Mitsubishi shifting problems

[Hemmen1]

we own a mitsubishi fm-mr straight truck with a six speed manual transmission, since we have owned the truck it has shifted poorly, we have broken two linkages to the transmission because it is so diffucult to shift. recently the clutch went out and we had a new clutch installed -- still shifts like hell. It seems to shift fine for the first 20 minutes or so then once it warms up it grinds into gear and can be hard to even get into gear -- the clutch is not out of adjustment -- Our mechanic has checked the slave cylinder and it is ok - he said they either work or don't work and there is no in between -- he thinks there is a linkage problem but I disagree since it shifts fine when cold -- any advice would be appreciated -- Darren

 

[JoeyD]

Could it be the lube inside. When cold the lube is thicker and when it warms up it thins out? Just guessing.

 

[Hemmen1]

Originally posted by jdecampo

Could it be the lube inside. When cold the lube is thicker and when it warms up it thins out? Just guessing.

The lube has been changed to what the factory "Manual" stated - Darren

 

[lgibson]

It sounds like there may be a leak in the slave, master, or lines. The more you use it the more air it sucks into the line. After sitting the air will eventually rise out of the lines and into the master cyl. Does the pedal feel any different between cold and after the "20" minutes? Check the hydrolics out good, not just the slave, and master, but the lines also. When it starts to grind, instead of just pushing down on the clutch once, try pumping the clutch a few times and then shift. See if that makes a different. It sounds like there is a leak under pressure, when you are on the clutch.

I have worked on thousands of transmissions and I would bet that is what it is without looking at it. Your mechanic should be able to tell you if it is a trans problem or not just by looking, and always get a second opinion.

 

[illflem]

It sounds like the syncro-mesh bushings may be worn and the thicker pre-warm-up oil is holding them closer to the right place. I had this problem on a older Nissan PU, the problem was that the wrong material was used for the bushings and they wore out rapidly, the trans oil had bronze looking flakes in it. Dealer replaced the bushings with new improved ones for free even though it wasn't a recall. Double clutching may work for you but is a PITA.