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Re: Transmission new and something ain’t right...

Posted: Sun Nov 10, 2019 7:10 pm
by JeepdaddyRC
The gear pictured above (with 0.022 axial play) is a brand new 2nd speed gear from RFJP (advertised as USA made with correct bushing).
I note a significant price difference between RFJP and another vendor that imports the 2nd speed assembly from Europe.
Or maybe the new synchronizer hub assembly is out of spec.
Joe, in your library of dimensions, do you know the correct axial length of the Gear, second speed assembly with bushing 638798 and the synchronizer hub?
I don't think the entire shim set from I have from RFJP will make up that play.

Re: Transmission new and something ain’t right...

Posted: Sun Nov 10, 2019 8:05 pm
by dinof
Contact Ron. He can help you figure out if the batch of gears he has are correct or incorrect, or your shaft is worn. This has to be fixed one way or another.

Re: Transmission new and something ain’t right...

Posted: Sun Nov 10, 2019 9:13 pm
by Joe Gopan
I'll check Monday.

Re: Transmission new and something ain’t right...

Posted: Mon Nov 11, 2019 12:24 pm
by Joe Gopan
I measured the lengths of two Synchronizer Hubs, A-6319.


The Length of the splined section of 638798 2nd Gears
These parts all dateprior to mid 50's, not offshore origin. I used ti recondition these good used 2nd gears with NOS BW Bushings and they worked as designed.

Re: Transmission new and something ain’t right...

Posted: Tue Nov 12, 2019 7:51 am
by JeepdaddyRC
Thank you Joe. I should have this T-84 removed again in a few days. I want to get it right this time.
I will measure the new synchro hub and 2nd speed gear and compare the dimensions of the new parts to the original OEM parts and your numbers above.
In theory, the distance between the mainshaft shoulder and snap ring should equal the sum of 1) 2nd speed gear assembly and 2) synchro hub - with about 0.002 to spare. Is that correct?
The blocking ring fits inside the synchro hub and does not take up space in this equation.
Is my thinking correct on this?

Pictures from Chuck Lutz to illustrate below:

Re: Transmission new and something ain’t right...

Posted: Wed Nov 13, 2019 9:44 am
by JeepdaddyRC
T-84 has now been removed and inspected while still attached to the transfer case (castle nut torqued to specs).
Excessive play at the several locations.
Findings and possible solutions:

1. The input shaft moves side to side and fore and aft.
Assumption: front bearing moving inside bearing retainer (original thicker snap ring used on bearing).
Solution(s): homemade gasket shim at bearing retainer shoulder to hold front bearing stationary, or remove material from bearing retainer.

2. 0.022 play at 2nd speed gear and mainshaft shoulder (photos above).
Assumption: new synchro hub and/or 2nd gear out of specs (will measure when disassembled).
Solution: shim between snap ring and synchro hub or new parts.

3. 2nd gear blocking ring play more than 3rd gear.
Assumption: mainshaft too far back in case.
Solution: shim(s) between snap ring and oil slinger.

4. Slight movement of mainshaft fore and aft.
Assumption: rear bearing not held secure between T-84 and transfer case (with castle nut fully torqued to spec).
Solution: homemade gasket to secure bearing at transfer case shoulder.

It looks like I have excessive end play at all possible locations that may explain jumping out of 2nd gear. Unfortunately, I did not fully understand the shim options at the time.

1. To those with more experience who have generously helped me thru this challenge, are the assumptions and solutions above correct?
2. Are there front and rear bearing shims available? Or, only homemade gaskets as shown by Gustl here:

Re: Transmission new and something ain’t right...

Posted: Fri Nov 15, 2019 8:41 am
by Wolfman
#1. There may be a little wobble in the clutch shaft but should not be excessive. Why there is a clutch shaft pilot bushing in the flywheel. Stabilizes the clutch shaft. Should not be any for and aft movement of the clutch shaft. Screws up the brass 3rd gear baulking clearance. Shim or different thickness front cover gasket for this one. Have seen some snap rings on the front bearing, loose in the outer race groove. That is a problem. The front bearing outer snap ring should be held up tight against the transmission case, but if the snap ring is loose in the bearing groove ???
#2 correct
#3 ??? You have it backward. Shims between the front snap ring and inner synchronizer hub tighten up the clearance on the second gear brass ring and sets the clearance between second gear and the main shaft. Do this first !!, then shims between the snap ring and rear main bearing tighten up clearance on the 3rd gear brass ring. The brass ring next to the input ( clutch ) shaft cone.
4#. The rear main bearing should be held tight against the transmission case. If not, this screws up the third gear brass ring clearance. Different thickness gasket between the transmission & T-case or shim in the T-case to hold the bearing forward. Parts on the rear of the main shaft need to be in place and the rear nut tight before checking the end play.
PM sent.

Re: Transmission new and something ain’t right...

Posted: Fri Nov 15, 2019 10:34 am
by r w devon
Hello all ,

I had a little play on the main bearing in the trans housing in the width of the bearing ( along the axis of the shaft ) which I assumed was due to slight manufacturing differences in pattern bearings . I measured the play when both boxes were bolted together WITH the gasket and used a diff pinion shim .
Very convenient.
BUT ... be extra careful not to over do it fo obvious reasons .