Topic: Atlas Dilemma

[sharpxmen]

It's true you don't have to come to a complete stop but the synchros are hard and only allow the down shift when going really slow (probably slower the lower geared it is, 5:1 slower than 3.8:1).  You put in the clutch and then hold the lever there as the vehicle loses speed.  Then at some point you are going slow enough and it just slides into gear, at higher speeds it is almost impossible to shift (which is good because shifting into low at speed could snap something or eject passengers out the front window).  It is very nice though that it doesn't grind the gears.

did you try to put the transmission in neutral? if you didn't you should as that would make shifting the t-case easier, just the clutch won't help as much as you'll end up with both primary/secondary gear train in the transmission including input shaft and clutch that will need to come up to speed to match the tcase output (a lot of rotational mass to be moved by the syncro).

[Jeffy]

Having syncro's is also nice onroad as well.  Where I'm at, you have to drive to get to snow.  We do get rain though and some flooding and mud slides.  In the past I've had to shift into 4Hi while doing 45-50 mph.

[neale_rs]

did you try to put the transmission in neutral? if you didn't you should as that would make shifting the t-case easier, just the clutch won't help as much as you'll end up with both primary/secondary gear train in the transmission including input shaft and clutch that will need to come up to speed to match the tcase output (a lot of rotational mass to be moved by the syncro).

Pretty sure I've tried it but I'll try it again to see the difference. 

[sharpxmen]

Having syncro's is also nice onroad as well.  Where I'm at, you have to drive to get to snow.  We do get rain though and some flooding and mud slides.  In the past I've had to shift into 4Hi while doing 45-50 mph.

syncros are not going to help with that (front and rear are locked together so there's no "free spinning" shaft to be rpm matched) you need to have same diameter tires (wear and air pressure) on front and rear and have the wheels straight, as long as that is there the front and rear d/s will rotate at the same speed and you can shift, if not you can't, and that is the same with or without syncros (same as with the transmission, when you press the clutch you have a free spinning input shaft that the syncro can match the rotational speed for, if you don't press the clutch you'd have to rpm match with the gas pedal to allow the collar to engage the gear) - not sure if I explained it well enough.

[neale_rs]

Pretty sure I've tried it but I'll try it again to see the difference. 

Tried it last night.  Didn't seem to go into gear at any higher speed but I agree it should be easier on the synchros.

[sharpxmen]

Tried it last night.  Didn't seem to go into gear at any higher speed but I agree it should be easier on the synchros.

should at least feel lighter when you shift, if you go from high to low you can help it if transmission is in gear and you rev the engine before pressing the clutch and keep slight pressure on the t-case shifter, would help bringing the transmission output shaft up in revs. The other thing you can try is to have the trans in neutral and keep slight pressure on the stick to give the shaft time to rev (something like when you try to shift in 1st at higher speed, you need to put slight pressure on the stick but not pushing it too hard before actually shifting into gear, the syncro would bring the gear/shaft up to revs by friction, if the difference is high it takes a bit to get there)

if you already did all that try the front (rear in neutral) and see if it's any different, wondering if the other syncro is not up to par or maybe needs some wear to get broken in (same with the transmission, sometimes when you replace the syncros it takes a little bit to get it working smooth, since you don't shift the t-case on a regular basis would take a while to get there).

[neale_rs]

should at least feel lighter when you shift, if you go from high to low you can help it if transmission is in gear and you rev the engine before pressing the clutch and keep slight pressure on the t-case shifter, would help bringing the transmission output shaft up in revs. The other thing you can try is to have the trans in neutral and keep slight pressure on the stick to give the shaft time to rev (something like when you try to shift in 1st at higher speed, you need to put slight pressure on the stick but not pushing it too hard before actually shifting into gear, the syncro would bring the gear/shaft up to revs by friction, if the difference is high it takes a bit to get there)

if you already did all that try the front (rear in neutral) and see if it's any different, wondering if the other syncro is not up to par or maybe needs some wear to get broken in (same with the transmission, sometimes when you replace the syncros it takes a little bit to get it working smooth, since you don't shift the t-case on a regular basis would take a while to get there).

Makes sense, to synchronize at 4.3:1 it would need to be spinning faster on the input end.  I'll try it.

[sharpxmen]

Makes sense, to synchronize at 4.3:1 it would need to be spinning faster on the input end.  I'll try it.

yeah, didn't realize you have 4.3, so for that you'll need to make sure the speed is reasonable for the resulting engine rpm (so in 1st and high at 1000 rpm going to lo would result in 4300rpm, not as dramatic with 2.6 or 2.7) - so you'll need to bleed off some speed or select a higher gear in the transmission with the t-case in neutral, then rev the engine a bit, press the clutch while applying slight pressure on t-case shifter and once the clutch is fully depressed then try to shift the t-case (should give you the feel when it's ready to go in)
it's like doing a double clutch shifting on a trans going from a high gear to a lower one

i was playing with my D300 this way but i have standard gears in it (so less difference in rpm), I can shift it this way but it always grinds since there are no syncros in it unlike your Atlas.

[aw12345]

For thew most part I can shift the Atlas on the fly, the front dig thing is over rated since when you run for a 1/4 mile or so with the lockers on the driveline is in a bind and you cannot just take the front or rear out of gear, tried it in a few situations and it takes some horsing around. So if you are teetering on the brink of flopping and you feel like doing a front wheel dig to get out of it, then most likely it isn't going to happen. Still compared to anything else that will directly bolt to a 4 banger it's the best and most durable option. Would not want to use anything else.