KRB64 wrote:KTA wrote:Begle1 wrote:KTA wrote:On a side note launching a high power cummins without using true manual low( which has the 1st/reverse band applied) will usually rip the overrunning clutch sprag out of the case, therby junking your tranny. I have 2 47Re cases that are trashed to prove it.
When are you in "true manual low" as opposed to what isn't true manual low?
On a stock valve body true manual low the one marked L on your shifter applies the 1st reverse band. When in the drive position D the 1st gear start is accomplished only with the overrunning clutch, the band is not applied. The 47RH/RE and 48 RE all have a kind of made in overrunning sprag, they don't bolt in like the 727.
OK, I know I'm jumping in here a little after the fact but back up for a second for me. I'm fairly mechanically inclined but the auto tranny is still a black hole for me - deep, dark and mysterious.
What I'm digesting is that a stock 518 behaves differently in "1" than when starting from a stop in "D" correct? So when loaded, I need to shift down to "1" and manualy shift up right?
If correct, what exactly is going on in there that makes this better for a loaded transmission?
And my apologies for digressing from the mag build theme...
I'm real GRAY in auto tranny but i will try!
If you understand how a planetary gear set work then i might be able to pull this off........Ya know the sun, planetary and ring gear .....Yes, no?
when you take off, with the shifter in D you take off in first gear with the rear clutch applied sending power, driven thru the planetary gear. the over riding clutch in stopped in its track as is the revers drum. hold the drum in place alowing first to happen.
when you release the go peddle and coast, there is no hold back from the tranny as the one way clutch, sprag, over riding clutch(what ever term you want to us) is not holding any more and is free willing or spinning back ward........and so is the reverse drum.
When you pull the shift lever in to L1 the revers band stop the drum(which also hold and keep the overriding clutch from spinning) allowing deceleration in first gear.
IN simple terms, when you have it in L1 you have.......say twice the holding power and the eng will hold you back.
In "D" and takeing off, not as strong and will shift into 2nt when you let of the go peddle(which will hold you back when decelerating with shift lever in "D"
Make sence????
If not, do a search on the net there way better explainaiton then i could give.
As far as having a heavy load and starting a way in "D" or L1...........L1 would only be necessary with tons of power and trying to take off from a dead stop and get to full speed as fast as you can............Just like drag racing
Flash.
91.0 non intercooled 3/4 ton 5sd ex.straight piped 16cm housing, timing bumped 1/16...Pump . Full power screw1/2 max with out removing the collar. Gear Vender over drive!
"NOW" with 2nt gen intercooler, turbo and 3"Coolertubz, Buy Tim (TWorline)"
