4 speed grinding on down shifts

[SMack]

My 4 speed started grinding on down shifts only when it’s warmed up ? Shifts like butter when cold will grind from 3Rd to 2nd and 2nd to 1 when hot. Running Red Line MT 90 trans only has about 3K on it. Clutch - PP TO bearing all new. Everything is new.

Any thoughts much appreciated...

 

[MCODECUDA]

Replace the fluid with conventional gear oil.

 

[dadsbee]

I'm running 20W50 motor oil in mine, never been so smooth. Mind you I generally only use the clutch when stopped. Power shifts smooth as can be, up and down gears.

 

[SMack]

Had 85-140 in it acted the same. I read on line where the red line was a possible fix it’s also recommended by Brewers. How’d you come to using the 20-50? I’m intrigued. I also read an article about how some shipped from the factory with ATF instead of gear oil !

 

[Ranger16]

When I had a gear clash problem (1st - 2nd, cold), Heavier oil only made it worse.
Penzoil Synchromesh manual trans fluid did the trick for me.

 

[steve340]

If your clutch is good you may have a problem in the gearbox. You have a good oil in it already I doubt another oil will be the magic bullet.
I assume you have double checked the shifter adjustments? Is the shifter in top condition?

 

[SMack]

Thanks Ranger16 it’s a thought. But the Red Line is full synthetic and was no help which is why I was thinking to go thinner yet?? Pokin and hopein at this point !!
Steve 340 yes the shift pack is new As well.

 

[SMack]

I did recheck the adjustments to the shift pack rods and clutch pedal but all was good. Tranny was freshened up buy a reputable place as well.

 

[steve340]

Ok sounds like you know a bit about cars.
If clutch and shifter are good almost 100% in the gearbox.
Probably something to do with the 1-2 syncro hub or blocking rings.

 

[SMack]

I think your right Steve. I’m probably in denial.
DadsBee mentioned running 20-50. in his. I might try a lighter fluid just as a last ditch effort before I yank it out...
Again.
I appreciate all of you folks help. This sight is great for that.
MOPAR or no-car

 

[dadsbee]

Remember that 20W50 equates to a straight 100W oil. You can run anything from ATF to 140 in an A833, just make sure it's not Hypoid that you've put in there the first time you filled it. My transmission has never been opened, has over 100K of harshness on it. I do need to pull it back out and check my front seal though, appears its leaking a bit after 51 years.

 

[SMack]

Thanks dadsbee my knowledge here is limited to say the least when it comes to the A833 and proper fluid at this point.
I didn’t now 20-50 =100w either
With regard to your Hypoid comment can you elaborate please. and thanks again in advance for the info.

 

[dadsbee]

Many think using rear differential 80W90 gear oil is fine in their manual transmissions. It's a hypoid oil and it and bronze don't get along...

 

[SMack]

Understood.

 

[steve340]

An A833 should have GL4 transmission oil in it.
Some will disagree of course but oil companies and manufacturers are pretty specific.

 

[SMack]

Got it. Thanks Steve340. Thanks for all the feedback guys.

 

[64SF]

Post #5..it solved my problem.

 

[SMack]

Got it. Thanks Steve340. Thanks for all the feedback guys.

 

[SMack]

Hey guys I’m back again. The more I read on line the more I think I should try either ATF of even Brad Penn 10-40. My thought is that if the tranny schists great when cold and fluid is at it’s thinnest and grinds when it’s warm could this work or am I crazy. As always any feedback appreciated

 

[steve340]

You haven't got anything to loose by trying another oil. If it doesn't work you will not have spent a small fortune.
Good luck.