Final drive gone south

[pglaves]

When I saw the OP pics, right away I went to a plugged diff vent.

For sure, bearings, loading/lubricant could be good reasons but in just around 45 years of being a pro-wrench, didn't matter to me who made what/when or where it worked, if I saw a fast diff/tranny failure that blew the seal out, I went to the vent.

There are several dynamics happening here. I am speaking specifically about the Oilhead and K bike final drives prior to the "big hole" final drives. The weight of the rear of the bike is carried primarily on that big ball bearing. But the mesh of the spiral gears of the crownwheel and pinion gear try to push the gears apart. The push is toward the big ball bearing causing some side loading. That ball bearing is specified by BMW to have extra clearance, and BMW has always specified GL5 90 wt gear oil with 80w90 as an acceptable substitute.

There was a time when owners and some dealers thought that thicker was better and used the new high-zoot 75W140 gear oil in final drives. This was OK in transmissions but out of spec for final drives and almost certainly led to numerous final drive failures.

There have been numerous well documented cases where the preload shimming of the final drives, from the factory, was too tight. This caused insufficient clearance in the ball bearing and observed failures. Venting may be an issue with ruined seals but not for destroyed bearing cages unless the seal failed, the lube got too low, and then the bearing failed. While this is a possibility I don't think this is very common compared to other causes where the bearing failed, thus destroying a seal.

And despite the notoriety of these failures, only 4% to 5% of the drives actually failed as best can be determined absent a clear answer from BMW. But a number of those drives failed more than once, but usually when not accurately re-shimmed different from the original factory shimming.

 

[AntonLargiader]

That's absolutely classic big bearing failure. The cage comes apart and tears the seal out. I see this all the time.

I don't see any reason to fear synthetic. One of the contributing factors is that if the FD is shimmed too tightly the balls can't redistribute themselves in the cage... seems some added slipperiness could only help here. If the FD is set up properly, just about anything would probably work for oil. Wouldn't even have to be hypoid.

I am beyond slammed with work. If Saddleman can get it turned around quickly, go for it. He's done a bunch of them.

 

[alke46]

That's absolutely classic big bearing failure. The cage comes apart and tears the seal out. I see this all the time.

I don't see any reason to fear synthetic. One of the contributing factors is that if the FD is shimmed too tightly the balls can't redistribute themselves in the cage... seems some added slipperiness could only help here. If the FD is set up properly, just about anything would probably work for oil. Wouldn't even have to be hypoid.

I am beyond slammed with work. If Saddleman can get it turned around quickly, go for it. He's done a bunch of them.

Sorry for not seeing this until now. Dave (saddleman) did the overhaul for me and it was a quick turn around. Very happy with his work and all the conversations we had via text message.

 

[alke46]

Got a follow up question for the forum. After having member Saddleman rebuild my FD, it is now working just as it should.

My question is, what year did BMW finally address this issue and change the FD models? Well, I mean the problem must have been taken care of with a new model bike, right?

TIA

 

[jammess]

In the past I've wondered if maybe it wouldn't be a bad idea to send one's final drive out to have the shimming checked. Call it preventive maintenance. Not sure how difficult it would be to attempt this as in DIY?

 

[saddleman]

Got a follow up question for the forum. After having member Saddleman rebuild my FD, it is now working just as it should.

My question is, what year did BMW finally address this issue and change the FD models? Well, I mean the problem must have been taken care of with a new model bike, right?

TIA

On most models 2004 was the last year on the 1150 cc motorcycles. The 2005 boxer 1200cc had the new style. On the K1200LT they used this style until the end of production in 2009.

 

[alke46]

Thanks Dave. I guess that pretty much answers the question I texted you yesterday.

 

[senseamidmadness]

In the past I've wondered if maybe it wouldn't be a bad idea to send one's final drive out to have the shimming checked. Call it preventive maintenance. Not sure how difficult it would be to attempt this as in DIY?

The procedure for doing this is shown in the official service manual, and it requires special Paralever-specific tools both for getting the final drive apart and for measuring the backlash. I'd say it's well beyond the realm of most DIY mechanics. You have to have access to metalworking machine tools (to make the special tools and fixtures and new shims) and machinist instruments, or have the money needed to find and purchase the BMW dealership tools and any required shims.

For how much those special tools cost, or the cost of having someone check your final drive shimming, you could instead just buy a used final drive and swap it into your own machine. There are dozens on Ebay for less than $300. It's not worth it unless you're already the-cost-of-a-motorcycle deep in tools.


Also to the original poster alke4346: BMW did solve this shimming issue when they went to the EVO Paralever, but they also introduced a couple more mind-boggling issues that the earlier model didn't have. Engineers, man. Sometimes they're idiot savants.

 

[alke46]

Also to the original poster alke4346: BMW did solve this shimming issue when they went to the EVO Paralever, but they also introduced a couple more mind-boggling issues that the earlier model didn't have. Engineers, man. Sometimes they're idiot savants.[/QUOTE]



Thanks for this bit of information. But what year was the EVO Paralever introduced?

 

[senseamidmadness]

The 2005 boxer 1200cc had the new style.

Saddleman posted this above and he's right. They introduced the EVO Paralever with the 2005 R1200GS and Wedge-type K1200 bikes, but kept making the K1200LT with the original Paralever final drive and flying brick engine until 2009.

The differences are quite obvious when you see them in person. The EVO Paralever has a hollow axle and it moved the torque arm to above the swingarm instead of below.

 

[alke46]

Saddleman posted this above and he's right. They introduced the EVO Paralever with the 2005 R1200GS and Wedge-type K1200 bikes, but kept making the K1200LT with the original Paralever final drive and flying brick engine until 2009.

The differences are quite obvious when you see them in person. The EVO Paralever has a hollow axle and it moved the torque arm to above the swingarm instead of below.

Thanks, I appreciate the information so that maybe I can learn a bit more about the brand.

 

[DEANTRIMBLE]

I have reading these posts with a great deal of interest. I have 2003 BMW r1150 rt with about 65,000 miles on it. On a trip September 2023 we had ridden from Kansas to Chattanooga, Tn in 2 days of interstate riding 80 mph+ average. Just outside of Chattanooga I began to hear something I thought it might be the road or a tire going flat. When I finally had a place to pull over here was gear oil all over the back wheel, the classic fd bearing failure. I was able to limp it in to Chattanooga and was then able to get it into Pandora Motorsport. They had it a couple of days and when I picked it up we discussed the repair and they said they had put synthetic gear oil in it, I told them that I didn't think that was the correct oil. But I was so glad to have it back I didn't argue. Now its time to drain the synthetic. What I'm needing to know is what brand do people use? I know it calls for gl5, 80-90 wt but are all gear lube oils created the same. Do some have moly added?

 

[pglaves]

Tom Cutter uses Castrol Limited Slip and so do I. That is the new name for their Hypoy C but Castrol says it is the same.

 

[m_stock10506]

Tom Cutter uses Castrol Limited Slip and so do I. That is the new name for their Hypoy C but Castrol says it is the same.

That's the answer! Castrol 80W-90.

 

[DEANTRIMBLE]

Ok thanks, that's what I needed to know. I've always thought castrol products were good quality. Ok another question, how often do you change the final drive? And is Castrol 80w-90 good in the transmission?

 

[pglaves]

Ok thanks, that's what I needed to know. I've always thought castrol products were good quality. Ok another question, how often do you change the final drive? And is Castrol 80w-90 good in the transmission?

I change final drive oil as part of a major service at 12,000 mile intervals. The Castrol 80w90 is also just fine in transmissions.

 

[jnrugg]

The new bearing is different than the old one.
The first time I had a dealer do the work and the bearing was warranted by BMW for 2 years.
It was shimmed too tight according to Anton who rebuilt it correctly the 2nd time.
I broke down on the way home from the Lebanon rally, but that is another story.

 

[m_stock10506]

Ok thanks, that's what I needed to know. I've always thought castrol products were good quality. Ok another question, how often do you change the final drive? And is Castrol 80w-90 good in the transmission?

Yes,, the 80W-90 is great in the gearbox too. The spec for the FD and transmission calls for fluid change each major service, 12,000 miles. The cost of the liter of gear oil is so small, I just change them both out at each engine oil change.

 

[RPGR90s]

I must be the only one in the country with a never serviced final drive. (2004 RT purchased new) with 135k miles. Only oil changes at same interval as engine oil and filter changes. (every 6k). And only used non-synthetic oil.

 

[riderr1150gsadv]

I have changed the FD oil every 6K miles along with the engine oil and filter. My 2006 1150 GSA got 100K miles out of the FD on before the main bearing was worn out. No drama there. I do use TS Moly oil in the FD and think it contributed to the longer service life. I still use it on my 2018 GSA .
https://www.tsmoly.com/oils-moly-gear-lube-p-135.html?rn=550903 YMMV