Gears & Axles Driveshafts | Rearends | Differentials | Gears | 12 Bolt | 9 Inch | Dana

T56/9in?

Old 03-15-2009, 03:06 PM
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Default T56/9in?

I just did a swap and now my car shifts alot notchier.

Along with the swap I put in a tunnel brace mounted torque arm, and switched drive shaftswith a buddy until we could put the other u joints in the other drive shaft.

She shifts fine at wot and very slow shifts (the time it takes to push the clutch in twice and then shift) but notchy on regular driving.

Any idea why this is happening?
Old 03-15-2009, 08:47 PM
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I'm wondering, is this a clutch type posi or a locker? I seem to remember the same thing with my T-56 right after I put in the 9" with the locker. Never knew what caused it but I suspected that the torsen was "softer" on the feedback through the driveshaft and into the trans. It also seemed that the switch magnified the problems I had with worn syncros. The trans would shift notchier, and 4th that had problems before would grind more often. 2 months later, I tore the trans down and faceplated 1-4th and had to replace 5&6th gear clusters as they were all worn out. I'm not in any way suggesting that the rear swap contributed in any way to the wearing out of the trans, it was already cooked, just that it slightly magnified the symptoms of an already worn out trans. Kind of like putting a "stethoscope" on it. Anyway,does your trans ever grind when shifting?
Old 03-15-2009, 09:24 PM
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it has a locker and it started when i got done with the swap. Ive felt and heard a grind from 4th but only when I coast for a sec. then try to go in 4th without pulling the rpm's up a little before doing it.
Old 03-15-2009, 10:25 PM
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Maybe since the locker has slop in it from the interlocking castle design of it, its sending a shock or feedback up through the output shaft thats upsetting the blocker rings. I'd try shifting faster and if that doesnt work, try pausing and letting the RPM's come down a bit more before shifting. With my trans, I learned a shifting technique that actually crossed over to how I now drive the synchro-less faceplated trans.
As you drive and go through the gears, what the synchro's are doing is acting like a brake. With the clutch in, obviously the output shaft speed cant decrease as the wheels dictate its speed, so the synchro slows the input shaft down directly whenever you go from 3rd to 4th and the 1-3 syncros slow down the input indirectly through the countershaft whenever shifting from 1-2 and 2-3. We'll forget about 5-6 so not to complicate things further. So I'm thinking that it may happen that the normal everyday shifting habits of most everyone may coincide with the moment the synchro assem is speed matching everything up for a nice, smooth shift. The action of the slight speed change from the driveshaft as the locker goes from loaded to unloaded, its about 45 deg. of yoke rotation as I remember, coincides with the synchro match, upsets everything and causes grinding. Just a theory...
Anyway, with a faceplated trans, there's no synchros to slow the input shaft down. To get a smooth, noiseless shift, you have to run the gear up, then pull the trans into neutral WITHOUT pushing in the clutch. See with the clutch engaged, you're using the motor to slow the input shaft and countershaft down since you dont have synchros. With experience, you learn about how to time it just right and then push the clutch in and shift to the next gear. I got good enough last year that I didnt even use the clutch most of the time. I just ran first up, pulled into neutral for a certain amount of time, then straight shifted to 2nd without a sound or very little clunk. Same for the next gears up. To downshift, you rev to speed up the input, push in the clutch, and downshift. Harder to do consistently BTW without noise.
Now YOU still have a synchro'd trans so you just probably need to either take a bit of the load off of the synchro assem. because of wear or change your shift timing to make the synchro do its job when the locker isnt transfering from lock to lock. If changing your shift timing doesnt work, when going into 4th, (since thats where you may be seeing the most consistent grinding) try pulling the stick into neutral from 3rd, let the motor wind down a bit (just a couple of tenths of a second) then clutch and shift. Its a bit odd to get used to at first, but then its second nature. Good luck!
Old 03-16-2009, 07:43 AM
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4th gear don't do it all the time every once and a while. And when I slow shift it works smooth and at wot it's smooth. It might be me but it felt like 2 gear was a little smoother after changing the pinion angle a little bit. I'm gonna go to -3* and see what that does. When I was backing into the garage to do the swap I was a little of a slope and while slipping the clutch I heard a metalic type of noise when it was loaded up and that was when the 10 bolt was in. I have a poly trans mount and stock motor mounts poly everything in the back you think that could have something to do with it? I don't see it being able to move that much.

I noticed this morning that with the clutch in and turning into the parking spot there is a clunking and feels like something sliding back and forth even when driving in a straight line I push in the clutch and hear the clunking by the trans.
Old 03-16-2009, 09:07 PM
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found out that I messed up on the pinion angle and set it tonight to -2.5 on the pinion and that got rid of the notchieness. I will do more testing with her tomorrow. thanks for the replies

nathan


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