SHIFTING PROBLEM

[rd200]

I have 65 d-100 with a 4 speed floor shift transmission. Once it is warm after driving for about 25 miles. the gears grind a little when going into 4th gear from 3rd gear. When cold it shifts smoothly All other gears work great. Any suggestions....

Thanks..

[facechicken]

Ok disclaimer....i really dont know all that much about manual transmissions.....that being said it sounds like your fluid gets warm and starts thinning out a little......i would say try a heavier weight fluid in there but like i said i dont know much when it comes to manuals.

[daytb]

Face sound like on the right track the blockers and syncros might be getting worn enough that when its cold the oils thicker keeping them meshed better. then as it warms its showing the wear more

[EGroscup]

I am going to x3 that one. I have had personal experience with a car that was terribly hard to shift when hot, changing the trans oil fixed it. E.