A Gearbox rebuild question ???????????????

[Garry H]

It is possible to check the clearance on 2 of the gearbox shafts once the box is assembled
It's a simple engineering with a bit of common sense
Any shaft that is tight when the endcover is tightened is incorrectly shimmed as simple as ! ( assuming you have got everythink else correct )
The way i see it there are a few people rebuilding gearboxes who don't understand whats going on but think they do

 

[Voyager]

It is possible to check the clearance on 2 of the gearbox shafts once the box is assembled
It's a simple engineering with a bit of common sense
Any shaft that is tight when the endcover is tightened is incorrectly shimmed as simple as !

I put my thoughts down as I'm not sure that I am doing it right and wanted to open the subject up for discussion.

I don't see how the end-float can be checked when the shafts are tight in the bearings and the bearings are tight in the case as nothing moves (by hand). Testing the float with a hot box would be possible, but the results would be wrong due to expansion of the case (co-efficient of expansion of alloy being greater than that of steel).

The Input shaft rear bearing can be seated when the rear cover is hot as the shaft slides through the front roller bearing. Once the rear cover has cooled the bearing is tight in the cover and the shaft won't move by hand.

Testing whether it turns freely is mis-leading as it can't be de-coupled from the Intermediate shaft - only from the output shaft when the box is in neutral.

With the output shaft - the hot rear cover is fitted, but the front Output shaft bearing is tight in the main case so the Output shaft can't be pulled-back to seat the bearing & shims fully (by hand).

I'm sure its possible to shim the box so that its free-running when cool - but does that mean that the clearances are correct . . I'm not sure??

When I tighten the end cover the box is running free - its only when it has cooled that it feels a bit tight. That's why I think its the contraction of the case that's causing the tightness not necessarily the lack of potential end-float in the box. That will show up when the box has been under load.

I'd like to know what Getrag do - I can't believe they have people spending ages shimming boxes until the feel right.

Its an interesting subject and I'll do some more digging and see what I can turn-up.

Thanks for all the input.

Bob.

 

[Garry H]

I put my thoughts down as I'm not sure that I am doing it right and wanted to open the subject up for discussion.

I don't see how the end-float can be checked when the shafts are tight in the bearings and the bearings are tight in the case as nothing moves (by hand).

Bob.

I can't understand why you can't figure it out it's simple
Of corse you can't move them by hand but with a bit of ingenuity you can move them and measure the end float on them very accurately
It's a pity you cant do the same trick on the intermediate shaft
Simple fact is the gearbox end cases warp and this means you cant just use a shimming plate and expect/assume to get it correct
You have to allow for the warp
You can clock the end cover on a mill and see how flat it is ( there not i have checked a few ) Then you can measure it to give you a good start point

 

[Voyager]

Hmmmm, Interesting.

I'll have to spend more time checking the end covers.

Thanks for that.

Bob.

 

[bonnylad]

Hmmmm, Interesting.

I'll have to spend more time checking the end covers.

Thanks for that.

Bob.

Clymer gives end cover bolts as 24 ft/lb Haynes gives 5-6 ft/lbs what a difference. My box was very stiff to turn at 24 ft/lb but acceptably free at 6 ft/lb
Thinking about it,...... 24 ft/lb is about right for a 10mm caliper bolt but not a piddly cover bolt.
First question for any one doing a gear box and having problems 'Are you using a Clymer manual?'

 

[SnowMec]

Interesting , informative and educational posts in this thread , I have a question for all you gearbox experts.
Where can you buy shims online to R100 gearboxes ?
How many variations of shims are there? And how many do I need to be able to do the service of R100 gearboxes ?
Best regards Alf

 

[Voyager]

Where can you buy shims online to R100 gearboxes ?
How many variations of shims are there? And how many do I need to be able to do the service of R100 gearboxes ?

You can get them from Motorworks:

http://www.motorworks.co.uk/vlive/Shop/Parts.php?T=5&NU=15&M=20&Ct=DA&SbCt=BA_15_20_DA_75&spPage=1

There are four common thicknesses: 0.20, 0.28, 0.38 & 0.50mm

BUT . . . You will find that there is some variation between them so when trying to set up a stack of a particular thickness measure it with a Micrometer and swap the shims about until you get as close as possible to the right value. It is possible to get it spot-on.

I have built up a reasonable stock of shims and have probably 20 of each nominal thickness, but you won't need that many to start with. There will be shims in your gearbox when you take it apart and you shouldn't need to vary what came out by much.

I would start with two or three of each thickness.

Bob.

 

[Ijustwanttoseethephotos]

New shims from my local BMW dealer are about a third of the price of the ones from Motorworks, it might be worth comparing the prices from BMW direct.

 

[SnowMec]

Thanks for the answers, I'll order shims in time before I start with the gearbox .
The nearest BMW dealer is 300km from me and they are hardly interested in selling parts for older bikes. They only sell new bikes and bike-clothes! Bike dealers in northern Sweden are not interested in older motorcycles, the do not work with them at all.
So I have to order all the parts for my motorcycle online, which applies to most things I buy.
So up here you have to order all the parts online and then do all the work yourself.
It is so when you live in the “wilderness”.
Best regards/ Alf

 

[Weekday Rider]

Thanks for the answers, I'll order shims in time before I start with the gearbox .
The nearest BMW dealer is 300km from me and they are hardly interested in selling parts for older bikes. They only sell new bikes and bike-clothes! Bike dealers in northern Sweden are not interested in older motorcycles, the do not work with them at all.
So I have to order all the parts for my motorcycle online, which applies to most things I buy.
So up here you have to order all the parts online and then do all the work yourself.
It is so when you live in the “wilderness”.
Best regards/ Alf

MOVE!

 

[SnowMec]

MOVE!

Do not think so, I live in paradise!
Daylight around the clock during the motorcycle season and 1-2 meters of snow during the winter when it's time to go snowmobiling.
Total freedom of nature with sport-fishing in all directions.
The best place in the world to live in for me!
Regards.

 

[ChasF]

How many days is the motorcycle season?

 

[SnowMec]

OT now but.
It is really nice to ride motorcycle here between May and Oktober.
But a real Viking rides 365 days per year .
It can be -40 celisus in the winter and then we have very few hours of daylight .
But the summer i fantastic for bike riding, dont be afraid of the mosquitoes!

 

[Weekday Rider]

Do not think so, I live in paradise!
Daylight around the clock during the motorcycle season and 1-2 meters of snow during the winter when it's time to go snowmobiling.
Total freedom of nature with sport-fishing in all directions.
The best place in the world to live in for me!
Regards.

I was making a joke. English humor . Sounds like my idea of heaven too. I've been to the north of Norway twice, both times in January. I loved it.

I've not been to Sweden but would love to take a look at those tall, blonde beauties Sweden is famous for.

 

[dr nosh]

Thanks for the answers, I'll order shims in time before I start with the gearbox .
The nearest BMW dealer is 300km from me and they are hardly interested in selling parts for older bikes. They only sell new bikes and bike-clothes! Bike dealers in northern Sweden are not interested in older motorcycles, the do not work with them at all.
So I have to order all the parts for my motorcycle online, which applies to most things I buy.
So up here you have to order all the parts online and then do all the work yourself.
It is so when you live in the “wilderness”.
Best regards/ Alf

You can still order genuine BMW airhead parts mail order from BMW dealers. For example Rainbow Motorcycles in the UK,

http://www.rainbowbmw.com/BMWETK/

Or direct from BMW Klassic:

http://shop.bmw-classic.com/index-ClassicDE-WFS-en_EU-EUR.html

 

[John Roberts]

The problem I had with shimming was the matter of measuring how far the bearing outer races protruded above the shimming plate, I found it very difficult to judge when the micrometer was making contact with the race without it being tipped over thus giving a false (low) reading. When I say micrometer I mean a depth micrometer which I used with a pair of ground parallels. The shimming plate I use is not a tight fit on the outer races and allows a slight amount of tipping, is this normal?

How do others manage?

 

[Beemerboff]

Just reread the complete thread , including Richie's post that the latter service sheets nominate 0.005 t0 0.015 clearance.
Anyone know if that is parts of and inch, or of a millimeter.?
And if it is parts of a mm, what sort of gear are you using to measure to 0.005 of a mm and where are you buying the shims which let you set it that accurately?