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Snort
Samba Member
Joined: April 02, 2005
Posts: 1957
Location: Seattle, WA
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 Posted: Sat Dec 26, 2015 8:55 pm Post subject: Re: Split case transmission rebuild DIY |
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| The point is neither one is right. It's a crap shoot. That is why you need to check the lash before and after. If the lash is correct then you are done. If not, then start taking measurements and do it by the book. Get in there, get oily and give it a try. |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Sun Dec 27, 2015 8:17 am Post subject: |
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| StockNazi wrote: |
| Bruce wrote: |
| Snort wrote: |
| Wild guess here. Maybe if the ring gear adjustment shims stayed on their original left/right locations relative to the case it would be correct. |
no
The sum total of the two shim packs will be the same, but the thickness on each side will likely be different. The backlash has to be measured.
| Snort wrote: |
| You would probably still have to check the pinion gear adjustment to fine tune the fit .... |
There's no need to check the pinion depth. The diff's axis position relative to the pinion gear doesn't change when you flip the diff, so if VW got the pinion depth right, it's going to be perfect. |
I replaced the small .1mm shim that was under the 1st/2nd gear slider hub as the og was badly worn. I tried a NOS .1mm shim first and the axial play, measured between 4th gear and bottom of top friction shim was around .21mm. I then tried a .15mm shim and measurment was then .16mm. Without guesswork has the axial play for 2nd/3rd/4th gears as .10-.25mm. That was for NEW parts, and it did not specify a wear limit.
Did I do this correctly, and am I correct in assuming this will not change my pinion depth measurment? I did not change/replace any of the shims under the double-roller bearing. |
Did I measure the axial play of 2nd/3rd/4th gear correctly? I used a feeler gauge between the top of 4th gear and top friction shim. That's the only place I could see to use a feeler gauge.
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
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| Posted: Mon Dec 28, 2015 3:19 am Post subject: |
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| Snort wrote: |
| I asked a professional VW transmission builder if he had ever done this and he confirmed that he had with good results. He also cautioned me that there is no guarantee of success. His method was to check the lash before disassembling the transmission, flip the differential keeping the shims in their original positions, and recheck the lash upon completion... if the lash is the same then all is good. If the lash has changed then shim adjustment is required. |
I agree with your pro trans builder friend. If the lash is the same, you're done.
There are two things you are doing by altering the shims on the diff. Total diff bearing preload, and ring gear backlash.
There's no doubt that by using the same bearings, shims, diff housing and case halves, if you reverse the diff, the preload will stay the same.
If there's an error in the machining of the diff, the factory will compensate for it with the shims. I think Snort's pro trans builder friend is successful flipping the diff that way when the diff is machined dead-on. But if the diff's machining is out, I don't think the flip described above will work. When it doesn't work, backlash will be way out.
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| overheard at the portland Swap Meet... wrote: |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Mon Dec 28, 2015 9:07 am Post subject: |
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| Bruce wrote: |
| Snort wrote: |
| I asked a professional VW transmission builder if he had ever done this and he confirmed that he had with good results. He also cautioned me that there is no guarantee of success. His method was to check the lash before disassembling the transmission, flip the differential keeping the shims in their original positions, and recheck the lash upon completion... if the lash is the same then all is good. If the lash has changed then shim adjustment is required. |
I agree with your pro trans builder friend. If the lash is the same, you're done.
There are two things you are doing by altering the shims on the diff. Total diff bearing preload, and ring gear backlash.
There's no doubt that by using the same bearings, shims, diff housing and case halves, if you reverse the diff, the preload will stay the same.
If there's an error in the machining of the diff, the factory will compensate for it with the shims. I think Snort's pro trans builder friend is successful flipping the diff that way when the diff is machined dead-on. But if the diff's machining is out, I don't think the flip described above will work. When it doesn't work, backlash will be way out. |
Ok, I will leave the shims in their original positions and check the backlash with what is marked on the ring gear. If it's not right I get to start from scratch I guess.
Question #2 is: Am I ok with the total axial gear play on the pinion shaft if I am within the .10-.25mm spec. when measured between top of 4th gear and the top friction washer?
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"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
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splitjunkie
Samba Member
Joined: April 04, 2006
Posts: 4094
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| Posted: Mon Dec 28, 2015 1:19 pm Post subject: Re: Split case transmission rebuild DIY |
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You wouldn't have to start from scratch if your backlash is off.
You can measure all of the existing shims to give you the total thickness of shims required. The combined total thickness of shims won't change.
If your lash is off you will have to try moving shims around or changing shims to bring the ring and pinion into proper mesh but the total combined thickness for all of the shims will still be the same so that will save you quite a bit of work. This is assuming that you don't change bearings or any other parts.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Thu Jan 28, 2016 10:12 am Post subject: Re: Split case transmission rebuild DIY |
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Ok, update on setting the backlash after flipping the ring gear. Pinion shaft shims were not altered. No bearings or any other parts were changed. My pinion depth should be spot-on.
After I flipped the ring gear/diff. I left the shims in their original position (same side of case) and measured the backlash. It was .63mm
This felt like alot of play to me and I am thinking the backlash was excessive.
I then swapped the shims from their original position (opposite side of case). The shims effectivley followed the diff. as it was flipped.
Backlash in this position was much lower at .35mm
This felt tighter, with some play and seems more correct to me.
According to the Bently the backlash spec. should be inscribed on the ring gear. I am having a hell of a time reading that number b/c it is written so poorly. I can not find any mention of a backlash spec. for a splitcase transmission.
Can someone give me a "safe" backlash spec. for a splitcase?
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).
"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
Thomas Jefferson |
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splitjunkie
Samba Member
Joined: April 04, 2006
Posts: 4094
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| Posted: Sat Jan 30, 2016 8:45 am Post subject: Re: Split case transmission rebuild DIY |
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did you measure the backlash before you changed anything? If not you should have to give you the original as the point of reference to shoot for.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Sat Jan 30, 2016 10:57 am Post subject: Re: Split case transmission rebuild DIY |
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| splitjunkie wrote: |
| did you measure the backlash before you changed anything? If not you should have to give you the original as the point of reference to shoot for. |
No, unfortunatly I did not measure it before I took things apart; this is my first rebuild/refresh so it has been a bit of a learning curve.
Is there a "safe" range or spec. I can shoot for?
I guess what I could do, since no bearings or gears have been changed is to flip the diff. assembly to the original position with shims in the original position and measure the backlash. That should tell me what the original backlash spec.
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).
"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
Thomas Jefferson |
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splitjunkie
Samba Member
Joined: April 04, 2006
Posts: 4094
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| Posted: Sat Jan 30, 2016 11:28 am Post subject: Re: Split case transmission rebuild DIY |
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| StockNazi wrote: |
| splitjunkie wrote: |
| did you measure the backlash before you changed anything? If not you should have to give you the original as the point of reference to shoot for. |
No, unfortunatly I did not measure it before I took things apart; this is my first rebuild/refresh so it has been a bit of a learning curve.
Is there a "safe" range or spec. I can shoot for?
I guess what I could do, since no bearings or gears have been changed is to flip the diff. assembly to the original position with shims in the original position and measure the backlash. That should tell me what the original backlash spec. |
Yep, put it back together as original and measure. I would either use sealer and
Torque everything to spec or do it clean and dry and torqued to spec to get as accurate a measurement as possible. Whichever way you do it you need to do it the same way each time so you are not introducing any variables.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Tue Feb 02, 2016 9:13 pm Post subject: Re: Split case transmission rebuild DIY |
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| splitjunkie wrote: |
| StockNazi wrote: |
| splitjunkie wrote: |
| did you measure the backlash before you changed anything? If not you should have to give you the original as the point of reference to shoot for. |
No, unfortunatly I did not measure it before I took things apart; this is my first rebuild/refresh so it has been a bit of a learning curve.
Is there a "safe" range or spec. I can shoot for?
I guess what I could do, since no bearings or gears have been changed is to flip the diff. assembly to the original position with shims in the original position and measure the backlash. That should tell me what the original backlash spec. |
Yep, put it back together as original and measure. I would either use sealer and
Torque everything to spec or do it clean and dry and torqued to spec to get as accurate a measurement as possible. Whichever way you do it you need to do it the same way each time so you are not introducing any variables. |
I put the diff. and shims in their original positions and checked the backlash; it is .32mm. Is it possible this was the original backlash, or have things just worn over the years?
Any suggestions on what to do? Leave things at .35mm or swap some shims around to get closer to .25mm; I would rather be on the loose side than have things too tight I believe.
I could reduce on shim by .10mm and increase the one on the other side by the same amount to maintain the total thickness of all the shims.
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).
"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
Thomas Jefferson |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
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| Posted: Wed Feb 03, 2016 4:10 am Post subject: Re: Split case transmission rebuild DIY |
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It's possible the diff has pounded the case a bit.
Look at the contact pattern at that lash and post the pics. Then decide what to do after that.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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splitjunkie
Samba Member
Joined: April 04, 2006
Posts: 4094
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| Posted: Wed Feb 03, 2016 12:26 pm Post subject: Re: Split case transmission rebuild DIY |
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You can paint the ring gear teeth with Dykem Blue and then reassemble the transmission. Rotate the transmission in forward and reverse for a minute or two each and make sure the axles are turning then carefully diassemble and remove the diff. The Dykem blue will be worn off the areas of contact which should be evenly centered if it is set correctly. If it is too far toward the center or outer edge of the teeth then the backlash is off and needs to be adjusted to bring it back to center.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Wed Feb 03, 2016 8:25 pm Post subject: Re: Split case transmission rebuild DIY |
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| splitjunkie wrote: |
| You can paint the ring gear teeth with Dykem Blue and then reassemble the transmission. Rotate the transmission in forward and reverse for a minute or two each and make sure the axles are turning then carefully diassemble and remove the diff. The Dykem blue will be worn off the areas of contact which should be evenly centered if it is set correctly. If it is too far toward the center or outer edge of the teeth then the backlash is off and needs to be adjusted to bring it back to center. |
I ordered some yellow gear marking grease this morning, should be here in a few days.
After looking at the backlash number engraved on the ring gear I think it does say 025mm
The way the shims are now:
3.8mm + .25mm shim on ring gear side/ 3.7mm on the other side.
I found a 3.9mm and a 3.6mm shim to swap for each side; that should bring the ring gear .1mm closer to the pinion gear and the backlash very close to .25mm
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).
"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
Thomas Jefferson |
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splitjunkie
Samba Member
Joined: April 04, 2006
Posts: 4094
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| Posted: Thu Feb 04, 2016 5:33 am Post subject: Re: Split case transmission rebuild DIY |
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Why not post a picture of the engraved number? sometimes having several sets of eyes is better than one.
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Chris
You know, a lot of these scratches will buff right out... Jerry Seinfeld |
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Stocknazi
Samba Member
Joined: June 18, 2004
Posts: 5150
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| Posted: Wed Feb 10, 2016 4:52 pm Post subject: Re: Split case transmission rebuild DIY |
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| StockNazi wrote: |
| splitjunkie wrote: |
| You can paint the ring gear teeth with Dykem Blue and then reassemble the transmission. Rotate the transmission in forward and reverse for a minute or two each and make sure the axles are turning then carefully diassemble and remove the diff. The Dykem blue will be worn off the areas of contact which should be evenly centered if it is set correctly. If it is too far toward the center or outer edge of the teeth then the backlash is off and needs to be adjusted to bring it back to center. |
I ordered some yellow gear marking grease this morning, should be here in a few days.
After looking at the backlash number engraved on the ring gear I think it does say 025mm
The way the shims are now:
3.8mm + .25mm shim on ring gear side/ 3.7mm on the other side.
I found a 3.9mm and a 3.6mm shim to swap for each side; that should bring the ring gear .1mm closer to the pinion gear and the backlash very close to .25mm |
Ok I have swapped the shims like shown above.
My backlash is now .25-.27mm; The ring gear is marked .025mm, so I am very close.
The grease pattern I have is:
I hope this is acceptable; what do you guys think?
_________________
WANTED:
58 Westfalia cabinet knobs (3 needed), roof rack, and (7) privy tent poles (silver painted).
"When the people are afraid of the government, that's tyranny. But when the government is afraid of the people, that's liberty."
"Resistance to tyrants is obedience to God."
Thomas Jefferson |
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calexican
Samba Member
Joined: June 11, 2008
Posts: 730
Location: El Paso, TX
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| Posted: Sat Feb 03, 2018 12:10 pm Post subject: Re: Split case transmission rebuild DIY |
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| This topic inspired me to consider jumping into my split case.... it then I got to page three and there is no outcome. Would be nice to know what happened with this before I take the leap. |
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nlorntson
Crazy VW Lady
Joined: March 13, 2004
Posts: 3783
Location: Twin Cities, MN
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| Posted: Sat Feb 03, 2018 12:52 pm Post subject: Re: Split case transmission rebuild DIY |
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| Transmission went back on the car and seems to work just fine other than a leaky nose cone so it will come out and get that fixed some day. |
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calexican
Samba Member
Joined: June 11, 2008
Posts: 730
Location: El Paso, TX
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| Posted: Sat Feb 03, 2018 3:52 pm Post subject: Re: Split case transmission rebuild DIY |
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| Great! Good to know. Thanks. |
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Bruce
Samba Member
Joined: May 16, 2003
Posts: 17290
Location: Left coast, Canada
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| Posted: Sat Feb 10, 2018 7:15 pm Post subject: Re: Split case transmission rebuild DIY |
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| StockNazi wrote: |
I hope this is acceptable; what do you guys think? |
I know I'm 2 years too late, but those contact patterns are no good. The coast pattern is too close to the ID of the ring gear, it needs to be centered on the tooth.
| StockNazi wrote: |
My backlash is now .25-.27mm; The ring gear is marked .025mm, so I am very close. |
The 0.025 is a number associated with the pinion depth when using the factory tools that nobody uses today. It's not related to the backlash.
_________________
| overheard at the portland Swap Meet... wrote: |
| ..... a steering wheel made from a mastadon tusk..... |
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[email protected]
Samba Member
Joined: June 24, 2015
Posts: 719
Location: Rialto. CA
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| Posted: Mon Jul 16, 2018 5:40 pm Post subject: Re: Split case transmission rebuild DIY |
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| Why don't they or anybody make performance gearings for these split case transmissions??? that would be great to have these transmissions more suited up with our 36hp performance engines .. |
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