3rd Gear Blocker Ring Wear

[calvinhunt]

� �� Over the years I've not tried to hide my lack of intelligence from my CJ-3A brethren on this site, so I'll go ahead and ask my question without worry of exposing my ignorance once again.
� �� It's been 6 years since my CJ-3A restoration project.� During that restoration, not knowing any better (I had not found this site yet), I installed all new aftermarket tranny internals purchased from undesirable locations through Omix Ada.� The following year, which was 1000 miles later, I had occasion to remove the shifting tower.� I saw tranny internals in a self-destruct mode.� The oil was all brassy.� The 3 steel synchromesh plates were nearly worn through from rubbing on the rough inner finish of the synchromesh sliding clutch sleeve.� So I removed the transmission, ordered all NOS internals and overhauled it again.� I got my parts, and advise, from George at Army Jeep Parts.� He advised me to set the main shaft end play to .012 using rear bearing shims available from him.� After trial & error dry run assemblies I got the .012.� After final assembly, with gasket dressing, and torqued to the transfer case I only had about .003 end play.� I called George who told me if the tranny still spins freely through all the gears that it would be okay.� I installed it.� Another year (and another 1000 miles) later I was experiencing difficulty shifting into 3rd gear without grinding.� I pulled the shifting tower again and could see no space between the 3rd gear blocking ring and 3rd gear.� I felt that this had occurred because of my lack of proper end play for the main shaft making the 3rd gear blocking ring too tight.� But... had that been the case why didn't the wear decrease as wear itself increased the the main shaft end play?
� �� Once again I pulled the transmission.� This time I just installed two NOS blocking rings and reassembled.� I again used George's rear bearing shims to obtain .012 end play.� When final assembly showed me I had .024 end play I decided to go with it to make certain I didn't induce undue wear on the 3rd gear blocking ring.� I did this knowing that too much end play could cause the common problems these T90 trannys have of jumping out of 2nd gear during vehicle deceleration.�
� �� It's now been 4 years (and 4000 miles) since doing that.� For the first 2 years I ran Gear Lube GL-4 gear oil (after being told by their tech rep that such was made for gear boxes containing yellow metals).� Then, after all the discussion here on the 3A Page where so many folks indicated that straight mineral oil would be best, I have run SAE 50 straight mineral aircraft engine oil for the past 2 years.�
� �� Last week I removed the shifter tower again.� Once again I saw brassy-colored oil.� And once again, as can be seen in this photo, the 3rd gear blocking ring is worn noticeably more than the 2nd gear blocking ring.
 What is going on with my transmission?  Is anyone else experiencing this? 
     When I was a kid I had an old 47 CJ-2A and in the few years I had it I put a lot more miles on it than I have on my present Jeep. During those years and miles I had ZERO transmission/shifting problems.  Those miles were HARD miles, too.  What's the difference? 

[athawk11]

Hi Calvin,

I'm going to be quick to admit my lack of experience regarding certain aspects of the Willys Jeep.� If I can get my other chores done, I will be rebuilding my first T-90 today.

For preparation, I have read everything I can find on this process.� I've also studied the transmission issues others experience.

Just a guess...

How about the pilot bushing where the imput shaft inserts into the crank?� If worn, this will cause premature wear on the transmission parts.

My issue is a slight grind when shifting into 2nd at higher RPMS.� On inspection, there is very little space between 2nd gear and the syncro ring.� The 3rd gear synchro has much more space.� The transmission shifts nicely in and out of 3rd at all RPMs.� So, my issue seems to be just the opposite of yours.

I'll be interested in reading what others might offer.

Tim

[1955CJ-5]

now I've been doing a little resarch on the T-90...mine has a noise with the OD installed...

Anyway, I found quite a spirited discussion on the 2a forum, and here is one post..


Quote According to Novak it should have some end play.
Novak is wrong, or you've mis-interpreted what they said.

According to Willys, there is ZERO end play.� If some end play were required, IT WOULD BE SPECIFIED IN THE SERVICE MANUALS (there is no such specification).� If "shims" were part of standard assembly procedure, THEY WOULD BE LISTED WITH PARTS NUMBER IN THE PARTS LISTS (there are no such parts).� If "setting" endplay were standard procedure, THE PROCEDURE WOULD BE DESCRIBED IN THE SERVICE MANUALS (there is no such procedure).

This "mainshaft end play" issue has occured before and has been nipped in the bud.� It's important to have the correct facts when explaining technical issues, particularly for people who may not be familiar with transmissions at all, much less the T-90.

THE T-90 MAINSHAFT HAS NO END PLAY!

The mainshaft is solidly clamped to the inner bearing race by the bull gear & nut.

The outer bearing race is solidly clamped between the transmission & transfer case.

At this point, the MAIN SHAFT CANNOT MOVE FORWARD OR BACKWARD at all.

Quote Setting at "0" means your jamming the outer race against the balls and the inner race and that means the bearing will overheat.
Nonsense.� There is NO axial loading on the bearing at all (unless something ELSE has been assembled incorrectly).

Quote I was told there is a Willys service bulletin somewhere ... there may be a spec somewhere but I am not going to look for it.
Yes there is: Service Bulletin 49-30.� It has been published here for over 3 years.

The paragraph you're talking about, and which I alluded to earlier, is:


(I guess this was a picture of the bulletin and it didn't copy, but it mentions the distance the syncro slider needs to move)



It has NOTHING TO DO with any "end play".� It is ONLY about proper engagement between 2nd. gear & syncro collar.� It is a service expedient (band-aid), to compensate for out of tolerance components.� With or without the shim, MAINSHAFT END PLAY IS STILL ZERO!


The entire discussion is here....

http://www.thecj2apage.com/forums/transmission-rebuild_topic20469.html

With the output gear firmly in place I have no endplay that i can feel...without the gear in place I can move the output shaft noticeably....

But I don't know what it all means....I've only got 500 miles on my tranny....

[Bob W]

Unfortunately I do not know why Calvin's 3rd gear blocker ring is wearing out prematurely. The Willys service bulletin (below) addresses the common T-90 condition of popping out of 2nd gear. I can tell you that step 6 does work quite well in solving the 2nd pop out problems.

[1955CJ-5]

Isn't that interesting?

No mention of main shaft end play....

Just "tighten the nut"

[Bob W]

Just to explain the 'end play' thing......

When the rear nut is tight there is no end play in the main shaft (except for a small amount from a worn rear bearing). With the rear nut loose there is end play in the main shaft as the shaft can move forward until it contacts the input gear. Measuring this end play allows us to set the position of the main shaft to help accomplish step 6. The shaft position is set with shims in front of the bearing or a longer spacer. Then when the nut is tightened again there is no end play but the shaft is where you want it to be now.

So, measuring the end play with the nut loose is just a technique that can be used to help determine the final position of the main shaft.

[1955CJ-5]

OK I think I get it...

But to check the "end play" you must have everything assembled, but no output gear or retaining nut.....T/C included?

To add or remove a shim you have to take it all apart again, or will the rear bearing slide off and out the opening in the back of the transfer case, leaving the shaft installed and all those roller bearings in place?

I don't remember if the bearing was pressed on or not...

Edit: Now I'm pretty sure that the T/C casting fits over that rear bearing and holds it in place...

[bretto]

Nope you have to check this with the tranny by itself but you have to clamp the bearing against the back of the tranny.

I believe I heard once that the shim mention in step 6, was an open sided shim so it can just be slipped in without full disassembly.

Speaking of tranny issues, mine has been popping out of #2.� I have been thru my tranny twice now in the past and thought I had it licked but nope.� I wonder if my shift fork maybe worn, not throwing the collar back far enough on #2.� I am waiting for a rainy day and finding an OD install, to tackle it though.

[calvinhunt]

Thanks Gents,
I appreciate the input and discussion.� I was hoping there would be a "magic bullet" answer about what I've been doing wrong to cause my 3rd gear blocker ring to wear prematurely.� Actually, it still shifts perfectly and doesn't jump out of 2nd, so I'm pleased.� I measured the gaps today: Blocker ring to 2nd gear is .038, blocker ring to 3rd is .019.� Hopefully the wear is slowing and it may serve me well for years to come.
�
Randy, That was certainly an interesting, and yes, spirited discussion you shared from the CJ-2A site.� However, Willys manuals of the time left lots of stuff out.� I'd hate to try to overhaul a tranny just using the vintage shop manual.
�
Tim, Yes, the pilot bearing in the flywheel needs to be in good shape.  I installed a new one each time I overhauled my transmission.  There are cheap ones and good ones.  Use a good one.  I think you'll enjoy overhauling your T-90.� But like I just said, I'd have another source as a guide for your overhaul.� Novak Conversions has a good one and it's available from their web site.
�
Bob, Thanks for posting the old service bulletin.� It is step 6 that we're focusing on here.� As I said, George at Army Jeep Parts told me about the shim.� He has them available as a set of varying thicknesses and they install just as the bulletin instructs.� He also told me to ream out the center of an old rear bearing so that it may slide over the main shaft (output shaft) and be clamped against the spacer mentioned in the bulletin.� Once the desired fit is obtained the new rear bearing is pressed onto the main shaft and the T/C is bolted to the tranny. Like Randy says, the T/C casting fits over the rear bearing upon bolt up.�

Brett, You are right.� When I was 18 years old I had a 56 CJ-5 that jumped out of 2nd gear on compression.� I checked with a Jeep dealer about it.� They had a .030 stainless steel shim (1/4 hard) that fit into the tranny just by removing the shifting tower and placing it just behind 2nd gear over the main shaft.� That moved 2nd gear forward, closer to the clutch sleeve for better engagement.� It was like a horseshoe but it was designed to close it some by bending the open tangs slightly together to retain it.� It took care of the problem.� I had the Jeep for more than a year after that and then sold it to a friend who had it for several years without the problem returning.� The Jeep dealer explained that it was not a Jeep part, rather an aftermarket item.� However, the .030 shim mentioned in the bulletin is installed when the tranny is being assembled with the bearing spacer and the rear bearing. 

[1955CJ-5]

Calvin,

I'm glad your transmission is still working well...the blocker ring wear is interesting and if I ever have occasion to remove my tower assy I'll check the gaps on mine..

Were you able to measure the gap between 2nd gear and the shoulder on the main shaft, as mentioned in step 5 of the service bulletin? Just curious of course...

Randy

Edit:...Maybe that service bulletin should be in the FAQ or some other easily accessible location.....

[calvinhunt]

Randy,

Yes, I did measure the gap between 2nd gear when pushed forward and the shoulder on the main shaft.  Sorry to say it was .025.  That makes we worry that it may not be long before my tranny starts jumping out of 2nd when on deceleration.  That is where the aftermarket shim would fit if one were available.  When that happens I'm going to try to use some 1/4 hard stainless sheets we have at the aviation shop and make one as close to what I remember having so many years ago on my CJ-5.  I hope I learn something from all this. 

[1955CJ-5]

Well I have learned plenty....a T-90 rebuild is much more than just installing a rebuild kit.......

Keep us in the loop.....

Randy

[Carls_jeep]

1955CJ5, the end play that is alluded to is actually clearance between the input and output shafts. There is no such thing as end play, it's clearance and I wish everyone would understand that.

To find the clearance you have to hone out a good used bearing so the bearing slips on the output shaft. You assemble everything and clamp the bearing retainer plate to the back of the tranny housing. Then with a dial indicator you measure the distance the shaft slides in and out in the bearing. That distance is the .003" to .014" listed in the service bulletin.

Some bearing retainers stick out from the rear of the case and that is called protrusion and that has to be accounted for with the correct thickness gasket to seal the tranny to the transfer cases. If the bearing retainer is below the surface of the rear of the tranny case the plate and bearing can slide back and forth and you will have more clearance between the shafts than is required.

Due to production tolerances anything is possible so check everything as you build the tranny and transfer cases. Take nothing for granted. I solved the clearance issue by making a bearing spacer to replace the original spacer that was to thin. Not everyone has a lathe to do this so you have to find a source of shims to fix the problem.

Since bearings are made to very close tolerances you don't have to worry about the thickness of a bearing being different. BUT, you do have to use a good bearing without a lot of wear in the balls and races to do the clearance testing.

On the other hand, people do just slap them together and it works, but maybe not very long.

[1955CJ-5]

Thanks Carl,

If I rebuild another, or rebuilt this one again, I'll have more knowledge of how it should be and will at least make an effort to do it "right".� Of course that means more tools!!

On a positive note the 3a transmission seems to be just fine after 500 miles...and the Cj-5 transmission is just fine after some 49,000 miles from the factory.....But the T/C is a little noisy in low range...

[Carls_jeep]

Calvin, I don't think the oil has caused the wear on the third gear blocking ring. It could just be a defective blocking ring. Maybe the brass alloy was not right or maybe it was a bad machine job. It seems like the minimum clearance between brass ring and steel gear is .030" but I'm not sure about that.

The only way I can shift my tranny without a little clicking in second and third gear is to double clutch in neutral. If I don't double clutch the synchros make a little noise when shifting in second and third.