Which syncro ring would you use?

[Talkwrench]

Ive got a few syncro [blocker] rings in my box of goodies. These ones are "older" ones Ive collected. The newer looking ones have a gap of [roughly] .036 to second gear and the older are more like .026 . slightly different teeth shape, both seem to fit well. Which would you use??

 

[Tim Ayers]

Talkwrench,

Hopefully Mac VP will jump in, but the answer can be both. My experience has been that you may not know which works best until you have the entire cluster together.

Had a similar issue with my recent build. It all looked fine, but once together, one of the snychros was not mating with the blockers correctly, causing a bind. Swapped it out and it fixed the problem.

Either way, make sure they spin freely without too much slop or rocking on the "cone" of the gear.

 

[Mac VP]

Generally the new rings will show a gap of roughly 0.050” on existing gears. Since the existing gear may have a slight amount of wear on its cone, this gap measurement can vary slightly. The used ring will still grip the cone enough for normal shifting but its service life is limited. New rings are not that expensive so it doesn’t make sense to do all the rebuild work (including removal and installation of the transmission in a closed drive vehicle) and suffer the disappointment of poor shifting due to worn synchro rings.

Don’t trust the appearance of the grooves inside the ring and assume that they are okay. Hand fit the ring against the cone on the gear with a bit of oil on the cone. When pressed together by hand, and counter rotating the two pieces, there should be some resistance and grip. If the ring turns freely the ring is probably worn. Also, check the concentricity of the ring by trying to rock it on the cone. If it rocks, the ring is bent and won’t function correctly.

 

[rotorwrench]

Yup. The cone and the teeth do all the work. They don't call them blockers rings for nothing. They have to grip well or they won't work. A conical seat can only be measured by the fit and that gap. A quarter is about as thick as that gap should be but Mac's advice on checking them is the way it is.