I'm picking up my Newell next week to drive home.
As the rig has a ZF 10 speed and my old rig has an Allison, I'm wondering what differences I should expect? Are there any tricks with hill starts, long descents etc? I'm assuming having at least 90psi air pressure is a good start as the ZF needs air.
To check the oil level in the transmission is it the same buttons on the controller as the Allison? Or is that irrelevant without the converter?
Thanking in advance for any advice.
Pete
Hi Pete,
I have a 12 speed ZF in my#1218 2008 coach, on the back of a C15 625.
The ZF transmission is exactly like a normal constant mesh manual gearbox, if yours's is a AS Tronic, it has a normal clutch IE friction plate and pressure plate.
Clutch actuation and gear selection are automatic, that is controlled by the gearbox Control unit, which is linked to the engine controller and brake system.
My 12 speed box is the same unit as yours with an addition of a half gear split on each of the 3 main gears.
Like any auto box if you apply a small amount of throttle whilst driving the gearbox controller will alter the change points automatically conversely accelerate with full throttle it will hold the gears longer before it changes, off the throttle down hills it will change down, a quirk with the 12 speed is that it will not select 12th until 60mph, if you manually select on the control panel it goes back to 11th after a few moments, this is standard ZF.
Oil level is exactly like a manual truck box to check and make sure it has the correct ZF approved lube not Auto trans fluid, and as you say both the clutch actuator and the gear changes are air pneumatically operated by the gearbox controller.
The 12 speed preselects 3 to start off, but you have to manually select 2nd or 1st if required if maneuvering ( this saves the clutch).
Another common issue is the clutch actuators go faulty and strangely do not fully disengage when out of gear and idling, this makes the clutch smell, just like it is or has been slipping, over here in the UK the ZF AS tronic is very popular so well supported, a ZF tech can plug into the coach and read all the stored parameters, tell you clutch wear % over temps (clutch) not box and over torque.
My coach has like a hill start function, lets say you are stationary on a hill facing upwards in slow traffic when you come off the footbrake there is a delay before the brakes release, this gives you time to apply the throttle without rolling back (that's why the box controller is linked to the brake system) once moving it all works like a full auto although it is not seamless like an Allison.
When you 1st start up with low air you will get the key pad flashing letter codes these clear once the air is built up.
Regards
Ian
To amplify what Ian has said about startup on a hill when roll back is possible test to see if you have the braking assist or not. Our coach 1202 has a ZF 12 speed and when I first started out I made a few folks behind us nervous as the coach rolled back. I found it necessary to get off the brake and apply a little throttle as quickly as possible. That advice was also given to my wife by Glen Edwards who taught her to drive our coach while we were in Miami, OK for service. The advice has served us well.
It took a little getting used to the feel of the ZF after driving the Allison on our previous coach because you can feel the ZF shift the first few gears off the starting line from then on is feels seamless.
Enjoy it and have fun.
Pete,
When you are at the factory have them check to see if they can program the transmission to use all 12 gears. My coach (1223) was listed as a 10 speed ZF when I purchased it but turned out the system could be reprogrammed to 12. Works seamlessly.
Best of Luck
Mike
#1202's (2007) was listed as a 10 speed on the build sheet. But we definitely have a 12 speed. Hope you're successful adding two speeds if you want to.
Just keep in mind when you come to a stop on an incline, the coach will roll back if you don’t keep your foot on the brake. Other than that, I love the 12 speeds especially in the mountains.
Hi Michael, some coaches like mine have a hill start function, when you release the footbrake on a hill the brakes hold, this gives you time to apply the throttle if you are slow, if you are very quick as soon as you apply the throttle the brakes release automatically, if you drive it correctly you never roll back.
Lelievre12,
Being a newbie myself I thought a more comprehensive guide might be helpful. The staff at ZF Corporate were very helpful. Within 48 hours they had emailed me a copy of the ZF 12 speed Astronic Operations Manual. I'm looking forward to reading it and hope it will be helpful to you too.
Bob
Does the ZF 12 speed get better fuel mileage than the Allison MH4000 six speed transmission?
Which one pulls mountain grades better?
The ZF 12 certainly pulls better on mountain grades due to the ability to use all 12 gears. From a standing start, the Allison is faster and shifts smoother. I would think the fuel mileage would depend on how you drove them rather than the design of the transmission itself. Certain if you use the ZF 12 to climb hills more quickly, it will consume more fuel.