Gears grind but only when hot...

I treat Motul gear lube like Frank's hot sauce and have yet to be disappointed.

kb58 wrote: The probl Gears are PPG straight-cut with dog-engagement. The LSD is a "WaveTrac", and because I had to pick something to move on with things, used Honda gear oil. Another thing, and this may be a big deal. When I'm cruising in 4th at constant speed, there's very little load on the straight-cut gears, and there's a fair bit of gearbox noise. I know what straight-cut gear whine is and this is different; it's like something's rattling or vibrating. It may be completely normal but because I've never run such gears, I don't know normal is. What do straight-cut gears sound like when speed is near-constant, with no speeding up or down? Is there a clattering associated with the gears going in and out of contact with each other?

There are PPG straight cut first and second gears in our K20 tranny. When we first zipped the car back up, they were VERY loud, but got quieter with time.

Here's a video, hope it helps in some way. http://www.youtube.com/watch?v=MMySXrHST8E

Id like to try a Rotrex sometime..

In reply to Vigo:

Let me know if you want to buy a complete setup for a CRX ;) (sorry to derail)

Thanks for the continued input.

I talked to someone familiar with this type of transmission and he pointed out that at constant speed, the engine/transmission speeds are dithering relatively to each other. When he said that I remembered getting a ride in a Hayabusa-powered Seven and it had the same problem. At constant cruising speed the transmission was kind of "clattering." It's apparently the engine speed varying slightly and banging the dogs back and forth. Completely normal and solved by the approach of "well don't do that." Speeding up or slowing down slightly avoids the issue.

Regarding the fluid, I have some Amsoil MTF that "Honda kids" go on and on about, as in it solves all sorts of transmission issues - though of course they're running syncros... amateurs

About the inability to shift to reverse when hot... there's only two ways that the spinning engine can spin the transmission when it's supposed to be disengaged: through the pilot bushing, or through the clutch...

... and to find out which is the troublemaker. While part of me wants to ignore it and hope it'll go away, I rather push through the problem and resolve it instead of hoping whatever it is doesn't do sudden and expensive damage. At this point the plan is to pull the engine.

Seems prudent.

Ive personally never had a problem with clutch wobble causing a dragging, but i make exception for the possibility that a twin disc might not have as much margin because it might not separate by as much.

I have had a problem where if you pushed the clutch close enough to the floor, the TOB actually hit the clutch disc hub and pushed it against the flywheel. I ground that down and fixed it (production issue).

I have had an issue where a car would shift normally at very low rpm, but seemed to have a disengagement issue at normal driving rpm (2k+). That turned out to be a pilot bearing issue. I did figure it out before taking it apart, which is good because i couldnt tell anything by looking at it. If you sat with the clutch in and the shifter just touching reverse to detect gear movement (although any gear would work in an unsynchronized box), you could rev it up and feel the gears start to move. It also made a 'loose bearing' decel noise that im not sure how to perfectly describe.