this is my first thread. my dad just recently bought a 79 peterbilt with a cummins big cam 400 III and 13spd. a few questions. there is blocks under the springs in the front. can you remove these to lower the front a little? also it has a 13 speed i guess. reverse left and forward and low left and back and 1-4 on a regular h pattern. then has a 3 postion selector for low, mid and OD. but it seems that maybe mid and od are the same? havent taken it all the way through yet. only to 7th. is it even a 13 speed? only drove it on the road once and had low tires so didnt take it far. any info on these subjects is appreciated.
I don't know about the springs... if these fine people can't answer your questions go to www.eastcoastlargecars.com . They live for this sort of thing.
pimpin da site E...haha
If I understand right your truck has a 3 position range selector on 1 button/switch, and does not have the normal 2 switches. Haven't seen on of those in years as the 2 button/switches are more the norm. OK, I am going to assume that you have a large 13 spd like a 12513 and not something small like a 6613, because then the shift sequence will be different. If you know anything about a normal 13 spd with the 2 buttons. The forward button is your high and low range and the button on the left side of the shift knob is your splitter for the high range. Your 3 position button would work similar, with the low and mid being the low and high range. And then the 3rd position being the splitter for the high range. So the shift pattern is as follows. Button on low, 1-4 in the H pattern Button on mid, 5-8 in the H pattern Button on 3 position will be high range in each of the 5-8 gears. To go through every gear in order and using your lowest gear down and to left of normal H pattern. Switch in low position. Low will be down to left as described above. 1st 2nd 3rd 4th 5th switch in mid position 6th switch in high position 7th switch in mid 8th switch in high 9th switch in mid 10th switch in high 11th switch in mid 12th switch in high Now you don't have to go through every gear in order unless you need it like on hill, etc. You can drive it like a 9 speed and only use the splitter in the high range if necessary. The splitter will give less of a rpm drop between gears so that on a hill if you need to downshift you won't lose rpm's, etc. The normal drop or rise in rpm's between gears is usually around 500 rpm's if driven like a 9 spd, the splitter will cut that in half to about 250 rpm's in the high range. And if you want to know how a 18 spd shifts, it is the same except that the splitter works in both the high and low range and low gear which gives you the additional 5 gears.
Why do you want to lower the truck? With a 13 speed, you run up through the low side, the when you shift to high range you split each gear as you run up through the pattern, in other words, when you shift to high range, and reach maximum rpm in the selected gear, pre select the O/D position on the shifter and lift the throttle for a second, you'll hear the transmission slip into overdrive. Next, as you approach maximum RPM in O/D, pre select Direct and shift to the next higher gear. As you shift, the transmission will shift back to direct, then you do step one over again. this is called splitting the gears. Kgmz explained it a little more thoroughly while i was typing.
just a better stance thanks all
If it has a 3 position selector, it likely has or had an RTO9513. 12513's used seperate range shift plunger and splitter button. Kevin
I would hope it has a 12513 instead of a 9513 with a Big Cam 400.
Something like this one?
if you have 500+ HP, you don't NEED to split the gears...heck, you don't even have to shift...
lowering front end You didnt say, what the truck is to be used for. Is it a semi or dump? Im guessing a semi. Most of these blocks are factory, I just added some to my Mack (dump) to raise it, I was tearing the bumpers off, I also added a leaf to help the load. Im also guessing that someone, put it there for a reason. Good Luck
Steve, great job explaining that. Learn something new everyday! Thanks!
That is what's called a "working 13" - first 3 gears in lo, then splitter to middle position, for 4-8, the all the way forward with the splitter for 9-13.
That's a retro- fit there, RollOver Pete... a 1970's workin' 13 in what looks to be a newer Dodge 4X4. I'd just bet with the transfer case in lo and the tranny in lo, that thing would pull like nobody's business. Assuming, of course, that it's equipped with the Cummins.
I've plumbed my bags through the gear selector. Low deflates them, direct holds them and the button by the gauge inflates them. Air comes from the XD4000 in the tool box.
That explains a lot. I was having trouble figuring out why that particular tranny, but I get it now- just the shifter head. That's thinking out of the box!:salute
If you look on the lower left rear side of the trans there should be a tag with the model number. It should start with the letter "R" and continue from there. An example would be RTO12513. That would give you an idea of what trans you have.
? Really?... I've never, ever seen a 13 spd that shifted this way. What model would that be? I've only ever seen 13s that the low side was shifter normally then you went to mid, and then used the od to split gears, as was described above.
I haven't seen one in anything newer than very early 80's. Lots of Internationals and Fords had them. First truck I ever rode in w/my gpa was an old IH4200 w/a 318 Detroit and a workin' 13. In fact, I drove an old L8000 dump truck for a couple weeks with one in it-think it was a 78 or 79 model.My buddy has one right now in an International dump w/a DT466. Not sure what year it is. Anyways, pretty sure that's why they're called workin' 13's, cuz they were mainly in local and const trucks, although my gpa's was (used as) a road tractor.