BannedCR500Riders.com

I have been cutting and modifying mine CRF 450 2007 frame and i found out that stock Y section is pain in the ass for reuse. So i dont wanna grind mine maintube down to make that stock y fit or remove cradles from center part of frame. So i think if i make billet y which look like yamaha yz250 section and yzf 450 2010 section. Also i want that i dont need to bend old tubings when assembling y section at place and i want that the new y section will make connection to end of tubes...

So heres is picture of that y section, so tell me what you think. Material thickness is quite similar than yz 250 and the tubing in the cradle. This y section weights 600grams more than the old y section cleaned for re use.

Whole part weights 1,1kg

Sorry mine bad english. I will give detailed drawings for free use. if i get some decent feedback. I dont wanna hide this, because i have got lots off useful information at this forum.

red lines at the picture represent hole at inside of y section, this is for weight reduction and giving more flex for this y section.

nice work what about provisions for the front engine mount on the y

i think to add that but i think it is hard to make that upper mounting place in right place. Also motor mount will work as extra support for that lower welding point.

its not that hard first cut the frame and get the motor in the frame in the correct location then take some measurrements

also the hieght of the exhaust to the engine mount doesnt change so all you have to worry about is the down tube and where you want to cut it in

yeah, its not that hard. But i want to avoid to remove or bend those lower cradles. I want to make y section which work like cut the y and lower mounts of and then weld new y section and motor mounts back in place.

I think it is recipe to avoid those broken welds, which are going because of there is tension at cradle.

I can be wrong offcourse. that why im asking your opinions.

Also when i make that y section that way i can make it at smaller piece of aluminium and less hours at milling machines.

what modeling program are you using im running solidworks

Proengineer

I saw a Service Honda the other day and it had the billet Y with the front mount cut in it like Greg's pic. I think it may be stronger in the way that you don't have to weld the mount and that eliminates the risk of weakening the tube above the front mount like where my frame cracked. (http://bannedcr500riders.com/board/viewtopic.php?t=9660 )

That way you just have one weld below the mount, so the engine act as a support for the entire frame too.

there is picture of "factory" version of this kind of y section. This is from yz 125 -10

there is new version of this design...

Nice Y section.. Ive done 3 of the AF conversions now.. The first one cracked at the welds from the tubes to the Y section.. I found that it was from the headstay flexing.. I don't have photo's to show but look at groutaone on youtube, he shows the same thing I'm talking about.. I'm doing 2 AF conversions now in 07 125 frames, this time I will have photo's of each stage of these builds & explain in detail how to rectify cracking.. I replace the whole tubes underneath, it's easy to roll new ones into shape.. Ullrich Aluminium sells 25mm square 3mm wall tubing cheap in Australia, sorry I can't give any advice for people in the US..

what are you on about mate which y and what advice you on about

I was just saying how when the cradle tubes break or crack at Y piece it can be caused by the motor rocking back from torque, especially in motard, so make sure the headstay plates are heavy enough to stop it so it's not pulling on the front engine mount under acceleration.. I've had this problem & heavier headstay plates was 1 way I fixed it..