Transmission Repair

[Mark K]

Maybe I'm just overly sensitive because I know I need to get mine out of there and fix my little problem -- the brief interruption of power while getting on it in second gear; but is everybody swapping gearboxes all of a sudden?

 

I almost feel guilty for letting it go, but I guess I've gotten used to it.....or drive around it.....I probably short-shift second or something. I don't even notice it anymore -- must be second nature. Anyway, the problem is not getting any worse, I can't remember the last time it skipped, and I'm not finding any bad things in the gearbox oil (I've been changing it every time I change the engine oil).

 

Am I ok to let it go? I mean, sometimes I have the extra time and sometimes I have the extra money, and once I had them both at the same time; but the desire is NEVER there to tear into the thing. I see too many unexpected questions/problems arise from operations just like this, and with me, no good deed goes unpunished.

 

There is nothing wrong with the bike except that little thing. I mean it is perfect. I think I've taken two cross-country trips since this issue surfaced and I'm planning another ~4K ride this summer! I have complete confidence that if I did have a problem on the road, it would not be the gearbox.

 

What would you do if it was your bike? Looks like we will all have some "free money" come early summer. Pay someone else to make it go away? I've never done that before in my life. Your thoughts?

[smiller]

Hi Mark,

 

What's going on is that your 2-3 shift fork is wearing out and thus not completely engaging the gear dogs, so the gears slip out on the first engagement try and then engage positively at the next dog, hence the apparent 'skip' in power.

 

This is not a uncommon problem for the M94 transmission in your bike and unfortunately the repair won't be cheap as you will have to open the transmission and replace the bad shift fork(s), have the gears undercut to prevent a recurrence of the problem, and probably do a 'clean bearing' upgrade on the input shaft. Sometimes a better alternative is to find a good used M97 tranny (which has these modifications from the factory.)

 

The good news (such as it is) is that you are not in any immediate peril. The problem will slowly grow worse over time as the shift fork continues to wear but if it's not bothering you that much you can probably continue to ignore it for a long time... I did...

[Mark K]

Yes, I thought about fitting an M97 replacement, but I'm in the "misalignment camp" when it comes to spline-related issues; and I do not have those issues now. With I replacement, I feel like I could be trading one set of problems for another, so I'll probably go with the rebuild route -- it's just so time consuming to have to ship the whole shebang off to Canada and wait. I'd probably forget how it all goes back together!

[smiller]

I would think the chances of getting nipped by the alignment issue are probably pretty remote, but still there is definitely something to be said for sticking with a known quantity... in my case I just didn't want to deal with the downtime, plus I like to do the internal transmission work myself and even kind of enjoy it. But from everything I've read Bruno will do an excellent job for you so that's also a good way to go.

 

Again, you probably don't have to rush into anything and can have the work done on your schedule, maybe wait until next winter when you have some downtime.

[snod]

I think Tom Cutter will take care of shipping to Canada, if you have him do your transmission work. Rubber Chicken is his web site. Tom did excelent work on my 1997. Mine didn't require undercutting, but I understand that he will send only the pieces that need machine work off to Bruno, and do all of the assemply work at his shop in PA. That way you don't have to mess with international shipping. No affiliation and all of that, just a satisfied customer.

[Beemr69]

BMW Grand Rapids , performed Steve (nevets)tranny rework recently , and accepted the tranny as a carry in rebuild to help , that way saving a days labor , 1/2 day out , 1/2 day back in , I dont know where you are in Ill. but you could possibly save shipping doing a drive in to GR.

[DavidEBSmith]

If you're looking for a shop to do the work, Jerad at Gina's rebuilt my transmission and did a fine job.

 

As to the alignment issue, I have no DATA on this, but I don't believe that there have been a significant number of alignment / spline issues on the R1100RTs. Almost if not all I've heard about have been on 1150s, which are a different transmission. I would not worry about doing a tranny swap on an 1100.

[outpost22]

At what mileage did you first experience this?

[smiller]

At what mileage did you first experience this?

I'll let Mark answer for his bike, but FWIW in my case (another '96 1100RT) I started to experience the problem at about 40k miles.

[guitardad]

I had the same problem with my '94 R1100RS, and I had Tom Cutter rebuild mine as well. 35kmiles on it since then, and if anything the trans shifts better than when I first got it back. Tom will do everything necessary to bring the trans up to the latest specs - clean bearings, etc. I'm very happy the work done on mine. The problem will only get worse with time. So I'd recommend having it rebuilt.

[Mark K]

At what mileage did you first experience this?

I'll let Mark answer for his bike, but FWIW in my case (another '96 1100RT) I started to experience the problem at about 40k miles.

 

This could have been more than two years ago. I posted about it here, but can't seem to locate it now. I would have noted the mileage in the post, but I want to say it was right around the low 40s as well.

[Mark K]

At what mileage did you first experience this?

 

I just read your signature line.......No wonder you're curious!

 

Like I said, it's really not a huge deal. You don't even miss it too much until you're pushing it on that twisty mountain road where you really, really need second gear. I get there only two weeks out of every 52, so I'm not missing much.

 

To the others......I looked into Tom Cutter's shop once -- I remember there was quite a wait time. It just didn't jive with my schedule. And David, thanks for reminding me of Gina's! They're almost close!! I could yank the gearbox myself and drop it off over there.

 

Sounds like it still may be worth comparing prices on the rebuild vs. swap, however. I'm still leaning toward the rebuild -- aside from that one issue, this gearbox shifts very, very smoothly and always has.

[smiller]

And David, thanks for reminding me of Gina's! They're almost close!! I could yank the gearbox myself and drop it off over there.

Keep in mind that whoever does it you'll need to have the shift dogs undercut if you want to banish the problem forever, and that's rather specialized work.

[Mark K]

Smiller,

 

It sounds like you did the rebuild yourself? Did you then have Bruno's undercut the shift dogs while you did the rest? I would love to do it myself if it doesn't take any/many specialized tools. I'm a fair wrench, but have never done any internal transmission work.

[smiller]

It sounds like you did the rebuild yourself? Did you then have Bruno's undercut the shift dogs while you did the rest? I would love to do it myself if it doesn't take any/many specialized tools. I'm a fair wrench, but have never done any internal transmission work.

I looked at the feasibility of doing the undercut work myself but forget it... no way without the proper machinist's tools and experience. So I found myself a good used M97 and rebuilt that. An oilhead transmission is not particularly difficult for an experienced home mechanic to tackle but you will need some special tools, such as pullers for the bearings, depth micrometer for setting shim packs, etc. That latter task takes a little ingenuity if you don't have BMW's special setup jig, but that lack can be worked around.

 

You could send the gearshafts to Bruno for undercutting and do the rest of the work yourself and save some time and money, but I wouldn't advise this unless you feel confident in your abilities. That's a call only you can make.

[Mark K]

Interesting....Thanks for the reply. I appreciate the thoughts.

 

I have or have access to those tools, etc. It may be worth a shot. It would be a great learning experience.

[smiller]

I can tell you it's an extremely rewarding feeling when you complete the job (or not, if you screw it up... )

 

I've been through a couple of them now and will be happy to provide pointers if you decide to delve into it. The trickiest part is shimming but a careful eye and a steady hand will get it done (along with some arithmetic.) First step is to review the service manual to get a taste of what you'd be getting into.

[Mark K]

Sounds like it still may be worth comparing prices on the rebuild vs. swap, however. I'm still leaning toward the rebuild -- aside from that one issue, this gearbox shifts very, very smoothly and always has.

 

 

That was me......not 4 days ago....

 

I jinxed myself! I went looking for the source of a hot, almost burning smell tonight and found the dreaded "chocolate-colored gear oil." No flakes on the magnet, but some in the bottom of the pan -- not a lot, but they're there. This is really not a good time; but, I suppose it could always be worse.

 

I should have kept my mouth shut.

[smiller]

Mark, that's interesting because I believe the problem at the root of chocolate-colored gear oil issue to be associated with the M97 model transmission, not the M94 in your bike. The shift fork wear that you are experiencing usually creates a darker but golden-colored metallic sheen to the oil. Is this perhaps what you are experiencing?

[Mark K]

I've been told I don't differentiate colors very well. This photo was taken last evening in the garage. I'll get another today in the light of day, but definitely not "milk chocolate".....it is much darker than that AFA I can tell.

[Mark K]

The shift fork wear that you are experiencing usually creates a darker but golden-colored metallic sheen to the oil. Is this perhaps what you are experiencing?

 

You're right, Seth. Outside in the sunlight, I can clearly see gold flecks.......well, not even flecks.....more like dust floating around in the oil. Nothing on the magnet, however. Must be brass??

 

That oil stinks to high heaven! Those are bubbles -- not shavings.

 

 

[/img]

[smiller]

Yep, what you are seeing is dissolved shift fork, and yeah, it is non-ferrous whatever it is. The shift fork material is actually pretty soft, seems like it might even be just some annodized alluminum alloy.

 

Anyway, you have all the classic symptoms so not much doubt about what is going on. Same notes apply... you'll probably want to fix it sooner or later as the problem will eventually get worse, but no emergency. The shift fork material is so soft that I don't think it will hurt the rest of the transmission, just change your oil frequently in the meantime.

 

BTW this is what one of your shift forks probably looks like:

[kiwiaudio]

Mark, this line is an instant classic in my book!

"sometimes I have the extra time and sometimes I have the extra money, and once I had them both at the same time"

 

I love that !!!

[keithb]

+ 1 on the line. I loved it too.

[Mark K]

What I'm not understanding is why the oil appears burnt and why it smells so bad. Is it the friction between the gear and the shift fork?

 

The reason I'm asking is I have had this skipping problem for more than two years. I just kept a closer eye on the gearbox oil by changing it every time I did the engine oil. It has always looked pretty much the same coming out as it did going in. Why the color change now?

 

BTW....I talked w/Gina's -- some ballpark costs...

 

labor to upgrade the gearbox: $500

shift forks: $100 per

upgrade kit (apparently there is a kit): $200

plus another $400 if I let them get it out and put it back.

[smiller]

What I'm not understanding is why the oil appears burnt and why it smells so bad.

Can't tell you that. Gear oil smells pretty bad even when it is new, have you compared new and your sample to be sure that there really is a burnt smell to it? I don't think that the friction between the shift fork and gear is nearly enough to burn oil, maybe something else is going on... know way to know for sure until the transmission is opened. If the oil really is noticeably burnt (vs. just contaminated) then forget my earlier comment regarding delaying the repair... you'll need to find out why ASAP.

[NonComp]

Is the shifter fork wear a result of an incomplete shift? In other words, second gear is half engaged? If my gearbox is showing signs of behaving the same way, is it better to get on it in second gear and force the skip to engage the cogs, or is better to limit the amount of time spent in second gear?

[smiller]

Is the shifter fork wear a result of an incomplete shift?

No, it is a result of the lack of undercut shift dogs on the M94 transmission (used from approximately '94-'96). Without the undercut dogs the gears (depending on various manufacturing tolerances) can want to walk out of gear once engaged. The can cause them to press against the shift forks and eventually wear then out. With undercut dogs (found on the M97 model) the gears will stay engaged very positively, preventing the problem. This is why replacing the worn fork(s) alone on an M94 will probably result in a recurrence of the problem, unless you have the shift dogs undercut as well. Or find a used or remanufactured M97.

 

If you are starting to see symptoms of the problem then one or more shift forks have worn and eventually you will have to perform a repair. If a particular transmission is prone to the problem (not all are) I'm not aware of any way to head it off, and while the problem most commonly shows up in second gear it can also show up in third, or rarely fourth. There's just no way to predict anything in advance, short of a teardown.

[NonComp]

I did tear down my gearbox last summer when I bought the bike to replace seals while I did the clutch. It had the beginnings of wear on the one shifter fork. Since I put it together, I've noticed a tendancy to skip in second gear on one particular uphill corner on my way home. I tend to shift early most of the time. I had no previous experience with the bike, because the clutch was shot when I bought it.

 

When I shift into second, I always get the feeling that it doesn't really shift cleanly the way it does in other gears. It feels a bit fague.

 

I'm thinking that, depending on how it behaves this year, I may pull it next winter and send it to Bruno. What would you recommend: have an M94 modified or find a used M97?

[smiller]

What would you recommend: have an M94 modified or find a used M97?

There are actually a lot of elements to consider in that question and there probably isn't a single answer that is best for everyone. There's nothing wrong with updating a M94 if you are certain of the skills of the person doing the work, and if so the result of custom repair work can be quite good (turnaround can be slow, but if you have a long winter to deal with that's not a big deal I guess.) The only minor downside is that some parts of the M94 are no longer available and it's conceivable that fact could complicate future repairs, but I wouldn't be too concerned about that issue as if your current unit is properly repaired it should last a very long time. And once repaired there are even some facets of an M94 that are better than an M97.

 

Your next option is a factory remanufacturerd M97, about US$1400 I think, which is probably a little more than you will spend with Bruno. But you will have a replacement unit ready so you can complete the entire swap in a weekend and be back on the road. The least expensive option by far would be a used M97, but these can be hard to find and their condition variable. I have purchased two used transmissions and both were fine, but of course YMMV.

 

So, all the options have their pluses and minuses depending on your own comfort level, budget, time constraints, etc. Hopefully the above comments will help you sort it out.

[Mark K]

......Your next option is a factory remanufacturerd M97, about US$1400........

 

Remanufactured gearboxes are now $2,600 ($2k from Chicago BMW). That is not my first option as of now.

 

Just dropped the bike off at Gina's BMW. I'll post the results and their recommended repair.

[smiller]

($2k from Chicago BMW)

Ouch. I was referring to the Chicago BMW price from the last time I checked, which admittedly was a while ago. looks like it went up 'a little.' I think I may have to get into this business...

 

Just dropped the bike off at Gina's BMW.

Their prices look reasonable (from your earlier post.) Did that include undercutting the shift dogs?

[Mark K]

Did that include undercutting the shift dogs?

 

I didn't ask that specific question. I will definitely do that when they call after their inspection. I would assume so, as they have an on-site machine shop.

 

 

At what mileage did you first experience this?

 

I'll let Mark answer for his bike, but FWIW in my case (another '96 1100RT) I started to experience the problem at about 40k miles.

 

 

 

This could have been more than two years ago. I posted about it here, but can't seem to locate it now. I would have noted the mileage in the post, but I want to say it was right around the low 40s as well.

 

 

I found that old post and I was just under 50k when I posted, so it would have been in the mid-40's when the problem manifested.

[Mark K]

Just an update.......

 

I think I mentioned I dropped the bike off last Saturday.... They were busy and didn't know when it would get on the hoist but assured me I would hear something the following week. Fine......let me know what you find in there.....

 

I called Thursday (after not hearing from them) to ask that they replace the neutral switch while they were in there. Service manager informs me that it's too late -- they have the paralever back on already! I'm shocked -- I was expecting an update when they cracked the gearbox.

 

All the shift forks were bad.....the bearings were upgraded although they all felt good. No gearsets needed replaced and in fact, the engagement dogs (even on 2nd gear) were barely worn.

 

Clutch splines were dry and there was some other issue with the clutch as well...can't remember what that was......something was warped..........

 

Anyway, I was told they were waiting on a clutch cable and I should expect a call Friday. No call came, so I called them back today (Saturday). The clutch cable that came was the wrong one, so it's still not ready. Wish I would have known as much -- I have an extra clutch cable at the house. They will obviously still need to road test it, so Tuesday evening or Wednesday at the earliest.....

 

It all made me sound like I'm some ham-fisted rider who nearly rode the thing into the ground! I really don't think that's the case and even passengers are impressed with the smooth ride. I have been especially careful since the 2nd gear "skipping" showed up a couple years ago.

 

We didn't get into all the details over the phone, but that's what I know so far. Anything specific I need to ask when I pick it up next week?

[Eckhard Grohe]

The use of 75-140W gear oil will make the tranny shift better. Try it. I did and was impressed with the results. Others on the site were too.

 

Eckhard

[smiller]

No gearsets needed replaced and in fact, the engagement dogs (even on 2nd gear) were barely worn.

Did they undercut the engagement dogs?

[Anton Largiader]

All the shift forks were bad.....the bearings were upgraded although they all felt good. No gearsets needed replaced and in fact, the engagement dogs (even on 2nd gear) were barely worn.

I hope it works out for you, but my experience with repairing these transmissions leads me always recut the shift dogs. I learned that the hard way, thinking the dogs looked OK and just replacing the fork. It wasn't enough, and I learned to appreciate how a slight amount of wear on the dogs was enough to bring the problem back. I simply never reinstall unmodified gears on a box that has kicked out of gear. Never.

 

A dealer near me rebuilt one for a local rider. I'm not sure what was and wasn't done, but the problem came right back. This problem needs some real care and experience to rectify. Hopefully the tech at Gina's had that.

 

If it comes back for you, at least it will be under warranty.

 

More info on this type of failure is on my website under "R1100 Transmissions."

[smiller]

Yeah, that's what I was getting at with my question, as the engagement dogs need to be undercut in order to prevent a repeat of the problem. Reference my explanation earlier in the thread as to why the shift fork damage occurs in the first place.

 

As Anton notes if you don't have this work done the problem will in all likelihood just recur. FWIW Bruno also agrees; I discussed this issue with him in an email exchange (when I was facing the same decision regarding rebuild or replace) and asked him if it was really necessary to cut the engagement dogs. His response was that this work definitely must be done and replacing the forks only would just be 'a waste of time' (his words, and he added a bunch of exclamation points.) I think anyone who has much experience with this issue will tell you the same; the root cause of the problem is pretty apparent by inspection.

 

If the dogs weren't cut then please ask what the tech exactly what he did to prevent the problem from recurring, maybe there is some technique we are not aware of. Absent that though the repair isn't complete.

[Mark K]

I didn't ask if the dogs were undercut. We really didn't get into the details (as you can tell from my post). In addition, I was speaking with the service manager who likely didn't touch the bike.

 

I will definitely ask that question AND what they specifically did to assure the problem does not reoccur.

 

 

 

Eckhard, thanks for the suggestion........I do use that oil.

[Mark K]

Did they undercut the engagement dogs?

 

Now I'm thinking that if they had undercut the gear(s), they surely would have mentioned it right away. OTOH, undercutting sounds like standard practice when making this repair.

 

I bet they didn't............

[Anton Largiader]

Undercutting is a very specialized affair, given that there are both dogs and 'doghouses.' Unless their machine shop is way beyond the norm, it's pretty much a given that they didn't do that. Plus they would have told you that they had added hours of labor to your bill.

 

The 'by the book' repair is to replace the damaged parts and then reassemble the transmission properly, and that's what I'd expect most dealerships to do. It can work. I do more than that, but it's very expensive.

[Mac]

Have you picked up your bike yet?I just found lots of metal on my drain plug on my 01 1100rt and will be calling Ginas tomorrow.Bob

[smiller]

Have you picked up your bike yet?I just found lots of metal on my drain plug on my 01 1100rt and will be calling Ginas tomorrow.Bob

Just a note, the problem Mark is experiencing is not common to the later model transmissions (as would be found on an '01), and shift fork metal would not show up on your drain plug magnet. Not to say that you don't have a problem, but FWIW it probably isn't the particular issue being discussed in this thread.

[Mark K]

Have you picked up your bike yet?I just found lots of metal on my drain plug on my 01 1100rt and will be calling Ginas tomorrow.Bob

 

What Seth said......

 

But, yes I did get it a couple weeks ago. Gearbox is very tight and they gave me a break on some labor costs. In the interest of full disclosure, however, there are a couple things that feel different (could be good or bad -- just new to me) so I'm going to take it back over for them to ride again in another week or so now that I've had a chance to shake it down pretty well. Overall, a good experience -- very quick service. Very fair.