Recently purchased a '78 R100/7 and shelled out the tranny in the first 500 miles. Are gearboxes a weak link on these old bikes? Someone suggested that sitting around trashes out the bearings and failure is common. Someone else has informed me that synthetic lube doesn't transfer the heat off the gears well and they overheat. Good source of used parts? Will another used tranny do the same? Any good rebuilt boxes out there? Any help would be appreciated trying to understand this thing.
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shelled out tranny
- Thread starter djkehoe
- Start date
Both of the old Airheads we refurbished needed tranny rebuilds, which started with ruined input splines from LACK OF SERVICING. The input spline shaft is $300+, and as long as you've got the gearbox apart, get new bearings and seals in the thing. A rebuild bill of $1000 is not uncommon, and anyone who tries to sell you a rebuilt one for less probably didn't go all the way.
The transmissions do last a long time when minimally maintained. My K75 gearbox has 180,000 miles on it with just annual gear oil changes and spline lubes every 3-4 years.
The transmissions do last a long time when minimally maintained. My K75 gearbox has 180,000 miles on it with just annual gear oil changes and spline lubes every 3-4 years.
J
James.A
Guest
I recently saved a long neglected transmission on an R75/6. If you go with a used box, try this.
1-drain all the old gear lube.
2-install transmission
3-re-fill with fresh gear lube. I use 80w90 hypoid.
4-using the rear wheel to turn the transmission, engage all the gears upshifting and back. If you have a helper you can do this holding in the clutch, otherwise take out the spark plugs.
5-Run the bike on the road enough to cycle all the gears a few times.
6- drain and re-fill.
The transmission I re-habbed in this manner had sat un-used for 6 or 7 years. When we started, it would only shift into first and second, and then sometimes not hold second. After the proceedure, the box works fine. A good dose of insurance for any used gearbox.
1-drain all the old gear lube.
2-install transmission
3-re-fill with fresh gear lube. I use 80w90 hypoid.
4-using the rear wheel to turn the transmission, engage all the gears upshifting and back. If you have a helper you can do this holding in the clutch, otherwise take out the spark plugs.
5-Run the bike on the road enough to cycle all the gears a few times.
6- drain and re-fill.
The transmission I re-habbed in this manner had sat un-used for 6 or 7 years. When we started, it would only shift into first and second, and then sometimes not hold second. After the proceedure, the box works fine. A good dose of insurance for any used gearbox.
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