my proposed front mount

I

impression

New Member
my proposed front mount

well., after many sheared bolts and frustration i've been thinking how i can get a front mount that works. I've got an MS Paint drawing up, it's not to scale but i think it's alright.


see attachment
 

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I would be betting on the welds failing. How about drill where the weld is and run a bolt through it instead or in addition to the welding?
 
yes, i had thought of using bolts instead of welds but at the moment i hate bolts as i've had upwards of 20 shear on me....

my bike's downtube is aluminum so drilling through is out
it's also 50mm diameter which means if i go the plate + U bolt/clamp the heads of the stock bolts into the holed will be on the downtube and i feel will cause slipping or torquing on the bolts causing more shearings :/

i was thinking something like this, but the original mounting bolts as seen in this pic will still protude onto my downtube :/

http://motorbicycling.com/attachments/f6/4526d1230773962-oversized-tubing-solved-img_1040.jpg

this is the bike it's going on, the rear bolts sheared because the front mount wasn't gripping enough and as it vibrated there was extra torque on the rear bolts which inherantly snapped like glass.

leftside.jpg

frontmount1.jpg
 
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I can relate, I just don't weld. Putting the bolts in place would strengthen the connections, overkill I suppose.

I built something similar to your setup, I seem to have a little too much vibration which I have not worked out yet.
 
Made a few modifications to your design.

1. Do away with the pipe and original bracket entirely.

2. Drill through and counterbore (couldn't get sketchup to do that but you can get the idea) engine side frame bracket and bolt bracket to motor mount with hex head bolts.
 

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Kevlarr said:
Made a few modifications to your design.

1. Do away with the pipe and original bracket entirely.

2. Drill through and counterbore (couldn't get sketchup to do that but you can get the idea) engine side frame bracket and bolt bracket to motor mount with hex head bolts.
Click to expand...

Kevlarr, when an HT motor is mounted in a standard V frame of the correct angle and tube diameter, the shear stress on the front motor mount bolts is eliminated. The mount that impression drew up in MS paint also removes the shear stress from the motor mount bolts. The mount that you modeled, while simple, relies on shear forces in the motor mount bolts to restrain the motor from any side movement. It could work but will be more prone to bolt failure.
 
I agree with venice,,,even 2 u-bolts (1 over/1 under the block mount )work well
with 2, there is no way for it to tilt/twist sideways either
 
Ok so im going to use to steel plate/U-bolt mounting technique(thanks venice and bill) because the front tube on my bike is to big. Question: The two rods that come out of the motor, do they need to be cut to the right length so that they can bolt to the steel plate or do they come out some how. Sorry this might be a dumb Q but Im learnin here.
 
Tcams_Zonie said:
Ok so im going to use to steel plate/U-bolt mounting technique(thanks venice and bill) because the front tube on my bike is to big. Question: The two rods that come out of the motor, do they need to be cut to the right length so that they can bolt to the steel plate or do they come out some how. Sorry this might be a dumb Q but Im learnin here.
Click to expand...


this is what i made, works well, just remember to double bolt/nut the u bolt and a dab of loctite :)


101_0209.jpg

101_0210.jpg
 
I was installing a 50cc on a delmar today and came up with this mount.1 inch tubeing and 1/4 x1 plate on top welded to frame.Does anyone know where to get the gray paint to touch up.H.D.
 

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impression said:
yes, i had thought of using bolts instead of welds but at the moment i hate bolts as i've had upwards of 20 shear on me....

my bike's downtube is aluminum so drilling through is out
it's also 50mm diameter which means if i go the plate + U bolt/clamp the heads of the stock bolts into the holed will be on the downtube and i feel will cause slipping or torquing on the bolts causing more shearings :/

i was thinking something like this, but the original mounting bolts as seen in this pic will still protude onto my downtube :/

http://motorbicycling.com/attachments/f6/4526d1230773962-oversized-tubing-solved-img_1040.jpg

this is the bike it's going on, the rear bolts sheared because the front mount wasn't gripping enough and as it vibrated there was extra torque on the rear bolts which inherantly snapped like glass.

leftside.jpg

frontmount1.jpg
Click to expand...

you can take a dremel and cut them down as you need too...
 
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