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Original Vanagon manual gearbox failures and solutions
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Waldi
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PostPosted: Thu Jun 22, 2017 3:11 am    Post subject: Original Vanagon manual gearbox failures and solutions Reply with quote

Please post here failures with pics and possible solutions.

Please don't post here "I have shifting problems"

Please don't post here "let's build a better new van gearbox"

Please don't post here "I use a Subi, Audi, or whatever gearbox"

Hello Mods, it would be nice to have this as a sticky post. I have already posted many pics and comments, but they are stranded deep into the forums.

It would save us a lot of time. Thx. Feel free to correct my bad English. Feel free to add other on-topic posts here.

Some time ago I was posting my gearbox cooling, or better said, an anti-heating solution.

Now I checked my system with data.

I use the Syncro JX fan which is originally located behind the left rear light.
Pics in my gallery.

Data is from yesterday with over 30°C in shadow. Maybe 35°C possible higher on street.
The shown pics are on a standing still van with engine off right after arriving home.
During driving the temp inside the bellhousing was about 55°C. With fan on 38°C. Driving was on flat road with 90km/h. The temp was stable and not rising. It would sure rise a lot driving uphill or faster.
I have the Syncro bellhousing with 2 tube connections and a TDI dust plate.
So there is a hole on the button and on the middle tube connector is no tube.
That's why the temp is lower on driving without fan on, than standing still.

With a gazer bellhousing without any air change, the temp inside will be a lot higher.

I am using a radio cooking temp gauge, so I can have the gauge on the dashboard while driving.

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amwaj
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PostPosted: Thu Jun 22, 2017 7:32 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

its well done anyway... Razz
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IdahoDoug
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PostPosted: Thu Jun 22, 2017 11:45 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

I am not sure if this is helpful, but my 1987 Syncro gearbox failed with sudden 3/4 gear shifting issues. I drove it 50 miles home in 2nd gear with the emergency flashers on and tore down the transmission. I found the 3/4 slider cracked badly, and the main bearing badly worn.

To fix it, I installed new parts and replaced the magnesium gear housing with an aluminum version, and installed the main bearing retainer and the South African oil splasher plates. It shifted and drove well after that.

Doug
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2016 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential. 1988 Mitsubishi Van w/ dual spinny seats, mid engine and solid axle.1990 burgundy parts Vanagon. 1984 Porsche 944, 1992 Lexus LS400, 1988 Toyota Supra 5 speed targa project in pieces.
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Waldi
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PostPosted: Fri Jun 23, 2017 12:16 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

I use this retainer.
A friend laser cuts them for me. Than there is some little flex work on it.
No work on the shield needed.

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I also dont use any paper gasket to the low gear housing, just a good sili seal.
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tjet
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PostPosted: Fri Jun 23, 2017 12:54 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

I overfill my Syncro trans.

I do it on a steep driveway.

I also flush & fill it every 7,000 miles or so. Sodo tip.

https://www.thesamba.com/vw/forum/album_page.php?pic_id=1609649
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Waldi
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PostPosted: Fri Jun 23, 2017 1:22 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Do you overfill your engine oil too ?
Or do you change it every 1000miles ?

There is no evidence this helps.
Ofcourse changing the oil also do not hurt, and having a look to the out screw is not wrong.
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Waldi
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PostPosted: Fri Jun 23, 2017 3:31 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

A lot of you have a temp gauge installed in your box and a decoupler.
Do you see any change in temps driving coupled or decoupled ?

I know there are factors for this, like tires, visco. But maybe seeing temps from different Syncros can say something.
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Sodo
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PostPosted: Sat Jul 29, 2017 9:22 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Waldi wrote:
A lot of you have a temp gauge installed in your box and a decoupler.
Do you see any change in temps driving coupled or decoupled ?
I know there are factors for this, like tires, visco. But maybe seeing temps from different Syncros can say something.


I noticed a few degrees difference (very little like 2*F) when I had one. I suppose because the front differential reduces the load on the rear R&P and pinion bearing. This is a good question, but I cannot help because my decoupler failed (and filled the NEW trans with metal) so I removed it. I will use a higher quality decoupler next time.

You KNOW I'd re-confirm if I could,,,, but lots of other members have temp gauges (+ decoupler).
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Last edited by Sodo on Sat Jul 29, 2017 9:40 am; edited 1 time in total
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PostPosted: Sat Jul 29, 2017 9:39 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

From other thread Syncro stuck in 4th

Flomulgator wrote:
Eroded mainsaft bearing inner race. When 4th gear is engaged, there is no movement between the two. When any other gear is engaged, 4th gear will have a speed differential against the inner race, which is rotating the speed of the mainshaft at all times:
(pic annotated by Sodo)
Image may have been reduced in size. Click image to view fullscreen.


This is a pic of the mainshaft bearing where 4th gear thrusts against the mainshaft bearing inner race. Flomulgator's 4th gear was broken, creating more thrust, but this same erosion occurs in transmissions that do not have a broken 4th gear. What causes this erosion? Is it from using in 3rd gear too much? Does the helical cut of 3rd gear press 4th gear against the mainshaft bearing inner race?
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....KTMs, GasGas, and a Stumpjumper
One apple every 8 hours will keep 3 doctors away - B Kliban


Last edited by Sodo on Sat Jul 29, 2017 9:49 am; edited 1 time in total
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ZsZ
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PostPosted: Sat Jul 29, 2017 9:49 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Sodo wrote:
From other thread Syncro stuck in 4th

Flomulgator wrote:
Eroded mainsaft bearing inner race. When 4th gear is engaged, there is no movement between the two. When any other gear is engaged, 4th gear will have a speed differential against the inner race, which is rotating the speed of the mainshaft at all times:
(pic annotated by Sodo)
Image may have been reduced in size. Click image to view fullscreen.


This is a pic of the mainshaft bearing where 4th gear thrusts against the mainshaft bearing inner race. What causes this erosion? Is it from using in 3rd gear too much? Does the helical cut of 3rd gear press 4th gear against the mainshaft bearing inner race?


Caused by the bearing of the shaft pressed in too much during assembly not leaving enough space between 4th (5th) and the bearing.
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Gnarlodious Premium Member
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PostPosted: Sat Jul 29, 2017 11:02 am    Post subject: Get a transmission oil temperature readout Reply with quote

My arduous journey to getting a temperature readout...

I am running the AAP 5-speed built by Mr GAS with numerous mods. Since I am pushing a Giles powered AAZ I wanted to monitor oil temps, so I had him tap the bottom for a ⅛NPT temperature sensor. I didn't know anything, so I bought a VW Bosch compatible sensor on eBay to get started. No specs were given on the page, only that it would work with any gauge. No identifying marks were found on the part.

On testing, I found it is NTC, or negative temperature coefficient thermistor. The hotter it gets the less it resists. More resistance means a cooler reading, which is what you get with longer wires like in the Vanagon. So the advantage to NTC is that long wires can be compensated by adding a low value resistor.

Upon testing, the eBay part was a standard Bosch temperature sensor M12. Type is specified by “ohms at 20ºC” (68F), which mine read at 67k = 67,000Ω at reference point. This apparently meant I had an 820Ω sensor but it was very inaccurate, because at 20C it reads 670Ω but should read 820Ω. Means it reads about 8ºC too cold, your oil is that much hotter than you think it is. Cheap generic crap from eBay.

So the problems of getting a transmission temperature the readout turned out to be:
1) You cannot get the Bosch temperature sensor in ⅛ threading with two header wires. There is a one-wire sensor and a huge square socket sensor typical to Jetta, nobody makes a 2-wire sensor suitable for under the transmission.
2) The Bosch system evolved in the simple analog era, the sensors are not compatible with any modern digital devices.

Solution: Abandon traditional automotive thermal sensors, adopt modern digital system.

Digital thermostat:
Upon experimenting with modern (non-automotive) digital thermometers, I discovered the measurement standard for sensors is 10kΩ @ 25ºc (77F), called a “10k NTC thermistor”. These are sold in various forms for cheap on eBay or Amazon and come with a 2-wire tubular probe. Note that there are other discussions on this site where users have laboriously made a compatible sensor for oil immersion. I searched high and low, but there was no affordable immersion sensor for the 10k processor.

After some hunting around I stumbled on this quality product, but nowhere does it say it is a 10k thermistor:
GlowShift ‘GS’ ⅛NPT temperature sensor
Glowshift technical support doesn't know anything, I determined its resistance on the testbench. Note that only their more modern “GS sensor” is compatible with the 10k microprocessor. At this time it is the best solution I have found.

I looked for a smaller in-dash .37" segment LED display for Fahrenheit but no such thing. This size would easily snap into a rectangular opening cut into the Vanagon's dashboard right of the heater outlet and left of the steering column. There are plenty of .56" segment displays but the size is too big for me, it would be bright large red digits and annoying while driving. So I settled for a backlit LCD display:
Fahrenheit/Centigrade Digital LCD Thermometer Temperature Meter
Note that when you buy a display you MUST scroll down to the specs and look for specs like:
Sensor type: NTC (10K/3435)
The final number is just the variety of probe, any 10k sensor will work.

Out of curiosity I temporarily set one up for my summer road trip pulling a small trailer. Ambient temperatures through Wyoming and Montana were around 95º (35c), temps in my transmission read at 160 maximum (71c). Probably not to worry since I am using a top quality synthetic oil (NOT Redline!).

The big advantage to this sensor is that it is compatible with various programmable thermostats and use it to drive a transmission cooling system. These are cheap and commonly used to control fish tanks, climate control, etc.

So the upshot of this story is, save yourself the trouble and get the Glowshift GS sensor from the start.
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Last edited by Gnarlodious on Sat Jul 29, 2017 11:07 am; edited 1 time in total
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gears
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PostPosted: Sat Jul 29, 2017 11:07 am    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Quote:

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Caused by the bearing of the shaft pressed in too much during assembly not leaving enough space between 4th (5th) and the bearing.[/quote]

No, definitely not that. I guarantee if 4th gear was straight-cut rather than helical, this wear would not develop.
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PostPosted: Sat Jul 29, 2017 12:52 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Sodo wrote:


...
Is it from using in 3rd gear too much? Does the helical cut of 3rd gear press 4th gear against the mainshaft bearing inner race?


No. If the pinion turns the 4th shifting gear wheel, its getting pressed to the other direction.

@ZsZ,
you cant change the clearance by pressing the bearing more on to the shaft.
Or sayed otherwise, the bearing is always pressed to the end. If not you cant get the "security ring" on.

The wheel is pressed towards the bearing running in 4-th.
If we say, there is no turning difference between both, does not mean there is nothing of movement.
I think especialy on 1,9er diesel with 1,6er flywheel there is "many" movement between both.
It is strange in this cases, that the gear wheel dont show any damage, but the bearing does. Weak steel.
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PostPosted: Sat Jul 29, 2017 2:02 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Waldi wrote:
Sodo wrote:


...
Is it from using in 3rd gear too much? Does the helical cut of 3rd gear press 4th gear against the mainshaft bearing inner race?


No. If the pinion turns the 4th shifting gear wheel, its getting pressed to the other direction.

@ZsZ,
you cant change the clearance by pressing the bearing more on to the shaft.
Or sayed otherwise, the bearing is always pressed to the end. If not you cant get the "security ring" on.

The wheel is pressed towards the bearing running in 4-th.
If we say, there is no turning difference between both, does not mean there is nothing of movement.
I think especialy on 1,9er diesel with 1,6er flywheel there is "many" movement between both.
It is strange in this cases, that the gear wheel dont show any damage, but the bearing does. Weak steel.


I had it on my own gearbox. Had to press the shaft back to allow movement on the 5th gear. There was a gap between the securing ring and the bearing so had to press back until it flushed with the bearing

I opened a gearbox once where the 4-5 synchro assembly was put in upside down. there the 5th was also damaged.
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Waldi
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PostPosted: Sat Jul 29, 2017 2:32 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Sorry, cant believe this on an original main shaft and a original 4th wheel.
Did you measure the wide of the gear wheel and the 4th baering surface on the shaft up to the synchronizer ?

And if you look to the pic above, the bearing inner ring is worn out over 1mm.

Edit:
Just measured a new gear wheel 29,40 and the shaft 30,00mm.
So not possible.
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PostPosted: Sat Jul 29, 2017 3:06 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Broken 4th and cracked bearing inner ring on my last gearbox work.
On a 16 Syncro Camper 2,8t with mTDI 5,43x0,82 and 235/70-16.
The box had 30k km after maintaining (not by me), 10 on the earlier AAZ with JX flywheel and 20 on the new mTDI/flywheel. Both intercooler and about 90 hp.

Edit:
Box had no bearing retainer.



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PostPosted: Sat Jul 29, 2017 3:43 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Fortunately, the solution to that occasional issue is straightforward .. splined-on synchro teeth:

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'87 Syncro GL 2.5

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Waldi
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PostPosted: Sat Jul 29, 2017 4:07 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

I will not believe all stock gears will break like some of them.
I think some have just a bad welding.

I i will ever break mine about 300k km old 0,82 4th , 200k with up to 4,5t and 100hp, i will buy yours Wink

And i am sure my friend will but one of them too, if it breaks again Smile

Also not sure what happened first, worn out and cracking bearing, or breaking 4th.

But i tend to believe the 4th broke, and due to very high horizontal pressure, because of the broken turning surfase the bearing cracked.

Edit:
Do you have 0,82 ?


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PostPosted: Sat Jul 29, 2017 4:08 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

In another thread, Sodo mentioned that the mainshaft bearing doesn't like sustained high rpm. Just to clarify that, it ISN'T the ball bearing that's rpm-limited. (I consider that bearing to be a good bearing .. not undersized like some companies seem to believe).

But rather it's the mainshaft NEEDLE bearing that's rpm-limited. This bearing (because of its small diameter needles) will actually weld itself at sustained 8,500 rpm. More to the point, it just wears itself out because it's a pathetic little bearing, with less than adequate lubrication.
Image may have been reduced in size. Click image to view fullscreen.


The solution is to machine the case and install the earlier Type I (113) bearing with larger diameter needles.
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'87 Syncro GL 2.5

Needed: Stock 14" x 6" Syncro steel rim
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Waldi
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PostPosted: Sat Jul 29, 2017 4:15 pm    Post subject: Re: Original vanagon manual gearbox failures and solutions Reply with quote

Yeah, ofc it is this needle bearing that does not like revs.
But it likes less a worn out pilot bearing.

Edit:
You can repair this bearing surface on the main shaft with a bearing sleeve if it is bad.
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