Bosch Starter Puzzle

[fdwilkin]

I don't know the history of my 1978 R100/7, but I suspect it has the original starter. The starter was getting weak, so--after confirming the battery and wiring were OK--I disassembled the starter. I found that the starter needed (at least) new bushings, a good cleaning and a bit of lube.

I also found the remnants of a large white plastic-like washer in the area of the drive housing/starter gear (about 35 mm OD, 25 mm ID).

What the heck is that? Where did it come from? Where can you buy this part? Thanks.

[20774]

Never been inside my starter, but maybe these sites might give some ideas about that part:

http://gallery.oldholden.com/Jack_s/...Starter+Motor/

http://www.thisoldtractor.com/gtbend...ir_-bosch-.htm

[AnnapolisAirhead]

I just rebuilt two Bosch starters, an 8-tooth on my '72 R60/5 and a 9-tooth on my '83 R100 based on Greg Bender's website. Both were the original starters and both have about 60k miles on the bikes.

Lots of things wear that are not evident (besides the brushes) and the bendix needed a good cleaning and lube like you mention. There is the large body that houses the winding/bendix assembly and the smaller body that is the solenoid. I took one of these apart, but it requires unsoldering two posts, then resoldering...not sure that was reall worth it.

The bendix is inside the larger of the two bodies with the gears/teeth partially exposed on the fully assembled starter. The bendix can come apart for a complete cleaning, but plan on spending the better part of a day getting the bendix clip re-assembled. I would strongly advise you to avoid doing this if you can clean with contact cleaner alone and relube the spiral gear on the shaft. The large body comes apart in three pieces, I'm sure you foud out: the buttplate, the winding body and the nose cone. There shouldn't be any washers between these three pieces.

Before you take the two long 9mm screws out that hold the nose cone and buttplate to the main body, you need to remove the tine dome cap that covers the shaft end. The only larger washer that you might be referring to is under the small shaft cap on the buttplate where the end (non-gear) of the shaft is held into place by 3 thin washers and a "C" clip that slides on easily. Where the shaft end protrudes through the buttplate, the is a washer about the size of a nickel that sits around the shaft as a water seal, held captive by the small dome cap.

I didn't run across any white plastic washer. I'm having trouble discerning where you found this (got a picture?).

[fdwilkin]

Thanks Kurt and AnnapolisAirhead.

The tractor web pages show the Bosch starter same as our Airheads!

Upon further investigation, I noticed that the starter gear assembly has a metal double-washer set, with the first washer nesting inside the hollowed-out second washer. The solenoid operating lever acts on this washer combo. It looks like the white plastic-like washer would fit exactly between these two washers (were it whole). Does this make sense?

[20774]

The tractor web pages show the Bosch starter same as our Airheads!

Upon further investigation, I noticed that the starter gear assembly has a metal double-washer set, with the first washer nesting inside the hollowed-out second washer. The solenoid operating lever acts on this washer combo. It looks like the white plastic-like washer would fit exactly between these two washers (were it whole). Does this make sense?

Which picture from the tractor site are you referring to?

[AnnapolisAirhead]

Thanks Kurt and AnnapolisAirhead.

The tractor web pages show the Bosch starter same as our Airheads!

Upon further investigation, I noticed that the starter gear assembly has a metal double-washer set, with the first washer nesting inside the hollowed-out second washer. The solenoid operating lever acts on this washer combo. It looks like the white plastic-like washer would fit exactly between these two washers (were it whole). Does this make sense?

That washer you are referring to as inside of the hollowed out area on the gear assembly (that's actually the shaft that the bendix rides on) is not a washer, it is a spring steel clip and the part I was referring to as not advisable to take apart (picture #32) in Greg's site. Picture #33 show the bendix off the shaft. It is a major pain to get that larger collar to pull up over the ring. I used three men, a mule, a carefully crafted vise jig and a three fingered bearing puller and an extra Jackson in the offering plate to reassemble.

How much of the starter did you take apart?

[fdwilkin]

The puzzle is that none of the manuals or pictures I have actually show the large white washer.

See picture 33 on the thisoldtractor site--they call this sub-assembly the bendix. The large white washer looks like it could fit around the shaft in the "rabbit ears" area (by finger of mechanic).

Clymer calls this same sub-assembly the starter gear. See page 398 (2001 edition). The metal double-washer set is toward the left of the part.

Hope this helps....

[AnnapolisAirhead]

The puzzle is that none of the manuals or pictures I have actually show the large white washer.

See picture 33 on the thisoldtractor site--they call this sub-assembly the bendix. The large white washer looks like it could fit around the shaft in the "rabbit ears" area (by finger of mechanic).

Hmmm, maybe someone was in there that should not have been. I think its a part that does not belong. Not in any Clymer's, Haynes or BMW manual I've seen and neither of my starters had one. The piece with the rabbit ears and gear teeth (which get thrown into the flywheel) is the Bendix including the spring. The shaft and windings just spin the Bendix. The solenoid is energized and throws the little metal arm that piece shaped like a "Y") to engage the Bendix gear into the flywheel. You probably know all of this, just making sure we are on the same page.

Clymer calls this same sub-assembly the starter gear. See page 398 (2001 edition). The metal double-washer set is toward the left of the part.

I think that refers to the spiral gearing on the shaft itself. Tomaaaaato, t'mato. We're referring to the same part. :-)

I got a little confused reading the printout of Greg's (ThisOldTractor) site because the text appears ABOVE the picture he is referring to. The double metal washer set on the shaft is a collar (the darker one) and a ring. The collar goes on first, open side up, then the ring rests in the recess cut into the shaft. Then (the hard part) is pulling the collr up over the ring. Took me a long time to do that.

I still don't see a white plastic washer anywhere in the starter. Is your start body stamps on the outside part of the main body, made in Spain?

[fdwilkin]

The starter has "Made in German" stamped on the main casing. I really haven't disassembled much of the starter--I found the remnants of the white plastic-like washer when I removed the "nose cone" or drive housing.

[AnnapolisAirhead]

You could ask a dealer, but sounds like it was patchwork from someone trying to fix the starter before. It should not be inside the starter, IMO.

[RandyB]

Plastic washer? I've had both mine apart in the last 2 weeks and ain't no washer in there.

Make sure you get that little yoke that moves the bendix back in correctly. Otherwise you get a clank when you push the button. I know this from experience.

The Haynes manual has pretty good instructions for this.