View Single Post
  #4  
Old October 6th, 2022, 07:05 PM
WE7X WE7X is offline
Member
 
Join Date: Sep 2013
Location: Issaquah, Washington
Truck: 1970 GMC RM-7500 based Motorhome
Posts: 80
Rep Power: 89
WE7X is on a distinguished road
Default Re: 1970 RM7500 clutch slave cylinder question

This response was from a very old posting, but the new slave cylinder worked fine after finding a small hydraulic leak.
I got an offer I could not refuse, to sell the old monster, so it was necessary to finally fix the clutch issue.
Turns out the hydraulic line had worn a pin hole at a frame clamp, so I could not build any significant pressure to operate the slave cylinder. The small amount of hydraulic fluid leaking ran along the frame rail for several feet, to a spring hanger, where it eventually dripped off a spring shackle, into gravel. It was very hard to even see the wet spot, and it took a lot of time to finally find the source of the leak.
The old motor home conversion (1970 RM7500-a school bus chassis with a 1954 Spartan Travel trailer for a body) is 38 feet long, so the clutch hydraulic line was over 30 feet of tubing ( rear engine configuration ) .
A roll of Ni-Cop tubing and a couple of hours work threading it through the frame cross members solved the problem.
The old motor home drove away just fine, with it's 401M purring nicely.
I have a spare Allison automatic transmission and adapter plate, starters and a couple of magnum heads, and a magnum exhaust manifold remaining, if anybody is looking for something like that in the Seattle area.
Rod J
Issaquah, WA
Reply With Quote