Second Gear problem 1100 GS

[mystek]

Hello
I'm new at this forum. I've bought at last summer an 1100 GS from UK(05.1998). Everything was fine, until I've took him out from winter sleep. On second gear, when I accelerate, in around 4-5 thousands RPM, my bike falls in to a little gap. This gap occurs always and only at second gear, by at least 3 kRPM, also when I accelerate constantly (this gap is very short, afterwards bike rides well). I've never had it on different gear. I've changed fuel filter and cleaned gas tank, checked fuel injector(but the were fine), changed spark plugs, cleaned connections in spark plug wrench, checked clutch regulation. Everything was fine, but my GS works as before. Have You got any idea what this could be?
Sorry if I've made some errors in my post, but I don’t use english so often.

with regards,


Mystek

 

[Steptoe]

I'm afraid it sounds like you have the well known 1100 jumping gearbox problem - It requires some work, but it can carry on for a long while in that condition without any other problems.

 

[mad man]

I'm afraid it sounds like you have the well known 1100 jumping gearbox problem - It requires some work, but it can carry on for a long while in that condition without any other problems.

mines in 3rd what causes it and how much would it cost to put right?

 

[mystek]

Thanks. I've read some posts about it. Is really the rounded dogs problem? http://www.largiader.com/tech/oiltrans/
I've also read that some 1100 owners with that same issue have changed whole gearbox? Is it really so complicated to repair it? Does someone have a good description, that I could read (I'll put my GS into service, but I don't want to be sticked into bottle)

 

[Colban]

I thought all the gearbox problems were on the pre 97 boxes.
The gearbox should have a number stamped on it.Would it indicate if it was an M97 box?.

 

[MattW]

mines in 3rd what causes it and how much would it cost to put right?

As in the link above it's a problem with the dogs rounding. The gear slips out and then is immediately bounced back in by the selector forks. This causes the 'skipping' feeling. It usually shows in third gear (probably because it's the all purpose gear on an 1100 and gets a lot of use). In the end the dogs and the shift forks wear out to the point where it won't stay in gear (but as Steptoe says with careful gearchanges it can last a long time). There are various theories as to why it happens to some but not others with most people thinking its down to poor initial assembly (shimming) of the gearbox. I've read lots about this as I have a '94 1100 with the gearbox especially prone to this problem It usually happens to the M94 boxes but I've read about it happening to the later boxes too.

As to getting it fixed, I've read about people doing it themselves but it requires a fair bit of mechanical skill and some special tools to take the gears off the shafts and reshim the whole thing when you reassemble it and of course you will probably need to either replace or ideally machine and undercut the dogs on the suspect gears. There are also some mods which bring the box up to the later spec. While I'm fairly brave with spanners, it's not the sort of thing I'd try myself - some jobs are best left to those with the experience.

Steptoe doesn't tend to promote himself in threads like this but he does this sort of thing as do Scriminger Engineering - both are highly recommended by people on here.

 

[mad man]

As in the link above it's a problem with the dogs rounding. The gear slips out and then is immediately bounced back in by the selector forks. This causes the 'skipping' feeling. It usually shows in third gear (probably because it's the all purpose gear on an 1100 and gets a lot of use). In the end the dogs and the shift forks wear out to the point where it won't stay in gear (but as Steptoe says with careful gearchanges it can last a long time). There are various theories as to why it happens to some but not others with most people thinking its down to poor initial assembly (shimming) of the gearbox. I've read lots about this as I have a '94 1100 with the gearbox especially prone to this problem It usually happens to the M94 boxes but I've read about it happening to the later boxes too.

As to getting it fixed, I've read about people doing it themselves but it requires a fair bit of mechanical skill and some special tools to take the gears off the shafts and reshim the whole thing when you reassemble it and of course you will probably need to either replace or ideally machine and undercut the dogs on the suspect gears. There are also some mods which bring the box up to the later spec. While I'm fairly brave with spanners, it's not the sort of thing I'd try myself - some jobs are best left to those with the experience.

Steptoe doesn't tend to promote himself in threads like this but he does this sort of thing as do Scriminger Engineering - both are highly recommended by people on here.

so what would happen when it goes completely?

 

[Noddy]

so what would happen when it goes completely?

That bit is simple. You contact somebody, who lives quite near to you and has a Scriminger rebuilt 1100 gearbox (with all the paperwork) sitting safely in his safe place.

 

[mystek]

I've taken an closer look in repair's manual and the BMW Parts catalog. I understand that the "23222325523 SHIFT GEAR FOR 2ND. GEAR" has to be changed? Is it recommended to change by the way some oteher parts(i supose I'll change clutch) to avoid some issues in future? If the dogs go round also on third gear, than also "23211451073 GEAR WHEEL 3RD GEAR" should be exchanged? My goal is not to do it my self, but to know what does the service man should do(to check if knows what is he paid for).
Thanks for all replys.

 

[MattW]

I've taken an closer look in repair's manual and the BMW Parts catalog. I understand that the "23222325523 SHIFT GEAR FOR 2ND. GEAR" has to be changed? Is it recommended to change by the way some oteher parts(i supose I'll change clutch) to avoid some issues in future? If the dogs go round also on third gear, than also "23211451073 GEAR WHEEL 3RD GEAR" should be exchanged? My goal is not to do it my self, but to know what does the service man should do(to check if knows what is he paid for).
Thanks for all replys.

A good mechanic who's experienced with bike gearboxes should be able to work out what needs changing when the box is stripped - it will depend on what you find when it is apart.

I've never had to remove / refurbish my gearbox but for what its worth, in your position I'd be thinking of the following:

• First - rule out any other possible fault before gong to the time and expense of stripping the gearbox (but it sounds like you have done that already)?
• Do the gears need to be changed as pairs (input and output)?
• Check the condition of the other gears / dogs (especially third), change if necessary?
• Is it worth changing all the bearings and seals when you have the gearbox in bits?
• Clutch (as you say above) - depending on your km's and its condition - possibly change it while the box is off?
• Crankshaft output seal condition?

There may be other things worth checking / replacing - hopefully some of the experienced people on here will add their thoughts.