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General Category => General Discussion => Topic started by: Kiwi_Roy on January 03, 2021, 07:57:08 PM
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I thought I had taken care of the generator mounting on my 72 Loop
I screwed exhaust studs into the block and braced it off the distributor stud with a piece of angle
To my surprise when I pulled the engine I found both studs sheared off flush, the generator was held by just the distributor bracket.
Any thoughts on why the studs would shear and what I can do about it.
Of course the broken studs are jammed in the block, I probably used lock tight for good measure.
Does an alternator conversion use the same two studs or is the alternator mounted differently?
I was wondering if the generator bracket was not sitting on the block correctly, perhaps rocking in the centre along the stud line.
Whats the latest thoughts on mounting a generator?
I think the path forward is to weld nuts onto the broken studs, does that sound right?
Larger studs perhaps?
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If they would have put the studs ninety degrees from what they did, probably never would break. I think mounting the generator or alternator on the frame and running a longer belt solves the problem but you have to carve up the front cover for belt clearance unless the alternator kit has solved that.
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The Scrambler Cycle alternator kit uses the same two studs.
Many times the "saddle" cast into the engine block gets worn and the result is a gap between the block and generator. I make an aluminum shim to fill that gap, which supports the front of the generator and helps prevent stress on the bracket mounting bolts.
If possible, I have the mounting area of the block machined flat. Otherwise, I flat file it as much as possible. Plus, I use larger o.d. flat washers on the mounting studs to spread the stress over a larger area.
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I could probably stick a pair of "J" bolts on the outer edge, I've already got those in place of the exhaust nuts which are well stripped, my Bro Kiwi_Kev suggested that, its been a couple of years with no problems there.
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The Scrambler Cycle alternator kit uses the same two studs.
Many times the "saddle" cast into the engine block gets worn and the result is a gap between the block and generator. I make an aluminum shim to fill that gap, which supports the front of the generator and helps prevent stress on the bracket mounting bolts.
If possible, I have the mounting area of the block machined flat. Otherwise, I flat file it as much as possible. Plus, I use larger o.d. flat washers on the mounting studs to spread the stress over a larger area.
Thanks Charlie, you can definitely see where the bracket has been working against the block, I thought I might try supporting it just at the outer edges so it pulls down in the centre, will try to file it flatter.
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I think the path forward is to weld nuts onto the broken studs, does that sound right?
Yep..
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The Scrambler Cycle alternator kit uses the same two studs.
Many times the "saddle" cast into the engine block gets worn and the result is a gap between the block and generator. I make an aluminum shim to fill that gap, which supports the front of the generator and helps prevent stress on the bracket mounting bolts.
If possible, I have the mounting area of the block machined flat. Otherwise, I flat file it as much as possible. Plus, I use larger o.d. flat washers on the mounting studs to spread the stress over a larger area.
I concur. I think that making sure the generator somehow rests on the saddle is very important in reducing the stress on the studs, and I made a similar aluminum shim for my Ambo. In my case, the threads in the crankcase were wollered out, and I re-drilled them and tapped them for HeliCoils. To redrill them in the frame required using a right-angle pneumatic drill. Then I initially had problems with the studs unscrewing themselves from the block, and finally settled on Nord-Lock lock washers, which are of a novel design that actually appears to work.
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The ribs cast on the crankcase seem to be dead flat, I am thinking about dishing them slightly so the bracket is resting on the outer edges rather than rocking in the middle along the stud centres, what do you think of that?
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Wouldn't it be better to have the bracket rest on a larger flat surface instead of four points? Is the motor in or out of the frame? Can you mill the casting to be flat?
I have a vested interest in this, so I thank you for bringing it up- I'm converting a newer SP motor to go in my Eldo frame and I'll want to put studs in to mount an alternator.
Oh- since I mention it- how deep are the two mounting holes?
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I had Cyclegarden remove the broken bolts as I couldn't seem to do it. Once they did that, they put in their heavy duty bracket and secured it. Haven't had a problem. I don't know if Moe has any others, as he doesn't seem to be selling on EBay anymore. Give him a call...
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Roy: One thing to check is your pulley, most are bent due to tightening up the screws too much on one and proceeding to tighten the others, make sure it is dead straight and do not over tighten the belt tension or bracket failure will reoccur. When tightening the screws rotate the crank and tighten the screws equally or a misshaped pulley will occur. DonG
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What Don G said. To add to it, you'll rotate the engine a few times while tightening the bolts. Just a turn at a time on the bolts. Best done when a bolt is lined up a little past the timing mark, just about where the belt enters the pulley. Snug that one and the one at the bottom, then rotate.
I just did the holes for a SP/G5. I don't remember how deep. Easy to do out of the frame, but can be done with a angle drill or drill adapter.
Tom