So i have 2 steering shafts and both of them are collapsed . The rivets that hold them look like plastic. what should I replace them with, would a metal rivet be too strong. I know it dosnt really matter unless you crash the car but I want it to be safe.

 

I'd use an aluminum rivet. There are plastic ones, but I'd be afraid of them shearing with normal use.

 

OK, should i used 4 or just 2

 

Those plastic shear pins are meant to break/collapse in a crash, so I wouldn’t replace them with strong steel rivets or bolts. If the shaft becomes too solid it may not collapse properly in an impact. Best to use OEM style plastic/nylon shear pins or the closest equivalent so it stays safe and functions the way it was designed to.

 

Reading through the first link posted by chat, I asked about aluminum and it was up in the air if they are OK.

Chat says this.

Standard DIY Replacement Materials
Because measuring exact polymer hardness at home is difficult, Mazda community builders use pre-tested materials known to match the necessary shear profile: [[url=https://www.rx7club.com/new-member-rx-7-technical-256/steering-collapsible-shaft-shear-pin-843874/]1]

• Nylon 6/6 Hardware: Standard Nylon 6/6 machine screws or rivets naturally meet the 8,000+ PSI shear standard. Thread them tightly into the column holes and shear off the excess heads.
• Delrin (POM) Rods: Cutting a pin out of a solid Delrin rod provides the exact structural stiffness required to remove steering wheel vibration while maintaining the crash-collapse safety feature.
• High-Temp Polyethylene (P-Tex): Skier base repair candles (P-Tex) can be melted and injected using a specialized gun. This material cools into a rigid, high-shore plastic that perfectly mirrors the factory injection process. [[url=https://www.rx7club.com/new-member-rx-7-technical-256/steering-collapsible-shaft-shear-pin-843874/]1, 2, 3, 4]

Chat response on aluminum:

The Only Safe Aluminum Alloys to Use
If you choose to use aluminum, you must only use dead-soft, unhardened aluminum. Do not use standard structural aluminum hardware.

• 3003-O Temper Aluminum: This is an incredibly soft, non-heat-treatable alloy. It has a low ultimate shear strength that closely mirrors the original rigid nylon, allowing the column to collapse smoothly under impact.
• Pure Aluminum Pop Rivets: Standard, cheap aluminum blind/pop rivets are typically made from soft 5000-series alloys. If you use these, you must punch out the hard steel center mandrel pin after expanding the rivet. Leaving the steel core inside will make the pin entirely unsafe.

 

I used aluminum rivets and they dont actually go thorough the second shaft. There are indents and the rivets sit in. I did a test run with a hammer and it seems solid but it still collapses.