Downshifting a 13 speed

I like splitting every gear. There’s something about 700hp straight piped rev matching and a sunroof ahaha.

 

How come so many people pre-select? I seen a lot of videos where people say pre-selecting is fine lol

 

Depends what you're downshifting for. If I'm coming down from highway speed to stop ... No.

But if I'm climbing, then yeah. That's the reason I have a 13 speed. No need to drop to 7, when 8 low does the job.

 

Read a roadranger manual some day. On the old RT/O's and OOs with 8 on the dash you HAD to preselect a split or the air cylinder sequence just didnt jive and theyd miss a split then grind until the aux dropped into mesh.

The RTLO and various other modern prefix units are so much more forgiving that drivers can get away with anything they want. Old models you had to preselect some shifts and post select others based on which direction you were going on the gears.

LoL. Ok.

 

Hmm i guess the few old timers i learned from have been doing it wrong too then. Mind explaining some more? I will. By pre select i mean a fraction of a second before u make the shift, both up or down on the RTLO and the same for UPSHIFTING w/o moving the stick on the older RT/RTO. As soon as you move the button it wants to shove the gear right in, it has no brain. You tell me how pre selecting isn't causing more stress?

Now with the old style RTO aux you don't for example say go 7H to 8L by pre selecting, you move the stick 1st then after it drops in you flip the switch and business like usual. Downshifting it won't grind and make you come to a stop to get straight again. I don't know the exact technical reasons but the old 14609B w/ 14613 aux that im in everyday works exactly like i just said. The rtlo is od in front/under aux.

 

Ill have to see if i can find my rto service manual and post a pic of the shifting instructions. I drive an RTLO now and shift it exactly the same as i did the RTOO with no issue. when i was starting out i had to have a note on the dash to remember eaton fullers instructions. Most times i accidentally deviated the rtoo would grind. Rtlo very rarely fusses about anything compared to the old units.

I never flip the splitter while passing thru neutral or while not under load, either from throttle or from jake.

Say youre in 6th over, have accelerated to whatever rpm and are going to upshift to 7direct. You should lift throttle, float stick out of 6, move to 7 and then once youve meshed 7th, drop the splitter back to direct and reapply throttle. Post select the splitter on upshifts. It takes a 500 rpm engine drop to mesh the stick, but once you mesh, you immediately split that 500 to 250 and get back in the throttle.

If your downshifting from 7direct to 6 over, say for a little extra oomph to top the hill, you stay on throttle in 7under, flip the splitter to over, then whenever you are ready, lift throttle and simultaneously float stick to neutral then start feathering rpm to mesh into 6th hole. Downshifts are preselect and because the auxbox will shift as you pass neutral, the stick motion only takes a 250 rpm difference.

I hope im explaining that clearly.

The trans only has 60 psi of air in it applied to about a 3 inch piston face to shift the auxilliary gears. Not enough force to move the sliding clutch on the shaft while under load. So you can flip the switch whenever you want. Its the lifting of throttle that will slacken the gear mesh and begin the splitter shift sequence.

 

You're doing it right. Hit the split button half a second or so before you make the gear change.

See, most drivers have never seen the inside of a transmission (hell some I'm pretty sure don't know what brand of truck they're driving!)

The range shift has an interlock attached to the side of the transmission. You can preselect the range any time but until the gear shift moves the shift bars to their neutral location, no air goes to the range piston. The splitter has no such interlock. The moment you hit that button the splitter piston is trying to force the transmission to split shift. So when a driver hits that splitter button half a mile before they need to, they're just causing unneccessary shift fork/collar wear.