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Syncronizer wear

Syncronizer wear

Syncronizer wear

I have an highway truck running in India with the Eaton 9106 6 speed transmission. Recently I replaced the Navistar I4 engine with an rebuilt engine, with substantially higher torsional vibration. I measure old engine at 300 rad per sec2 vs new rebuilt at 900 rads. Everything works ok except that my transmission synchros are wearing substantially. Even with a few shifts in lower gears and mostly highway miles (high 5-6 shifts) all the synchros are worn in 15,000 kms. Is this common with higher torsionals?

RE: Syncronizer wear

I suppose it is possible. So is the torsional damper on the rebuilt engine new? How do you measure the vibrations?
Most trucks that I have been around use nonsyncronized transmissions because they are a number one wear item especially with such high torques to deal with.

RE: Syncronizer wear

"Recently I replaced the Navistar I4 engine with an rebuilt engine, with substantially higher torsional vibration."

The rebuilt engine is also Navistar I4? The references I found suggest I4s were carburetor, not diesel.
If it runs noticeably rougher than the old worn engine, it sounds likely the rebuild was not of high quality, or when the original fuel or ignition system was re-installed mistakes were made.

1 - How are you identifying torsional vibration?
2 - Are your measurements at idle or under load ?
The torque variation of an inline 4 is substantial.

A damaged or improperly adjusted clutch that does not disengage completely can damage synchronizers quickly.

3 - Was bell housing alignment checked ? Some engines require re-aligning the bell housing when blocks are swapped. A mis-aligned bell housing, or one installed without the alignment dowels or fitted bolts, will cause the input shaft to bind, which also can cause shifting issues, among other problems.

5 down, 15 to go.

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