Rattling from primary
Road Warrior
Joined: Sep 2014
Posts: 1,271
Likes: 246
From: Columbia SC
Photos say a hundred words, if I know what I am talking about.
Bearings are blackened, I assume from heat, if so, confirms what I read from a person (forum based) who rebuilds HD transmissions.
He keeps a collection of these blackened bearings to show people, he says in EVERY instance they come out of trannys that ran heavy weight oils and gear lubes in them.
Shockproof comes to mind, not sure about redline people like shockproof cause it cuts down and gets rid of the clunk, well, if it was a good thing HD can do that too.
Now what I do know, people who promote gear lube in transmissions against the advise of the manufacturer should think twice about. It depends on how the transmission was designed, even automobiles, some run gear lube and MANY run plain old oil.
If a heavy lube in used in the transmission, it can and will cause bearings to run hotter then designed for, really that simple.
Thinner fluid cooler bearings. The key is what the manufacturer recommends.
In this case Harley recommends OIL not GEAR lube.
So use oil. I use Formula + but anyone would be fine with regular 20/50 motor oil too.
Transmission was not designed for gear lube, sure I guess you could run a 75/85 gear lube but people go nuts thinking more is better and end up at 90 and more.
Bearings are blackened, I assume from heat, if so, confirms what I read from a person (forum based) who rebuilds HD transmissions.
He keeps a collection of these blackened bearings to show people, he says in EVERY instance they come out of trannys that ran heavy weight oils and gear lubes in them.
Shockproof comes to mind, not sure about redline people like shockproof cause it cuts down and gets rid of the clunk, well, if it was a good thing HD can do that too.
Now what I do know, people who promote gear lube in transmissions against the advise of the manufacturer should think twice about. It depends on how the transmission was designed, even automobiles, some run gear lube and MANY run plain old oil.
If a heavy lube in used in the transmission, it can and will cause bearings to run hotter then designed for, really that simple.
Thinner fluid cooler bearings. The key is what the manufacturer recommends.
In this case Harley recommends OIL not GEAR lube.
So use oil. I use Formula + but anyone would be fine with regular 20/50 motor oil too.
Transmission was not designed for gear lube, sure I guess you could run a 75/85 gear lube but people go nuts thinking more is better and end up at 90 and more.
Intermediate
Joined: Jun 2007
Posts: 42
Likes: 12
In this case Harley recommends OIL not GEAR lube.
So use oil. I use Formula + but anyone would be fine with regular 20/50 motor oil too.
Transmission was not designed for gear lube, sure I guess you could run a 75/85 gear lube but people go nuts thinking more is better and end up at 90 and more.
So use oil. I use Formula + but anyone would be fine with regular 20/50 motor oil too.
Transmission was not designed for gear lube, sure I guess you could run a 75/85 gear lube but people go nuts thinking more is better and end up at 90 and more.
Last edited by otterhigh2; Jul 26, 2017 at 09:11 AM.
Road Master
Joined: Jan 2016
Posts: 1,143
Likes: 433
From: Menifee, CA
Back in 1983 I bought a brand new Volvo. MANUAL five speed tranny with a solenoid activated OD.
The tranny was loaded with ATF. Per factory spec. When I changed tranny oil every 30k I used ATF and never had a prob.
I thought it was weird that a manual tranny would have such thin fluid in it, but I'm sure the Volvo engineers know a lot more about their tranny than I.
The tranny was loaded with ATF. Per factory spec. When I changed tranny oil every 30k I used ATF and never had a prob.
I thought it was weird that a manual tranny would have such thin fluid in it, but I'm sure the Volvo engineers know a lot more about their tranny than I.
Road Warrior
Joined: Sep 2014
Posts: 1,271
Likes: 246
From: Columbia SC
Motor oil and gear oil weights (viscosity) are not measured the same, there is a different scale for each. In the real world 50 weight motor oil (20w 50) and 90 weight gear oil (75w 90) are virtually the same thing. The reason to use gear oil in a tranny is better shear properties.
I do not agree on ignoring what the manufacturer of my $20,000 bike says when it tells me to use oil in the transmission and not gear lube. I follow the recommendations, just like I did on my Honda automobile that told me to use motor oil in the transmission.
They know more.
Last edited by alarmdoug; Jul 28, 2017 at 08:35 AM.
Road Warrior
Joined: Apr 2007
Posts: 1,382
Likes: 404
From: Illinois
These MDG bearings are known problems. The races get galled as seen in the pics. Will often grind the ***** flat and there will be glitter in the trans lube. HD very recently redesigned the bearing which is now a single row vs the double row. Time will tell.
Mine failed at 48k and I ran manual tensioner.
Baker has a new MDG bearing out which has tapered rollers, but it's pricey.
Mine failed at 48k and I ran manual tensioner.
Baker has a new MDG bearing out which has tapered rollers, but it's pricey.
Last edited by VDeuce; Jul 28, 2017 at 08:44 AM.
Seasoned HDF Member
Joined: Oct 2012
Posts: 11,226
Likes: 3,049
From: St.Louis Mo.
baker recommends redline shockproof in their transmissions. i know guys that have well over a 100,000 miles running redline in their trans with no problems. the problem here is junk bearings and primary chains run to tight. i always run my rear belt right at the loose end of HD'S specs.
Intermediate
Joined: Jun 2007
Posts: 42
Likes: 12
If you re-read my post you will see that mentioned what gear lube (up to 85) and what oil weights. Oops, I see I should have said 90.
I do not agree on ignoring what the manufacturer of my $20,000 bike says when it tells me to use oil in the transmission and not gear lube. I follow the recommendations, just like I did on my Honda automobile that told me to use motor oil in the transmission.
They know more.
I do not agree on ignoring what the manufacturer of my $20,000 bike says when it tells me to use oil in the transmission and not gear lube. I follow the recommendations, just like I did on my Honda automobile that told me to use motor oil in the transmission.
They know more.
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Road Warrior
Joined: Sep 2014
Posts: 1,271
Likes: 246
From: Columbia SC
I'm not arguing or disagreeing, it's your bike, run what you want. You said people were running heavier weight oils and lubes in their trannys, I simply pointed out that 90 weight gear oil and 50 weight motor oil are virtually the same weight, they just have different numbers on them because they are measured on different scales. As to what the manufacturer of your bike recommends, they recommend what they sell, and they don't sell a gear lube. If they did, they would tell you that's what you need. Since the early 80s I've used synthetic oil, ATF and gear lube in all of my bikes (I've even used 75w 140 gear lube in an 06 that had the dreaded 4th gear whine, had 124k miles on a twice rebuilt motor and the original trans when I sold it) and many have used synthetics since they were introduced in 1972. At the time HD didn't have a synthetic so they said never use synthetic oil in their motors "because it was too slick" and would cause a phenomenon that they came up with called "bearing skate" whereby the outer race would spin in it's fitting. In about 2003, when they came out with Syn3, the same "engineers" proclaimed that every modern HD motor ever produced should be running their synthetic oil in all 3 holes. In about 06 or so they came out with formula+ (which is a 50 weight if measured as an oil and a 90 weight if measured as a gear lube by the way) and suddenly every primary and tranny should be running that. In all honesty, a harley transmission is not a high tech piece of equipment, a couple of rows of gears and some shifter forks. Almost any reasonable lube will give it a long and healthy life unless it's one of the relatively rare ones with a bad part like a bearing. Now the primary is a different story and has more specific needs. But again, if you like running what the manufacturer recommends go for it, it's not terrible.
75/90 is NOT heavy weight, its the same as 20/50.
But you are an example of what the mechanic claims, 140 gear lube is WAY over a 50 weight oil and it is his claim by using this wildly out of spec oil your bearings are running so hot they blacken.
Never mind the fact that gear lube is CORROSIVE and the product has to be made for a corrosive fluid to be used, clearly since HD does not recommend gear lube in a transmission they do not have it in mind. This corrosive gear lube can also blacken any yellow metals in the transmission.
(btw way, just discussing here)
Road Warrior
Joined: Sep 2014
Posts: 1,271
Likes: 246
From: Columbia SC
baker recommends redline shockproof in their transmissions. i know guys that have well over a 100,000 miles running redline in their trans with no problems. the problem here is junk bearings and primary chains run to tight. i always run my rear belt right at the loose end of HD'S specs.
But we also know many others with over a hundred thousand miles running standard HD Formula+ ... just saying.
Im a little passionate about this as just finished a trip to the Smoky Mountains, once home I was due for my clutch adjustment and primary oil change, I always use Formula +, just because ... anyway, darn bike clicks through gears like a Swiss Watch. Just perfect but others want a super quiet transmission and put way to heavy oils in it thinking they are doing good but those heavy oils circulate through the bearings slower/hold more heat and bearings run hotter plus the corrosive effects of gear lube added in.
(im no expert, just explaining why I do what I do)
I mean just seems like common sense, Harley (or any bike maker with a separate sump)can put heavy weight oil in any transmission and make it whisper quiet at no additional cost, there is a reason for everything. You can do the same to an engine, invent and run a oil like 70 and the engine will be quiet too.
Last edited by alarmdoug; Jul 30, 2017 at 07:41 AM.