Diff blew - now 3rd and 4th gears grind :-(
01-21-2004, 08:11 AM
#11
[QUOTE]Originally posted by Road Rage
I don't quite see how synchro action would be affected by viscosity, as it is the ceofficient of friction that really determines synchro action. Plus, MT-90/MTL combo is higher vis than MTF.
I don't quite see how synchro action would be affected by viscosity, as it is the ceofficient of friction that really determines synchro action. Plus, MT-90/MTL combo is higher vis than MTF.
01-21-2004, 03:13 PM
#13
Rev,
Is your clutch releasing cleanly. If its dragging at all it will cause crunching.
Could be a warped driven or pressure plate, or loose facing.
You should be able to tell if its harder to push the car into 1st from neutral with the engine runnning than it is without it running. Also, does it crunch into reverse with the engine running. Sometimes this only happens if the clutch is hot and things start warping.
I've also had experience with ceramic race clutches where they stick to the flywheel after a hard shift and take a bit to knock them free for the next gearchange. I think the copper content helps glue them to the flywheel.
One fix is to lift the clutch in neutral mid gearchange to slow things down. It only requires a quick snap up/down and with practise wont slow you down too much.
Speedracer.
Is your clutch releasing cleanly. If its dragging at all it will cause crunching.
Could be a warped driven or pressure plate, or loose facing.
You should be able to tell if its harder to push the car into 1st from neutral with the engine runnning than it is without it running. Also, does it crunch into reverse with the engine running. Sometimes this only happens if the clutch is hot and things start warping.
I've also had experience with ceramic race clutches where they stick to the flywheel after a hard shift and take a bit to knock them free for the next gearchange. I think the copper content helps glue them to the flywheel.
One fix is to lift the clutch in neutral mid gearchange to slow things down. It only requires a quick snap up/down and with practise wont slow you down too much.
Speedracer.
01-21-2004, 06:06 PM
#14
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Similar symptoms & on chis's track--- I had a pilot bearing go bad on a truck. The flywheel never completely released from the input shaft & the syncros wore themselves out trying to sync up the shafts against the friction cause by the bad bearing. The truck would grind 1-2 shift always & other shifts when cold. It was almost impossible to make the 1-2 shift when below -20F. Took both hands on the shifter & a big grunt.
I agree with Cris that if you double clutch you may run for long time. I ran that truck with shot syncros for 75K miles.
I agree with Cris that if you double clutch you may run for long time. I ran that truck with shot syncros for 75K miles.
01-21-2004, 08:42 PM
#15
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In my case, it seems like the problem is that the syncros can't slow the shaft down fast enough but they can speed it up fine. So if I'm stopped and I try to put the clutch in and go right into 3rd or 4th without waiting at all, I get a little grind (but only with 3rd and 4th). If I put the clutch in and wait a second, then it goes into gear fine. On upshifts, if I wait like 5 seconds between gears OR if I double clutch the upshift, it goes in fine. Downshifts give me relatively little trouble whether I double clutch or not (although as a habit I always do).
I'm willing to check the clutch out because that would certainly be a lot easier to handle than rebuilding/replacing the whole trans, but why would only 3rd and 4th give me problems if that was the problem?
I'm willing to check the clutch out because that would certainly be a lot easier to handle than rebuilding/replacing the whole trans, but why would only 3rd and 4th give me problems if that was the problem?
01-22-2004, 06:16 PM
#16
Rev,
From memory, 1st and 2nd gear have multiple syncro rings stacked together where 3rd and 4th have single syncro rings. 1st and 2nd have lots more material to wear away and a stronger syncro action. If your clutch is OK you may find that you have worn out your syncros. It is possible to measure the wear by measuring the clearance between the syncro out section and the gear. This only requires the casing to be opened up with the gears all left assembled. Once syncros have worn to the point of butting up against the gears they provide no syncronising action. The crunching is your dog teeth wearing away. Ideally you should replace the syncros asap to avoid trashing the outer sliders and dog teeth on the gears.
Sounds to me like its time for a 3/4th syncro refresh. While its apart replace the clutch as a preventative measure. You may want to consider an ultra light solid centre clutch disc. The more weight you can get out of the clutch disc the easier time the syncros have, and the quicker your gear changes.
Speedracer.
From memory, 1st and 2nd gear have multiple syncro rings stacked together where 3rd and 4th have single syncro rings. 1st and 2nd have lots more material to wear away and a stronger syncro action. If your clutch is OK you may find that you have worn out your syncros. It is possible to measure the wear by measuring the clearance between the syncro out section and the gear. This only requires the casing to be opened up with the gears all left assembled. Once syncros have worn to the point of butting up against the gears they provide no syncronising action. The crunching is your dog teeth wearing away. Ideally you should replace the syncros asap to avoid trashing the outer sliders and dog teeth on the gears.
Sounds to me like its time for a 3/4th syncro refresh. While its apart replace the clutch as a preventative measure. You may want to consider an ultra light solid centre clutch disc. The more weight you can get out of the clutch disc the easier time the syncros have, and the quicker your gear changes.
Speedracer.
01-22-2004, 09:02 PM
#17
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[QUOTE]Originally posted by chris_barry
Rev,
From memory, 1st and 2nd gear have multiple syncro rings stacked together where 3rd and 4th have single syncro rings. 1st and 2nd have lots more material to wear away and a stronger syncro action. If your clutch is OK you may find that you have worn out your syncros. It is possible to measure the wear by measuring the clearance between the syncro out section and the gear. This only requires the casing to be opened up with the gears all left assembled. Once syncros have worn to the point of butting up against the gears they provide no syncronising action. The crunching is your dog teeth wearing away. Ideally you should replace the syncros asap to avoid trashing the outer sliders and dog teeth on the gears.
Sounds to me like its time for a 3/4th syncro refresh. While its apart replace the clutch as a preventative measure. You may want to consider an ultra light solid centre clutch disc. The more weight you can get out of the clutch disc the easier time the syncros have, and the quicker your gear changes.
Rev,
From memory, 1st and 2nd gear have multiple syncro rings stacked together where 3rd and 4th have single syncro rings. 1st and 2nd have lots more material to wear away and a stronger syncro action. If your clutch is OK you may find that you have worn out your syncros. It is possible to measure the wear by measuring the clearance between the syncro out section and the gear. This only requires the casing to be opened up with the gears all left assembled. Once syncros have worn to the point of butting up against the gears they provide no syncronising action. The crunching is your dog teeth wearing away. Ideally you should replace the syncros asap to avoid trashing the outer sliders and dog teeth on the gears.
Sounds to me like its time for a 3/4th syncro refresh. While its apart replace the clutch as a preventative measure. You may want to consider an ultra light solid centre clutch disc. The more weight you can get out of the clutch disc the easier time the syncros have, and the quicker your gear changes.
01-23-2004, 03:58 PM
#18
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if you are after customed strengthened box or dogbox
contact these guys
http://www.gearbox-racing.com/
as far as I am awared they have made at least a set of custom helical gears for the s2000
It's not cheap but you may not get taxed because you are from oversea
contact these guys
http://www.gearbox-racing.com/
as far as I am awared they have made at least a set of custom helical gears for the s2000
It's not cheap but you may not get taxed because you are from oversea
01-24-2004, 10:05 AM
#19
Rev,
Since you think this problem corresponds to your rearend problem, a long shot but it's possible you damaged a tranny bearing that carries thrust load which has created some axial play in the gear sets. This sometimes shows up as popping out of gear in my experience (non-S2000).
If so, parts would be cheap and labor would be you .......
Good Luck
Since you think this problem corresponds to your rearend problem, a long shot but it's possible you damaged a tranny bearing that carries thrust load which has created some axial play in the gear sets. This sometimes shows up as popping out of gear in my experience (non-S2000).
If so, parts would be cheap and labor would be you .......
Good Luck
01-25-2004, 04:31 PM
#20
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Yeah, I tend to think that once I pull it apart, I'm going to find a fairly obvious failed/bent part. The question is how much the damage has spread from driving it like this. I'm being very easy on it now and hopefully the syncros aren't taking too much wear.
Also, although I have my doubts that this is a clutch problem, if it turns out that the clutch has been dragging, that will probably mean all the syncros will be in bad shape - in which case it'll probably be nearly the same price to just buy a new trans.
----------------------------------------------------
Does anyone have a SURE FIRE way to check if the clutch is dragging? Here's what I've tried so far... If I'm at a stop and put the clutch in, the shaft in the transmission immediately goes quiet. HOWEVER, if I try to cram it into 3rd or 4th as soon as I put the clutch in, I get a little grind. BUT If I wait a second, it will go in without issue - which means it is disengaging. Even if I rev the engine, once the clutch is in, I don't seem to get a grind... This leads me to believe there is probably supposed to be more preload on the bearings than there is and the shaft keeps spinning freely when it should be slowing down from preload.
If I double clutch my upshifts into 3rd or 4th, I don't get a grind. This also leads to the idea that the clutch isn't dragging. If the clutch were dragging, letting the clutch out would just exaggerate the effect. Again, it seems like the input shaft in the trans doesn't slow down fast enough, so letting the clutch out at neutral slows the shaft down enough that the syncros can work. If the clutch were dragging, then the engine should already be slowing the shaft down without letting it out at neutral.
So in short - right now, I think RT is dead right. I think one of the bearings is trashed and I have no preload right now where I should. I just hope the syncros have not gotten messed up...
Also, although I have my doubts that this is a clutch problem, if it turns out that the clutch has been dragging, that will probably mean all the syncros will be in bad shape - in which case it'll probably be nearly the same price to just buy a new trans.
----------------------------------------------------
Does anyone have a SURE FIRE way to check if the clutch is dragging? Here's what I've tried so far... If I'm at a stop and put the clutch in, the shaft in the transmission immediately goes quiet. HOWEVER, if I try to cram it into 3rd or 4th as soon as I put the clutch in, I get a little grind. BUT If I wait a second, it will go in without issue - which means it is disengaging. Even if I rev the engine, once the clutch is in, I don't seem to get a grind... This leads me to believe there is probably supposed to be more preload on the bearings than there is and the shaft keeps spinning freely when it should be slowing down from preload.
If I double clutch my upshifts into 3rd or 4th, I don't get a grind. This also leads to the idea that the clutch isn't dragging. If the clutch were dragging, letting the clutch out would just exaggerate the effect. Again, it seems like the input shaft in the trans doesn't slow down fast enough, so letting the clutch out at neutral slows the shaft down enough that the syncros can work. If the clutch were dragging, then the engine should already be slowing the shaft down without letting it out at neutral.
So in short - right now, I think RT is dead right. I think one of the bearings is trashed and I have no preload right now where I should. I just hope the syncros have not gotten messed up...