OzVMX Forum

Clubroom => Tech Talk => Topic started by: monaro308 on June 25, 2010, 01:41:28 pm

Title: More joys of Ali frames
Post by: monaro308 on June 25, 2010, 01:41:28 pm: Its a slow day so here you go...
http://www.thumpertalk.com/forum/showthread.php?t=898718
Title: Re: More joys of Ali frames
Post by: monaro308 on June 25, 2010, 01:49:38 pm: Heres another i prepared earlier :P

(http://i199.photobucket.com/albums/aa250/hjcoupe/broken500afframe.jpg)
Title: Re: More joys of Ali frames
Post by: Hoony on June 25, 2010, 02:00:34 pm: shit, how did the rider fare?
Title: Re: More joys of Ali frames
Post by: vmx42 on June 25, 2010, 02:03:41 pm: It looks like a Honda CRF Two-stroke conversion gone horribly wrong.

Ouch!
Title: Re: More joys of Ali frames
Post by: monaro308 on June 25, 2010, 02:13:24 pm: Not sure hoony,it was in the same thread as the one at the start...a few pages into it.
Wouldn't be a nice feeling to have that happen.
Title: Re: More joys of Ali frames
Post by: VMX247 on June 25, 2010, 02:25:40 pm: Not nice.
kids are so rough these days ::)
Mum and Dad pouring money into the little arena cross champ. :P
who said "the countries broke"

quote;No one will buy this bike with a great big weld where there shouldn't be a weld. :o Easy decision, replace the frame.

stick it on ebay with a real cool write up
oops perhaps he better just leave the country..
Title: Re: More joys of Ali frames
Post by: monaro308 on June 25, 2010, 02:27:51 pm: Makes changing the spark plug a breeze now :D
Title: Re: More joys of Ali frames
Post by: oldfart on June 25, 2010, 03:59:02 pm: What a clever piece of engineering ;D push a couple of buttons on the side of frame and hey presto- you can work on complete top end.
Title: Re: More joys of Ali frames
Post by: Hoony on June 25, 2010, 04:06:18 pm: i wonder if this was a "Service Honda" CR500AF or an owner built machine?

be interesting to see if the early alloy frame bikes last like our old VMX steel jobs!
Title: Re: More joys of Ali frames
Post by: Ji Gantor on June 25, 2010, 04:21:10 pm: I am interested too Hoony.

Tight nuts

Ji
Title: Re: More joys of Ali frames
Post by: VMX247 on June 25, 2010, 04:34:45 pm: Quote from: Hoony on June 25, 2010, 04:06:18 pm
be interesting to see if the early alloy frame bikes last like our old VMX steel jobs!
nothing much on the threads here ;D
http://ozvmx.com/community/index.php?topic=6186.msg61164#msg61164
big engine in wrong frame.
but nothing really substantial.
http://ozvmx.com/community/index.php?topic=7800.msg75635#msg75635

(http://i146.photobucket.com/albums/r259/vmx247/suzuki.jpg)
Title: Re: More joys of Ali frames
Post by: CamP on June 26, 2010, 01:23:32 pm: Quote from: Hoony on June 25, 2010, 04:06:18 pm
i wonder if this was a "Service Honda" CR500AF or an owner built machine?

be interesting to see if the early alloy frame bikes last like our old VMX steel jobs!

Service Honda frames are built properly and don't break. The shade tree frames are the ones that snap.
Title: Re: More joys of Ali frames
Post by: JohnnyO on June 26, 2010, 01:47:57 pm: Quote from: VMX247 on June 25, 2010, 04:34:45 pm
Quote from: Hoony on June 25, 2010, 04:06:18 pm
be interesting to see if the early alloy frame bikes last like our old VMX steel jobs!
nothing much on the threads here ;D
http://ozvmx.com/community/index.php?topic=6186.msg61164#msg61164
big engine in wrong frame.
but nothing really substantial.
http://ozvmx.com/community/index.php?topic=7800.msg75635#msg75635

(http://i146.photobucket.com/albums/r259/vmx247/suzuki.jpg)
I've seen a few steel frames break like that back in the day, '80 KX420 and '79 YZ400 and also saw Darryl King snap a steel perimeter frame KX250 in half at a Brisbane supercross.
Title: Re: More joys of Ali frames
Post by: caps 999 on June 27, 2010, 10:34:33 am: honny the snaped 500af was a home made one in england the welds didnt penetrate deep enough on the gusset where the put the replacment cradle in the frame the below photo was taken before the snap if you look in the circle you can see where the frame is sperating
(http://i187.photobucket.com/albums/x197/caps999/ddd.jpg)
Title: Re: More joys of Ali frames
Post by: VMX247 on June 27, 2010, 10:44:59 am: was it a 450 frame ???
boy child vmx247 8)
Title: Re: More joys of Ali frames
Post by: caps 999 on June 27, 2010, 10:46:16 am: crf250 i believe
Title: Re: More joys of Ali frames
Post by: All Things 414 on June 27, 2010, 11:59:31 am: Quote from: caps 999 on June 27, 2010, 10:34:33 am
(http://i187.photobucket.com/albums/x197/caps999/ddd.jpg)

I bet at this stage he was thinkin' "YEAH I'M COOL. OH MAN I'M SOOOOOOO COOL YEAH. NEGST TIME ROUN' I'M REALLY GUNNA WHIP DIS MAMMA! YEAH I'M COOL" etc, etc....AAAAAUUUUUGGGGGGGGGGGHHHHHHHHHHHHHH!!!!!! :D
Title: Re: More joys of Ali frames
Post by: firko on June 27, 2010, 12:02:30 pm: It's not all ali frames. Here's Tommy Thompsons Mk7 Bully at a Dargle vintage meet in the mid 90s. Tommy brought it to a stop without crashing. .
(http://img.villagephotos.com/p/2005-8/1062154/tommys%20bully%20break.jpeg)
Title: Re: More joys of Ali frames
Post by: Rossvickicampbell on June 27, 2010, 05:30:29 pm: I can spot the problem - don't use riding number 60 ;D
Title: Re: More joys of Ali frames
Post by: Maicojames on June 28, 2010, 01:15:25 am: ....and everyone said # 13 was bad.
Title: Re: More joys of Ali frames
Post by: Marc.com on June 28, 2010, 05:42:28 pm: I think a lot of frames will break with suitable effort, some easier than others.....mid 80s KXs spring to mind.

Definitely combining CR500 vibrations with odd plates welded on to a previously age hardened, heat treated alloy frame doesn't surprise me too much. But until you do it you will never find out ;D
Title: Re: More joys of Ali frames
Post by: GMC on June 28, 2010, 10:23:34 pm: Quote from: caps 999 on June 27, 2010, 10:34:33 am
honny the snaped 500af was a home made one in england the welds didnt penetrate deep enough on the gusset where the put the replacment cradle in the frame the below photo was taken before the snap if you look in the circle you can see where the frame is sperating
(http://i187.photobucket.com/albums/x197/caps999/ddd.jpg)

I doubt any frame would just suddenly break in two, this bike would have been handling a bit “funny” before it let go completely.

My 2000 model KTM 300 had its swingarm break clean through just in front of the axle where the webbing is still thin.
I pulled over 3 times to check to see if I had a flat because it was behaving weird.
Thinking it must be me I parked it and as I got off I noticed something shiny on the swingarm. Close inspection revealed it was broken clean through.
It was lucky I didn’t do any jumps with it like this as I doubt the other side would have held up by itself. With the chain being the only thing holding the rear wheel on I doubt the result would have been pretty.
Title: Re: More joys of Ali frames
Post by: Nathan S on June 28, 2010, 11:07:53 pm: I've seen plenty of Al MTB frames crack - cheapies and the really good ones and everything in between. Back before I really understood the concept of 'metal fatigue', I speculated that all alloy MTB frames would crack eventually. Now I know they will...

I don't like it as a frame material. It has its advantages, and I'm sure that the manufacturers build them with a heap of extra weight to bring the fatigue life up, but I still prefer a good chromoly frame.