Syncro 's Tranny Pop out at 4th after rebuild

#63692

Hi All,

First of all , sorry for my writing skill in English , I'm Thai.

After 2nd of rebuilding my syncro's tranny, the 4th still pop-out.
The 1st time of rebuilding was because the lever ( the one that has white ball head ) and the shifter axel. So dissembled then changed the axel, most of roller that available and syncromesh. Then assembled and put back to my van. After a short test run, the shift pop-out from 4th gear while driving , not immediately. So it needed to be dissembled again.

The 2nd time of dissemble, we found that the 3 pins and spring wire of 3/4 sleev/hub were in wrong possition. So we put it back and assemble them back to my van. Unfortunately, it still pop-out. This time I drove for a month to learn popping characteristic. I've learn that it would pop-out when engine ran at high acceleration. Holding shifter by banjee cord would help but not so good.

We put it out from my van and then we put the tranny to the "tranny rev'ter " as pic links below

The 3phase electrical motor drive the 1:3 gear then drive the tranny.

Put tranny to 4th position by manual then start the e-motor. Rev it up to 1200rpm then the tranny rev to 3600 rpm. No pop-out !!!!!!!!

That must because the tranny has no load, no wheels attached.

I think it would be the same result if it put some brake mechanical to tranny's end shaft.

Here are the plan if the tester pop out :
1. It "must be" something inside that cause the popping.
2. I have the old , unusable syncro tranny from my friend. I'll drill some holes to old tranny's case to use them as special tools as describe in Brentley 's manual. The Jig for inspect shaft assembly.

3. My mechanic said it might because the new syncromech has thicker tapper. Is it possible?

Sent from Boon's iPad2

#63695

I have had this problem with at least 3 syncro transmissions. It seems the taper roller bearings at the end of both the mainshaft and countershaft get wear and allow excess play. This allows the two shafts to "push" out of proper alignment when the force of the two gears (4th gear set at the end of the shaft) mesh, making them "jump" out of gear when under load.
With a tired transmission, you will observe the shift lever moves forward and back when driving in 4th gear depending on whether you are on the throttle or off the throttle. A tight fresh transmission will have no movement and a worn trans will have as much as 3" movement at the shift ball, all without touching the lever.
You need to preload the taper bearings on the mainshaft and countershaft when assembling the transmission, and this is where a jig makes this possible. Too much preload will destroy things, and not enough will jump out of gear.
This is a very simplistic explanation, but may help.
-Donny

Show quoted text

----- Original Message ----- 
From: "Hanniboon" <hanniboon@...>
To: <Syncro@...>; <subaruvanagon@...>
Sent: Thursday, May 10, 2012 4:06 AM
Subject: [subaruvanagon] Syncro 's Tranny Pop out at 4th after rebuild

Hi All,

First of all , sorry for my writing skill in English , I'm Thai.

After 2nd of rebuilding my syncro's tranny, the 4th still pop-out.
The 1st time of rebuilding was because the lever ( the one that has white ball head ) and the shifter axel. So dissembled then changed the axel, most of roller that available and syncromesh. Then assembled and put back to my van. After a short test run, the shift pop-out from 4th gear while driving , not immediately. So it needed to be dissembled again.

The 2nd time of dissemble, we found that the 3 pins and spring wire of 3/4 sleev/hub were in wrong possition. So we put it back and assemble them back to my van. Unfortunately, it still pop-out. This time I drove for a month to learn popping characteristic. I've learn that it would pop-out when engine ran at high acceleration. Holding shifter by banjee cord would help but not so good.

We put it out from my van and then we put the tranny to the "tranny rev'ter " as pic links below

The 3phase electrical motor drive the 1:3 gear then drive the tranny.

Put tranny to 4th position by manual then start the e-motor. Rev it up to 1200rpm then the tranny rev to 3600 rpm. No pop-out !!!!!!!!

That must because the tranny has no load, no wheels attached.

I think it would be the same result if it put some brake mechanical to tranny's end shaft.

Here are the plan if the tester pop out :
1. It "must be" something inside that cause the popping.
2. I have the old , unusable syncro tranny from my friend. I'll drill some holes to old tranny's case to use them as special tools as describe in Brentley 's manual. The Jig for inspect shaft assembly.

3. My mechanic said it might because the new syncromech has thicker tapper. Is it possible?

Sent from Boon's iPad2

------------------------------------

Yahoo! Groups Links

#63721

Hi,
?
Just went back from vacation to reply mails. Many thanks to Donny ans Daryl.
I suspect to the preload either. BTW, I'll change 3/4 hub and sleeve as well.
?
Thanks and I'll update the result later. Hope that will be last time assembling.
?
Hanniboon.


________________________________
 From: Donny Lang <indigo@...>
To: subaruvanagon@...
Sent: Thursday, 10 May 2012, 21:59
Subject: Re: [subaruvanagon] Syncro 's Tranny Pop out at 4th after rebuild



?

I have had this problem with at least 3 syncro transmissions. It seems the
taper roller bearings at the end of both the mainshaft and countershaft get
wear and allow excess play. This allows the two shafts to "push" out of
proper alignment when the force of the two gears (4th gear set at the end of
the shaft) mesh, making them "jump" out of gear when under load.
With a tired transmission, you will observe the shift lever moves forward
and back when driving in 4th gear depending on whether you are on the
throttle or off the throttle. A tight fresh transmission will have no
movement and a worn trans will have as much as 3" movement at the shift
ball, all without touching the lever.
You need to preload the taper bearings on the mainshaft and countershaft
when assembling the transmission, and this is where a jig makes this
possible. Too much preload will destroy things, and not enough will jump out
of gear.
This is a very simplistic explanation, but may help.
-Donny
----- Original Message -----
From: "Hanniboon" <hanniboon@...>
To: <Syncro@...>; <subaruvanagon@...>
Sent: Thursday, May 10, 2012 4:06 AM
Subject: [subaruvanagon] Syncro 's Tranny Pop out at 4th after rebuild

Hi All,

First of all , sorry for my writing skill in English , I'm Thai.

After 2nd of rebuilding my syncro's tranny, the 4th still pop-out.
The 1st time of rebuilding was because the lever ( the one that has white
ball head ) and the shifter axel. So dissembled then changed the axel,
most of roller that available and syncromesh. Then assembled and put back
to my van. After a short test run, the shift pop-out from 4th gear while
driving , not immediately. So it needed to be dissembled again.

The 2nd time of dissemble, we found that the 3 pins and spring wire of 3/4
sleev/hub were in wrong possition. So we put it back and assemble them
back to my van. Unfortunately, it still pop-out. This time I drove for a
month to learn popping characteristic. I've learn that it would pop-out
when engine ran at high acceleration. Holding shifter by banjee cord would
help but not so good.

We put it out from my van and then we put the tranny to the "tranny
rev'ter " as pic links below





The 3phase electrical motor drive the 1:3 gear then drive the tranny.

Put tranny to 4th position by manual then start the e-motor. Rev it up to
1200rpm then the tranny rev to 3600 rpm. No pop-out !!!!!!!!

That must because the tranny has no load, no wheels attached.

I think it would be the same result if it put some brake mechanical to
tranny's end shaft.


Here are the plan if the tester pop out :
1. It "must be" something inside that cause the popping.
2. I have the old , unusable syncro tranny from my friend. I'll drill some
holes to old tranny's case to use them as special tools as describe in
Brentley 's manual. The Jig for inspect shaft assembly.

3. My mechanic said it might because the new syncromech has thicker
tapper. Is it possible?


Sent from Boon's iPad2

------------------------------------

Yahoo! Groups Links





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Syncro 's Tranny Pop out at 4th after rebuild