cowboy_trucker

Yea just turn that around on me bagging the truck. How often are you bobtailing around? I get about 10 miles a year that I dont have a B-train behind me so I dont think Im hurting anything too much. You are telling me that lifting off in high range bobtailing is harder on the truck then on a 9% grade with 63,500kg? This thread is about shifting a 13 speed anyway. Shouldnt be dwelling on this topic

fschiola

Absolutely correct! You can wipe out an auxiliary in no time pre-selecting. these aren't like the new transmissions. I didn't see the picture of your shifter, but I'll give you the shift progression on a Roadranger 13 speed. The shifter will have a switch on the shifter stalk( low down and high range up) as well as a splitter button on the shift **** (direct toward the rear, and overdrive to the front of the truck). The pattern is a standard 5 speed with reverse being in the full left and up position and first gear in the left and down position. If you wanted to go through the full shift progression, start in second and shift each gear to 5th which is far right and down. While moving the shifter to the 2nd gear position, move the low high range **** up while moving through neutral. Then while in the 2nd gear position, move the **** on the shifter into the overdrive position. Then move the shifter into the 3rd gear position at the same time as you move the **** button into the direct position, and so forth. When you split a gear, up or down, with the **** button, you can minimize damage to the transmission but clutching the shift and not pre-selecting. You can also utilize the 1st gear position while in high range and direct, like when making a turn, the ratio of the gear will fall between actual 4th and 5th gear without changing ranges.

It would be easy to show you, but it's hard to tell you this way. I hope this helps.

DetroitDiesel71

Here is a pic of the shifter in my 72 brockway. Thanks for all the help

fschiola

OK, if you can make heads or tails out of my last post, the shift progression is the same except all of the splits are on the ****.

P Kennedy

I believe the model will be a RTO6513 or most likely RTO9513 (Roadranger Transmission Overdrive) behind a 8V71 NA (318) and if you follow the hot rodder crowd suggestions you will be rebuilding the old girl prematurely$$$$$$ This series of trannies had NO preselect protection built in and it does not matter which selection you make air is put on the shift fork right away. If you don't like the style of shifter a newer design from a 14 series or later can be plumbed in and prevents the "range" shifter from being preselected. Starting in higher gear than off the idle will result in "premature" clutch failure, usually 2,3 or 4th low range bobtail will "lift" off the idle with ease. All Roadranger transmissions can be skip shifted ( No Splits) in high range (400-500 rpm shift vs 200-250 rpm split shift ). Roadranger trannies used coarse straight cut gears until the 14 series came out resulting in less gear to gear tooth contact. All RR with range splitting trannies are timed and have air synchronizer range shift mechanisms but as mentioned earlier 13 & 18 spd's drive through the Aux to the output yoke which fails 1st when brutalized. Shifting - Low Range L,2,3,4,5 clutch-1 move range selector going through N clutch-2,(double clutch method) 2nd Direct high range, clutch-2nd Over, clutch-1 2ndO clutch-2 3rdD, clutch-3rdO etc. Low gear high range is not recommended (it's in the stinkin book for a reason) and of course downshifting is same process backwards with a lot more skill and finesse. If the unit starts to grind changing ranges the air synchro hub is starting to go. I personally prefer an RTO14515 but behind your big block Chevy the 13 under load works wonderful due to the narrow power band of the 2 stroke (1800-2150 rpm) peak power and torque. And yes for those wondering some us did pull trains (120,000lbs) through the mountains with DD318's and NTC290 Cummins some time between dinosaurs and 18 speeds with 600 HP engines. Oh yah some where in there they started putting padded interiors, air ride and AC in for hard working people. PK