Gearbox: Mix moly and non-moly synchro rings?

**tubut** · #1 (**permalink**) 10-20-2003, 12:54 AM

Hi all,

I have some gearbox questions:

1. What happens if you mix moly and non-moly synchro rings?

2. Does it hurt to use mineral SAE 90 oil on non-moly rings?

3. How about synthetic oils?

Any advice, hints or comments are greatly appreciated.

Ruedi

120 · #2 (**permalink**) 10-20-2003, 06:26 PM

Ruedi,

I can only repeat what I have heard as I have no direct knowledge;

I think the two types of rings vary a tiny bit in size, some machining is done to moly synchros to get them to fit on a 101 trans, or perhaps it is the other way around. The old synchros use Dentax gear oil although a synthetic the P racers use can be used.(swepco 200?) Some of the newer oils tend to leak= empty trans.

On the giulietta list everyone favors the newer tranies, getting away from the old synchros.
Again, what I have said is prolly riddled with mistakes, but I think the general point is, later is better.

OK everyone correct me on this.

**ossodiseppia** · #3 (**permalink**) 10-28-2003, 07:27 PM

I don't know what moly and non moly are. I can tell you that the Giulietta ones are different from the Giulia ones. They are not interchangeable. If you want to use Giulia ones in a Giulietta tranny, I believe you need to change out the sliders as well.

alfajim · #4 (**permalink**) 10-28-2003, 10:05 PM

Don't mix them they are too cheap to not just replace them all and the three sliders. The gearbox is a place where it is not cost effective to cheap out. Do it right when it is out and you will never do it again. Use a good synthetic oil it does help I have used redline MTL,shockproof (you better know how the seal it up perfect or it will come out everywhere with the shockproof),and several others all worked well and improved the cold shifting. I have 60,000 on my spider gearbox and second gear syncro workes perfect.

**tubut** · #5 (**permalink**) 11-04-2003, 12:12 AM

Thank you all for the good advice.

The problem I'm dealing with is that I have no idea what synchros are inside the gearbox I have (for a 2600 Touring Spider). In '62-'63, they had non-moly, but switched to moly in '64.

I was hoping to (a) not having to open the box to find out and (b) not kill the gears using the wrong oil.

Cheers,

Ruedi

alfajim · #6 (**permalink**) 11-04-2003, 11:08 AM

You can remove the drain plug and fill plug and look inside to see what style syncro's are in there a bright flash light and a mirror help.