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Broken rear upright


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Happened yesterday at VIR on my 240Z. 44 year old casting with who knows how many miles, 10 years of racing plus the VIR curbs and one cracked through. Luckily I noticed before it totally came apart. Havent taken apart yet to get a good picture. So anyone seen this and reinforced to prevent? Its one of my biggest fears racing the Z is something breaking like this with modern sticky tires. Also APB out for replacement beefier later 260/280 uprights if you know of or have some available please let me know. Hopefully near central Illinois but will ship if have to. I want to replace them all front and rear and am currently out of commission for in the meat of the race season.

 

Cameron

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Did the crack start at the screw holes where the parking brake cables would attach?

 

Did you have screws installed in the holes?

Wrong side. Those holes are in the back, the front side cracked where there are no holes.

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Damn. The sort of stuff you just put out of mind. I guess everything, given enough time/abuse, is prone to failure. 

 

Were there signs of failure or did you just get lucky on an inspection?

It was really loose. Still drivable but could feel something wasn't right. Then under yellow noticed it felt like dirt car where the rear haunched up under power and the steering wheel was about 10 degees off center going straight. Got real lucky because made a couple laps in anger like that.

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  • 2 weeks later...

So now finally found replacements. Also found one front spindle is shot. The bearing race is worn down to where the bearing is spinning on the shaft and flopping around. So going to just change all four corners including upgrading to the beefier 280 parts. Plan to install new bearings and have to section them. Has anyone found and tested weld on reinforcements to stiffen or strengthen the uprights? I remember Cary talking about testing deflections and it was a lot.

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I tested 240 parts and found they would move a lot more than expected.  280 struts will be better but you can create a sheet metal gusset from the tube to the spindle housing.  Jon did this on his car and I can dig up some pics I have buried somewhere if you need.  You have to figure you are putting  a lot of stress on your parts with bigger sticky tires, a lot more HP and torque, and now aero.  

 

Here's an image of a Ground Control modified strut.  Note the gusset used to stiffen the spindle

 

 GcE30Mod1(20).jpeg0708_sccp_02_z%2Bproject_corolla%2Bgroun

 

The next step is to build a custom housing but when you get there it's probably time to start seriously looking at an a-arm retrofit. I have been playing around with a simple design that uses Nascar and dirt track pieces.  I can't decide if a 7 inch upper is long enough (allows for 3 inches of suspension travel) or a longer upper is needed.  At 7 inches I don't think you have to put holes into the engine compartment for mounts.

 

Cary

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What Cary said ^^^ I have seen it done before, plus put a spacer sleeve between the two front wheel bearings. This obviously provides support to the stub axle, of course the spacer has to be machined just right to keep the bearings happy. 240 struts should really not be used on a race car, particularly when stronger OE items are available. Mr Nissan did the upgrade for a reason.

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