T-90 1st/Rev grind from stop

[Mastiff]

Is it normal at all for a T90 to grind going into 1st or reverse from a dead stop? It's not terrible, but it buzzes. My clutch fork and throwout are both fresh, so I think I should be good there, but maybe not. I just rebuilt this trans, so it kills me to think of my brand new gears getting slowly ruined.

It was only a few months ago I did the rebuild, but I can't think of why it would buzz the first time, but if get it in gear, then take it out (without actually driving) I can go back in with no buzz. Every time I stop at a light or whatever, it wants to buzz again on its way back into 1st.

[Will Marsh]

Originally Posted by Mastiff

Is it normal at all for a T90 to grind going into 1st or reverse from a dead stop? It's not terrible, but it buzzes. My clutch fork and throwout are both fresh, so I think I should be good there, but maybe not. I just rebuilt this trans, so it kills me to think of my brand new gears getting slowly ruined.

It was only a few months ago I did the rebuild, but I can't think of why it would buzz the first time, but if get it in gear, then take it out (without actually driving) I can go back in with no buzz. Every time I stop at a light or whatever, it wants to buzz again on its way back into 1st.

That is characteristic of a non-synchro 1st gear. It's the way the trans was built.

The fix is to Double clutch it into and out of first. Step on the clutch, pull it into neutral, let the clutch out, then step on the clutch, pull it into gear, and let the clutch out. That's how a non-synchro trans is designed to be shifted. A T-98/T-18 four speed is the same. Some of the early (Pre 1960) 4 and 5 speeds are completely non-synchronized, and you have to do that on every gear change. We're all spoiled with the newer ones.

HTH,

Will Marsh

[Scott Hickman]

T-90 is not synchronized in Reverse or First.
Only shift into them when completely stopped.
So, depress clutch, move the shifter into 2nd gear, keep the clutch pedal depressed. then shift into either first or reverse.
Putting it into 2nd will slow down the rotating mass inside the trans so that your shift into R or 1 goes smoothly.
Also be sure you are useing the correct lubricant in the proper quantity.
Change the lube every 12 months or so.

[Dana Strong]

Will, I think he said from a dead stop; the rest of the gears should be stopped if the vehicle isn't moving. If the clutch has been out while the transmission was in neutral, the input shaft would have been spinning and needs a few seconds to slow down after the clutch is depressed; if it isn't doing this, either the clutch is dragging or the pilot bearing in the flywheel is. One solution is to slip the transmission into a higher gear first, then into first, all while the clutch is depressed, but this does cause some unneeded wear on the synchronizer for the higher gear, so is just a temporary trick, not a proper fix.