Bennett shifter air leak? - Printable Version
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+--- Thread: Bennett shifter air leak? (/showthread.php?tid=8106)
Bennett shifter air leak? - BusNit - 08-11-2024
I had the shifter sent out and rebuilt last year or so. Today while admiring how clean and leak free my coach is, there was a distinct sound I could pick up with my ears. The sound was more like a very low humming pitched sound. When I put my finger around the shifters vent cap, the sound changed. With the excitement of a five year old on Christmas Day, I ran out of the pit and went to grab my high dollar air leak tool. (Soap bottle) sure enough my 54 year old hearing is still superb as I found this leak despite all the ambient noises from the ac’s running on the coach and at the house.
I sent a text with these pics to TH Anderson and hope I get a response tomorrow.
Should this thing be venting off when parked?
Curious if this may have been a cause why I could not get it in gear at one of my fuel stops a couple months ago…
What is the purpose of this? Looks like it’s connected to a solenoid.
RE: Bennett shifter air leak? - Jack Houpe - 08-12-2024
That looks like a fitting leak brother.
RE: Bennett shifter air leak? - BusNit - 08-12-2024
It's a vent cap according to the Bennett site. Not sure if as you set it from neutral to drive does the solenoid allow the displaced air to vent out that fitting.
RE: Bennett shifter air leak? - BusNit - 08-13-2024
I spoke to the crew at TH Anderson and they suspect it is an internal shaft seal that's allowing air to escape through the vent. The vent is supposed to allow air to pass when the internal shift rod moves to displace air in its normal operation. Spent the morning removing the shifter and dismantling part of it to make it smaller to send in a box. The backplate is at the powder coat shop.
RE: Bennett shifter air leak? - Jack Houpe - 08-14-2024
This is all new to me I find it very interesting thanks for the pictures.
RE: Bennett shifter air leak? - BusNit - 08-14-2024
This is old tech and rarely seen unless you drive a refuse truck which most of these shifters were used on. I believe Allison went to a keypad style setup in '94? It's all new to me as well. The only real reason T.H. Anderson services these is due to the fact they are primarily used on oil field pump transmissions. If not for that, I would have to learn to dissect and make parts for this.
RE: Bennett shifter air leak? - [email protected] - 08-14-2024
Many of the bus conversion guys were using those stone bennet shifters, I had not messed much with them, always wondered how they made them stop at the right spot.
RE: Bennett shifter air leak? - BusNit - 08-14-2024
I never opened up the magic box portion of it. Probably switch contact detents and more of a mechanical method of where the shaft should be in relation to selection on dash switch. I decided to invest some time in myself by studying for the HAM radio license and leave the shifter to the pros.
RE: Bennett shifter air leak? - [email protected] - 08-15-2024
(08-14-2024, 07:19 PM)BusNit Wrote: I never opened up the magic box portion of it. Probably switch contact detents and more of a mechanical method of where the shaft should be in relation to selection on dash switch. I decided to invest some time in myself by studying for the HAM radio license and leave the shifter to the pros.
Gotcha, that is kinda what I figured they were doing. I have seen some really nice air cylinders with position feedback. I actually had 4 of them that I got from refuse to energy facility I was working at. They actually took them out of service because the position repeatability was not accurate enough for them, they went with hydraulics. These were for air dampers that feed the burn chamber where they burn the trash.