Clark CY50:
Transmission slip when hot

This CY50 is an old 1964 5klb with holden 6 motor (factory fitted from new)
(unit is actually a CYF50 (Friction clutch) but has had transmission changed to auto long time ago.)
The machine is for home use & gets very little work.

I get serious transmission slip when engine is hot (winter use no problem) both forward & reverse.
Have to wait for cool down to drive again.
I checked tranny oil pressures & are within spec. (didn't check when slipping though will try again)

Is hot slipping an oil pump problem or friction plate wear issue ?
I don't have time to rebuilt right now but might try "transmission fix" additive.

Any further info will be helpful
Thanks
  • Posted 18 Jan 2010 11:54
  • Discussion started by tonigau
  • Queensland, Australia
Showing items 1 - 3 of 3 results.
Try running TDH in its ***
  • Posted 27 Jan 2010 09:09
  • Reply by CLTL
  • Ontario, Canada
Thanks mrfixit,

Im going to make an extension hose for my pressure gauge so I can see easier as it warms up.

I did have a problem with the inching lever last year, the spline shaft clamp was not tight & it would not return properly, had to cut widen the clamp gap, fitted a GR8 bolt & it tightened up good. I will look close at this valve operating.

I spoke to transmission rebuilder yesterday & they advised "transmission fix" additive is only good for short term remedy by swelling seals to improve pressure.

I will check & clean the pump screen. (The line filter was pretty cruddy when I checked it (probably the first clean its had in 20 years))

One thing I wonder if ATF is available in heavier viscoscity ?
  • Posted 19 Jan 2010 06:40
  • Reply by tonigau
  • Queensland, Australia
It sounds like more of a pump or pressure problem rather than the clutch plates because it is slipping in forward and reverse. Could be once the oil gets hot, and thins out, the pressure drops due to the pump. The screen that filters the oil to the pump may be just about plugged and after running a while does get plugged. Then after shutting off it clears itself a bit. Also, how about the inching valve? If it is the one mounted on the top of the transmission, they have a problem with the springs breaking. Check to see if the lever going into the trans is being pushed all the way back by the springs to engage the trans.
  • Posted 18 Jan 2010 22:39
  • Reply by mrfixit
  • New York, United States

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