Transmission / Overdrive: O.D. Transmission Oil

[Drifter22]

I had my T-86 transmission rebuilt by a company in Tavares, FL. First and second gear work OK, but third gear will grind if you don't wait 5 or 6 seconds before shifting. I used 30 wt. non-detergent and I've tried several oils that were similar, but it still grinds. I pulled it and they took it apart and replaced a cage on sprag or something, not sure anymore, but it stills dose it. I noticed that the first mile or so it shifts OK, but it will grind if shifted to quick. I was wondering if it would hurt anything if I put 90 wt. gear oil in it as I think the oil is thinning enough to cause this?

Thanks, Gene

[JoeHall]

Sounds like the synchronizer ring and/or bell housing misalignment with the motor block. I seriously doubt it is the oil, though its worth a try to switch it. I run nothing but Red Line MT90 synthetic oil in Stude overdrives, and it works great, in all weather.

[StudeRich]

Just as long as you buy the NAPA or Farm Tractor Store API GL-1 Mineral Gear Oil, it will come in 85W-90 or 90Wt. and that's fine, any Brand that is GL-1 ONLY, no combos.

I would also check the Shift lever Grommets and the Column Grommets if your Model uses them they may need replacement.
Also disconnect the Linkage at the Trans. and readjust for Neutral in Both the Trans. AND the Column shifter.

[SN-60]

I've always used straight 30W in Stude standard w/od transmissions with no problems!.....easy shifting in warm OR cool temps!

[JoeHall]

Also, do not try to speed shift the T86. They do not like that. Get used to, "feeling" the gears slip into place, and it will last much longer. Another indication of bell housing misalignment to check for is if it jumps out of 2nd gear into neutral, if going down a long incline and left in 2nd gear. Insure it is not freewheeling in 2nd, for this test (either engaged in conventional 2nd gear or engaged in 2nd OD).

[kxet]

Also check pilot bearing for wear, it aligns the input shaft.

[Drifter22]

Thanks for all of your replies. It's a floor shift and as far as I know the bell housing came with the engine. I'm going to try the oil, that's easier then pulling the tranny.

[bensherb]

Just as long as you buy the NAPA or Farm Tractor Store API GL-1 Mineral Gear Oil, it will come in 85W-90 or 90Wt. and that's fine, any Brand that is GL-1 ONLY, no combos.

This is what the factory service manual and the OD manual both say. I had to track down GL-1, found it at Tractor Supply, for $15 a gallon. It works great in my 3 speed OD trans. Shifts smooth as glass.

[karterfred88]

Since it is the synchro that allows locking the input shaft to the main shaft, any irregular movement of the input shaft will cause "grunching", although rebuilt, I would suspect the original input gear and main shaft were re-used, the roller bearings at that juncture wear both over time, so even with new rollers the accumulated wear makes that synchro touchy, especially if the pilot bearing has substantial wear also. Gear oil of a different viscosity may help for awhile, but eventually the cause will need fixing. I'd bet replacing the pilot bushing will help it more than an oil change. Just my best guess.

[jackb]

Sounds like the tranny was well worn prior to rebuild ? My experience (not relatively expansive) has always found the 2-3 shift to be the least problematic. I find my T86 w/ GL-1 does not like "hot" shifting. That is a very warm drivetrain shifting around town... If I could find that old Harley 50W non-detergent, I'd go with that in a heartbeat. Instead of STP, I'd dump that thick stuff in my early Studes with bookoo miles.....

[Bud]

I've been using Amsoil 75W-90 synthetic manual transmission oil or full synthetic SAE 50 manual transmission oil that we use in the Fuller Road Ranger transmissions in our over the road tractors. In the Southern California climate, the SAE 50 works really well in the Studebaker transmissions. I've been using the Amsoil Manual Transmission oil in the 4 speed in my 62 Hawk. The old four speed really shifts nice with the Amsoil oil in it. Bud

[kxet]

The OD unit likes GL-1, as specified in manuals, I fried 2 OD uniits with 90wt. gear oil running on Nevada hiways about flat out in the 60s. The hyphoid stuff is not good, they get real hot.

[altair]

If everything is properly aligned you can shift in to top gear with out the clutch, I have done it many times.