A-745 Transmission Lubrication

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
When I rebuilt the A-745 in my '66 Fury, I was unable to locate new synchronizer rings. I think I got it all done to specs from the FSM, but it will "drop out" of second gear (it is three-on-the-tree). I have Dexron for lube, but am wondering if a change of lube might make an improvemant. Several times i have read that Type-F fluid has different friction characteristics, but would it shorten the life of other components. I also know that some have used 90 wt oil, but would that worsen the problem. One other thought- would a stronger spring in the lockout/detents prevent the dropout? Thanke in advance for the good advice. Lindsay
 

Davea Lux

Old Man with a Hat
FCBO Gold Member
Joined
Mar 27, 2017
Messages
8,943
Reaction score
8,105
Location
Cornelius Or
For starters, you should be using SAE 50 gear oil in this transmission. Dexron will not cause the transmission to drop out of second gear. (Hotrodders used Dexron to get a faster shift, Dexron lacks fiber needed for cushioning of the gear mesh) Several things can cause this transmission to drop out.. Most common is the linkage adjustment not allowing the fork to go "over center" and lock into second gear. A worn slider or second gear hub will also cause the transmission to drop out of gear, as will a worn center bearing. Down load the FSM at www.mymopar.com and check the linkage adjustments in the transmission section and report back.

Dave
 
Last edited:

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
A check in the FSM confirms that ATF is the reccommended lube for the A-745, A-833 calls for 80W or 90W with ATF as an alternative. The linkage is adjusted as per FSM. All bearings have been replaced. All parts were inspected for wear, but my inspection may not have been objective enough. FWIW I will re-chcck the linkage adjustment. Could you explain the reference to "over-center" in this context?
 

CBODY67

Old Man with a Hat
Joined
Mar 27, 2011
Messages
7,456
Reaction score
4,579
Chrysler, for some reason, spec'd atf for many of their manual transmissions, as GM spec'd normal gear oil. Then GM would change their oil specs to atf and back, for some year ranges of the same manual transmission or manual transfer case.

Obviously, the atf would put less load on the running engine than any viscosity of gear oil. Which would mean more power to the ground.

Check the linkage adjustments and such, too.

CBODY67
 

Davea Lux

Old Man with a Hat
FCBO Gold Member
Joined
Mar 27, 2017
Messages
8,943
Reaction score
8,105
Location
Cornelius Or
A check in the FSM confirms that ATF is the reccommended lube for the A-745, A-833 calls for 80W or 90W with ATF as an alternative. The linkage is adjusted as per FSM. All bearings have been replaced. All parts were inspected for wear, but my inspection may not have been objective enough. FWIW I will re-chcck the linkage adjustment. Could you explain the reference to "over-center" in this context?

The gears usually have a high spot in the center. The linkage pushes the slider over this point so that the torque does not disengage the gear. The bearings all have to be within specs for that to work. If your application has any rubber grommets on the linkage,be sure to check them for excessive wear as wear can make enough slop to keep the gear from properly engaging.

Dave
 
Last edited:

68 4spd Fury

Senior Member
Joined
Aug 17, 2014
Messages
1,132
Reaction score
755
Location
Syracuse, NY
I agree that the linkage may be the culprit, once fully in gear it should stay. Also the lobes on the shift levers and/or the detent balls and spring may be worn.
 

my5thmopar

Member
Joined
Feb 2, 2020
Messages
75
Reaction score
36
Location
TN
I had that issue with my A745 in my 64 D100. You can get the spring washers at the hardware store for the column. I had to hunt for the grommets when I rebuilt mine. I used some sorts of clutch grommet for one of the thick ones. I don’t remember which one though. It shifted very smooth without issues after the rebuild.
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
So to start, I will check for and repair wear in the linkage before re-adjusting as per FSM. If this does not "do the trick", I can do some internal inspection/repair over the winter. Any ideas where I can get the synchro rings? Also, any thoughts on possible benefits in changing the type of lube? You have given me some helpful thoughts. Thanks!
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
Linkage is now tight and adjusted to FSM specs. Hope to test drive this evening. In an old thread, which I can't find, it was noted that lube level should be just lower than the filler plug hole, so I removed a bit of fluid. Thanks again! I'll post the results of my test drive. LC
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
Just got back from a test drive. Linkage is smoother now, but there is no improvement in the "popping out of gear" problem. So I guess my next move is a tear down over the winter, unless someone has another suggestion. Lindsay
 

PH27L7

Well-Known Member
Joined
Mar 10, 2020
Messages
603
Reaction score
861
Location
Pittsburgh, PA
I actually don't care at all for using ATF in these transmissions because I feel it accelerates wear. My preference is MT-90 Redline synthetic. It is much better than 90W gear oil & is really good when cold. I use it in all my cars with manuals which amounts to a half dozen. It's unlikely to solve your gear jumping issue though, you have to thoroughly inspect the internals to see what the issue is, probably the synchros if your linkage is set up correctly. Synchros for the 3-speed are not hard to find, google part # 2124472.
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
Thanks! Found several suppliers! I'll gat a set and be ready to repair when the snow flies. Till then I'll have to hold it in gear by hand.
 

my5thmopar

Member
Joined
Feb 2, 2020
Messages
75
Reaction score
36
Location
TN
Few more things. How is the down shift from 3rd. If it’s smooth, I don’t think you have a synchro issue. When the shift to 2nd is complete, the synchro is out of the equation. The short lever should be at the rear of the transmission. Also, the levers should be in alignment at the column when in neutral. You can put the transmission in 2nd with the column rod disconnected. Then move the shifter to 2nd and see where the rods line up. Sometimes you can fudge the alignment to fix the issues. That’s all I have.
 

68PK21 440.6bbl

Old Man with a Hat
Joined
Nov 29, 2017
Messages
7,692
Reaction score
7,003
Location
Siren City
Worn synchros are the cause of your problem but replacing them only is not the cure. The key word here is 'Teeth'.
The clutch gears, countershaft gear, & main drive pinion need to be replaced if the 'Teeth' are worn, broken or missing.
From the FSM:

INSPECT.GEARS.100.jpg

INSPECT.GEARS.101.jpg

INSPECT.GEARS.102.jpg


Area's (Arrows & circles) in red are areas to inspect & replace. (plus also your springs, clips, balls, bearings etc)

INSPECT.GEARS.103.jpg


INSPECT.GEARS.104.jpg


INSPECT.GEARS.105.jpg


To replace the input shaft, clutch gear, and counter shaft can be expensive and now also hard to find. I wouldn't wait on these items if they are needed.
I was going to post on this thread then realized you had taken all apart and put back together so... I'll wait and let's see.
I just happened to come across this AD for 4 speed parts, notice the "AND MUCH MORE", ya may want to keep this number and talk to him for 3spd parts or leads if your finding parts to be a problem. It's a shame you didn't post up pics of when you had it apart.

MOPAR A833 4 SPEED TRANSMSSION PARTS AND MUCH MORE.jpg



.
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
Thanks! All parts were inspected as per the FSM. All bearings. seals replaced. Clearances set to spec. The only parts that were a little suspect were the synchro rings. At the time I could not source new ones, so..... This all was done before I "found" this site. Now, in addition to suspecting the 'rings, I question the detent balls and spring as well as the detent notches in the shifting lever. It does not seem to "snap" into gear as I think it should.
my5thmopar had a few more checks that I will do on the linkage, and then it will be a winter project. Be prepared for pictures! Thanks! LC
 

Davea Lux

Old Man with a Hat
FCBO Gold Member
Joined
Mar 27, 2017
Messages
8,943
Reaction score
8,105
Location
Cornelius Or
Thanks! All parts were inspected as per the FSM. All bearings. seals replaced. Clearances set to spec. The only parts that were a little suspect were the synchro rings. At the time I could not source new ones, so..... This all was done before I "found" this site. Now, in addition to suspecting the 'rings, I question the detent balls and spring as well as the detent notches in the shifting lever. It does not seem to "snap" into gear as I think it should.
my5thmopar had a few more checks that I will do on the linkage, and then it will be a winter project. Be prepared for pictures! Thanks! LC

If you are certain the transmission is up to specs, did you check the pilot bearing? A worn pilot will cause the front shaft of the transmission to flex and not run true, that will also cause problems keeping it in gear.

Dave
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
Few more things. How is the down shift from 3rd. If it’s smooth, I don’t think you have a synchro issue. When the shift to 2nd is complete, the synchro is out of the equation. The short lever should be at the rear of the transmission. Also, the levers should be in alignment at the column when in neutral. You can put the transmission in 2nd with the column rod disconnected. Then move the shifter to 2nd and see where the rods line up. Sometimes you can fudge the alignment to fix the issues. That’s all I have.
I shifted to 2nd, Jammed the shifter handle and disconnected the 2-3 rod at the column. The rod was at the "top" of it's travel- Fully engaged in 2nd gear. I do get an occasional "grind" on downshift from 3rd to 2nd.
Thanks for all the input. It looks like a winter project. I store the car in the garage where I live, so access is no problem- Just the lack of heat! I am able to heat my workshop. LC
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
hey, t
EPSN0251.JPG
EPSN0252.JPG
EPSN0257.JPG
EPSN0259.JPG
here! I'm back on the track after 6 months. Trans is out, disassembled and inspected. I have new synchro rings, a synchro shim, detent interlock spring and a complete spare trans on hand.
I measured the "synchro float" to be 0.085" (Spec is 0.050" to 0.090"). Visual comparison of the removed and new synchro rings shows lvery little wear. Clutch gear shows slight wear on the teeth on the"second gear side". (pictures to follow) The new detent interlock spring is slightly longer and stiffer than the removed spring. The mostnotable wear, however, is on the second and direct shift lever detent notches. the second gear notch has been "repaired" with bronze, nnd the bronze appears worn. That lever from the spare trans shows no wear.
Now, I will try to post some pictures:

EPSN0254.JPG


EPSN0255.JPG
 

'66 Fury I

Active Member
Joined
Aug 19, 2019
Messages
201
Reaction score
253
Location
Moncton, NB, Canada
Sorry about the "messed up" post! The second pic shows the clutch gear. Note that the teeth on the left side are "sharper" than the teeth on the right (second gear) side. The third and fourth pics show the worn repair on the shift lever. The fifth pic shows the wear on the second gear side of the clutch gear. The sixth pic shows the sharper teeth on the direct gear side.
Now I will attempt to perform a "measured" inspection of the synchro rings.
My major thought is that the new interlock spring and good shift lever might solve the problem.
Should I be striving to attain a "float" as near the tighter end of the spec as possible?
As usual, any thoughts or reccomendations are welcome.
Thanks! Lindsay
 
Top