Brand new Syncro Tranny. I have a Question.

[insyncro]

None of the coatings I may end up using are black, all grey.

One of the transmission threads has links to some of what I have purchased and experimented with, but due to many, many more pressing endeavors, thermal coating testing has been on hold.
I should resume during the heat of the summer and should have a finalized transmission/front diff cooling system built and installed as well.

[Jeff's Old Volks Home]

That's pretty much what I was going to say next.
Jeff.

[snowsyncro]

SJ, I understand the physics, and that is all good stuff and very interesting. I don't mean that sarcastically -- it really is very interesting. But for the real world case of transmission temperature reduction, I just don't think there is any measurable effect. I think if there was you would see it more widely adopted. I used to race Honda motorcycles back in the air-cooled days, when Honda was at the top of their game, and there were no black engines or transmissions that I can recall. I think if there were any real performance advantage or endurance advantage, it would have made its way into racing machines first.

But I did paint the cylinder fins of my 1970 750-4 black during a rebuild

RonC

[Jeff's Old Volks Home]

In my racing days, it was taboo to even think of painting an engine. But old wives were in charge if I remember.
Jeff

[IdahoDoug]

It seems to me that while black may emit heat faster than other colors, it cannot outweigh the physics of heat transfer. A metal object radiates heat off its surface, in a process that is literally a flow of heat like a river from hot inner to cool outer. But the essential interface in our case is when the heat is transferred from the last molecules of the outer skin of the trans to the air. Interrupt that with a layer of insulation and you slow down the flow of heat hugely. Of course. But stay with me.

So a layer of paint is actually a thin layer of - what? Pigment and binding solids? Epoxy, solids and pigments? I really don't know, but whatever it is, if it does not transfer heat as fast as aluminum (which is fast), then you are in fact adding a layer of insulation that thermally "decouples" the raw aluminum from the passing air.

In short, unless the coating transfers heat faster than the aluminum, then I simply cannot see a thermal heat shedding advantage. Yes black may be the best, but I see it as the best color if you HAD to paint something and accept a slowing of heat transfer.

I use this principle with an annual spring cleaning of all radiators on all my vehicles. I spray Simple Green or a weak degreaser I mix from concentrate on the front and back of the radiators and AC condensers. Let soak, then spray out. I have recorded changes in AC temp at the interior vents of several degrees simply from cleaning the fins of insulating dust so they transfer heat directly to the air.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[insyncro]

Adding a fluid cooler will displace heat far better than any coating on the cases or bare cases.

[syncrodoka]

Protecting the AL would be the only good reason to paint it.
My all AL tranny is due to come back from regearing and painting it is still up in the air but since it will live in a salt air environment it will likely get paint.

[rubbachicken]

can it be done without stripping the trans, i don't have the money to strip burni's trans, but if i could fit a cooler to it, i think i would.

[IdahoDoug]

I wouldn't let the possible transfer of heat dissuade me of painting the trans. I also would paint, and I would wonder if the high gloss paint would lead to less dust accumulation vs the rough and porous raw aluminum, providing easier cleansing with an easy soap spray. Overall impact might be better heat transfer if you gently cleaned a component like the trans once a year, ya know?

At the end of the day it would be hard to measure paints impedance of cooling, and as stated many of you are adding real cooling strategies to your gearboxes anyhow. So things move in the right direction. You might as well look good doing it. How about using some of that VW racing blueish grayish color some Dokas sport on your trans's? If you all picked a meaningful color like that to indicate a trans modded for cooling or with internal oiling plates and used the same color it would be kinda cool.

Anybody ever think about adding selectable heat for cold climate use? Like a freeze plug style heating element? I hate the feel of a cold manual trans! Warm, flowing oil is much better for the gearbox, much like cooler oil helps a hot gearbox.
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1987 2WD Wolfsburg Vanagon Weekender "Mango", two fully locked 80 Series LandCruisers. 2017 Subaru Outback boxer. 1990 Audi 90 Quattro 20V with rear locking differential, 1990 burgundy parts Vanagon. 1984 Porsche 944, 1988 Toyota Supra 5 speed targa, 2002 BMW 325iX, 1982 Toyota Sunrader

[Jeff's Old Volks Home]

A transmission heater, that's an idea. My John Deere tractor has a heater that warms up all the fluids, it holds 30l or so. It makes starting up and going right to work possible.
I'm like you, I let me transmissions warm up a bit before I ask much of them.
Jeff

[insyncro]

[Syncro Jael]

I agree, the transfer of heat by painting would be like standing next to a "Black" wood burning stove and a "White" wood burning stove. They will both heat your house, burn you when touched, and the difference would be nill. Maybe that would be a great "Myth Busters" idea? Hahaaa

Since I live in an area that uses salt on the roads (Great Salt Lake) Utah lots of it! I just wanted the added protection of a paint coating and if I am making the effort in painting it, a little scientific approach might not hurt.
_________________
1987 Syncro Westfalia Hightop - NAHT
Subaru EJ25 Forged Frankenmotor, Triple Knob.
Jael = (Mountain Goat)

[insyncro]

[derekdrew]

The paint on the bolts is torque indication paint that is meant to mark all the bolts that had been completely through the entire torque sequence so as to know you don't need to check the torque of that bolt tightness any more. There are neat little torque indication pens for this purpose, and I imagine they do double duty in slowing the onset of corrosion.

Transmissions built after 1990 will NOT as a matter of course have the superior OEM 3rd generation 3/4 slider hub that was nitrate coated. My guess is that very few transmissions in North America have the nitrated 3/4 slider hub in them right now.

Kim Brennan reports that he thinks Daryl was aware of the 3 different OEM verions of the slider hub, and if so, then presumably Daryl would have avoided installing or reinstalling any 1st or 2nd generation slider hubs in any of his rebuilds, at least if he thought the rebuild might see a high power engine in it later.

I don't know how to tell a 3rd generation nitrated slider hub from a 2nd generation VW "improved" non-nitrated slider hub. My guess is that all transmissions built by the factory after 2000 would have the better nitrated 3rd generation slider hubs but that year is not something I heard and has no basis in anything... its just a wild guess at a guideline for safety.... like.... if you don't want to check it.

I would NOT expect ANY syncro transmission, whether from South Africa or not, to have oiling plates in it unless it had been an aftermarket rebuild. The oiling plates, I thought, were only for 2WD and we adapted them (all over the world) to syncro. So, my guess is that if you came across ANY transmission with oiling plates in it, then that transmission has probably been to an aftermarket rebuild shop such as aatransaxle, German Transaxle, Dennis Haynes in Long Island, an European rebuilder, etc.

From the point of view of high power engines, my guess is that 97% of all transmissions that exist in North America have borderline defective 3/4 slider hubs and these should not be re-used. I would say that only the 3rd generation VW OEM 3/4 slider hubs should be re-installed in any syncro transmission, or else the Weddle racing hub$ should be used.

I do not know where to buy the 3rd generation VW OEM 3/4 slider hubs, but I doubt that very many 2nd generation VW OEM slider hubs are in the factory VW distribution system in Germany. It would be interesting to compare the OEM 3/4 slider hubs from Weddle (which are very cheap right now) with the OEM VW slider hubs from VW of America (if they still sell these) with the 3/4 slider hubs you would find in Europe and are represented as either nitrated or 3rd generation OEM VW and see if they are the same or not.

My guess is that Daryl could put this to bed in 1 minute after he comes around.

I would love to know whether VW was able to resist the temptation to "dump" the weaker 3/4 2nd generation slider hubs into the aftermarket or foreign markets. If they did, then you could say, "Oh oh.... I bought a dumped 3/4 inferior sliding hub".

About the coating on the transmission, I know nothing beyond the advice from the factory to spray wax on it every year or two, which sounds kind of lame. I do feel that the use of fans pointing directly onto the rear transmission for high power engine vans in inadequately explored in our community. Such fans might be much better at removing the heat than an external pump and radiator, but I really don't know. I believe that some Germans were talking about simply making an air scoop, and as stupid as this sounds, I think there is something to this. The air scoop can either lower itself under the van at any speed above X mph (or bring air from the front grill as somebody argued.)

In New York they had commercials, "Its 11 oclock. Do you know where your kid is?" Now we can say, "You are operating a syncro. Do you know where your 3/4 slider hub came from? If you don't know, you may be in trouble."

I would not use any factory South African transmission, new or rebuilt, without installing the mainshaft retaining plate that Daryl offers (or, the Weddle version maybe). So you have to crack them open not only to do the oiling plates but also the retaining plate. If you are using that transmission with a 2.1L WBX or lower, then you don't have to do any of these things. But keep in mind that this is a serious disease, and it will progress over time to unpredictable domains, like your choosing a larger engine next year. So it is better to take your disease inoculation now and be prepared, if you can handle the futzing.

Below is reproduced my note to the syncro list about the 3/4 slider hub that has all the alarm in it that matched my feelings on the day I found out about all of this. If one was in an alarmest frame of mind, you would say that nearly all syncro transmissions on the road in North America are junk. That is clearly an exaggeration, so I think its fine if somebody hits me on the head with something.

To moderate the severity of this post, we can also ask whether *anyone* has ever seen a broken 3/4 slider hub that had rounded holes in the 3 corners in North America. If there are not that many reports of this, then the issue may restrict itself to the really high power diesels where it was first noticed with the 2nd generation slider hubs.
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3-4 Sinister Slider Scares, Horrible Hubs Hubub
Syncro List <[email protected]>
Date: Sat, 01 Feb 2014

I was reviewing info in my hard drive from Graz and noticed an interesting fact that would be of interest to any transmission rebuild, relating to the legendary 3-4 slider hub failures that were endemic with early transmissions.

Traditionally, what many of us have been told is that the slider hubs were failing because the three holes in them were square, which caused stress fatigue, and eventual failure. Any transmission builder will replace a square hole 3-4 slider hub automatically during rebuild time with the later design that VW introduced that has rounded holes to prevent unexpected failures.

What is new (to me anyway) in this email is that apparently there are *three* generations of 3/4 slider hubs from the factory, and the intermediate version was introduced in 1990 into production, but was also seen to be experiencing failures with powerful engines even though it had rounded holes!
I was told that the new rounded corner 3/4 slider hub was failing with engines of more power than the original engines, such as powerful diesels and such.... possibly including the 5 cylinder Audi engines of South Africa.

Then, "Later they nitrated ther surface and since this time the synchronizing hubs are strong enough for TDI engines."

The implication of this is that a transmission builder should not automatically assume that if a 3/4 slider hub with rounded corners in the three holes is strong enough to handle whatever engine may be thrown at it. In the event of any doubt, it seems that the builder should be sure, at the very least, to install the final OEM nitrated design if he is designing the box for engine-upgradeability.

I am not sure why nitrating the hub would help.

To me, the information is very dismaying because it means that hundreds of the intermediate strength non-nitrated-design rounded-hole slider hubs may currently be installed in Vanagons and Syncros, and some of these vehicles will receive engines of upgraded power and will have more vulnerability than they would otherwise as a result. If the date 1990 is right, then most syncros in the USA except possibly the last two years have weaker hubs, whether the holes are rounded or not.

The vulnerability of the 3/4 slider hub hubs has long been known as a serious issue to our West Coast transmission experts from the earliest days, and companies like Long Enterprises and Weddle Industries offered special hubs and hub rebuilding services. Weddle today offers their own manufacture of hubs as a matter of course to the race crowd, and you can see a picture of them here: http://www.weddleindustries.com/products/new-products/weddle-syncro-and-vanagon-parts . Weddle also has plenty of these racing hubs and VW OEM 3/4 slider hubs available at very reasonable pricing. I have not asked them if their OEM 3/4 slider hubs are the 3rd generation nitrated design or are only 2nd generation design. Because of the prevalance of the lower power 2.1L engines in the past, I even doubt that many who had the 2nd generation hubs in North America experienced a failure from that condition, yet.

That is, I wouldn't be surprised if the non-nitrated 2nd generation rounded corner OEM hubs are sufficient for the 2.1L engines that came stock on all our north american vans, and I wouldn't be surprised if the 3rd generation OEM nitrated rounded corner hubs are sufficient for all other non-race driven Vanagons and Syncros. If one were gripped with hub horror as a result of reading this email, or a slider scenario scares, I suppose it would be safer still to pay up for the racing-quality hubs Weddle sells, although that might be overkill and depend on budget.
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Derek Drew
derekdrew - a t - derekmail - dott - com

[Jeff's Old Volks Home]

I've personally never seen a failed 3/4 slider that has been replaced. I've replaced a dozen or so and to the best of my knowledge they're all still going strong. It's a one time fix. There are NO oiling plates in this tranny. I have a set here from Gowesty, but I really don't want to open up a new box to install them.
I'm planning on waxing the exterior, change the oil often, keep it cool and drive it like Id like it to last. I've never, not ever had transmission problems with any of my vans that was related to driving style. I had an early 3/4 slider fail, a case corroded and leak and a rebuild from a less than reputable transmission builder fail. I've driven in excess of 500000km in vanagons too.
My doka has the oiling plates, latest slider/hub sleeved gear carrier, but I've been known to carry a 2000lb camper in the bed from time to time. That tranny has 80000 trouble free kms.
Both my syncros have close to 200hp diesels too...
I'm sure I can make a new tranny last, at least till my credit card recovers.
Jeff

[derekdrew]

WOW!
See Paul Guard's detailed analysis and photos of the four types of 3/4 slider hubs in his thread on related drivetrain topics here: http://www.thesamba.com/vw/forum/viewtopic.php?t=568039&start=80
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Derek Drew
derekdrew - a t - derekmail - dott - com

[nmerrill]