Boxerworks.com

I have a 98RT with approx. 74,000 on the ODO (miles)

I have no history on this machine. When I first received it (Ebay), I removed the trans & lubed the splines, Inspected the clutch lining etc...replaced rear bearings in the back half of the swing arm joint, changed lubricants etc. All the splines looked very good. Shortly thereafter, it was discovered that the engine had a low knock sound at hot idle. Diagnosis was a worn tear main (thrust) bearing. The Engine was then replaced with a 14,000 mile engine from a 95-96 R1100RS.

Since the rear 1/2 had just recently been apart & inspected......the decision was made to remove the entire rear 1/2 as an assy as per BMW service instructions. I found that trying to get the entire rear half correctly aligned to slide back on to the back of the engine was VERY difficult because of the cumbersome weights of the whole assy trying to tip the trans over sideways. I would always choose to disassemble the swing arm from the trans if I ever attempt a trans removal again.

Which brings me to my question. Since having a good engine in the machine.....I find that the "rattle" of the transmission in neutral is particularly concerning. As one would expect, the noise goes away when the clutch is dis engaged.
To me, the noise seems excessive. I am suspecting a defective or damaged input bearing in the trans.
One should note that in the attempt to re seat the transmission after the engine change, there was a considerable amount of prying, levering and even some gentle hammering (rubber hammer) used in the attempt to get the trans to slide back in. It is conceivable to me that the front bearing could be damaged from the excess efforts in re installing.

I have no previous experience with oilheads.....so I'm seeking opinions from other oilhead owners about how much rattle should be considered normal????

Do I pull this transmission for the third time? I have 85W90 Syn lube in it. Generally it performs well but has a slight tendency to grind a small bit on the 2-3 upshift.

Opinions please?????
Regards, Ibjman

This was a known issue with the first year transmission. I've heard it was "fixed," by changing the design and including some orings inside to prevent the rattling noise, but the noise was not actually a mechanical problem, only one of perception. A 98 tranny shouldn't have that rattle, but there's the possibility that the bike received a used transmission before your ownership.

If it's an early tranny, I wouldn't worry about the noise at all. If it's a 98 transmission, it's possible that one or more of the prophylactic orings have failed, and there's not a real mechanical problem, or it could be that there is something more amiss. Regardless, I wouldn't worry about it at all as long as your drain plug shows no bits of grenading parts. Change the tranny lube more often than called for and keep an eye out. If it shows no problem, I wouldn't worry.

BTW, make sure you're using the current BMW synth gear lube, I think it's something like 85-140. That stuff doesn't thin as much when hot and will provide as much cushion as possible to keep things quiet.

thank you for the great information!
Is there a way to identify the year model trans?
My noise is not as bad when warm.......mostly bad when first started.
Sometimes, I think I can hear the same or similar sound at low speeds while traveling in gear......which would not be a "rattle". Not sure.....seems like a lot of ghost noises in this oilhead seem to come & go.

Only other concern is that the trans tends to grind a bit on the 2-3 upshift. I can usually avoid that if I short shift it a bit (lower rpm).
Thanks again, Regards, Ibjman
PS hope to see any & all of you this July in St. Paul and or this June in Panguitch, UT

I don't know how to identify the year of the transmission. If you can't find anything on the web, I'd ask a dealer service guy.

This is an M97