360 6 speed, only 5th gear grinding

Hi ...

5th and 6th use the same sliding sleeve but use diferents synchro rings and synchro cones.

When you engage 5th gear you move the sliding sleeve over the synchro ring and synchro cone making the selected pinion stop. The synchros are used as a clutch.

When you select 6th gear the sliding sleeve with travel to the opposite side and do the same.

If the syncrhos are worn they will not stop the pinion and what you hear are the teeth of the sliding sleeve grinding against the teeth of the pinion/synchro.


Probably the synchros are worn for any reason on 5th gear...

All the best

 

What portogts is trying to say is that although the synchros are very close together on the same mountings,

You can wear one out without wearing out the toher.

You can also wear out the sliding sleves making the gears hard to select when the tranny is cold, but after warming up they shift just fine.

 

Also the gear may not be engaging correctly due to a "speed" mismatch. The syncros and teeth must "sync" and sometimes the gear oil can affect this. What are you you using for gear oil?

We see this a lot with people changing to a very slippery synthetic gear oil from a conventional. The blocking gears then are so free that they spin at a different speed than the cluster and they don't engage smoothly. An excellent gear oil can sometimes be a bad thing. Depending on the application and the particular oil we have come up with a few blends to help this. For example for older Audi gearboxes we found a combination of 2 qts of Redline MTL90 to 1qt Redline Shockproof Heavy behaves like a conventional oil in terms of lining up the blocking gears, but is still a much better gear oil overall.

Or..as above the syncro may be bad. Kind of unusual for upper gear syncros to go bad before lower gears though. We see 2nd going out as the most common.

 

So that begs the question of the OP.....

1) What was the original gear oil used?

2) What gear oil was used when it was changed?

 

Your worn clutch is exacerbating your problem. A non-slipping clutch and a heavy gear oil could give you perhaps thousands of additional miles before you'll have to tear down the tranny to replace your failing synchro, or you could just do the work now on both the clutch and tranny, then use the correct gear oil instead of a heavy gear oil.

 

I had the same problem with his 360...The problem is its very hard for a mechanic to adjust the cables back perfectly for it to allow the shifter to go in smoothly. one of the employees at I95 Exotics which is an exotic car rental in Miami solved the problem for me simply by removing the shifter cover and sanding the edge so it would move a bit more to the right... and guess what IT WORKED. in the begining i didnt wanna sand or grind anything but i ran out of options and even the dealer didn't really know what was wrong.. sometime they tell me its the cable , or the transmission or sync or the clutch which showed me that they didnt really know what is going on.

I thank the guy at I95 Exotics for solving my problem.

you guys should check them out if you ever go to Miami and wanna drive something nice like a ferrari or a lamborghini or a bentley...

Check their website.... www.i95exotic.com

 

I had the exact same problem and did the same fix as the previous poster. I had 20 mil shaved off of the right side of the reverse lockout block (located right under the stainless gate). Works perfectly now. When the car is sitting still, move the shifter all the way to the right and see if the shaft actually touches the right wall of the gate. If it does not, then the block underneath is holding it up. Sometimes simply repositioning the lockout block a little to the right before retightening the gate screws will solve the problem, but sometimes you need to shave that little extra off. Remember that you don't want to move the block so far to the right that your 1st-2nd gears start to suffer.

 

What kind of 75W90 oil was used, exactly?

With the earlier transaxles (from the 1970's and early '80's) the feeling is that Red Line 75 W 90 NS is the best choice because it does NOT have the friction reducers almost all gear oils have. These friction reducers are included so the limited clutch plates do not bind, but they make the oil so slippery that the synchros don't function well.

If you get noise from your limited slip plates (sounds like a moaning noise when you turn) with this oil you can add small amounts of Limited Slip Additive until it goes away.