Thread: Welding Cracked Chassis Rails

Hello All,

At the 1:36 minute mark of this youTube video the bloke repairs a crack in a Toyota FJ40 chassis
EP32 - Chassis and axle Strip down and repairs FJ40 - YouTube .

How sound does this approach seem to you? The funny thing is that the raised dog poo profile weld that the FJ40's previous owner performed is the same style of weld currently featuring on Snowy. Perhaps the same bloke did both repairs on the FJ40 and Snowy!

Admittedly Snowy was a farm vehicle and after he was grossly overloaded, the repairs would have been done out in the field and carried out at a 'she'll be right' level of quality. No consideration needed for future road-worthies as Snowy was already relegated to just being a farm vehicle back then. So the job was done to the required standard at the time. I am the one making the situation more heightened by subjecting Snowy to a future road worthy inspection and a subsequent higher set of quality parameters than a field repair that has probably already held securely for years.

Kind Regards
Lionel

Hey Lionel, you're looking at Street Rod construction which is different. Maybe check out NCOP16m VSB14 Light Vehicle construction and modification, Section LZ Appendicies, Section C Heating and Welding of Steering components

https://www.infrastructure.gov.au/sites/default/files/migrated/vehicles/vehicle_regulation/bulletin/files/NCOP16_Appendices_V2.0_01Jan2011.pdf

Interesting video, I would just clean the area, remove the old weld, mark the crack and reweld the crack. The weld should penetrate the metal, chassis are really not that thick in metal that they need to be ground. The principle of drilling the holes is to catch the crack and remove the end of the crack which is a stress raiser which leads to the cracks propogation. The reality however is that the crack has already spread beyond that hole and it won't have done anything - theory vs reality.

Its also worth working out why it cracked and what the best method to preventing it reoccuring is. Plating isn't always the answer.

Originally Posted by Slunnie

Hey Lionel, you're looking at Street Rod construction which is different. Maybe check out NCOP16m VSB14 Light Vehicle construction and modification, Section LZ Appendicies, Section C Heating and Welding of Steering components

https://www.infrastructure.gov.au/sites/default/files/migrated/vehicles/vehicle_regulation/bulletin/files/NCOP16_Appendices_V2.0_01Jan2011.pdf

Interesting video, I would just clean the area, remove the old weld, mark the crack and reweld the crack. The weld should penetrate the metal, chassis are really not that thick in metal that they need to be ground. The principle of drilling the holes is to catch the crack and remove the end of the crack which is a stress raiser which leads to the cracks propogation. The reality however is that the crack has already spread beyond that hole and it won't have done anything - theory vs reality.

Its also worth working out why it cracked and what the best method to preventing it reoccuring is. Plating isn't always the answer.

Hello Slunnie,

I managed to track down a mob in Coolum, Queensland who specialise in chassis repairs, extensions and shortening. I sent them some photographs and I have subsequently been quoted a reasonable price to get the job done professionally - which will include plating. The other interesting fact I learned is that it requires a Blue Plate for an approved repair. They did also give me the opportunity of getting a full chassis brace kit installed - I will give that a miss. Part of the repair will be checking out the whole chassis for any undesired bends or twists.

I will leave it in the hands of a professional crew and get all the legislative boxes properly ticked. The next available place in their workshop is in late March 2024 - so watch this space...

My suspicion of how and where the chassis rails cracked is that the farmers played a game of how many one tonne bags of fertiliser it took to break a Defender while you drive it over a rutted paddock. It is only a guess and I doubt the former owner would respond to an email about how the chassis was cracked. Chassis crack... what chassis crack?

Thank you Slunnie for the link to the Light Vehicle Construction and Modification link - much appreciated.

Kind regards
Lionel