| Author | Message | ||
| Joe Bigwind
Rating: N/A |
My 4106 is equipped with an 8V71, V730, William Air throttle, and Stone-Bennet air Shifter. Last summer I got the rear tires planted a little (6 inches) in soft turf and it wouldn’t pull out, spin or rev-up (engine RPMs). Dug a small trench and it came right out. Wondered about it but had other things to do. Yesterday tried to back it up our new 15-percent-grade driveway. Same thing, got about 20 feet up, slowed to a stop with full peddle but far from full throttle. Got it up by backing up with a running start but just barely. Thought there must be an adjustment to the throttle position feedback to the V730 or something. My buddy with a 4601 & V730 says he has spun his rears when stuck in the mud, why can’t I? Thanks, Joe | ||
| Brian (Bigbusguy)
Rating: N/A |
Rear end ratio is to tall . What you will end up doing is heating it up fast when the converter is stalling out. Or you motor is under powered. I would check to see if you are getting full throttle. If not you will not be getting full power. Thats my only guess I can think of. Brian 4905 4 speed manual Oregon? | ||
| Joe Bigwind Rating: N/A |
Thanks Brian, I'm not getting full throttle but am applying full peddle. Joe | ||
| M9 Man Rating: N/A |
I had a similar problem with my MCI-9. Come to find out, my throttle was not opening all the way up. You might want to check into that and rule that out before trying anything else. JR | ||
| Jack Conrad (Jackconrad)
Rating: N/A |
Can you rev engine to the max governor speed with no load on the engine? Do you have an air throttle? If you have an air throttle, how much air pressure do you have on the air supply line to the throttle pedal assembly? Check the diaphram in the air throttle actuator that is on the govenor, it could be leaking. You can get a replacement from Luke at US Coach. We carry a spare in our "just in case" box. If you are getting full throttle response at the govenor, sounds like a gearing problem. Hope this helps, Jack | ||
| john w. roan (Chessie4905)
Rating: N/A |
they make a torque converter with a different torque multiplication ratio for that trans.Maybe you need the other one...IF EVERYTHING ELSE CHECKS OUT OK. | ||
| Joe Bigwind Rating: N/A |
I have a William Air throttle and Stone-Bennet air Shifter. When I manually move the throttle to max rotation at the engine, the eng revs up big time (so I want to run and hide) but I have not checked actual gov speed. Just because it screams at me like my wi..., er, what I mean, is that an indication of full throttle or do I need to verify rpms? I get the same results depressing the peddle, in neutral or running 3rd gear on the flat. It will go 80 mph no problem. Doesn't this imply it is not a gearing prob? But I do have trouble maintaining speed on what seem to me to be moderate but long climbs (15-percent-grade for 1/4 mile); drops down to below 40 mph. I will check air supply press at peddle; what should it be? Also, can I check that I am getting full rotation of the throttle regardless of rpms? Thanks to all, Joe Shelton | ||
| John that newguy Rating: N/A |
Joe- Some of my empty thoughts? Sounds like you have a bus typically geared for line work in a fairly level area, and only experiencing the normal idiosyncrasies of that model... Reverse isn't like 1st gear in any bus... it's more like 2nd gear; Starting out on any small hill presents problems... Dying on a long grade in 4th gear without shifting down at the appropriate point, is normal.... and a good way to take years off the engine.. Should shift into 3rd at 55.. (1st=15, 2nd=30/35, 3rd=55, 4th=80ish). The engine revs fine and gets you to 80+mph... what throttle problem? | ||
| Mike (Busone)
Rating: N/A |
I hate when I am dying on a long grade in 4th gear. I would rather be living.  | ||
| David Hartley (Drdave)
Rating: N/A |
How is 2nd gear? Second and reverse gear uses the same clutch pack in the tranny on V-730 /V-731's, If reverse is soft then second gear will be soft also. This usually means a rebuild is due. If your bus will do 80 mph then your rear end gearing is too tall for applying power properly in low gears. A V-series Allison will heat up really fast if you get stuck and will overheat the internal hydraulics and not want to pull a load. It's all down hill from there, all the way to rebuild time. | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
Joe, If you put your coach in gear while stopped, will the engine rev up normally when you try to start rolling, or does it sound like it's being lugged? If it sounds like it's being lugged, there is a possibility that the third member in the converter is not being held when it should. This will result in you having about 1/3 of normal stall torque. It would account for some of what you describe. A tachometer will confirm this condition if it exists. The third member's job is to increase engine RPM at converter stall and to convert the increase in RPM into torque. If it is not held during startup, the converter becomes a fluid coupling instead of a torque converter. When you gain speed and the engine RPM starts to climb too high, the third member is allowed to rotate. This holds down engine speed until you reach the top of the gear and it is time to shift. It will not be difficult to figure out if this is what is happening to you. For what it's worth. Tom Caffrey PD4106-2576 Suncatcher | ||
| FAST FRED Rating: N/A |
When you get this figured out . I would go to the (sounds like the torque converter is locking at near idle How many "shifts" do you feel on a flat road?) Daris site and find out what RPM your pulling at "80mph" with a 730 and normal rear ratio in a '06. 2100 is book max , you should hope for a bad speedo , cause if its a REAL 80 your way way overspeeding the engine. FAST FRED | ||
| john w. roan (Chessie4905)
Rating: N/A |
I don't want to sound like a smart alec, but are you sure it is a v-730? 80 sounds like 4:11 and 2700 with a v730. | ||
| Joe Bigwind Rating: N/A |
I'll address your questions/suggestions in order: John that newguy: "Dying on a long grade in 4th gear without shifting down..." in a climb, I shift the 3-speed V730 to 2nd when my speed slows to 45 mph. David Hartley: "How is 2nd gear? i.e. is it soft" I don't know how to tell if 2nd is soft. Would this indicate a soft 2nd gear: On moderate climb (15-percent-grade for 1/4 mile) I dwn sft to 2nd when she slows to 45 mph but bus continues to slow to about 35 or less. If I hit the hill hot I can keep the speed up. I have a trany-temp gauge & keep'r cool (never over 185). Tom Caffrey: "engine lug when start rolling from stop" Seems to rev up fine from stand-still. Tom Caffrey: "tach will confirm this condition" & "will not be difficult to figure out if this is what is happening" Tom, could you please give me a bit more direction on how to confirm condition if I had a tach? Thanks FAST FRED: Where is the Daris site? john w. roan: "you sure it is a V730?" yep I have a rebuilt V731 if my trany is the prob. Replacing the 731 valve body with the 730 valve body should make it a 730 as I understand it. Thanks so much for all your time. My 06 will be on the market soon. Joe Shelton 4106-2119 | ||
| David Hartley (Drdave)
Rating: N/A |
David Hartley: "How is 2nd gear? i.e. is it soft" I don't know how to tell if 2nd is soft. Would this indicate a soft 2nd gear: On moderate climb (15-percent-grade for 1/4 mile) I dwn sft to 2nd when she slows to 45 mph but bus continues to slow to about 35 or less. If I hit the hill hot I can keep the speed up. I have a trany-temp gauge & keep'r cool (never over 185). If reverse doesn't want to pull the load while trying to back up a driveway, And since 2nd gear and Reverse gear clutches are shared, You might find it necessary to keep applying more power under loads such as going uphill when in second gear, listen to the engine speed if the rpm's spike higher than they used to you may have a clutch pack slipping that makes the application of more power to overcome the slippage. Then figure that the torque converter lockup is probably happening in second gear where in most cases it is supposed to. The rpms will drop slightly and then start to go back up as the clutches slip until the rpm range is high enough to shift into third gear and onto another clutch pack. I have an 80 model RTS with a bad second gear clutch, It won't backup at all, Nor will it shift into third because it can't get past second. But as long as I am only going forward in first it will pull stumps and buildings. I have not fixed that one as other projects have shifted my attention several times so it just sits awaiting a whole cradle package. Someday either the junk man will get that 102" RTS or I will get around to it. | ||
| Tom Caffrey (Pvcces)
Rating: N/A |
Joe, if the third member is not being held, stall RPM will likely be under 1000. If it is being held, then it will be way over 1000. This won't be hard to see with a tach. From your description of "Seems to rev up fine from stand-still.", I don't think that this is your problem. Good luck finding out what it is. Tom Caffrey PD4106-2576 Suncatcher | ||
| joe bigwind Rating: N/A |
I'll try and rap this up. Before I pull the tranny: David Hartley: "If reverse doesn't want to pull the load while trying to back up a driveway.." While backing up 15-percent-grade, bus slowed to a stop with full peddle but far from full throttle. I was tempted to sit on the bumper and let mom drive while I manually moved throttle. David you say if it is necessary to keep applying more power under loads I may have a clutch pack slipping. But I apply max peddle but the engine doesn't sound like its under load and the rpms don't come up. I just want to be sure it is the tranny before I change it out. Thanks every one. Joe Shelton | ||
| Jim Bob Rating: N/A |
Joe, If I were wondering about throttle travel, I'd air the bus up good, then shut off the engine. Turn the "ignition" back on & have someone put the pedal to the floor (engine NOT started, but ign on) while you stand at the rear & observe if the throttle goes all the way open & stays there. (I'm guessing that you have already checked the throttle lever/air throttle cyl travel with the pin out to be sure the lever goes all the way open.) Revving up with the engine running won't tell you if you're getting full rack opening because in neutral the engine will hit top RPMs (governed RPMS) with very little fuel. You could get 2100 RPMs in neutral but not get full fuel to make full horsepower when in gear. You're a brave man. I have a stick shift bus & I wouldn't attempt to back up a 15% hill! I don't think I'd do a 7% hill that way. Is there some way you can arrange to drive up & turn around? | ||
| Buswarrior (Buswarrior)
Rating: N/A |
Hello Joe. Brief answer, family steaming mad for me to go.... Before you do anything, you must confirm whether the fuel delivery system is actually making it to full fuel. The motor can spin to the governor with very little fuel in neutral, and will drive adequately with the fuel system only making it part way open. It requires you to confirm that the fuel rack and all the bits and pieces are actually opening the injectors all the way. Much of our driving does not take the motor to full fuel for long, if at all. This is a completely different issue from the position you are holding the throttle pedal up front. Check the simpler stuff before you go fooling with the transmission! happy coaching! buswarrior | ||
| Bill Endres
Rating: N/A |
Joe : Been on vacation so am late with a response. Sounds like you are getting a lot of suggestions. Do you know what size injectors you have? N60? Most hounds and RTS's had N60 injectors unless they were used in hilly country then they had larger injectors. You may have to increase there size, a 15 deg. is awful steep for backing. Like some others said, check throttle opening with engine shut down. If you have a tack generator that is driven off the blower, are you getting at least 1500 RPM when stalling out? Stall pressure should be at least 265 PSI. Pump may be worn or seals leaking or clutches slipping, this is kind of hard to diagnos. Sounds more like you need a good deisel mechanic to check the set up on your throttle, rack and govenor settings also he can check each individual injector to make sure they are not plugged and are working OK. If you can find a mechanic that works for and on city transit busses, they are usually pretty good with the Detroits. Good Luck. Bill |