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raygreenwood
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Joined: November 24, 2008
Posts: 23130
Location: Oklahoma City
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 Posted: Wed Dec 11, 2024 8:12 pm Post subject: Re: Manual gear oil. |
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| Wildthings wrote: |
| raygreenwood wrote: |
While my transfer case has symchros just like types 1, 2 and 3....my final drive is hypoid. In cross section ....say....looking from the drivers side, an 091 has its pinion intersecting the ring gear at the 9 o'clock position. My ring gear comes from the left side just like the 091....but intersects the ring gear at about the 5 o'clock position and maybe closer to 6 o'clock. It is hypoid but as they say it's a lightly loaded hypoid. |
Pretty sure than the 002 and 091 are both low offset hypoids, which is what GL-4 hypoid oil is specced for. |
Mmmmm....not really. They have a spiral bevel gear. It may have a VERY slight offset but is not hypoid in its tooth contact "action". If you want to consider that "hypoid"...ok....but barely.
One key visual is that most hypoid final drives have a "bell shaped" or reverse cone shaped pinion gear which is opposite of what the 091 has.
This is stolen from Ratwells site so I am not sure whether this is a 002 or 091.
I outlined the pinion gear in yellow and the ring gear would be where the red ring is. The blue dashed line "should" be the ring gear centerline if this cross section sketch is accurate which its pretty close.
The pinion contact offset from the centerline of the ring gear is very small.
This next one is from a 003 automatic. I am trying to find a similar exploded view of the 004 I have....but books are few. The 004 from a 412 has the nearly identical pinion position as a 003...I recalled that it was down around 5 oclock instead of up around 2 oclock like the 003....but its not. Its up around 2...but it also has the distinctive reversed bell shaoe of the pinion.....both of which are splined onto the shaft.
Also the very tight spiral of a hypoid pinion is very noticably different from a spiral skew bevel.
Here are two shots of the 004 pinion gear. The teeth are very deep and have very thin outer edges. A lot of tooth contact and sliding friction.
To be sure that you understand how different this is....that ring of bolts on the right are the bell housing just forward of the pressure plate.
Ray |
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Wildthings
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Joined: March 13, 2005
Posts: 52330
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| Posted: Thu Dec 12, 2024 12:17 am Post subject: Re: Manual gear oil. |
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| raygreenwood wrote: |
Mmmmm....not really. They have a spiral bevel gear. It may have a VERY slight offset but is not hypoid in its tooth contact "action". If you want to consider that "hypoid"...ok....but barely. |
The definition of a hypoid gear is a SPIRAL GEAR where the axes are non intersecting. The 002, 091, and the 004 in your Type 4 car all have SPIRAL GEARS that have non intersecting axes and thus are ALL hypoid gears. The definition is very clear, no where in the definition is the amount of offset mentioned, if the offset of a SPIRAL GEAR is greater than zero it is a hypoid gear. |
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raygreenwood
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Joined: November 24, 2008
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Location: Oklahoma City
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| Posted: Thu Dec 12, 2024 8:12 am Post subject: Re: Manual gear oil. |
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| Wildthings wrote: |
| raygreenwood wrote: |
Mmmmm....not really. They have a spiral bevel gear. It may have a VERY slight offset but is not hypoid in its tooth contact "action". If you want to consider that "hypoid"...ok....but barely. |
The definition of a hypoid gear is a SPIRAL GEAR where the axes are non intersecting. The 002, 091, and the 004 in your Type 4 car all have SPIRAL GEARS that have non intersecting axes and thus are ALL hypoid gears. The definition is very clear, no where in the definition is the amount of offset mentioned, if the offset of a SPIRAL GEAR is greater than zero it is a hypoid gear. |
Correct....Technically...sure...the 091 and 002 are BARELY hypoid as I noted. They are barely off-axis. A lightly loaded hypoid gearset....which is why it can use GL-4.
However, don't fall into the poor practice so many automotive people have by instantly seeing "spiral bevel" ring gear and calling it hypoid. Not the same.
Yes....and axis the offset they are speaking of is the pinion ceterline axis that it rotates around versus the center ring gear axis that the ring rotates around.
So as I noted......sure....if you really want to split hairs, the 091 and 002 may BARELY be considered as hypoid. However what it IS is a spiral bevel gear with a very small level of off-axis mesh.
Meaning, it (the 091) has a lot less tooth contact and spiral pitch (which also makes it more efficient than what is generally considered hypoid)....but is not really considered "hypoid".
This is also why it does not require the additional EP additives of GL-5.
Here is soemone else who gets it as well. Very simple explanation.
https://www.youtube.com/watch?v=DhCyz7k7ifQ
Wiki explains it very well. And make note...the first paragraph is defining "spiral bevel"...which it should be because ALL of our differentials are spiral bevel as a baseline gear tooth "type".
And....the first picture IS of a spiral bevel gearset and its almost a dead ringer in layout and offset to the 091 and 002.
The second paragraph is gear tooth "handedness" and the third paragraph is about "Hypoid Gears"....and the illustration is EXACTLY what I am speaking of. NOTICE the "cross hair" drawn in the center of the ring gear?
The horizontal axis line ...which the pinion is clearly below...is the "offset axis" that makes the gearset HYPOID....and not JUST having spiral bevel gearing
It clearly shows the offset off the pinon gear. And YES the degree of offset is important.
https://en.wikipedia.org/wiki/Spiral_bevel_gear#:~...ng%20gear.
Its a very short, 1 page wiki. Its worth it to read all of it
The visual excerpt: The red arrow points to the axis line of the ring gear/diff and the red line shows the axis of the pinion shaft and gear. Once those are no longer in line....the gear set is hypoid.
Another clear visual:
And the degree of offset is critical and ideally...should not exceed 25% of the ring gear pitch diameter from this MIT document about calculating gears for production.
https://www.mitcalc.com/doc/gear7/help/en/gear7.htm
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| It is recommended that positive pinion offset be used because of the increasing diameter of the pinion, higher face contact ratio, pitting and bending load capacity. ln general, due to lengthwise sliding, the offset should not exceed 25 % of the wheel outer pitch diameter and, for heavy-duty applications, it should be limited to 12,5 % of the wheel pitch diameter. |
A good explanation as to why the 003 and 004 hypoids have the pinion shaft crossing over the rin gear and the pinion is reversed. It is because this keeps the same maximum offset but increased gear surface mesh (and sliding andfirction to some extent)....but allows having a reduced diameter for the ring gear (compactness). It also makes them much more smooth and quiet.
So is the 091 and 002 "hypoid"...yes...technically but not to a significant extent to where they require a higher level of EP additives.
Ray |
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SGKent 
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| Posted: Thu Dec 12, 2024 1:00 pm Post subject: Re: Manual gear oil. |
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I don't know if these show enough detail. One area of concern for a bus trans is that the area where the diff is, is cut off from the gear area by only small openings for the gear fluid to move back and forth. As a result there is reduced cooling on 4th gear and the nylon/plastic needle cages melt with sustained high speed driving in hot weather. The plastic distortion captures the needles which in turn stop rolling and flat spot /spall. That damages 4th gear and the main shaft. It is why new old stock main shafts for these are made of unobtainium, and why they are reproduced today. I know that when I was looking for one many years ago, even then builders like Rancho had many transmission rebuilds on hold trying to locate 091 main shafts. Getting the correct gear lube and grade is very important on these buses. They are survivors but nothing lasts forever.
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70bus
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| Posted: Thu Dec 12, 2024 1:22 pm Post subject: Re: Manual gear oil. |
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A (possibly-unknowable) question: what transmissions are specifically at risk for moly damage, or brass damage. Assuming that's not the same thing.
Reading the many threads, it appears some gears we are discussing are moly coated, some not; some are brass, some are steel; some brass compositions may have changed over the years.
Anyone have a reference work or experience with these changes? I have a mid-60s RGB and a late-69 002 - were either using moly coatings? Progressive refinements has many details about teeth, angles, hardening... but not composition or coatings. I assume somewhere would be a dealer update sent to service departments?
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Craig K
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HarryFD
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| Posted: Thu Dec 12, 2024 1:56 pm Post subject: Re: Manual gear oil. |
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Interesting thread. As I noted above, my 091 transmission was recently rebuilt by German Transaxle of America (Bend, Oregon). When I pick the transmission up, I am required to use BG Ultraguard to maintain my warranty. It is a synthetic GL-5 lubricant.
Why should I try to second guess someone who has seen more transmissions than most of us will see in a lifetime?
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70bus
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| Posted: Thu Dec 12, 2024 2:14 pm Post subject: Re: Manual gear oil. |
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If the rebuilder specs something - especially if required under warranty - one could assume they have rebuilt it with components needing that spec... maybe modern replacements for brass gears, etc. It wouldn't be second-guessing a rebuilder to suggest using GL-4 in a transmission of unknown internal components, rebuilder and fluid history, etc. Just playing it safe.
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Craig K
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"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams
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raygreenwood
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Location: Oklahoma City
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| Posted: Thu Dec 12, 2024 4:06 pm Post subject: Re: Manual gear oil. |
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| SGKent wrote: |
I don't know if these show enough detail. One area of concern for a bus trans is that the area where the diff is, is cut off from the gear area by only small openings for the gear fluid to move back and forth. As a result there is reduced cooling on 4th gear and the nylon/plastic needle cages melt with sustained high speed driving in hot weather. The plastic distortion captures the needles which in turn stop rolling and flat spot /spall. That damages 4th gear and the main shaft. It is why new old stock main shafts for these are made of unobtainium, and why they are reproduced today. I know that when I was looking for one many years ago, even then builders like Rancho had many transmission rebuilds on hold trying to locate 091 main shafts. Getting the correct gear lube and grade is very important on these buses. They are survivors but nothing lasts forever.
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Wow....that's actually a little worse than what is on the 004. I think we get some of the same issue....rearward slosh from forward inertia when moving so you get high oil level in the diff and low level in the gear section.
Ray |
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raygreenwood
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| Posted: Thu Dec 12, 2024 5:49 pm Post subject: Re: Manual gear oil. |
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The other strange thing I forgot all about with regard to the type 4 transmissions I deal with.
I have already mentioned that they are a high offset hypoid final drive ....higher than the bus...so technically by modern standards they differential shoudl probably run GL-5.
The vast majority of 004 transmissions I have owned and worked on have brass synchros just like 091 and 002.....but.....I think VW was moving toward what is required to really run GL-5 oil because....
A few years back when I was tearinng down one of my spare 004's and getting ready to rebuild it (that one is still going to get finished but its packed away for the moment)....I found that it has STEEL synchros.
I looked in my spare parts pile and found taht one of the 004 I destroyed years earlier that I have all the gearsets for...also had steel synchros. One of the guys in the 411/412 forum noted that after a certain point in either late 1972 or 1973, the 004 went to steel synchros.
So...VW was trying to move forward on their last major aircooled model. They equipped it with a high hypoid ration transverse or offset hypoid differential and then startd running steel synchros.....both are the main modern requirements for running GL5.
Ray |
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SGKent
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| Posted: Thu Dec 12, 2024 6:32 pm Post subject: Re: Manual gear oil. |
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| Quote: |
| what transmissions are specifically at risk for moly damage, or brass damage. Assuming that's not the same thing. |
| Quote: |
| Interesting thread. As I noted above, my 091 transmission was recently rebuilt by German Transaxle of America (Bend, Oregon). When I pick the transmission up, I am required to use BG Ultraguard to maintain my warranty. It is a synthetic GL-5 lubricant. |
There have been only TWO (2) issues that have been mentioned over and over and over in this thread.
1) The synchros on a standard 002 and 091 transmission, are made from brass. That is a yellow metal and it is attacked by some of the sulfur EP compounds in SOME of the GL5 gear oils. That is a slow process. Not every GL5 gear oil has the same chemicals in it. GL5 is an industry rating and not a formula.
2) Some if the four VW bus synchro rings in each bus transmission are coated in molybdenum, which is a process that lengthens their life, and makes smoother shifting. There is no way to know what type synchro is in a transmission without taking it apart. VW used what they had available when they built the transmission, and if a rebuilder built it they used what they had available or wanted to use. Moly coated synchro rings are considered an upgraded higher performance product than uncoated ones. SOME GL5 gear oils, but not all, have EP additives that soak into the moly and make it so slippery that the ring cannot grab the gear to speed it up or slow it down. That causes failed shifting. Once it happens it is instantly and it does not go away with another oil change or flush from what I have been told by more than one transmission builder.
If a builder like German Transaxle decides to use a specific type or brand synchro ring, and a specific brand gear oil, they have control over that combination. Maybe they used all 4 non-moly rings instead of the upgraded moly ones. In that instance I would see no problem with the owner using only the recommended gear oil specified by the trans builder. HOWEVER, if someone does not know who built the transmission, or whether VW used molybdenum coated synchro rings and how many the day they built a transmission, using an unrecommended gear oil is rolling the dice with the transmission.
these are synchro rings
This is a photo of 091 gears. You can see the brass synchros sitting up against each gear and slider
Ray - here is a photo of the needle bearings that came out of my 091. They got so hot from the PO's driving that the plastic melted. Some late bay and vanagon owners who use larger HP water cooled engines have to modify their 091 or 094 to install an oil sprayer that moves gear oil thru an external gear oil cooler then sprays 4th gear with the cooled fluid to keep the temperature down on long grade climbs. The only needle replacements available now are steel caged ones that Weddle sells (2 photos above). They are designed to not melt. This is not a problem when someone is running around in a 1600 single or dual port early bay because there is not enough HP to fubar things. But later bays have more HP and heat. Of course the speed limit was 55 mph back then so high speed use was not really the problem it has been since 1995 when that speed limit was lifted.
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70bus
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| Posted: Thu Dec 12, 2024 7:17 pm Post subject: Re: Manual gear oil. |
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That's what I was after. Thanks!
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Craig K
70 Neunsitzer
65 Pritschenwagen
"If Von Dutch was alive, he'd walk in there with a pistol and shoot these people." - Robert Williams
Raul the 65 singlecab
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raygreenwood
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| Posted: Thu Dec 12, 2024 8:41 pm Post subject: Re: Manual gear oil. |
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SGKent....yep...I know some of your pain....but not melting the nylon pain. A couple of years back there was a discussion I think in the performance section asking about cooling of the gear oil (like what can you do) on type 1 or type 2 transaxles.
Many of the comments stated that its not necessary and that the gear oil does not get that hot. I think I and a couple of others stated....uh...yeah it does. I know I stated that they should drop into the Vanagon forum. Those guys have gotten serious on oil sprays and circulation because its a known issue.
I have actually measured the temps on long highway runs of the gear oil in my 004'....with all of the issues I have already noted. And, it was not until a handful of years ago when I relaized that the design of my final drive gearset creates more friction and heat than most.
I have seen common gear oil temps of 185* in my 004. I have seen peak gear oil temps of 225*.
Thats about the limit for nylon 6 and I also have some nylon needle bearing spacer rings. Yep....its a problem and one of the things I have been backburner looking into as well....cooling oil sprays.
Of course, even with the oil slosh issue mine has as well, I just do not have the load a bus has. Great pictures. Interesting thread.
I also believe and know that there are nuerous GL-4/GL-5 oils that have inhibited sulfur and other additives thats "should" make them fine for GL-4 and brass.....but the damn documentation sucks so bad from most manufacturers....its just hard to know for sure.
That is the real problem.
Ray |
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SGKent
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| Posted: Thu Dec 12, 2024 11:38 pm Post subject: Re: Manual gear oil. |
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| Quote: |
I also believe and know that there are numerous "GL-4/GL-5" oils that have inhibited sulfur and other additives that "should" make them fine for GL-4 and brass.....but the damn documentation sucks so bad from most manufacturers....its just hard to know for sure.
That is the real problem.
Ray |
right there with you Ray.
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Wildthings
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| Posted: Fri Dec 13, 2024 4:01 am Post subject: Re: Manual gear oil. |
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| HarryFD wrote: |
Interesting thread. As I noted above, my 091 transmission was recently rebuilt by German Transaxle of America (Bend, Oregon). When I pick the transmission up, I am required to use BG Ultraguard to maintain my warranty. It is a synthetic GL-5 lubricant.
Why should I try to second guess someone who has seen more transmissions than most of us will see in a lifetime?
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GTA REQUIRED the use of a GL-4 oil until Redline MTL arrived on the scene and began destroying transmissions. I had given Redline MTL a shot most of two decades ago and got it out of the transaxle in maybe 300 miles as from the noises the tranny was making it was obviously not doing its job. |
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metahacker
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| Posted: Fri Dec 13, 2024 10:41 am Post subject: Re: Manual gear oil. |
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| this thread got me really poking around and the more i study and call/email people in the know, i think BG Ultra-Guard 75w90 PN 75032 (above) is the be all, end all. |
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raygreenwood
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| Posted: Fri Dec 13, 2024 5:11 pm Post subject: Re: Manual gear oil. |
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| metahacker wrote: |
| this thread got me really poking around and the more i study and call/email people in the know, i think BG Ultra-Guard 75w90 PN 75032 (above) is the be all, end all. |
I have seen that reccomended across a range of BMW, Mercedes, Volvo and Porsche sites as well.
I had never heard of it until it was brought up in the this thread.
This thread is excellent and it actually mirrors the exact conversation and questions across those other sites.
Lets do some summing up before we continue because there are several problems with the GL-4/GL-5 gear oil compatibility issue. Not everyone has all of the problems but all of them ARE legitimate issues.
Summing up:
1. So the #1 problem is poor documentation and information transfer. It is not that we cannot get a dual GL-4/GL-5 rated gear oil or even a straight GL-5 that is PROBABLY compatible with our "brass" synchronized manual transmissions.....its that we do not have any SURE idea about the safety of most of them.
2. Then there is the moly coated synchro issue. While any particular GL-4/GL-5 dual rated oil "MAY" actually have been formulated to be safe for yellow metals (sulfur wise) the sulfur is not the only thing in some GL-5's that make it slicker. While the brass may live, the moly coating might be damged.
3. Then we get back to the ORIGINAL underlying issue which is that long term usage of high sulfur gear oils (GL-5) in transmissions that do not see a lot of miles and are prone to water condensation....are prone to corrosion from the sulfur/moisture/heat mixture. What it actually does is corrode the copper that is in the brass making the surfaces porous...and they wear or deform quickly.
4. And then you find a dual rated or GL-5 that does not eat yelliow mwtals... but its too slick and shifts lik crap.
On that 3rd one, while searching for information for yellow metal safe gear oil....I keep coming across some good threads from Bob Is The oil guy.
About 10-12 years ao ther was guy whose handle is "Molekule"....sounds likea chemist. He has had some useful information.
In one thread a person is speaking about the TEST used to find out if a gear oil is "yellow metal safe". It is actually the copper strip tarnish/corrosion test ASTM D130-10
| Quote: |
| The Copper Strip Tarnish Test (ASTM D130-10) is a standard test of a lubricant to indicate how corrosive it is to copper alloys that may be in a transmission. |
He has a list of oils in this thread that show whether this test was done
https://bobistheoilguy.com/forums/threads/copper-strip-tarnish-test-10-gear-trans-fluids.171491/
Bob is the oil guy is a pretty good site but I got to this thread from a link in another BITOG thread and my anti virus keeps pinging me saying this site is compromised.
Ray |
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SGKent
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| Posted: Mon Dec 16, 2024 3:04 am Post subject: Re: Manual gear oil. |
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Just as an FYI, I personally do not have a bone to pick with anyone in this thread for their recommendations, and I think there is a lot of good information changing hands. However, we are at the mercy of the Internet, along with good advise from people who build transmissions, yet confronted with old wives tales too. But, from an owner's viewpoint who has newly rebuilt 091 with all moly coated sychros, last thing I need is another rebuild. Erik in El Cajon would shoot me I think. Maybe someone who has time can call German Transaxle and confirm with them that they are actually using moly coated sychros in their trans rebuilds, and that it works with their brand oil BECAUSE there is also a possibility that they are using only non-coated synchros so they can control the slippage, something someone with known or unknown moly coated sychros would not know. I have read that some bus transmission builders will not use coated synchros even though they are better because of being burned over the GL5 moly synchro slippage issue.
long read but I guess we are not alone. https://www.widman.biz/uploads/Transaxle_oil.pdf
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SGKent
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| Posted: Tue Dec 17, 2024 12:58 pm Post subject: Re: Manual gear oil. |
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I saw this on Summit Racing today for about $15 a quart. Driven is a product out of Joe Gibbs Racing.
Driven Racing Oil GL-4 Gear Oil
| Quote: |
Driven Racing Oil GL-4 conventional gear oil is designed to deliver maximum performance and protection. The formula features proven oil technology to provide application-specific performance for gear boxes, transaxles, and transmissions that call for GL-4 gear oil. Utilizing high-quality base oils, Driven GL-4 protects yellow metals and offers proper synchronization to prevent gear clashing in synchronized manual transmissions.
Driven Racing Oil classic mineral formula features:
* High shear protection
* Safe for all yellow metals
* Protects internal synchronizers
* Extended change internals |
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cdennisg
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| Posted: Tue Dec 17, 2024 1:10 pm Post subject: Re: Manual gear oil. |
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| SGKent wrote: |
I saw this on Summit Racing today for about $15 a quart. Driven is a product out of Joe Gibbs Racing.
Driven Racing Oil GL-4 Gear Oil
| Quote: |
Driven Racing Oil GL-4 conventional gear oil is designed to deliver maximum performance and protection. The formula features proven oil technology to provide application-specific performance for gear boxes, transaxles, and transmissions that call for GL-4 gear oil. Utilizing high-quality base oils, Driven GL-4 protects yellow metals and offers proper synchronization to prevent gear clashing in synchronized manual transmissions.
Driven Racing Oil classic mineral formula features:
* High shear protection
* Safe for all yellow metals
* Protects internal synchronizers
* Extended change internals |
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Looks like you can buy it directly from Driven, and cut out any middleman profit.
https://drivenracingoil.com/i-30497794-go-80w-90-c...T_VRydXsj9
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HarryFD
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| Posted: Tue Dec 17, 2024 4:29 pm Post subject: Re: Manual gear oil. |
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| SGKent wrote: |
Just as an FYI, I personally do not have a bone to pick with anyone in this thread for their recommendations, and I think there is a lot of good information changing hands. However, we are at the mercy of the Internet, along with good advise from people who build transmissions, yet confronted with old wives tales too. But, from an owner's viewpoint who has newly rebuilt 091 with all moly coated sychros, last thing I need is another rebuild. Erik in El Cajon would shoot me I think. Maybe someone who has time can call German Transaxle and confirm with them that they are actually using moly coated sychros in their trans rebuilds, and that it works with their brand oil BECAUSE there is also a possibility that they are using only non-coated synchros so they can control the slippage, something someone with known or unknown moly coated sychros would not know. I have read that some bus transmission builders will not use coated synchros even though they are better because of being burned over the GL5 moly synchro slippage issue.
long read but I guess we are not alone. https://www.widman.biz/uploads/Transaxle_oil.pdf |
I wrote GTA about my rebuilt. They did not indicate the type of syncros used. The meaningful excerpts are as follows:
"... we have done a lot of research on this BG Ultra Guard Gear Oil, and we feel it is one of the best. It is safe for all syncros listed. ...
Thank you,
GTA
On 2024-12-17 12:22, Harry wrote:
Hi:
You recently rebuilt a VW 091 transmission for me. It is working great with no drama. Thank you!
A question amongst my VW friends has come up and I was hoping you can share some details of what was done to my transmission and why you recommend only the BG Ultraguard Transmission oil.
The question I am being asked is what type of synchros were installed. From what I have been able to gather, there are brass (yellow metal) ones, uncoated steel ones and moly coated steel ones. "
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Just add further confusion, for my 1973 911, at the recommendation of Steve Weiner and Jeff Gamroth (you can look them up), I use SWEPCO 201. I have been told that they offer the best life for my transmission based on years of racing experiences.
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1970 Deluxe Sunroof Bay Brilliant Blue/Cloud White
1971 Jaguar XKE 2+2 V12 Coupe
1973.5 911 Targa
2009 MB C300 |
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