Clark GPX30E:
anyone modified lift valves for smoother response?

saved a old Clark from a trip to the scrapyard, valve handles were severely worn(10mm pins had been replaced with 3/8 bolts, ate the levers out) reslotted levers, oversized pivots, made new pins/rollers to fit new lever slots....
Anyways, levers are now good, no slop, smooth...but the 'down' on some of these Clarks dont throttle real well...was wondering if anyone out there had done any mods like notching spool, maybe changing to heavier pilot operated check spring to try and smooth operation?
it does throttle, but lever from slow to fast is only maybe 1/8" in 'down', more like 1/2" up/tilting... I like the smoother feel of our Mitsubishi lift/drop throttling, would love for the Clark to have same kinda feel to it...
years ago I worked on a lot of big old broaching machines, several times modded spools with a little chamfer or groove to soften transitions, imagine similar should be possible here, havent looked into spools/lands yet, figured couldnt hurt to ask in here first :)
  • Posted 3 Oct 2018 12:58
  • Discussion started by tc429
  • Ohio, United States
confidence: that feeling you have right before you realize the mess you got yourself into...
Showing items 1 - 4 of 4 results.
been a while- trucks all done, really happy with how it turned out... for a little video of it, go on youtube and search 'saving a old clark' should be the first one to pop up.
thanks again Tom_P for the tip on the lift valve spool, better than its ever been :)
did try one other stupid mod- 3" stainless screws as tire studs, the thing couldnt even be moved on snow...will see how they hold up once the snow is gone...expect them to be a little 'clicky' on dry cement, just hoping they dont tend to unscrew, dont think they will...
  • Posted 5 Feb 2019 13:30
  • Reply by tc429
  • Ohio, United States
confidence: that feeling you have right before you realize the mess you got yourself into...
Tom_p - thanks, thats all it was, lift spool was spun...had a few minutes today, flipped it around, smoother than its ever been :)
brakes got all done, everything working great...moved it today though, a new hydraulic leak...think its line from tank, havent got under to look...need a forklift jack next

still messing with wifes truck, welding done, filling/blocking/painting starting tomorrow i hope...rust was worse than expected
  • Posted 5 Nov 2018 11:51
  • Reply by tc429
  • Ohio, United States
confidence: that feeling you have right before you realize the mess you got yourself into...
will give it a try. manual lists spool markings for what circuit, but dont mention rotation- but still easy enough to try :)

Ive got to get these brakes back together(parts due tomorrow) and get back to other things needing done before winter, so might be a long while- my wifes been patient, but ive been tinkering with this thing for 5 weeks in the evenings, and have GOT to get after her truck before winter...gotta cut/weld a quarter panel section in, get paint done before winter, along with odds and ends house stuff... and hope to pour a thick pad for a lean-to to park this 5 ton neon green white elephant in before it cracks my floor :)
  • Posted 5 Oct 2018 08:50
  • Reply by tc429
  • Ohio, United States
First check if any reference marks exist on the hydraulic valve stems.
the marks could be dots lines or letters. On some Clark hydraulic vales the spools have to be located in the correct direction only two options, so try that first. Just turn spools 180 and see if any improvement.
  • Posted 5 Oct 2018 06:15
  • Reply by tom_p
  • Alberta, Canada

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