cracked in frame

[oldfart]

This is why I always sand blast my frames prior to painting .
Rm 400 T front down tube @ tank mount bolt hole  I've put it down to abuse 
 
 

[DR]

you must be just plain lucky Stew in all the bikes I've built and owned the only 1 to have a cracked frame is my little XR/YZ80 and it was cracked when I bought it. I hand sand all my frames back to bare metal so it's not as though I've missed anything. Maybe it's more the '79 and onwards models as all mine are '78 C's and earlier and the biggest problem I've found with these is the lower frame rails under the engine can rust out, boring a small ventilation/drain hole on the lowest part of the cradle on both sides fixes this problem

[Marc.com]

I was at the Suzuki factory car today, we were discussing their quality policy compared to Toyota, interesting given that Suzuki are cruising with a 20% share selling to VW for 2.8 BUSD and Toyota are having their pants sued off at the moment/

I think the welding on the frame may tell you why it cracked. Recently I modified C frame and there wasn't much metal under those shock mounts but a lot of MIG filler. Not sure you could butcher it any more than the factory did.

[tony27]

Not the nicest weld in the world, wonder how much is actually attached to parent metal. Are all their frames that badly done back then or is that a one off?

[oldfart]

This frame in particular, weleding was sub standard and standard and should of been binned.
Most of welds are cold      see below as I have re-done all  main craddle welds as a safe gurad.
 

[Marc.com]

Not the nicest weld in the world, wonder how much is actually attached to parent metal. Are all their frames that badly done back then or is that a one off?

I was going to take some photos of the 125C frame I blasted and painted, welds were appalling, like I said they had gunned in a heap of filler from the MIG to fill any holes. Also the weld area around the swingarm bolt looked like a Parrot with dysentery had laid it down.

[Marc.com]

This frame in particular, welding was sub standard and standard and should of been binned.

Most Japanese factories work on zero defect policies. Suzuki doesn't, its is very much about price and they accept a few rejects. Still it is Toyota getting their ass sued off in states at the moment.

[Davey Crocket]

Those 400 and 250T frames use to crack at the bottom rear of the cradle, weld a brace underneath Stu.

[PERM250]

hey stu that was welded by a friday robot about 4.25 pm. but no problem for you mate a man of your genius it will be better then new when your finnished. and have a great chrismas   

[firko]

I hand sand all my frames back to bare metal

Jeez Doc,hand sanding!, talk about dedication to duty and masochism! In the 30 odd vintage bikes I've restored or rebuilt over the years, I only ever hand sanded one....the first, my 350 Maico. Since then my friendly media blasting guy gets the gig.

I was going to take some photos of the 125C frame I blasted and painted, welds were appalling

Now I don't intend to insult Suzuki owners but I have to agree with Marc, of all of the frames I've seen over the years Suzuki takes the "birdshit welding" honours by a country mile. I've seen Suzuki welds that totall missed the butt and many of the welds look like they were squeezed out of a tube. The steering head snapped chean out of our old '76TS250 that became the donor for the TM/TS $100 project bike. It's always been a wonder to me that more didn't break.
 
 

[DR]

I agree the welding looks bloody woefull on many Japanese bikes from the 70's and 80's but, you have to remember any defects that you are finding now are showing up 30 odd years of misuse and abuse after the fact. In the case of the competition bikes they were only basically designed to run a season or 2 at most and then be ditched in favour of the next generation items. Many were and are still race bikes today. Considering the amount of bikes produced in this era compared to the amount of problems I've actually witnessed in 30 years of said production I'd say the dud or failure ratio is extremely low. These days you get your arse sued off if things fail so the birdshit welds should be a thing of the past..hopefully. Bottom line is yes, the welds on most early jap stuff are nothing short of hideous!  

[monaro308]

I wouldn't complain about a 30+ year old frame when you get a 1-2 year old MX frame doing this.
Known to happen 06+ and 07+ yzf/wr aluminium frames at the steering head

[oldfart]

Ah so he or she has quit thier job with Suzuki and started up with Yamaha. 

Yes I must agree that most of the Rm and Pe around 1980 - 81  have bird shit welds, at steering head gusset

[k2000x]

my 125 yz done the same at peg mounts and head stem aswell...

[All Things 414]

I wouldn't complain about a 30+ year old frame when you get a 1-2 year old MX frame doing this.
Known to happen 06+ and 07+ yzf/wr aluminium frames at the steering head

That can't be good. Weld looks ok. Maybe poor engineering if a few are doing it? What do you do once that happens?