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coyote99 09-01-2008 06:26 PM

Tranny issues, ax15 or nv3550
So I have posted on this once before but am deployed and still havent solved this issue. My ax-15 (60k miles) makes my entire jeep shudder(kinda like chugga-chugga-chugga as the whole jeeps bounces in rythem) when I press in the clutch, have it in first gear, and start to roll backwards slowly, it does it also to a lesser extent if in second and rolling backwards with the clutch in, but it doesnt do it at all in any other gear or neutral (and it doesnt do it if rolling forward). So I thought it may be my clutch not disengaging all the way and grabbing, but as I think about it I have had no signs of clutch wear or throw-out bearing whine. So I was thinking that since the clutch was pushed in (seperating power from the tranny) and (correct me if Im wrong) when the jeep rolls backwards it spins the driveshaft which spins in the tranfer case which still spins the (1st or 2nd) gear in the tranny. So... Im thinking there might be binding of gears in the tranny causing the shudder. Any input on this theory? About the ax-15 or nv3550, I have a nv3550 that was just rebuilt but with 120k miles that i could put in, or I could rebuild the ax-15. I have heard positive and negatives on both trannys, any suggestions? Thanks and sorry for the long post.

coyote99 09-02-2008 02:53 PM

bump for no help

jeeperman 09-03-2008 08:37 AM

To me, it sounds like you were on the right path with the clutch, as you have NO other issues with the transmission, either forward or reverse. Any issues putting the Jeep in first gear when stopped? Sounds like the slave cylinder going bad to me, but it could be something completely different. (How's that for taking a stand?:rolleyes:) Other than that, I got nothin'. Good luck tracking it down.:wavey:

4Jeepn 09-03-2008 01:34 PM

I will offer my 2 cents:

1. Does it do it in 4wd?
2. Have some one look at the rear driveshaft as you go back wards and look for odd movement or rotation, binding etc in shaft to driveline etc.
3. Check for play in output yoke and rear pinion yoke
4. check t-case and tranny mounts
5. Check the u-joints in driveshaft.

coyote99 09-03-2008 02:25 PM

Jeeperman, now that I think about it (its been almost 7 months since I have been able to drive it) I faintly recall being in the habit of having to go to second then first gear if i stop without engine braking, because it wouldnt go into first if I didnt, or Id have to double clutch. It might be the slave cylinder, but would that cause it to shudder? And only in first and second?

4Jeepn - I have checked most of hose things except to see if it happens in 4wd. Regardless, correct me if Im wrong, but if it had anything to do with the transfer case or driveline, then it would do it regardless of what gear the tranny was in, but it only happens when it is in first or second and rolling backwards.

coyote99 09-03-2008 02:55 PM

Jeeperman, I have been banging this around in my head about the slave cylinder. Transmissions are my weakest link, so now is a good time to learn, but correct me if I am wrong in my logic. The slave cylinder activates the clutch, if it was going bad, then the clutch would not fully release, therefore slight torque would still be applied to the tranny. Since it might just be barely catching, then the torque would only be slight and not noticed when sitting still, but when rolling backwards the gears are (1st and 2nd) spinning in reverse rotation and the slight torque is now causing resistance trying too spin the gears the right way, causing the shuddering. I also think that it only does it in first and less so in second because the gears are so low, but in 3rd and above, its not enough torque to cause resistance, and in reverse the gears are spinning the right way so there is no resistance. I need to try and see if it will do it while rolling forward, while in reverse, with the clutch in. If this is the cause, I will be one happy smart SOB. Unfortunately its going to be another two months til I see her again and test this theory.

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