d 21 manaul transmission

[bobr1948]

OK, I rebuilt the manual transmission, clutch, drive shafts. I know that the clutch engages and disengages properly. I used GL4 fluid. I find that first thing in the AM, ambient temp being around 35 F, if I disengage the clutch if feels like the E brake is partially engaged. Also shifting is very stiff. After 20 minutes the transmission sifts smoothly and no more slowing down if I disengage the clutch or put in neutral and let it coast.

My guess is the fluid is much too viscous. It took me 20 minutes just to fill the transmission and that was after heating the fluid and filling in from inside the cab with a hose to the transmission. The stuff is like cold honey.

Is this the correct fluid? Anyone else have this problem. A transmission guy says use 10 - 30 motor oil but I have read that breaks down the brass alloy in the bushings and synchro's. Help!

Thanks

Bob

[Frankie Pintado]

I've had a hard time getting information about the transmission on my D21. My manual trans works, but it's starting to get a little difficult. I tried calling the dealer to ask them what the fluid type was and they said they couldn't help me (seemed kind of strange).
I threw in some Mobil 1 80w 90. It was horrible immediately. Then I changed it out for some cheap NAPA brand gear oil and it is better, but not great. I don't know why, but it really didn't like the Mobil 1.

Where did you get the rebuild kit? I need one, and also they might be able to tell you what kind fluid you need.

[bobr1948]

I had an ex tank mechanic who has his own one man transmission shop rebuild it.

After he removed the guts he called me and said he could not figure out why the transmission was "hanging". I brought the shifter lever with me. I looked at the tailshaft bushing which was very worn, but all the bearings and synchro were all good. What was missing and I found it in the bottom of the case, was a white plastic bushing that fits on the end of the shift lever and goes into the internal shifter linkage. It had worn and dropped out. At least it had not gotten ground up in the transmission. We decided not to rebuilt the whole transmission (just a partial rebuild, bushings and bearings) as there were not stripped gears or bad synchros. I have learned that you have to be very very careful when you go to stab the shifter linkage into the transmission so as NOT to dislodge that white bushing. Now the transmission shift perfect, just like a new one. All told cost me $225.00 which was a deal compared to others.

At first I went to Autozone and they sell a rebuild kit which includes the synchros, bearings and bushings for $150.00. But I have had so much trouble with their crummy rebuild parts that I would by elsewhere whenever possible. I don't know where my guy gets his parts but I could ask him, if you let me know.

One thing is Penzoil has a bulletin out that G4 is NOT interchangeable for G5. Also should NOT use regular oil as it will break down any brass parts in the transmission which include the tailshaft bushing.

[Rev_D21]

GL4 is the only fluid that should be in the D21 manual transmissions. GL5 eats the synchros over time. I have Redline MT90 in my trans but others have used Redline MTL with good results as well. Avoid the bottles that say that GL5 replaces GL4, that is a lie as they do not interchange and will cause harm to your transmission.

[RT22]

try some synthetic GL4 they tend to aid the stiff shifting when cold

[bobr1948]

Thanks for all you responses!