple things here.
1. Did you keep the C-washers near the rear mainshaft bearing separated into front and rear sets when you disassembled? The manual says they can be different thicknesses.
2. Are you re-using your mainshaft and countershaft bearings? If not, you will need to tolerance and shim the transmission to within that tolerance or the sucker will be either too sloppy and break, or be locked up. There are shims that go either above or below the great big snap ring (that you used the puller on), for the input shaft and counter shaft front bearings. For the output shaft, make sure the C washers are correct (or if they're the same size, don't worry about them) and there is a thrust washer that goes in between the output shaft bearing and the 1-2 gear pack. This sets the correct tolerance for the output shaft. There is also another thrust washer on the other side of the bearing and the whole shaft is squeezed down by the nut on the end.
How far did you take this thing apart? What parts are different? Let's start with that and we can get you going. Nothings broke yet!!!!!
1. Did you keep the C-washers near the rear mainshaft bearing separated into front and rear sets when you disassembled? The manual says they can be different thicknesses.
2. Are you re-using your mainshaft and countershaft bearings? If not, you will need to tolerance and shim the transmission to within that tolerance or the sucker will be either too sloppy and break, or be locked up. There are shims that go either above or below the great big snap ring (that you used the puller on), for the input shaft and counter shaft front bearings. For the output shaft, make sure the C washers are correct (or if they're the same size, don't worry about them) and there is a thrust washer that goes in between the output shaft bearing and the 1-2 gear pack. This sets the correct tolerance for the output shaft. There is also another thrust washer on the other side of the bearing and the whole shaft is squeezed down by the nut on the end.
How far did you take this thing apart? What parts are different? Let's start with that and we can get you going. Nothings broke yet!!!!!
#14
Senior Member
You need to measure first. This is one of those measure ten times, cut once type things. You can see if you can get new shims from Mazda. They might carry them. If not, you can buy shim stock and make shims. The thrust washer that goes in between the 1-2 gear pack and the output shaft bearing is also clearanced, so you'd need to check that it is in spec. The output shaft doesn't use shims. It uses different thicknesses of thrust washer instead to take up its position. Is it possible that you have that washer installed incorrectly?
Before you start ordering stuff, you need to go through and re-inspect your work. Did you get the gear packs pushed back on the shaft in their correct position? Is there a washer or spacer in the wrong position? Print out the manual and cross off that each piece is where it needs to be and is moving or not moving correctly. Start from square one.
Before you start ordering stuff, you need to go through and re-inspect your work. Did you get the gear packs pushed back on the shaft in their correct position? Is there a washer or spacer in the wrong position? Print out the manual and cross off that each piece is where it needs to be and is moving or not moving correctly. Start from square one.
#15
Senior Member
Thread Starter
You need to measure first. This is one of those measure ten times, cut once type things. You can see if you can get new shims from Mazda. They might carry them. If not, you can buy shim stock and make shims. The thrust washer that goes in between the 1-2 gear pack and the output shaft bearing is also clearanced, so you'd need to check that it is in spec. The output shaft doesn't use shims. It uses different thicknesses of thrust washer instead to take up its position. Is it possible that you have that washer installed incorrectly?
Before you start ordering stuff, you need to go through and re-inspect your work. Did you get the gear packs pushed back on the shaft in their correct position? Is there a washer or spacer in the wrong position? Print out the manual and cross off that each piece is where it needs to be and is moving or not moving correctly. Start from square one.
Before you start ordering stuff, you need to go through and re-inspect your work. Did you get the gear packs pushed back on the shaft in their correct position? Is there a washer or spacer in the wrong position? Print out the manual and cross off that each piece is where it needs to be and is moving or not moving correctly. Start from square one.
also what end play should I be looking for on all shafts? I cant seem to find any specs on the online FSM or my book
Last edited by Paulc19; 01-21-22 at 05:28 PM.
#16
Senior Member
Thread Starter
FOUND THE ISSUE! the input shaft bearing wassnt on all the way so the input shaft was deeper than it should have been, everything is working now
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j9fd3s (01-23-22)
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