Craddle cracked, snapped...

asteroid500 · Post by **asteroid500** » August 20th, 2010, 5:45 am

gregrobo wrote:well boys we lit up the 450 conversion today not a vibration runs smooth as silk we did add abit of round stock drilled and tapped between the headstay to take any harmonics it may of had the head stay looks to be about 15-20mm longer than msdesertriders setup not a great deal,anyway lots of different ways to get to the same point have a good a good weekend riding fellas

How about some pics Gregrobo

bearorso · Post by **bearorso** » August 21st, 2010, 6:53 am

Good idea, Gregrobo.

Here's a thought, perhaps take the time to ride with the spacer, then without it. It would be an interesting thing to try. It may perhaps make little difference, as it looks like you've used 5 to 6.6mm plates that are hefty in themselves, but it may well do so.

If you've seen the late model KTM 4t head stays, you'll see what I mean about the directed forces within them. I've seen a few break on pro level riders 250s. I've also seem blokes ride without them, who've felt they handled better, then blokes ride with stiffer ones I've made up for them - with various opinions. Some preferred the stiffer plates, some didn't. This is from blokes I know can assess a bike. Just shows you how people can like things that are so different.

blackz34 · Post by **blackz34** » October 6th, 2010, 5:29 pm

Here's what I managed to fab as my next headstay, you think it should be OK? I'm using '02 CR125 upper engine mounts.

And before anyone ask, no this is not a gap in this pic, just shadow!

Post by **AlisoBob** » October 6th, 2010, 5:48 pm

Looks good!

bearorso · Post by **bearorso** » October 7th, 2010, 1:24 am

Put some holes in that solid (well , I assume that's what it is) chunk of alloy the plates are going to. It's a head steady, on an AF it really isn't an integral part of the frame strength / engine interface, as it is on a steel, back bone frame. Looks good.

craigf40 · Post by **craigf40** » October 7th, 2010, 2:09 am

that will work perfectly

blackz34 · Post by **blackz34** » October 7th, 2010, 4:25 pm

bearorso wrote:Put some holes in that solid (well , I assume that's what it is) chunk of alloy the plates are going to. It's a head steady, on an AF it really isn't an integral part of the frame strength / engine interface, as it is on a steel, back bone frame. Looks good.

You mean I should drill some holes (or a bigger one) to lighten it? I can do that.

nmdesertrider · Post by **nmdesertrider** » October 7th, 2010, 7:26 pm

Looks better than mine, that's for sure. Just make sure you clear the tank before you weld it up.

bearorso · Post by **bearorso** » October 8th, 2010, 12:44 am

blackz34 wrote:
bearorso wrote:Put some holes in that solid (well , I assume that's what it is) chunk of alloy the plates are going to. It's a head steady, on an AF it really isn't an integral part of the frame strength / engine interface, as it is on a steel, back bone frame. Looks good.
You mean I should drill some holes (or a bigger one) to lighten it? I can do that.

Yep. whatever takes your fancy - it's a serious chunk of alloy that will still have big dimensions after you get creative with it. It isn't going to fail. Even if it isn't that good an alloy

blackz34 · Post by **blackz34** » October 12th, 2010, 3:30 pm

nmdesertrider wrote:Looks better than mine, that's for sure. Just make sure you clear the tank before you weld it up.

It will have a gap of about 1/4" - 3/8", so no problem there.

Yep. whatever takes your fancy - it's a serious chunk of alloy that will still have big dimensions after you get creative with it. It isn't going to fail. Even if it isn't that good an alloy

I'll see wha I can do, thank you for all your comments. Keep the suggestion comming!

blackz34 · Post by **blackz34** » October 13th, 2010, 7:48 pm

Here's what I did:

dubious01 · Post by **dubious01** » October 13th, 2010, 8:35 pm

Looks good!
I am betting your problems will be solved if the welder knows what he's doing, and is pre heating the billet parts

blackz34 · Post by **blackz34** » October 14th, 2010, 1:19 pm

dubious01 wrote:Looks good!
I am betting your problems will be solved if the welder knows what he's doing, and is pre heating the billet parts

Speaking of that, how long or what temp should be achieve while preheating? You would preheat just the billet parts? Not the rest (little brackets, frame rails etc...?)

Also, what rod would be the best? I know nothing about welding and would like to verify that with my welder before he begin. I trust him but just want to make sure. I read somewhere about 5356-SG AL M65 (or MG5 i can't re-read myself!)

dubious01 · Post by **dubious01** » October 14th, 2010, 3:48 pm

I would be regurgitating stuff I read, and I am certainly no pro on the topic... just makes sence to get good equal even, penetration, the heavy pieces should be preheated..
I will let someone who knows chime in here...

nmdesertrider · Post by **nmdesertrider** » October 14th, 2010, 7:41 pm

You don't need to go crazy with the pre-heat, about 200F

5356 is superior to 4043 in every specification
4043 is not compatible with 700x series aluminum, which many believe these frames are made out of.

mxdogger · Post by **mxdogger** » November 8th, 2010, 6:44 pm

blackz34 wrote:
nmdesertrider wrote:I'll put my 2 cents in again on this subject- my first frame had a neat hoop design that used the 450 mounts and went around the back of the head.

From the start the bike vibrated too much and the head stay continually cracked. The nipples on the radiators cracked after only a few months.

The next frame I used 125 brackets and cut a block to make everything fit together- less vibration and no problems.
I don't care if you don't trust butt welds, the other way will screw up your bike. Do it the right way.

[/img]
So those are 125 brackets? Do you know what year? Thay look to have almost the good lenght...

looks good to me, i will be tearing into my 05 crf450 soon for a AFC con. one of my biggest issues was the headstay design. from all the info i have read i think bearoso go it right about the twinspars needing to flex freely on the crf450 frame. honda did it by bolting the headstays to the side of the motor and spars allowing the spars to stay seperate from each other so they could flex.

with the designs that bolt the twinspars together via the cylinder head you loose that flex making the frame rigid thus causing fatigue cracks and maybe more. I will opt to go with a larger headstay frame mount and use some stock cr or crf250 headstays to duplicate the way honda did those frames thus allowing twinspar flex the way honda intended them to be.

BannedCR500Riders.com

Craddle cracked, snapped...