Poo - Another Dead Denso. I Have a Cunning Plan...

[Magwych]

I an working through several issues as a result of long term storage of my 2008 GSA. The high mileage does not help but the bat shit has been hell on rubber items.
I had been pleased that I seemed to have survived alternator issues, fuel tank, fuel sensor strip, starter relay, tyre pressure monitors, all fixed.
Doing a full engine service, oil, plugs, filters, valve clearances, rear drive oil, brake fluid flush and alternator belt change. Here is where I came unstuck: Turning the engine over on the belt pulley it was clear the belt was just sliding over the alternator pulley. I know it was working just a few weeks ago, I had measured battery terminal voltages with the engine running to check the alternator. I guess the shock was too much and the alternator has oeobably exploded.
I haven't the time to strip it down again in order to remove the alternator, but I do have a plan...
Reading the many threads on the fragility of the 60A Denso alternators I had been looking for second hand R NineT Denso units. I don't fancy changing crank pulley and belt size to match the Bosch alternative. The R NineT units seems to have increased in asking price recently, probably as working units become rarer and GSA owners suffer theirs detonating.
Then I hit upon another model that uses a Bosch 55A unit, has the smaller pulley, the same crank pulley as the GSA and the same belt. That means I should only need to sort out the wiring connector for the ignitor circuit, and have almost the same charging capacity.
I am not going to pass on details yet, not until I have secured a unit for myself at their curent much cheaper S/H price - and can confirm the fit.

 

[Santa-2512]

Best of luck - pretty sure i looked through both Denso & Bosch catalogs,

Plenty match the case size & power output & pulley size.

The sticking point is the hole spacing on the footplate - nothing anywhere near

Lets hope you have a winner

 

[Pukmeister]

Best of luck - pretty sure i looked through both Denso & Bosch catalogs,

Plenty match the case size & power output & pulley size.

The sticking point is the hole spacing on the footplate - nothing anywhere near

Lets hope you have a winner

Mart, if the casting is the same I’d be happy to drill one for you to fit the Hexhead bolt spacing.

 

[Santa-2512]

Mart, if the casting is the same I’d be happy to drill one for you to fit the Hexhead bolt spacing.

I dont think any of the castings feet were the same - that being the issue

I did wonder if a spacer block was the option along with a longer belt - but clearly not ?

 

[Slipperyeel]

I did wonder if a spacer block was the option along with a longer belt - but clearly not ?

That was my first thought, but then I got to the end of your text!

Are holes 'just out' or a completely different footprint?

Sent from my SM-S908B using Tapatalk

 

[Magwych]

I am waiting on the delivery of a R1200R Bisch unit, BMW part # 12317715081, Bosch # 124120015.
The pulley size is correct, the R1200R uses the sane 4PK582 as the 2008 Adventure and the same crankshaft pulley.
I am making some assumptions on the fit, but at €65 I am willing to take a punt. If necessary I will try to modify the mounting feet.
Curiously, on my 2008 GSA the parts fiche comments that the Denso 60A alternator requires an additional wiring adaptor cable fir a Denso alternator. When I have a chance to remove my old Denso I will be able to have a closer look at what is there.

 

[Steptoe]

Curiously, on my 2008 GSA the parts fiche comments that the Denso 60A alternator requires an additional wiring adaptor cable fir a Denso alternator. When I have a chance to remove my old Denso I will be able to have a closer look at what is there.

There is a thread in the 1200 section showing the different loom attachments for Bosch and denso and bmw part numbers. It’s a pretty straightforward swop short loom swop, it all plugs in and the bmw kits even contain the crimps etc, think the last one I bought was about £14

 

[crumbles]

If you scroll past my posting ,
At the bottom you will see the thread...

 

[Magwych]

If you scroll past my posting ,
At the bottom you will see the thread...View attachment 313316

Thanks.
I stopped following threads on the subject because they mostly seem to refer to another thread here, or on another forum, which then refers to other threads. Then, once you get redirected to ADVRider it soon descends into a pissing up the wall contest with little content of merit l.
I'll have a look at yours, the title looks promising

 

[Magwych]

@Ianak thank you for your PM requesing information.
If we keep the conversation public, others may benefit from it too I am only going to reply here, unless the conversation subject needs to be one-to-one.
I am not in a position to measure my Denso pulley nor have I received the Bosch. I am under the impression, from bouncing around the internet, that the Debso is 55mm, as is the Bosch unit that I have identified. When it is delivered I will make some time to strip the bike down, again, to measure.
Meantime, perhaps the thread that crumbles started (see last 2 posts) will answer your question definitively "what diameter is a Denso alternator pulley"? My belief is that on the MU R1200GSA it is 55mm. Are you not able to measure your own? They are usually 55mm or 87mm, the latter used 9n most, but not all, Bosch units.
If my readings were correct, the 40A Bosch units had the larger size, longer belt, running at a lower rpm for any given crankshaft rpm than the 60A Densos. The 55A Bosch units had the same size pulley and belt as the 60A Denso units.

 

[Magwych]

The good news is that the Bosch is a perfect direct drop
My Denso is dead, case split between the mounting feet. It does not rotate.
On my R1200GSA, there is a short section of wiring with a plug fir the Denso alternator one end, and a socket identical to a Bosch alternator socket on the other. The stock wiring loom has the plug to connect to a Bosch alternator.
One question though : The Denso unit has a capacitor mounted externally; has the Bscho git an ibternal capacitor, or do I need to plan to swap over the one from the Denso? You can see it in the second photo below

 

[Magwych]

Found ny own answer... I removed the brush holder to cgeck the brushes before fitting. The holder appears to have an integrated capacitor. Measuring the resistance across the brush terminals (not mounted to the alternator) it could be seen to go from a few mega ohms to infinity over the course of a few seconds. That behaviour is typical of a capacitor, so I am asuming no external one is required.
A 55W Bosch alternator in a 2008 R1200GSAdventure . Note the loose frame strut on the left, necessary to get the units in and out. The ABS pump makes removal tricky..

 

[Pukmeister]

Magwych, try drenching your old Denso alternator in WD40 then get a spanner on the pulley nut:

My old 2008GSA Denso alternator had seized and the casing had cracked between the mounting feet. I pulled off a chunk of casing and got the rotor freed up and it worked again just fine.

I later replaced it with an as new unit from USA but kept the old Denso as a spare, they are like hens teeth.

 

[Magwych]

Magwych, try drenching your old Denso alternator in WD40 then get a spanner on the pulley nut:

My old 2008GSA Denso alternator had seized and the casing had cracked between the mounting feet. I pulled off a chunk of casing and got the rotor freed up and it worked again just fine.

I later replaced it with an as new unit from USA but kept the old Denso as a spare, they are like hens teeth.

Great idea, I may give that a try one day
As it is, the Bosch is a perfect fit. The pulley is the same size as my old Denso so the new belt that I had just bought went straight on. The wiring was a dulirect connection, no modifications required at all.
At €65 for a S/H R1200R Bosch alternator with plenty of brush length left I am well chuffed. The only difference may be the electric output, the Denso states it is 60A whereas the Bosch says it is 55A. Over on ADV Rider there was done "debate" regarding the ratings, I got bored reading it.
If the Denso and Bosch outputs are both measured at 14V, I can live with 8% less power being supplied. If the weather dictates heated vests as well as grips I now have the luxury of being able to use a car instead The bike no longer has to do a 110 mile round trip commute, all year round in all weathers.

 

[Magwych]

It's back together and working perfectly
Whilst doing this I have been giving it a service and putting the original silencer and headers back on.
I had forgotten how much easier doing the belt was with the Keihin headers...I had to take the crashbars back off just to put the belt cover back on

 

[MWH]

Is there any preventative measures that can be taken to stop this kind of thing happening?

Maybe squirting WD40 in it etc? Or would that attract dirt?

Dreading this happening!!

 

[Mistacat]

I have always sprayed ACF50 around the top of the engine and into the alternator when the tank is off.
Used a cheap touch up gun 150 psi gives a very fine mist.
Done this from new and not a spot of corrosion, bike used all year round and has done 96 K miles .
Hands get dirty when working on the bike but I prefer that to removing corrosion.

 

[Steptoe]

Is there any preventative measures that can be taken to stop this kind of thing happening?

Maybe squirting WD40 in it etc? Or would that attract dirt?

Dreading this happening!!

I’ve a very large pile of useless 1200 alternators…. Do not wash the bike (especially pointing a jet washer up into the front shock area) and then put it away in the garage for long periods. I’ve only had a couple of bikes with seized alternators that were used daily, but they were used all year round, both with around 100k miles. I’ve had an immaculate bike with only 20k miles, washed and then put away during winter. Alternator was a mess….. but what do you expect with crap quality ali, copper, hot and cold enviroment and then left to let nature get to work in a damp/wet enviroment…. What is strange is I’ve never had a single 1100/1150 alternator fail due to corrosion.