Grinding issues after rebuild.

[pjtoledo]

gear meshing 101

gears are convoluted. they are ground with a curve that enables them to roll against each other, not slide. there is essentially no moving friction. similar to a roller bearing.

syncros need the correct amount of friction to bring the mating cone up to speed. but not too much to slam, or too little to slip excessively.

hypoid gears in the differential have massive sliding, that's why they need heavy gear lube.

choose your lube carefully, a future life may depend on it.

 

[SenorNoob]

^That sounds right, but I can assure you my transmission has some friction. (Probably because it set at the end of the driveway for 10 years.) The transmission get hotter on long drives than the engine does.

 

[MADMODDER]

We had a bit of cold snap here in north GA the last few days, during commuting hours. Which, for me, is before the sun is up and after the sun is down.

Tells me when the oil is a bit thicker, its not an issue.

I find it hard to believe I'm having syncro issues when everything looked great last August. But the only other things it could ve is bad oil or shifter bushings.
Unless I put in the wrong spacers when messuring the lateral throw. But I expect any resulting issue would affect all the gears and much sooner. Its been about 10kmiles ago.

I'll reinspect the bushings and looking into the synchromesh.

"MTF" is Manual Transmission Fluid, right?
I know that to be 75w90 and the likes. Seems a bit thick, no?

 

[pjtoledo]

We had a bit of cold snap here in north GA the last few days, during commuting hours. Which, for me, is before the sun is up and after the sun is down.

Tells me when the oil is a bit thicker, its not an issue.

I find it hard to believe I'm having syncro issues when everything looked great last August. But the only other things it could ve is bad oil or shifter bushings.
Unless I put in the wrong spacers when messuring the lateral throw. But I expect any resulting issue would affect all the gears and much sooner. Its been about 10kmiles ago.

I'll reinspect the bushings and looking into the synchromesh.

"MTF" is Manual Transmission Fluid, right?
I know that to be 75w90 and the likes. Seems a bit thick, no?

75-90 is hypoid gear oil. totally different stuff and totally wrong for your transmission.
it does not pump thru the small channels as easily as automatic transmission fluid.

FYI: "hypoid" is a style of gear design, the type used in differentials where the pinion is offset from the ring. there is massive sliding action between the teeth.
it is technically more correct to say gear oil for hypoid type gears.

yes, many years ago manual trannies used gear oil. they were designed a bit different then.

 

[pjtoledo]

^That sounds right, but I can assure you my transmission has some friction. (Probably because it set at the end of the driveway for 10 years.) The transmission get hotter on long drives than the engine does.

the key word there is "moving".. or sliding friction. heat is generated from pressure at the contact points, be that roller bearings or teeth rolling against each other.