rust by the pinion cup

[matt]

Question so bike has a good joint boot everything looks good but around the outside of the cup is rusted why is there no mention of gasket or silicone between swing arm and rear diff (4 bolt area) ?    I cannot believe the tolerances are that good back there were they meet. That is my question what do you think

[wiggydotcom]

Not sure exactly what you are asking but if you saw rust colored dust in your pinion cup area, how is your dust seal where your shaft goes into the pinion cup. That seal helps keep the grease/final drive oil in your cup. Also, are you holes clear at the bottom of the pinion cup? These weep holes allow your pinion cup and driveshaft to get lubed by final drive gear oil. And finally, are the splines greased? It's a combination of all three that keeps the splines from wearing.

[The emperor has no clothes]

I would think if the rust is just on the outside of the cup you are ok. I would clean it up with some steel wool and apply a light coat of grease to prevent future rust.

[matt]

I figured it would be okay but lets say the seal is not great well I have seen talk on hear about water probably getting by ujoint boot. Well what if water is getting in between swing arm and diff?   I dont think it would hurt to put permetex sealer there it peels of easy not permanent.   Was just throwing that thought out there

[The emperor has no clothes]

I figured it would be okay but lets say the seal is not great well I have seen talk on hear about water probably getting by ujoint boot. Well what if water is getting in between swing arm and diff?   I dont think it would hurt to put permetex sealer there it peels of easy not permanent.   Was just throwing that thought out there

I don't think it would hurt anything. But I think have a good boot and seal properly installed is far more important.

[matt]

Well thats what I am getting at there was a good boot on and some how water still must have gotten in there and the only other spot I see is were two pieces of metal bolt together  I have a hard time believing that area is water proof with out some type of seal

[Ricky-D]

Simply assuming that it is rust(from water intrusion), because of the color is foolhardy.

Many, many forum members have found the same on, or in the pinion cup assembly.

Cleaning and new grease has always been the remedy.

Water can only get in that area if the boot is mounted improperly, or is defective.

Naturally, of course, a determined person could get water in there, if they tried hard enough.

***

[matt]

Well I guess sorry I had a thought. Consider myself a good wrench but was just throwing some thing out there but rereading every thing I guess I should just ask ricky then I would realize why I keep my thoughts to myself thanks again to all that answered.   I guess being an ase truck tech and an auto ase master tech for over twenty years guess I still have a lot to learn. 

[Willow]

There is a seal on the shaft that should keep oil on the pinion gear side and water out.  If yours is not there it is an issue.

[matt]

Willow as always I appreciate any input from you maybe I am just asking or not expressing myself right I see were people have shown lots of rust on there pinion and were some people say things on grease or two holes plugged well after time of moisture getting into some thing rust will occurs so I have serviced a few valks have new boots new seals plenty of grease and oil in diff holes clean. But any time two materials meet its a chance for a leak. I understand u really dont need a seal there as you are not trying to keep fluid in but if u are in the rain tire spitting why would you not put a little permatex sealer in between diff and swing arm its the only spot any moisture can get in there if boot is good.  Willow very good to hear from you and always I enjoy any and all conversations we have hope all has been good for you.   Matt

[Rio Wil]

There has been a huge amout of time and resources devoted to trying to sort out the conditions of what causes the "red rust"......the best I can tell, is the rust (actually ground up heated lube/metal flakes) has its origin at the contact point between the aft end of the drive shaft and the fore end of the pinion shaft (where the big pinion cup nut is located). This contact point should in theory be lubed by the oil in the final drive by way of the two small holes in the bottom of the cup. One of the holes is drilled and cross drilled presumably to act as a scooper hole and pump a   small bit of oil into the pinion cup for lubrication of this point as well as lubing the drive shaft and pinion cup splines. It happens often that not enough (or any) oil is pumped into the P-cup, therefore many have been lubing this joint with a variety of thicker lubes and other snake oil.  Some work and some does not....it is often a crap shoot as to what you find when you pull the drive shaft from the pinion cup. For many their choice of lube and method has been successful and for others who might follow the same procedure, it doesn't work....WHO KNOWS WHY?????
It does appear if you let the lube job go much beyond the 12-15 K mile mark, that the red rust will begin to creep from the contact point mentioned above and soon will engulf the entire set of splines. There is no water seepage/leaking involved here at all. The longer it goes with out proper lubrication, the more the red rust results from the heat and grinding of dry contact between the splines, ergo the massive wear that can occur in a seemingly short time. When re-inserting the drive shaft/final drive back into the u-joint, there is a point (about a 1/8 inch from fully mating) where spring pressure is encountered.....this is a result of the drive shaft aft end seating on the fore end of the pinion shaft......not a lot of pressure but if not kept lubed by some means.....the "red rust" will begin to form....one of the Oregon guys inserted a thin teflon? washer at this contact point but I don't know the results..........the seal mentioned in many posts is simply there to keep "what ever lube" thats in the splines.....in the splines.

I am sure there will be those that differ in opinion to the above, that is their evolutionary right....
 

[Gryphon Rider]

My best guess is that any water that gets in there is condensation from the air, the same thing that causes rusting inside motorcycle gas tanks.  Also, I know that I'm contradicting accepted doctrine, but I have a hard time believing that the pinion cup holes do any "scooping" of final gear oil from the final drive.  Centrifugal force of the spinning drive shaft would, rather, evacuate any fluid that should happen to get in there.  Unless the final drive has been tipped forward, I don't think anyone has actually found gear oil in the pinion cup.

[The emperor has no clothes]

My best guess is that any water that gets in there is condensation from the air, the same thing that causes rusting inside motorcycle gas tanks.  Also, I know that I'm contradicting accepted doctrine, but I have a hard time believing that the pinion cup holes do any "scooping" of final gear oil from the final drive.  Centrifugal force of the spinning drive shaft would, rather, evacuate any fluid that should happen to get in there.  Unless the final drive has been tipped forward, I don't think anyone has actually found gear oil in the pinion cup.

I've yet to find any gear oil in mine.

[Ricky-D]

There've been a few that have posted pictures of pinion cups all sloshed up with lubricant (gear oil) from the pumpkin.

I attribute that to having overfilled the pumpkin.

Lots of denials, but the evidence is in the pictures and the experience of the forum.

I too, think the theory about the holes is "pie in the sky".

***

[Rio Wil]

There has been a number of posts over the last many months that have indicated that the oil holes do indeed accomplish the lube purpose in their final drives. I am beginning to wonder if the manual is in error about the quantity of oil required for the scooper hole in the p-cup to do its job.  This does not seem to be as a big issue in the gw gl1500 as in our Valks.... if I remember correctly, the gw 1500 final drive is a less bulky unit, (less internal volume) than the Valk but I think it requires the same 5.+ oz per refill. The ring gear and pinion gear inside the drives consume the same internal volume and if the gl1500 case is more compact, the lube level in the drive would? be higher and making the scooper hole more effective.  Wonder if we should be putting 7.+ (or 6.+)...pick a number.....in the Valk drive. A guy called Farther indicated he filled his final drive while leaned on the kick stand until it ran out the overflow hole, but I have not heard what the results are in terms of spraying oil out the vent or did the p-cup get an increased level of lubrication from over filling? I am not a fan of the scooper hole theory, except for the fact that one of the two holes is not only drilled parallel to the axis of the cup, but has another hole drilled at an angle to intersect the axial drilling and it has one smoothed edge on the leading surface and a sharp edge on the training surface...the direction of rotation should cause a scoop action. At highway speed this cup is spinning at 2000-2500 rpm....plenty fast to scoop a bit of oil and even slightly pressurize its delivery to the inside of the cup........despite the obvious centrifugal force that is also occurring....   

[HayHauler]

Matt, here's my $.01875.

I don't think water is getting in via this flange, unless you are riding her like a sport-tourer.    But, I don't think it will hurt to put a fine coating of rtv silicone formagasket on it.  As long as it is very light it will not have any affect on the mechanical operation of the rear end.

Also, as long as those 4 bolts are the last thing tightened, after torqueing the rear axle nut, you shouldn't have a problem.

Hay 
Jimmyt