Rear Knuckle Material Specifications?

[murph]

Does anyone have the material specifications on the skyline/silvia rear cast steel knuckle?

The reason I ask is that last weekend I broke a rear knuckle at the track, throuch the lower balljoint mount up to the wheel bearing. The crack is obiously due to fatigue and there are several outher craks in the same area.

What I want to do is weld reinforcement gussets up from the bottom edge of the lower baljoint block up towards the lower brake caliper mount and from the rear of the lower balljoint mount to the shock mount, to reduce the stress concentration around the failure.

Obviosly this upright is a bin job, but I want to reenforce the the new knuckels, as apparently this a common problem with the skyline/ silvia rear end, and I dont want this happening again.

The car is enginered and road registerd, but welding to a upright is a big no go zone if the material specification is unknown, and id prefer not to have to get spectro analasis done as its not cheap.

[Dan_J]

fronts are cast iron so i'd assume its would be for the rear, altho gtr/ gts4 rear ankles/ knuckles are alloy

[xntrq]

I've got them if you're looking to buy new used ones and replace yours, give me a PM if you want.

[Risking]

I wouldn't say that's a common problem with a Nissan rear end at all.

I've never seen that particular breakage before. I've seen cracked & broken subframes (we are repairing one at the moment in an S15) and broken arms but never an upright like that.

[Duncan]

I guess that failure is directly related to one or more big hits. I have never seen one break like that either.

The most common failure I've seen other than bent arms is the inner mount for the arm ripping off (upper or lower), they are probably worth reinforcing.

[Risking]

Yep. Lower inners break off all the bloody time.

As well as broken castor rods

Never seen an alloy or steel upright break

[murph]

I have had 1 customers drift car with this failure.

and have have had a r33 road car with a cracked upright in this position which we found before total failure, this car had a large wheel to kerb impact tho

And have a couple of mates who have seen this happen over at Ebisu

I have never hit a kerb with the car, or any real impact, have had it on the car for 4 years. Only major load i can think of which would cause that would be jumping turn 1 apex at mallala have done that many times.

yeah i previously had a crack starting on the rear LCA mount on the cradle, fixed that one decently tho before it propergated.

[boostn0199]

Had an exact identical break yesterday in my 33 just snapped mid drift.

[Dave.TAS]

Very very common breakage, have seen at least 10 and know of heaps more.

Best solution is driftworks rear knuckles.

You could reinforce it, same process as welding front knuckles

[boostn0199]

Very very common breakage, have seen at least 10 and know of heaps more.

Best solution is driftworks rear knuckles.

You could reinforce it, same process as welding front knuckles

Yeah only problem driftworks you lose the drum handbrake. Checked my other side just out of interest and cracks have already started at same place so yeah definately is a fatigue issue over sustained hard track use, thats what im doing now reinforceing like my modded front knuckles.