Cracked Sub Frame

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wyndzer · #1 Post by **wyndzer** » Sat Oct 04, 2003 12:47 pm

Just to make things clearer, are you talking about the sub-frame(the part that the seat is on basically) or the the engine frame rail? Either way a competent aluminum welder will be able to weld it.

jake1981 · #2 Post by **jake1981** » Sat Oct 04, 2003 2:10 pm

You have to make sure you're using the right materials. I'm sure if it's just the sub frame you'll be fine, but somebody was telling me that the frames were pressure welded, or heat treated or something so make sure you're using the right materials. I'm just making sure that it doesn't require any specific welding techniques.

4strokemadman · #3 Post by **4strokemadman** » Sat Oct 04, 2003 3:02 pm

The Subframes (and frames for that matter) are made from 6061 Aluminum heat treated to the TCannondale (A proprietary Cannondale heat treatment) condition. If you weld it, it will be very soft in and around the weld. It will more than likely keep cracking again and again, unless you weld then heat treat.

In the very early days we cracked the subframe mounts on the main frames during testing. We only had one machine running and we welded over the crack to try to keep us going for a while. We ended up welding it like 5 or 6 times because it kept cracking through. In the end we just retired the frame.

Hope this helps.

cannondale27 · #4 Post by **cannondale27** » Sun Oct 05, 2003 1:54 am

I would say if it is heat treated to whatever a airplane wing is you would be fine.

cannondale27 · #5 Post by **cannondale27** » Sun Oct 05, 2003 12:44 pm

Big winky ran into same problems dealing with powdercoating.Here you go.

Powdercoating c-dale frames, please read!
Today I went and talked to modern heat treating in erie, pa. what ever you do DO NOT powdercoat your frame it WILL lose the temper. the process goes like this.... the frame is heated to around 1000 degrees to normalize it, then it is placed in a solution to prepare it for tempering, it is then heated up to 350 degrees and then "aged" for the resulting t-6 temper to the alum. heating this tempered frame to the 425 degrees required for powdercoating will destroy the temper and you will have a pretty, but useless frame.

http://cannondaleriders.com/vbb/showthread...t=powdercoating

fourwhls · #6 Post by **fourwhls** » Mon Oct 06, 2003 1:33 pm

I had the same problem with my subframe or engine craddle. It cracked parallel with one of the welds below where you would drill for the engine mount update.

I welded it about a month ago and as of last weekend it was still good to go. I will check it again tonight to verify that status. I just cleaned it well and welded it thoroughly with 6061 rod.

After the previous comments, I will keep an eye on it.