Steering rack mounting failure

[alackofspeed]

Please see the below picture taken of the rack mount on my car.

[TRex 7]

Oh that don't look to good , thanks for the info

[bigrich]

Was this fracture part of the original Marlin chassis, or the modified front end?

..looks like original, but thought I'd clarify.


..also - looks like the weld has just fractured clean away - fatigue cracking? or poor weld initially? - what's the weld penetration like on the fracture face?

Ta

[alackofspeed]

This at the time of failure was an unmodified area of my car - all steering elements on my car were as fabricated by Marlin.

In light of the failure I have now repaired and modified the steering mounts.

My goal of this post was just to alert owners to the failure and indirectly suggest checking / monitoring of other cars.

[limpabit]

Hi everyone.

I'm having a moment here trying to figure out the bit that's gone wrong! Are we talking about the weld where the diagonal section joins the main bracket where the two nuts are?

I see a section clean cut through but looks like part of a rubber gaiter or something over the UJ.

[alackofspeed]

John, please put your glasses on!

You see the diagonal tube with the weld on it, well that should be connected to the angle section on to which the rack mounts.

The gaitor is something I fitted to minimise dirt and water ingress to the car via the aluminium bulkhead. Normally the rubber tab you see hanging over the metal tube, would be between the rack and the tube, but I'd been pushing things around and displaced it from its normal location.

[bigrich]

Oh dear - I was hoping that the bit that failed wasn't OEM.

Has anyone else got problems in this area? Welds should not just fail?

[eaa53]

We don't treat our cars like John does, if he tootled about and accelerated slowly and did not apply the brakes so hard and as for track days well.... what do you expect!

John your the mechanical expert was it a faulty weld? its difficult to tell from the picture, looks like no penetration to the RHS mount. Could be a tool of a welder on a bad day?

I will hit mine with a hammer and see what happens.


JohnC

[alackofspeed]

I wouldn't like to speculate publicly as to the cause of the weld failure.

As for track work, whilst the mean load seen by the car is higher than road use by a fair margin, the peak transients are higher on the road I'd suggest. Pot holes and other hideous imperfections in the road surfaces send some very savage loads through the car.

To justify that statement, I'd suggest that it's very rare to do anything on track (except in a crash) that would knock geometry out of alignment, yet on the road it's not uncommon for a vehicle's tracking to be knocked, and worse still a tyre / wheel partially fail.

I'm unsure exactly when the weld failed (there was rust on the two mating faces), but I do know it came to light at my last airfield day.