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bad syncro?

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T

TexasKnucklehead

Jedi Knight
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So if I'm looking at a syncro ring, where would I look to see that it is bad and/or worn? My TR6 is apart, and I had a little trouble, only when cold, shifting into second. But I can't see anything any different on any of the rings. As long as I'm replacing first gear, I'd like to be sure it's all well now. About 4 years ago I replaced all the syncros and bearings, and all still looks well (aside from the missing tooth on 1st).
 

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There was a rash of bad synchro rings a few years back. They worked in some cases but not in others, and AFAIK no consensus was reached on what was wrong with them. Some said the angles were cut wrong, others said the material was wrong.

The usual way to check for wear is to slide the ring firmly onto the cone of the gear, and measure the distance between the synchro and the face of the gear. As I recall, "new" is around .050", "replace it" is about .030", and "won't work" is around .020".

But how much force it takes to move the shift ring on it's hub is also important, since that is what forces the synchro ring towards the gear. Some folks forget to check the force, and it's usually too low (apparently the springs get weak with age and heat).

Without meaning to reopen the lubrication wars, I'll just say that faster shifting when cold is one of the benefits of using 20W50 VR1 or Redline MT90.
 
TR3driver said:
Without meaning to reopen the lubrication wars, I'll just say that faster shifting when cold is one of the benefits of using 20W50 VR1 or Redline MT90.
Click to expand...

I agree with Randall about the oil, mine did not want to go into 3rd when downshifting. I switched to Redline MT90 and the downshift problem went away and all the gears have been smoother.
 
Tex, looks just like the ones I put into my tranny.

Dick
 
Here is a picture of a well worn synchro ring. Came out of the tranny that I re-built. Lotsa brass filings at the bottom of the tranny case.
 

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Looks fine?

Maybe my eyes are going, or the picture is not clear enough for me. The outside tangs need to be as sharp at the top center ridge as possible. From the picture(maybe camera angle) it looks as if there are a number of worn outer synchro tangs. If there are any that are beveled or flattened, time for new synchro. Would also be a good idea to take a file and trim the flashing off the upper tangs.

When installing a new synchro it is a good idea to take a little lapping compound and lap the synchro to the gear. Doesn't need a whole lot of time or energy expended, and a good cleansing when done lapping. This helps the brass "seat" to the steel collar of the gear.
 
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