Welding up twin skin chassis
Submitted: Saturday, Sep 11, 2004 at 23:05
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TonyH
I have a Hj 47 ute stripped down to a bare chassis, and am about to start putting it all back together.
I am chasing opinions or peoples experience's with welding the 2 skins together much like the newer chassis which are continuously welded from one end to the other.
I'm convinced it won't be a problem, but just thought I'd throw it out there first.
Regards
Tony Harding
Reply By: Member Eric - Sunday, Sep 12, 2004 at 08:26
Sunday, Sep 12, 2004 at 08:26
Sorry Tony , a little confused here . Welding the 2 skins together ? are you trying to say , you would like to box the chassis ? This means fabricating a steel plate to weld to the end of your c section.
if this is what your talking about , then its a good idea to gain strength in a chassis . Make sure you dont do a continuous weld all the way through. This will stop a crack from running from one end to another.
AnswerID:
76080
Follow Up By: TonyH - Sunday, Sep 12, 2004 at 14:31
Sunday, Sep 12, 2004 at 14:31
Eric
The chassis rails consist of 2 "C" sections riveted together to form the box.
FollowupID:
335923
Follow Up By: Member Eric - Sunday, Sep 12, 2004 at 15:58
Sunday, Sep 12, 2004 at 15:58
ok. I see your reason for wanting it welded lol as I said , dont do a continuous wield
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335926
Reply By: NissanofOld - Sunday, Sep 12, 2004 at 08:56
Sunday, Sep 12, 2004 at 08:56
Chassis welding is a tricky thing. Years ago I worked at an engineering firm where they had some top notch welders and a neighbouring trucking firm used to bring in their old trucks from time to time for repair, as they developed cracks in the chassis.
The welders always used what are called 'low-hydrogen' welding rods, because the chassis' were made from high-tensile steel and using anything else could induce further cracking. It might not be noticable at first, but could become a real problem later on. From a liability point of view, the welders were making sure that they could not be sued.
You could possibly use other methods (eg MIG), but I'm not sure how good this might be and so you should check things out thoroughly with a specialist before proceeding. An automotive engineer that provides certifications for mods might be a good place to start and if you want the vehicle to be legal, you'll need this certification in any case.
AnswerID:
76082
Follow Up By: dirt-teaser - Sunday, Sep 12, 2004 at 09:39
Sunday, Sep 12, 2004 at 09:39
You'r right here, not many welders like to play with a chassis, I didn't like the idea of extending the one mentionned below. The client took the responsability. For the MIG, it's just as good, if not better, but still would need to follow the same procedure mentionned. Bolher Steel can supply you with the right MIG wire.
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Follow Up By: TonyH - Sunday, Sep 12, 2004 at 14:34
Sunday, Sep 12, 2004 at 14:34
MIG actually produces a low hydrogen weld of a very high strength
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Follow Up By: NissanofOld - Sunday, Sep 12, 2004 at 17:53
Sunday, Sep 12, 2004 at 17:53
MIG is a great all-round welding option and the engineering firm had those and then some; but for some reason, the welders always used an arc welders and rods. Never thought to ask.
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Follow Up By: TonyH - Sunday, Sep 12, 2004 at 23:06
Sunday, Sep 12, 2004 at 23:06
Did some hunting around on the net (monster trucks and drag racing site) and apparently the TIG is the bees knees for welding chassis rails and chassis manufacture.
Can't find anything about welding riveted chassis though.
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335947
Reply By: dirt-teaser - Sunday, Sep 12, 2004 at 09:14
Sunday, Sep 12, 2004 at 09:14
Hi Tony,
It won't be a probleme, but do not run one continuously weld. I would suggest
2" of weld every 4. Also use low hydrogene welding rods, and pre-heat the chassis to around 150 degrees C. After welding, let it cool down SLOWLY, DO NOT cool it down with
water. Even better if you could cover it up with a blanket. The material used in chassis is h/t steel, and the weld could crak if the job hasn't been down properly.
6 or 7 years ago,I extended a LC ute chassis to fit a small drilling rig, and up to now, the
drill rig hasn't been lost on the road.
AnswerID:
76083
Follow Up By: TonyH - Sunday, Sep 12, 2004 at 14:45
Sunday, Sep 12, 2004 at 14:45
That is what I had intended and was surprised, when I bothered to look under a 75, to see the chassis fully welded.
Will probably stick with an intermitent weld as it's just as strong, if not stronger and will allow a bit of flex not to mention the amount of gas and wire I'll save ;-)
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Reply By: Member - Jeffrey - Sunday, Sep 12, 2004 at 23:33
Sunday, Sep 12, 2004 at 23:33
Hi TonyH,
I am a structual welder,ticketed an all..my advice is it is really a job for someone who is thouoghly trained !! DO YOUR HOMEWORK practice on throw away rail section first use stick only low hyd..very strong and flexable but takes experience to run them,somebody mentioned dont quench,dont!! keep the breaze off it as
well dont forget distortion control methods aswell....good luck.mig...yeah rite!
Jeffrey
AnswerID:
76140
Reply By: Well 55 - Monday, Sep 13, 2004 at 07:26
Monday, Sep 13, 2004 at 07:26
The idea behind the "C" section chassis rivited together was to allow for flex when traversing rough terain, weld the rails together even stich welds will reduce the flex and develop cracks and also reduce the off road ability.
AnswerID:
76149
Follow Up By: banjodog - Monday, Sep 13, 2004 at 10:03
Monday, Sep 13, 2004 at 10:03
Probably not a good idea - I read years ago in a Toyota manual that the 45/47 chassis can/made to twist up to 200mm from one corner to the opposite corner in off road use. I.E. - left front to the right rear.
The chassis are made to flex this much when loaded with cargo - if the chassis is to tight it will eather crack or something else will let go.
BTW - you may jeopardise yourinsurance or rended the vehicle unroadworthy. If it's not made to be welded by the manufacture and the vehicle is involved in an accident, no doubt there will be a "please explain" from lots of people.
Just check first with local transport dept - they are usually negative on any chassis mods. QLD transport used to make the owner replace the chassis - no repairs of ANY kind no matter how small. But like most things - it's only illegal if you get caught.
The main question you need to ask yourself is what will I really gain by doing this. If you really want a fully welded chassis buy a vehicle that has one.
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335968
Reply By: Peter 2 - Tuesday, Sep 14, 2004 at 18:57
Tuesday, Sep 14, 2004 at 18:57
Don't weld it, it isn't necessary, 45/47 chassis are far stronger and more flexible off road than any 75 series.
As has been mentioned 2-300 mm flex diagonally off road keeps the
wheels on the ground. That is why the old trucks with hot rivetted chassis generally perform better in hard terrrain in standard trim.
AnswerID:
76359