Adjustable Front Motor Mount

I wish I had metal shop.

It is hard to take a new design idea to test having to pay someone else to do the cutting and and bending for a prototype, but if you are lucky like me you have a metal shop literally right around the corner.

I have really grown tired of customizing a front mount for most every bike because the motor mounts 'won't play nice' with the frame so I set out to make a mount that should fit most anything I ever build again, and I am starting with this existing direct drive bike someone else built and converting it to Jackshaft Shift Kit bike so the customer can use his 7-speed derailer gears.

Considering JS kits dual great motor mounts and 3rd 'height keeper' clap and shaft I could have just used what was laying around and use the existing frame hole bolt to secure it to hold the front...



But that is a frame hole mount and I hate those.
I would rater squeeze the frame a bit and use standard parts than compromise the frame by drilling a hole in it.

This first version will work dandy for this build, it just a custom 'L' bracket with a secure muffler clap to attach it to the frame on the side.
I will get to why that is important in a bit, but here are the test fit pics.



Note the grove to slide the motor up and down, important for a JS bike.



Nothing to it really, just a prefect fitting $1.50 muffler clamp and custom 'L' bracket. The rub with the bracket is not having the tools to do it yourself, that sucker cost me $35 to have made today!

It does the job though, and it doesn't get in the way on the left side of the bike where the tailpipe comes down and leaves space to get to most anything you want to adjust.



More tomorrow when I wrap this up, it's been a long day.

camlifter said:

nice idea. you should make the bracket out of 3/16th and put a gusset in the 90* bend. looks promising.

Click to expand...

I agree. For a regular direct drive motor setup 3/16" or even 1/4" will be used, that was the thickest the sheet metal shop had and this is not a direct drive, it is a Jackshaft drive.

There is no side lateral pull, all the pull is directed down.
Besides the 2 muffler clamps 6.5" inches apart securing the JS to the seat post, there is also an adjustable vertical stud holder keeping the motor from moving down.

I do think this design would be perfect for left direct drive mounts as well, besides putting some meat where you need it, against the right side downtube, and you get the added bonus of no pesky left mounting blocks that tend to get in the way of tailpipes. Heck, even the new 2010 muffler with the heat shield fit with room to spare.



I think she turned out quite nice and an absolute pleasure to ride.
It goes through the gears smooth, and flat hauls a$$.
And vibration? Pffttt, all I felt was the that front tires imperfections at 40.





I took her for hard 20 some mile run up and down hills to get the new chains broke in, now is when I will really appreciate that adjustable front mount as the motor needs to go up a bit ;-}

Venice Motor Bikes said:

Think about what would happen to a customer if that mount eventually failed & the rear mounting bolts quickly followed while riding that bike going 'flat out at 40 MPH'. Just think about it for a minute....

Click to expand...

I agree, 3/16th or 1/4" steel needs to be used for stock rear mount and direct drive, but hey it's a forum and where we share so let's think about This Particular Mount.

"What would happen if the front mount failed.."

Better yet, what would happen if there was NO Front Mount At All on this bike?

The main direction the motor will want to move is almost straight down, but with a very slight tendency to want to twist to the right.



Heck, take the Jackshaft portion completely out of the picture and look at the upper and lower main mounts themselves. Just that dual mount with a flat piece to the motor with it's bracket removed is way better than stock.

In this case there is even a 3rd mount to combat that downward force!
The front mount has no downward load.

Now for the sake of argument the rider beats it to heck and never tightens a single thing and all three of those muffler clamps get loose enough to move, which is really loose to even slide one...
The motor will move down and slightly right under power.

OK, the motor has about ~3/8" twist before the muffler hits the frame to the right, about the same before it hits the pedals to the left. The chain from the JS to the Freewheel Chainring will be loose and jump, and the rider will feel like an idiot for not doing any basic maintenance.

But please, tell me again how that 1"x1"x1/16" area of unsupported galvanized steel of my bracket can fail, and why this was the worst solution to This Mount when it does exactly what I needed it to do?