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Hati

Gear box seal question

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Hati

Hi Gents,

 

Noticed a drop of oil under the rear uni joint section of the swing arm of my '05 RT,  so investigation followed. First I cleaned up the oily dirt on the underside of the swing arm and went for a short ride to see if the oil returns. At the last service, (previous owner took it to the local BMW dealer), they overfilled the engine, so I wanted to make sure it's not engine oil that I am seeing. I know about the different smell of the gear oil, but for some reason I can't tell that easily if the oil is gear or engine...

 

Anyway, the oil drops returned, so dropped the FD to see if it is it's input shaft seal or the gearbox output shaft causes the leak. I found a couple of teaspoon's worth of oil in the swing arm and only a very minimal amount around the FD input shaft, so the money is on the gearbox output seal.

 

This rises the question: should I change all the seals at rear of the gearbox? From what I can tell the most "used" seal is the output shaft, the seal under the clutch slave cylinder and the gear indicator pot seem to do a lot less "work", but due to the amount of hassle required to get to these, I would be inclined to change them, but I don't remember reading about the later two seals failing much (my bike has done 48000 kilometres), and I cannot see any leaks around them... The seals only cost a few dollars so the only factor would be likelihood of them failing. What is the general view on these?

 

How often do the gearbox input seals fail on the '05 bikes? I may have a leak/weep there too.

 

Thanks for the assistance.

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dirtrider
3 hours ago, Hati said:

Hi Gents,

 

Noticed a drop of oil under the rear uni joint section of the swing arm of my '05 RT,  so investigation followed. First I cleaned up the oily dirt on the underside of the swing arm and went for a short ride to see if the oil returns. At the last service, (previous owner took it to the local BMW dealer), they overfilled the engine, so I wanted to make sure it's not engine oil that I am seeing. I know about the different smell of the gear oil, but for some reason I can't tell that easily if the oil is gear or engine...

 

Anyway, the oil drops returned, so dropped the FD to see if it is it's input shaft seal or the gearbox output shaft causes the leak. I found a couple of teaspoon's worth of oil in the swing arm and only a very minimal amount around the FD input shaft, so the money is on the gearbox output seal.

 

This rises the question: should I change all the seals at rear of the gearbox? From what I can tell the most "used" seal is the output shaft, the seal under the clutch slave cylinder and the gear indicator pot seem to do a lot less "work", but due to the amount of hassle required to get to these, I would be inclined to change them, but I don't remember reading about the later two seals failing much (my bike has done 48000 kilometres), and I cannot see any leaks around them... The seals only cost a few dollars so the only factor would be likelihood of them failing. What is the general view on these?

 

How often do the gearbox input seals fail on the '05 bikes? I may have a leak/weep there too.

 

Thanks for the assistance.

 

 

Morning  Hati

 

I have seen a few trans output seals leak on the 2005 1200RT, never seen a slave cylinder area seal (rear input shaft seal) leak (but it sure is possible).

 

By far the biggest leak area on the early (2005 era 1200) that I have seen is the rear engine seal for the balancer shaft. This leaks engine oil.

 

Probably the most used seals on the transmission are the input shaft front & rear seals as those are spinning  all the time that the  engine is running & clutch engaged. Output shaft seal only sees spinning when the vehicle is actually moving.

 

If it were my 2005 motorcycle I would (first) clean the oil residue up so I could watch for future leaks, then change the transmission gear oil to a conventional  (non-synthetic) GL-5 gear oil. Then ride the bike for a while to evaluate.  

 

Conventional  gear oil, as a rule,  has more seal conditioner in it & might just stop the rear seal seep.

 

 

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blalor

Oh, that's interesting on the oil types, DR. I have a probable output shaft seal leak on my '07 with 50k miles.  I was planning to do the repair over the winter, but changing the oil could maybe defer that job.

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Hati

Thanks for the input DR. I'm going to change the gearbox output seal as a minimum, I am quite OCD with oil leaks on my bikes, but leave the other seals alone. I have heard about mineral oils being a bit more seal friendly, so I will give that a go. I have not been convinced by what I read about synthetic v. mineral oils over the years that minerals are so much worse as long as the prescribed oil change period is observed.

 

In regards to the potentially leaking balancer shaft seal, can that be checked without removing the gear box?

 

I had a quick look at the reprom photos, looks like you can change that seal without removing the clutch. Is that correct?

 

Thanks again.

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dirtrider
2 hours ago, Hati said:

 

In regards to the potentially leaking balancer shaft seal, can that be checked without removing the gear box?

 

I had a quick look at the reprom photos, looks like you can change that seal without removing the clutch. Is that correct?

 

 

 

Evening  Hati

 

In regards to the potentially leaking balancer shaft seal, can that be checked without removing the gear box?-- Sort of, you can't see the seal or seal area but you can kind of track the  oil seep back to the trans seam just below the balancer shaft area. (no guarantee that it is  the balance shaft seal that is leaking but a pretty good chance).

 

I had a quick look at the reprom photos, looks like you can change that seal without removing the clutch. Is that correct?-- It would be difficult without removing the  clutch/flywheel  parts as the top part of the seal is covered by the flywheel. I'm not sure  if you could work the seal in or not  as I always remove the clutch parts to get a straight angle to drive the seal in straight. It's a LOT of work to remove the trans to access the rear balancer shaft area so no way am I going to shortcut driving that seal in straight & properly.

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Hati

Thanks again DR.  I picked up both, the gearbox input seal and the balancer seal too. If I have to get the gearbox out, might as well change both of those even if only one is leaking. I know what a big job it is, have done the clutch and spline lube on my CL.

 

One last question: is the resting oil level below or above the balancer shaft seal? May need a new oil filter if it's above...

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dirtrider
4 hours ago, Hati said:

Thanks again DR.  I picked up both, the gearbox input seal and the balancer seal too. If I have to get the gearbox out, might as well change both of those even if only one is leaking. I know what a big job it is, have done the clutch and spline lube on my CL.

 

One last question: is the resting oil level below or above the balancer shaft seal? May need a new oil filter if it's above...

 

Morning  Hati

 

Engine oil level is well below the balancer shaft seal even at top of sight glass.

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Hati

Excellent. Thank you very much indeed.

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Hati

Pays to listen to one's gut and pick up all the parts that might be needed :D Both seals (engine balancer and gearbox input) were leaking. You were correct DR, the balancer shaft seal cannot be done without the clutch housing cover removed.

 

Is everyone on here uses the clutch bolts once only? I thought initially that these were the stretch fit ones, but I was wrong. These bolts don't even get torqued up too much (12 Nm). I reckon it's quite safe to use install them at least twice, if not more.

 

On the down side pulling the swingarm out, revealed two stuffed bearings so I won't be able to finish the bike tomorrow. We have a long weekend here so Tuesday is the earliest I can get replacement bearings.

 

 

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