+- Arctic Offroad Forums (http://www.arcticoffroad.com)
+-- Forum: Talk (http://www.arcticoffroad.com/forumdisplay.php?fid=3)
+--- Forum: General 4X4 (http://www.arcticoffroad.com/forumdisplay.php?fid=9)
+--- Thread: any slush box mechs out there? (/showthread.php?tid=1559)
any slush box mechs out there? - coldtaco - 22 Jun 07
Can you school me on the basics of auto transmissions? Like what not to do, what to do. Does going into and out of neutral bad? Like coming to a stop at a red light or coasting to a stop? What about downshifting for engine breaking? Thanks.
any slush box mechs out there? - TJVigilante - 22 Jun 07
I know that you can't flat to an auto in neutral...the pump won't work and you'll be running your input and output shafts dry. I don't think coasting to a stop is a bad idea. Downshifting is fine...that's what the 1,2,3, etc are there for.
any slush box mechs out there? - AKMark - 23 Jun 07
Downshifting for engine braking is bad. You put opposite forces on the clutch packs that they weren't designed to take. Folks that do this usually find lots of little bits of metal in the pan every time they pull it. I've never heard of a decent trans shop that recommends this with anything but HD trannys. (Like the ones you see behind diesel pickups nowadays, as those are designed to be used as an engine brake.) I should clarify, if you start down a hill in 2nd or 3rd, and leave it there, it's not so bad. If you shift to 2nd or 3rd while going down a hill, that's when bad things happen. 1, 2, & 3 are there for holding gears during acceleration or decel, not for shifting to slow you down. Most transmissions will not shift back a gear unless they are below a set speed for said gear to keep you from making it worse than it is.
Flat towing a 4x4 vehicle with the trans in neutral doesn't affect the input and output shafts. Having the T-case in neutral does, as it doesn't pump when it's in neutral. Short trips aren't a big deal, but in the long run, you will burn things up. That's why folks suggest pulling the shafts when towing. You can leave the T-case in 2wd to keep the pump moving and keep the bearings happy, but there are lots of reportable cases where a vehicle has hit a bump and the manual trans has jumped into gear, that normally doesn't happen with an auto, as if you leave it in neutral, even if it shifts to reverse or drive, nothing bad will happen. If it somehow jumps to park, that's a different story.
Heat kills an auto more than any other thing. You cannot run enough coolers. Monitor the heat, if you can keep the trans from ever going above 200 degrees, your trans will probably last a long time. If you frequently see temps in the 280+ range, your trans will not make 80K before it gives out. I know one individual that uses a 700R4 in his vehicle that's his wheeler, tow rig, and DD. (No it's not me) He has the stock in radiator cooler which doesn't do much, then it routes to an RV style cooler (like I use) that hold about 1.5 quarts of fluid, then routes to another slightly smaller cooler that has it's own built in fan that comes on when the temperature of the fluid leaving the trans gets above 175 degrees. He runs the lockup kit made by bowtieoverdrives which allows him to lock the torque converter in 2nd through 4th keeping it cool and happy. He has two temp guages on his setup to verify he's cooling the fluid effectively, both are attached to lines where they enter and leave the trans so he gets affective readings on what it's doing. The average temp of the fluid returning to his trans is about 85 degrees when it's warmed up. Not to shabby and helps in making the trans last. I should mention this is used behind a custom twin turbo 6.2L with more mods than I could list in a short time period.
Coasting to a stop either in gear or not isn't a big deal. An automatic will pump whenever it's in gear or neutral. GM's (there may be another manufacturer that does this, but to date I haven't seen one) also pump when in park. I used to do this when my ZJ was an auto as it seemed to need less brake to slow down in neutral. Just don't forget to put it back into gear or folks will look at you funny when you hit the gas as the light turns green.
any slush box mechs out there? - coldtaco - 23 Jun 07
Ok, so engine breaking is a NO-NO
But I can shift into neutral when coasting or coming to a stop, like at a red light
I don't plan on flat towing my Taco, but if I was too, I would just put the transfer case into neutral and then what with the transmission? Leave it in park?
We are getting rid of the Taco
so I won't be doing any extra cooling stuff. Had the fluid changed a while back, can't remember when probably around 40,000mi.So, do I put trans temp gauges on the Rav? I like to downshift it too and put in neutral. I guess I will stop the downshifting, not that it helps much on that one for some reason, don't know if the computer is not letting it do too much?
any slush box mechs out there? - AKMark - 25 Jun 07
Putting the T-case in neutral while flat towing doesn't lubricate the bearings. I would pull the rear driveline, as flat towing for very long wouldn't be good to your T-case.
I would run a gauge on the pressure line going to your cooler to give you an idea of how hot yours is getting. (An additional cooler cannot hurt) If you downshift once in awhile, it won't do much, but do it a lot and you can plan on rebuilding your trans earlier than others do.
any slush box mechs out there? - coldtaco - 25 Jun 07
How come putting transfer case in neutral does not let the bearings get lubed? The only bearings that would be spinning would be the one that the rear driveshaft went through the housing and anything else that is connected to the shift mechanism? These bearings would be sitting in the oil/soaked yes? no? Do all the bearings get pressure fed oil? Where would this pressure be supplied from? Seems like when I saw my transfer case appart it did not look like there was any means of pressurizing the oil?
any slush box mechs out there? - AKMark - 26 Jun 07
The pressure inside the T-case is produced when the mainshaft (the one that runs from the engine to the rear driveshaft is engaged. Which when you put the T-case in neutral, disconnects that and doesn't spin the little pump setup inside.
The bearings don't get oil soaked, but do get pressure fed oil/fluid. When I first pulled my 231 apart I didn't see what looked to be a pump, but when I looked twice I noticed my mainshaft fed fluid to a filter which had a tube that shot fluid at the bearings on the shaft.
any slush box mechs out there? - coldtaco - 26 Jun 07
Ahh, I see