Neutral Switch (Transmission) - R100 GS

[GlobalRider]

I received my BMW order last week with my neutral switch, aluminum sealing ring and the three aluminum gaskets for the center and rear muffler which needed to be removed for better access to the neutral switch. And sure enough, it was wet.

While I had the center and rear muffler off, I gave them a bit of chrome polish. And since it was warm and sunny out, a few beers to help things along. OK, so I don't have big miles on it, but I do clean it now and then and that keeps the rust off. Not bad for 33 years.

1990 BMW R100 GS - Center Muffler - Top - SM.jpg

1990 BMW R100 GS - Center Muffler - Botton - SM.jpg

1990 BMW R100 GS - Rear Muffler - Outside - SM.jpg

1990 BMW R100 GS - Rear Muffler - Inside - SM.jpg

The next step was removing the rear engine mount stud (295mm long with it being threaded 22 mm at each end for an M12 x 1.50 nut).

In case the engine could pivot about the front stud, I inserted an M12 bolt. I cut off the threaded portion just to leave the smooth shank for a length of about 65 mm, just under 3 inches.

1990 BMW R100 GS - Rear Engine Bolt 1 - SM.jpg

1990 BMW R100 GS - Rear Engine Bolt 2 - SM.jpg

The spacer is in very tight...I'll get to it the next day and once I get it out, I'll run it in my lathe and take a few thou off so that it is a tight slip-fit..and not a press fit . In any case, no pry bars...not the way I do things.

1990 BMW R100 GS - Rear Engone Mount Spacer - SM.jpg

[STEVENRANKIN]

Alex, like you, I don't use pry bars. In the case of the engine spacers if they don't fall out, it means the engine is not straight or properly supported with the bolts out. Just saying.

I love the polish work. Where are you at and do you do bike detailing for a price, LOL. St.

[Visian]

The spacer is in very tight...I'll get to it the next day and once I get it out, I'll run it in my lathe and take a few thou off so that it is a tight slip-fit..and not a press fit . In any case, no pry bars...not the way I do things.

1990 BMW R100 GS - Rear Engone Mount Spacer - SM.jpg

So, Alex, what did you do to get the spacer out?

[GlobalRider]

So, Alex, what did you do to get the spacer out?

Yeah what a job. I've listed some things to do and not to do get the spacer out. If your spacer falls out, you may be applying pressure to the engine casting which is a no-no when it comes to castings.

Rear Engine Mount Spacer Removal

Better get a beer out because I'm about to write a novel.

First of all, I hardly needed a rear engine mount stud to hold that spacer in place. No matter what I did, it might as well have been welded in place. Yeah I guess I could have slipped a pry bar between the engine casting and the spacer, but if I wanted to do that, I could have taken my GS to a dealer.

Big mistake and why it took me so long. Thinking the cavity ahead of the spacer was wider than where the spacer mounts, I was thinking of driving it forward by hitting it with a block of wood and hammer into that cavity and then angling it out. Doing that lifted the spacer up towards the neutral switch due to the machining of the engine block. Apparent in the second photo when looking at the engine casting machining. So, don't do that.

The big job now was getting the spacer back to where it was. I used nylon straps wrapped around the spacer in a loop with a block of wood in the loop and hammered the block back. That took forever working both ends of the spacer.

So now I got it back to where it was but higher than its mounted position. Good, so I used some plastic shims and a pry bar to lift it up which reduced the amount of material between the engine block casting and the spacer, reducing friction. The straps and hammer method pulled it out of position.

I glass beaded the engine mount stud and the spacer which had rust within the hole. When slipping them into position, I greased them as well as the cavity in the frame, engine and spacer.

I put the spacer in my lathe and took a hair off each end. It fit but very snugly. The factory spacer already was chamfered at the ends for easy insertion. They could have done the same to the hole making it easier to feed the engine stud through it.

1990 BMW R100 GS - Neutral Switch Location - SM.jpg

1990 BMW R100 GS - Neutral Switch Installed 2 - SM.jpg

1990 BMW R100 GS - Spacer Installed - SM.jpg

[GlobalRider]

In the case of the engine spacers if they don't fall out, it means the engine is not straight or properly supported with the bolts out.

The spacer sits between an engine casting that is one piece. They do not flex all that much. I did have the front engine mount loosened.

Those gold colored bolt heads that you see are my own doing and stop about 3/8" short of the spacer. They are just there in shear should the rear of the engine pivot down which was not an issue after all.

[GTRider]

Rather than taper the hole in the spacer, I find it easier to use a tapered pin to align the spacer on reinsertion. The pin is made from a long bolt with the threaded portion cut off and then gradually tapered to about 5mm in diameter at the point.

Be very cautious about shortening that spacer as the crankcase housing is one cast piece and the spacer fits snugly for a reason. A small taper filed on the leading edge is usually enough to get the spacer started so it can be tapped home.

Best,
DeVern

[20774]

I had read that reinserting the spacer is made easier by putting it in the freezer for a few hours. That doesn't help the next time it has to come out, so maybe cutting a skoosh off the ends would be helpful.

[GlobalRider]

Be very cautious about shortening that spacer as the crankcase housing is one cast piece and the spacer fits snugly for a reason.

As I mentioned above, I shaved off a hair and at that it still needed a tapping in and fit snugly. I know about castings and cracks but luckily not from experience.

[GlobalRider]

I had read that reinserting the spacer is made easier by putting it in the freezer for a few hours.

Yup, you can "drop" bearings into hubs that way. In fact bearing into the freezer and warm up the hub as well in an oven.

[GlobalRider]

One thing lead to another and when you need to take the rear wheel off so that the middle muffler can be removed, you tend to clean up the drum in the wheel and brake shoe area while you have them off.

Final Drive & Hub - 2.jpg

Final Drive & Brake Shoes - 1.jpg

All together again and 100% leak free.

As for replacing the neutral switch, I can see inserting the push-on terminals with it in place and nothing removed could be next to impossible, especially if they are a tight fit as mine were. But I wonder if shops don't install the neutral switch without removing anything and just having a self made and bent 19mm wrench to loosen it and tighten it. As long as you get it started, you are home free.