Getting ready to place an order for parts for my transmission rebuild and was looking for opinions on which of my synchro rings are good enough to flip.

In the picture the order they came out of the transmission is 1st, 2nd/3rd, 4th/5th.

It's obvious that 1st is done. 3rd looks to me like I could reuse it, very little wear. What about 2 and 4/5?

The coating on 2 is a little rounded at the peak. On 4/5 the moly coating is worn just past the half point of the peak.

Would these be considered good enough to flip or should I replace them?

I would probably only use 2 & 3. 4th & 5th are doable flipped but if you are going through all the trouble I would replace those too. Find a good tailshifter for a donor. For that matter I am sure I have a few used ones in better shape. Shoot me a PM if you'd like a few used ones. I'll make you a deal on some

I'd only replace 1st. The other look perfectly usable to me.

There is more to the story than the syncro side that faces the slider. Replace them all while it's apart. Dog tooth is probably shot on first and most likely the slider.

When you flip the syncro, the worn area is now in the dog tooth side and that effects the overall OD of the syncro.

Do it once....do it right

nice and rough.

I posted pics of my 1st gear slider and dog-teeth in another thread. Dr Evil gave my slider a thumbs up but suggested I replace the dog-teeth (which I plan on).

....TOSS...1st and 2nd gear syncro,s...........reuse 3rd 4th and 5th.

Thanks Marlo for the great pic's for us who might be doing this rebuild.

??for the Experts: Is this a normal pattern to see in most old trannys? Why is #3 so perfect - normal wear? or was the driver someone who skipped 3rd gear a lot?


Thanks.

That may not be the 3rd gear synchro; it could be 2nd gear. When I pulled everything apart I was careful to make sure I kept everything from 1st, the main shaft, and pinion shaft separate but I didn't mark which synchro was 2/3 or 4/5. So the third synchro in the picture could be either 2nd gear or 3rd gear.

And I have no idea what kind of mileage was on this transmission. I was told by the PO that it's the original transmission to the car and there was an issue, but can't remember what he said the issue was.

....................so the information you provided to us in the second sentence of your post is incorrect?....the sycronizers are not in order of removal...1st thru 5th.?..........generally you can reuse 3, 4, 5.....if in your case you can figure out which is which.

[/quote] ....................so the information you provided to us in the second sentence of your post is incorrect?....the sycronizers are not in order of removal...1st thru 5th.?..........generally you can reuse 3, 4, 5.....if in your case you can figure out which is which.
[/quote]


Yes, I did not mark them when I removed them (should have). That's why I grouped them as "2/3" and "4/5".

I don't think the picture sequence matters as long as the sliders and spyders are good. Each should be judged as a separate case. Here's what I think...

- Replace 1st
- It doesn't matter which direction the third one goes back in
- flip the rest and put them anywhere you like

Good luck!

Sliders look good to me. Sharp pointy teeth on both sides and very little wear. What kind of wear do you look for on the spiders?

Here are a few pix that will show you the wear I'm talking about. If the spider is worn, the slider will be as well on the corresponding contact surfaces.

Here is the unloaded (downshift) side of a spider "foot". It looks nearly new

Click to view attachment

Here is the very worn side of a spider "foot"

Click to view attachment

Here is the corresponding wear on the slider that mated to the above.

Click to view attachment

Hope you never see this. Obviously there is wear in-between these two extremes.

This worn pair manifested itself as a "bump" when shifting into that gear before the dog teeth engaged... almost like it was in gear already. But you could push the shifter farther and it would go into gear normally.

Good luck

Thank you, great information and pics!

My spiders have slight wear which looks similar to the left side of your "bad" spider (mine look a little less worn than that). I do not see any unusual wear in the slots of the sliders.

If there is only minor wear, couldn't you "flip" the spider since the torque and spin is always in the same direction on the shaft? Wouldn't that change the contact surface where the spider interfaces with the slider?

Yes, especially if you don't downshift a lot. However the following applies.

1. Flip the slider as well and make sure that...
2. your dog teeth on both gears are worn symmetrically. Otherwise you're putting a worn surfaces next to a fresh/different ones.

Makes for more metal in your fluid as the surfaces get used to each other.