Intermittent "crunch" noise on shifting in 3rd and 4th

Clutch not fully disengaging?

 

I have a 2002 360 spider, 34k, same thing. Sounds exactly like a motorcycle dog-box shift. Downshifts flawlessly.
1-2 good, 2-3 noisy, 3-4 noisy, 4-5 good, 5-6 good.
F1 hyd oil clean and topped up. Maintenance on hydraulics and gearbox oil always done on time. Clutch at about 40%.
Only other F1 quirk is sometimes the car doesn't go into reverse from neutral on cold starts on the first try. Once I put the car into first gear, shifts from 1-R or N-R everytime with no noise.

Like others, I was thinking synchros, but with consistently flawless downshifts, it just doesn't fully fit. Seems more likely a timing issue synchroning the shifts.
If the actuator or 3rd gear selector in the gearbox is slow or sticks, my understanding is that it could be 'late' and therefore out of synch.

Any thoughts?

 

Check your coolant reservoir for traces of oil.
360s are prone to cross contamination between gearbox oil and coolant.

 

Check the gearbox oil first. If the gearbox is over full, it is likely the heat exchanger in the middle of the intake. As the coolant system makes more pressure that the trans fluid through the heat exchanger, it will be adding coolant to the trans fluid. It may not put any oil in the coolant.
If that is the case. Drain it, replace the heat exchanger and use AFT to clean the transmission. Fill it with ATF, run it on a lift (or stands) with no actual load. Drain and repeat until clean. Put in the proper gear oil and drive it. I have done this before with great results in the end. However, if it has damaged the syncros and it still crunches after cleaning and fresh gear oil, then syncro replacement may be needed.

 

Ouch!

 

Ferrari Tech is correct and syncros can be intermittent when they are going south. But they dont work well in antifreeze. In my experience ring gear wear is usually what kills them when they are running with antifreeze.

 

I had a similar problem in my 2000 360 coupe, the transmission was making noises so I called GTE Engineering and they tested and fixed my actuator that was getting bad. About the fluid in the transmission they did a cocktail of oil to make it run like a swiss watch.

 

You're right, but it's simple to look at coolant first. I've done a couple of these repairs. There was oil floating on the coolant and the coolant level was low (because it was going into the gearbox).

 

Thanks for the replies.
Just changed the gearbox oil. Old oil was perfectly clean. Replaced with Redline 75W90NS.
Did not inspect the filter screen. When cold, shifts are now completely silent. Once warmed up, the noise returned, albeit at reduced volume.
I also noticed that the noise can occur at any time, involving almost any gear change, up or down, although most occurrences are with 2-3 & 3-4 upshifts.
Apparently this is a common thing with these cars. I have concluded it is normal and requires no action.