Attaching torques arms on a "weak" setup

[ibellisch]

My build was a GT Aggressor 3.0. I'm running stock golden motor parts and it does just shy of 50kph. For 6 months I've been relying on the torque of the nut, friction and torque arm to hold the axel from spinning out. Over the months, it has been grinding a bit of the dropouts until it couldn't stop spinning the axel out recently. The torque arms I had were golden motor stock torque arm. It's time for me to attach doctor bass torque arms and I'm unsure of what to do. School is starting soon (2 days) and I don't have time to order anything. My frame is aluminium btw.

Take a look at the axel in the stock dropout.

Those two shaded spots are where the bolts would go if I were to bolt it.

This is how much the Doctor bass torque arms have in contact with the drop outs.


This is the thickness of the dropouts with reference to the torque arms.


The side with the derailleur is the side I'm more worried about. The two holes for where the bolts would go, land exactly on the middle of the crack between the two metals.


I've been advised to grind the derailleur's metal piece to make it flush with the rest. But, I can't seem to get hold a grinder anywhere.

I am concerned about the structural strength of the drop-outs if I drill two holes on the said spots for bolting the torque arm. I can't mount the torque arms on the inside because it takes enormous strength to stretch those chain and seat stays apart (the Left and Right rear triangles). I see that some of you glue with DP420 but there are none available close to where I live. I live close to canadian tire though (for canadians) There's JB Weld and I've seen some of you mentioned that but I'm not sure how strong that is and it's winter(not sure if the coldness affects the strength).
I was thinking that maybe I can bolt one side and maybe use the glue and just use the glue on the other side.


Thank you if you've reach this far and please do drop a comment or two.

 

[Doctorbass]

Hi

I would suggest to install the T-A ( no derailleur side) with two 5/16" or M8 bolt at the location i have shown in the picture: ( these bolt are availlable at Canadian Tire)

As for the other side i agree that it would be great if you could just grind the derailleur's metal piece to make it flush with the rest and install the T-A on the top of that with two bolt.

If you could add some JB weld between the T-A and your frame it would be excellent. be carefull to have great surface preparation ( clean ( no grease!), grind it a bit to get it abrasive, than glue it and bolt it!

Doc

 

[e-beach]

Step 1: Contact Doctorbass and ask for assistance. Follow his directions exactly, even if it takes you longer then you want it to.

Step 2: Find the best bus route or another way to get to school until you can attach the Doctorbass dropouts as per his instructions.

IMO bolting to one side and epoxying to the other is fine on a low to medium powered hub motor, but it has to be a very good job....no shortcuts.

The look of your dropouts is really bad to me so I would be cautious. Better to take the bus to school for a week or two while getting it all together then having the hub motor snap off and causing you injury....not to mention school books in the gutter.



EDIT: Doc, you beat me to the first replay.... ..... :lol:

 

[ibellisch]

Thank you guys. But, on the side with the derailleur's metal piece. --> The piece is bolted on plus how am I supposed to drill on a crease (where the two metals meet).

 

[friendly1uk]

Don't DB sell these with derailleur mounts? I'm sure I have seen some.


Do you realise you always had the right bits, but fitted them wrong? It's not to late either. Though if you motor is a single piece shaft, you don't need an arm drive side anyway. You can just fit the db on the non drive side and if you like, use your torque washer drive side instead. Engage the tab in a frame recess though. Just a single hole under the derailleur plate. .


If you going to glue arms on, you can just sand the parts as a key, but sink in a drill bit just 1mm on both parts and you won't actually need any adhesion. Your glue will set as an interlocking part.

 

[e-beach]

Inexpensive grinder attachments can be purchased for a hand-held power drill. Not the best option, but if used carefully and with patience decent to good results can be obtained. It can take a while to get the shape you need or want, but it is doable.