emmotto
09-10-2013, 12:29 PM
Last weekend I performed a gearbox transplant on my '69 Series IIa 88 - taking out my ailing gbox/tcase and swapping it for a rebuilt gbox/tcase and replacing my clutch pressure and driven plate at the same time.
Prior to the operation my box was noisy, notchy, rattly and jumping out of 3rd. Much metal had been found in the oil and the 3rd gear synchro had ceased synch'ing - I had to double clutch going into 3rd as well as 1st and 2nd. Several weeks ago a rumbly, rattly sound appeared, even at rest in neutral - which made me suspect a worn main shaft front bearing.
Preparing for the swap we discovered that the 4wd lever mechanism was stuck in the freewheel case so we tried (I tried) to free it and in undoing the pivot pin I snapped it off (it was frozen too). After messing with a drill and easy-out to no avail, we swapped transfer cases and installed the rebuilt gearbox but the original transfer case.
The rest of the deal went reasonably well except for an hour lost messing with a defective new slave cylinder (gave up and reinstalled the original).
So - rebuilt gearbox (nice and quiet, smooth, not rattly, stays in gear etc), new clutch (both plates and pilot bush), new gearbox mounts and it's like a brand new truck! Except for one thing...
There's a definite rumbly vibration that was never there before with the old, crappy tranny. Hard to tell with 100% certainty but it appears to be driveline related somehow. Driving under load or coasting there's this kind of vibration that seems independent of what gear you are in or what speed the engine is turning - it's felt in neutral as well. I tried coasting down hill with the engine off and not certain if I felt it or not - need to try that again. Also thinking of turning freewheeling hubs to freewheel (they're in drive now) and possibly removing front driveshaft to further isolate where it's coming from.
Any ideas?
I'm thinking of putting t-case in neutral and running the clutch in and out to see if that will reveal anything - ie; if rumble exists while not rolling but clutch let out than maybe the gearbox not rebuilt so good (bad bearing). If no rumble with clutch pressed or not then definitely running gear...
The vibe is very reminiscent of what it felt like when I had a bad u-joint.
Prior to the operation my box was noisy, notchy, rattly and jumping out of 3rd. Much metal had been found in the oil and the 3rd gear synchro had ceased synch'ing - I had to double clutch going into 3rd as well as 1st and 2nd. Several weeks ago a rumbly, rattly sound appeared, even at rest in neutral - which made me suspect a worn main shaft front bearing.
Preparing for the swap we discovered that the 4wd lever mechanism was stuck in the freewheel case so we tried (I tried) to free it and in undoing the pivot pin I snapped it off (it was frozen too). After messing with a drill and easy-out to no avail, we swapped transfer cases and installed the rebuilt gearbox but the original transfer case.
The rest of the deal went reasonably well except for an hour lost messing with a defective new slave cylinder (gave up and reinstalled the original).
So - rebuilt gearbox (nice and quiet, smooth, not rattly, stays in gear etc), new clutch (both plates and pilot bush), new gearbox mounts and it's like a brand new truck! Except for one thing...
There's a definite rumbly vibration that was never there before with the old, crappy tranny. Hard to tell with 100% certainty but it appears to be driveline related somehow. Driving under load or coasting there's this kind of vibration that seems independent of what gear you are in or what speed the engine is turning - it's felt in neutral as well. I tried coasting down hill with the engine off and not certain if I felt it or not - need to try that again. Also thinking of turning freewheeling hubs to freewheel (they're in drive now) and possibly removing front driveshaft to further isolate where it's coming from.
Any ideas?
I'm thinking of putting t-case in neutral and running the clutch in and out to see if that will reveal anything - ie; if rumble exists while not rolling but clutch let out than maybe the gearbox not rebuilt so good (bad bearing). If no rumble with clutch pressed or not then definitely running gear...
The vibe is very reminiscent of what it felt like when I had a bad u-joint.