PR: Proprietary Items Grosset Starter Motor

bmetcalf

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The '70's and '80's BMW starter motor is in a housing on top of the engine:

4525703439.jpg
 

Bill Cannon

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As a BMW dealer I can tell you that Valeo is one of the makes that airhead BMWs use and they have a long reliable life. The brushes and springs are very similar to the Grosset starter, however, I don't think the BMW uses the planetary gear system as it has sufficient gear reduction by virtue of the large flywheel ring gear.
The Grosset system turns the gearbox mainshaft so the mechanical (dis)advantage of the primary drive puts much more strain on the starter and increases the strain on the reduction gear train on the over-run.
Bill
 

BigEd

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As a BMW dealer I can tell you that Valeo is one of the makes that airhead BMWs use and they have a long reliable life. The brushes and springs are very similar to the Grosset starter, however, I don't think the BMW uses the planetary gear system as it has sufficient gear reduction by virtue of the large flywheel ring gear.
The Grosset system turns the gearbox mainshaft so the mechanical (dis)advantage of the primary drive puts much more strain on the starter and increases the strain on the reduction gear train on the over-run.
Bill
I've not dismantled the starter motor on my Rapide so I don't know if it has internal reduction gears. There is a train of gears in the aluminium transfer gearbox that takes the drive from the starter motor output gear to the mainshaft. I think this is what provides the required mechanical advantage. It has worked fine for me so far.
 

greg brillus

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I've had two instances with these kits installed where the starter engaged itself whilst riding, the only visible clue was the ammeter was going near off the dial. After I got home from a short ride around the block the battery was red hot, I mean..... really hot. I put the bike up in its center stand and when I moved the handlebars the starter began turning the engine over by itself. I quickly worked out that it was the button on the bars at fault. Apart from replacing the button with a better one, no harm was done. On the second bike, I had a suspicion that the same had happened but this time it did some damage. The small pinions that support the small transfer gears in the alloy drop housing that Eddy mentioned had seized to the gear and spun the pinion shaft in the alloy housing...........This kit had only just been installed by someone else, so it was all like new. To repair the housing and make a new special pinion cost about 150 to 200 pounds. I feel this happened because the starter had been engaged without the owner knowing, and the pinion and its gear could not handle that constant use/abuse. I always use top quality buttons for the starter on these now, and I strongly recommend some form of isolation switch to kill the system. Wouldn't be fun watching your bike propel forward off its stand if some young 5 year old wonders what the shinny red button on the bars is for.................:eek:.
 

stu spalding

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Sorry........ok, I know the system is a compromise, but most of the issues seem to be the actual motor itself, either the plastic planetary gears are too weak and fail, or now corrosion issues. I have installed some of these kits myself, but I must say they are on bikes that get used very little. Surely with the massive range of starter motors on the market, that some must be better than this. Any thoughts..............?
Hi Greg, I've mentioned this before but here goes again, at one time Herve Hamon made a direct replacement for the Grosset motor using, I believe, a Toyota Celica motor. this is better in every respect but as Herve has started making his own system I'm not sure whether these are still available. A future project for me will be a solenoid engaged dog clutch to replace the sprag clutch but this is still wafting about in the nebulous miasma between my ears. Cheers, Stu
 

greg brillus

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I get your point Stu, but I think the amount of room for something large enough is the big problem. Even if a ring gear could be used on the clutch chainwheel, it is still quite small. The pictures posted on here that showed a sprag clutch on the ESA and a small chain/sprocket driven by a cross shaft through the kick start shaft hole seemed quite clever, but complex and costly to make. On your own machine you can play around with whatever to make it work, but to do it commercially................o_O
 

clevtrev

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I've had two instances with these kits installed where the starter engaged itself whilst riding, the only visible clue was the ammeter was going near off the dial. After I got home from a short ride around the block the battery was red hot, I mean..... really hot. I put the bike up in its center stand and when I moved the handlebars the starter began turning the engine over by itself. I quickly worked out that it was the button on the bars at fault. Apart from replacing the button with a better one, no harm was done. On the second bike, I had a suspicion that the same had happened but this time it did some damage. The small pinions that support the small transfer gears in the alloy drop housing that Eddy mentioned had seized to the gear and spun the pinion shaft in the alloy housing...........This kit had only just been installed by someone else, so it was all like new. To repair the housing and make a new special pinion cost about 150 to 200 pounds. I feel this happened because the starter had been engaged without the owner knowing, and the pinion and its gear could not handle that constant use/abuse. I always use top quality buttons for the starter on these now, and I strongly recommend some form of isolation switch to kill the system. Wouldn't be fun watching your bike propel forward off its stand if some young 5 year old wonders what the shinny red button on the bars is for.................:eek:.
If you read the instructions, the wiring diagram includes a switch in the system.
 

Albervin

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I have an isolation switch on my Shadow but it is not used to stop the bike. Its sole use is to isolate any draw on the battery. With an Alton + electric start it is only commonsense.
 

Bill Cannon

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I've not dismantled the starter motor on my Rapide so I don't know if it has internal reduction gears. There is a train of gears in the aluminium transfer gearbox that takes the drive from the starter motor output gear to the mainshaft. I think this is what provides the required mechanical advantage. It has worked fine for me so far.
Eddy I had the Grosset on my bike and can tell you that it does have nylon planetary gears within it, although they did not cause any problems on my bike.
 

BigEd

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Eddy I had the Grosset on my bike and can tell you that it does have nylon planetary gears within it, although they did not cause any problems on my bike.
Thanks for that Bill. The starter motor is off the bike at the moment so when I have a moment or three I'll have closer look.
 
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