Thread: GMC 4000 rear axle vacuum shift
View Single Post
  #1  
Old September 18th, 2020, 03:56 AM
Crosshairs6 Crosshairs6 is offline
Member
  
Join Date: Jun 2014
Location: Pollock, Louisiana
Truck: 1961 GMC 4000 (Fontaine flatbed) w/ 305B engine
Posts: 53
Rep Power: 76
Crosshairs6 is on a distinguished road
Default GMC 4000 rear axle vacuum shift
I have a 2-speed T150 rear axle and a SM420 transmission.
I have to maintenance manual for the subject truck and I don't see anything written regarding to required vacuum pressure that is optimum for shifting the truck. I have traced to vacuum lines and identified where the rubber connectors are to separate and test with a vacuum gauge. I just don't know what the pressure should be.
Picture attached of the T150 rear axle with the shift chamber installation.
Thanks in advance for any information.
Attached Images
File Type: jpg 20200917_193304.jpg (3.50 MB, Multiple views, 7 clicks)
__________________
USMC Retired
Pollock, LA.

Own a 1961 GMC 4000 (Fontaine Flatbed) with a 305B engine
Reply With Quote