Syncro Transaxle rebuild: Part 1, Initial inspection / stand

[tjet]

I'm in the process of rebuilding my syncro transaxle, and I figured this would be a good place to start my documentation with photos. Note, I have never rebuilt a VW trans before. I do have some experience replacing a broken gear in a Muncie 4 speed. As for not sending it out for a rebuild, I have a few reasons:

1- I want to learn a new skill.

2- I want to understand how a VW trans works. I have an idea, but the slider hub operation baffles me.

3- Its just too expensive to have a pro do it. Even though I own a syncro with front and rear lockers, it's a rusty vehicle that would be destine for a junkyard if it was anything else. No need to start gold plating things at this point. Also, I have a son in college in Germany getting his masters in engineering. I've been sending him 1500 euro a month. (Still cheaper than any decent US college). I'm not complaining, but I'm on a budget.

4- I want to add some expensive goodies inside of it. These items are what pushes the overhauls up there $$ (racing gears, LSD, internal mods)

5- I want to encourage other people to try hard things.


On Floor:

On engine stand:

Initial drain plug inspection:
Seems like the old gear oil itself is magnetic. I did put a stack of Neodymium magnets on the plug before I removed it.

Finally, this will be a long-term project. I will be working on this after work. I'm hoping I can get it completed my summer.

Also, I made this video looking through the drain plug hole. How do I get the ring gear to rotate?


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[Sodo]

Excellent.
It helps a lot of members when a project starts at 'ground zero'.

[tjet]

Also, I should mention that this all started with a road trip breakdown. I ended up leaving my syncro mid trip in a storage unit in New Mexico, and I flew home to Connecticut. I paid for an entire year to get a discount. 1 year of storage in NM would be like 1.25 months here in CT . Note - I drive a lot of older cars, sometimes cross-country. The storage unit idea has always been a last resort option for me. Out of over a dozen coast-to-coast trips, including a 50 year old corvette, this is the first time I was forced to do it.

Here are the related threads:

https://www.thesamba.com/vw/forum/viewtopic.php?p=9986264&highlight=#9986264

https://www.thesamba.com/vw/forum/viewtopic.php?p=9996281&highlight=#9996281

https://www.thesamba.com/vw/forum/viewtopic.php?t=523156&highlight=

https://www.thesamba.com/vw/forum/viewtopic.php?t=776571&highlight=

[tjet]

[Sodo]

[dobryan]

Before you open up anything I would take it outside and power wash it then hit it with a degreaser and power wash again. You do not want to work with crud all over it.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[old_man]

I look forward to this thread as I have done an almost identical thing.

I will give you a warning, however, that style of engine stand may have a tendency to tip. Be careful. You have this style.. Less tippy versions are either this or this style.

I think I have a thread somewhere that shows a lot of the work for a 2wd as well as a parts list if you need it.

[MsTaboo]

You're gonna want to download this PDF, the factory service manual. Note, it's from 1986 and has info about the factory solid shaft/decoupler that is NA.
Take the time to read the latter service section before you take any tools to the transaxle. If I remember correctly there are some measurements you need to take before disassembly.
https://www.thesamba.com/vw/archives/manuals/1986_vw_syncro_service_manual.php

Dobryan's advice about working clean is paramount. Keep in mind that there are specialist tools needed to do the job correctly. I contemplated doing mine myself, I have loads of precision measuring tools from my work as a machinist but opted to pay $$$ for a rebuilders experience.

I cleaned up mine by hand with lots of PB Blaster, Simple Green, Varsol, wire brushes, and a couple rolls of paper towels!

Good luck!
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'90 Syncro Westy 3 knob w/Zetec

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[tjet]

I actually attempted to clean this thing with 3 cans of Gunk outside. The only thing it did was stink up my house 2 days after I brought it into the basement - even after it was washed off with multiple pots of stove hot water. I think this has some undercoating on it. I guess I can give it a try again with a heavy duty (non-toxic / non- flammable) degreaser and hand scraping, but I really don't want to move it again. It would need to be cleaned where it's at. I was more concerned about a harsh chemical or water getting inside of it during the cleaning process.

I just noticed a crack on the bellhousing, too. I removed this trans about 8 years ago, so it's possible I did it then. Not a major bummer though, I will get another.

Thanks for all your insightful input. I will read through those manuals today (I'm off tonight)

[MarkWard]

You should measure the ring gear backlash when you remove the bellhousing. This will tell you a lot and if you are reusing the ring and pinion, you will want to shoot for the same backlash if near spec.

Second, once you remove the cv drive flanges and the plastic side carrier locks, take a center punch and dimple a mark on the case and another mark on the ring adjuster before you back it out. I use 2 marks for one side and single marks for the other. This will prevent mixing up sides. You should also measure the depth of the rings in relation to the case. This works better than counting turns. Depending on what parts get used, this step gets you to a good starting point.
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[tjet]

Thanks for the tip on the engine stand old_man, and I will read through the manuals before taking it apart, as well as mark critical reference points.

Finally able to clean it up and get the trans code.

WD-40 and scotchbrite pads seems to clean it up best so far.

[tjet]

I opened it up Couple of videos. I don't any see damage at this point, but I'm not an expert on wear.


Link


Link

[Sodo]

No pitting, that's the first win.

My uneducated opinion on the wear pattern is....
The wear is not starting at the beginning of the tooth, and it's not going off the end of the tooth.
So that's good.

We'll see if any genuine experts chime in.
Recommend to wash the oil off so the wear patterns on the tooth surface pattern are more visible (dry).
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[old_man]

I can't tell if it's the light, the camera, the focus, or the oil but it looks like pitting, spalling, or whatever on some of these on the drive side of the gear. I am no subject matter expert though.

This is what my diesel pinion looked like when I rebuilt. I, unfortunately, don't have a picture of what my gear looked like. I can't recall anyways. I have a pic of what one looks like after 4th gear explodes but that's probably not useful for you.

[crazyvwvanman]

What about a closeup video of the pinion gear teeth too?

Mark

[tjet]

[MarkWard]

Measure the ring gear backlash before you undo anymore. You can see the pinion gear teeth with a flashlight, but they are not easy to really visually examine assembled.

Your next step will be to remove the ring gear assembly to get access to the large pinion nut for further disassembly.

Where did the closeups come from after the video post? Those teeth look suspect.
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[tjet]

I think old man grabbed those images from the video. I will try to get some close up pics and check the backlash before I take it apart.

[crazyvwvanman]

With the tranny out and the bell housing off the pinion gear teeth can be viewed with a bright flashlight.
Put the tranny in gear, hold 1 cv flange still and turn the other.
That will rotate the pinion gear so you can examine each tooth in sequence.

There are only 7 pinion teeth turning 34 ring teeth so more wear/damage expected on the pinion teeth.

Mark

[tjet]

Here you go


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