HI, I HAVE A D6R 9PN00598, I AM GETTING A MOMENTARILY GRINDING NOISE WHEN I SHIFT INTO ANY GEAR. I HAVE CALIBRATED THE MODULATORS AND CHECKED PUMP PRESSURE AND IT STILL DOES IT, ALSO IT SEEMS LIKE THE AS SOON AS YOU TOUCH THE BRAKE PEDAL THE BRAKES LOCK ON IMMEDIATELY? ANY IDEAS?
Have you done anything basic such as checking the transmission oil colour/smell and whether there is anything in the suction screens.? Next I would suggest that you check the priority valve pressure.
oil has been replaced and new filter put on, screens were good but cleaned them anyway
Service brake pedal switch adjustment.?
The switch on the pedal? I'd like to mention also that when i was calibrating the modulators, the odd time when the pressure was dead on spec, sometimes randomly it would drop from 370 psi to about 160 and then it would kick back in and stay on spec
You have a switch and a position sensor in that assembly. The switch is over to the left as you sit in the seat and has 2 wires IIRC, one of which is batt+. When the pedal is pushed the switch controls a solenoid valve that dumps all brake pressure. Effectively what it is doing is applying the parking brake. Normally this only happens when the pedal is fairly close to the bottom of its travel.
ok i will check that, what about the momentary grinding when foot on the brake and going into gear, even when i upshift from first to second and second to third
If you eliminate the possibility that the brake switch is in any way related to the problem the you’re going to be digging into the brakes or the transmission, maybe both. Does the grinding noise come from the transmission or from the brakes.?
It comes from the transmission, i can look through the cover on the back of trans where the modulators are and when it grinds i can see the crown gear shutter when its doing that, it seems that when the pressure is being applied to the which ever speed clutch, that split second when the pressure goes from 0 to the spec is when it does it, as soon as it gets to spec it stops and its in gear
Snatch the transmission before it breaks something major.
A thought just occurred to me. Have you looked at the condition of the universal joints on the drive shaft between the converter and the transmission.?
Yah Ujoints are good, i went and pulled transmission and checked out bevel gear assembly, everything in there looks good, i disassembled the transmission and everything in there is good, i am wondering if it is a pressure issue going to the modulators, if there is a problem in the priority valve would that affect how quick oil is getting to the trans. I am pulling priority and brake control valve off now to clean and check
With your description of the brake symptoms as being like a hair trigger I’m wondering if the problem might be in the brakes. The priority valve supplies the brakes first then the transmission, so if there was a problem causing oil loss in one or other brake pack it could be producing symptoms in the transmission. Maybe try to pressurise each brake patch separately to check for internal leakage past the seals.?
So how would i go about doing that?
Not sure TBH. In the past I have come across people installing a blanking plate in the parking brake release line then pressurising the brake from the test point on the final drive spindle. Unfortunately I don’t have access to the system at the moment so can’t supply details.
If you come across how to do that i would greatly appreciate it
Brake piston leakeage? hook a dial on the test port @ spindle, operate PRK BRK and or service brake, how fast it comes to system pressure tell´s about condition of the sealing. (eng idle) park brk release show system press. service brk full dwn show 0 press. if the leak is too high might not get the pressure past pry valve.
ok im wondering how i would do it with the transmission out, i have the brake valve out to check and clean, i am wondering if i make a plate to bolt down where the brake valve sits and only make two pressure ports in it, one for the left brake and one for the right and then pressure it up that way to see if i have leakage? Think that will work?
ok im wondering how i would do it with the transmission out, i have the brake valve out to check and clean, i am wondering if i make a plate to bolt down where the brake valve sits and only make two pressure ports in it, one for the left brake and one for the right and then pressure it up that way to see if i have leakage? Think that will work?
Well, if u already have the TXM out u can test TXM piston seals with compressed air. Or u simply invest in the future, reseal it!!! make sure TXM is not the problem. Press to the TXM system goes from priority valve. So u can tap at PV or on the rear where oil enter TXM. I´m not sure where system pressure regulation is, but´s either at PV or Filter assy, so u got also to deal with that. Reseal brakes/steer clutches takes less than 2 hour if its finguer tip control. cost is low. its also u should consider...
BTW, how can u hear grinding in the TXM? thats quite weird without visible destruction, sure all TMX gears are sound? planetary, sun gears a outer rings? also the needle brakes? Did u guys look at P1 and P2 pressures?