240z SCCA vintage race car, restoration

[AydinZ71]

Updates:

 

1) tow-eye mount complete. 
2) hood bump-stops installed on rad-side of strut towers. These can be replaced with quik-latch if the hood vibrates at speed.

3) pass-through holes in rad support for oil cooler lines.

 

finishing touches before I can primer the front-end 

[clarkspeed]

Looking good. You are so far ahead of me on the front. I am still in the roterssere for a few more weeks until I can access that area.  I am also adding 4 tie downs to the underside of mine for strapping to the trailer. It makes hooking and unhooking so much faster. I do that on all my cars.

[AydinZ71]

7 hours ago, clarkspeed said:

Looking good. You are so far ahead of me on the front. I am still in the roterssere for a few more weeks until I can access that area.  I am also adding 4 tie downs to the underside of mine for strapping to the trailer. It makes hooking and unhooking so much faster. I do that on all my cars.

Thanks Clark! Smart to build-in some tie-down points. I’m super impatient, but I’m closing-in on finally being able to primer the bare steel. Everything you see mounted is just to ensure fitment before primer. Your chassis is more ambitious than mine so I can certainly understand the extra time you need.

 

I need to fabricate the front sway bar mounts so finally got-around to sectioning the front struts. Got the whole suspension mounted (except the steering rack). Once the sway bar mounts are welded-in, I need to close some holes in the firewall and I should be ready to primer. 

[clarkspeed]

Yes, yes, and yes.

 

I have a big surprise reveal for my struts. But you will need to wait for that.

Edited January 21, 2022 by clarkspeed

[AydinZ71]

ok guys... I totally underestimated the sway bar. Being a complete novice, i totally neglected this scope.

So I am putting my front suspension on to mock-up the new chassis mounts for a sway bar. CLEARLY, my 1+" of front track is creating a problem getting on the OEM-style sway bar that came with the car (I am assuming it is the 1" MSA bar). The bar does not reach the wider spacing between the the control arm sway-bar attachment points. So, I have two choices right now:

 

1) Cut this bar, and weld-in 1" of material to make it longer

 

2) fabricate a new, custom sway bar

 

I am certainly capable to do #2, but I do have some questions before I get started:

 

1) For those that fabricated their own, how did you handle the end-link connection between the sway-bar arm and the control arm? I am assuming a double-sided rod-end with shackles on the ends of the sway bar and control arm?

 

2) is there a clear performance advantage to the custom sway bar at this point? To be specific, do I need more torsional rigidity for a track car than the 1" bar can provide? My front springs are currently #350lb. 

 

thank you all in advance for your help!!

Edited January 21, 2022 by AydinZ71

[clarkspeed]

My recomendation is a multi piece bar from Speedway Engineering like your picture. Reasonably priced and more importantly, you can swap out bars of you need to. Plus you can find them used on ebay depending in the size. I would not try to lengthen one or bend one myself.  On the other hand,, I would not be afraid to weld on some angle iron brackets or similar to the existing OEM style bar you have if that can make up the difference. OR an offset bracket attached to the control arm.. I have some examples if I can dig up the pictures. And yes, adjusters and rod ends for the links.

[AydinZ71]

Thanks Clark! So I think I see all the parts I would need. I’m eyeing a 1-1/4” .188 wall 36”. I’m going for the aluminum arms. Now the OEM style bar “arm” has an angle (about 30 deg?) outward so the bar avoids the wheel/tire during steering. Any recommendations on how to bend the AL arm  to accommodate as well? I suppose I could cal them Monday and ask if they can pre-band for me. 
 

meanwhile, I need to re-fabricate the OEM mount location to meet EP anyways, so I went ahead and lengthened the bar. I recognize the welded metal does not meet the stiffness of whatever alloy they used but now the bar makes it across so I can fab the chassis mounts. Just for shits and giggles, I did quench and hammer the weld so it’s harder than mild steel but I’m not going to use it anyways. It might just snap in half. I might want to see that. 

[AydinZ71]

Okie dokie. I dived into the deep-end and got all the parts ordered for the sway bar

 

As Clark suggested, speedway engineering bar. Got their alluminum arms too. They are local so picked them up today. Also ordered end links that will work with LCA attachment point and through-holes I need to drill into the AL bars. Also ordered two Alluminum housed bearings for the bar from McMaster-carr. Il take pics when I have it all mocked-up. Here are some pics of the parts I have and on order. 

i will fabricate the mounting of the bearing to the chassis. 

 

[clarkspeed]

18 minutes ago, AydinZ71 said:

Okie dokie. I dived into the deep-end and got all the parts ordered for the sway bar

 

As Clark suggested, speedway engineering bar. Got their alluminum arms too. They are local so picked them up today. Also ordered end links that will work with LCA attachment point and through-holes I need to drill into the AL bars. Also ordered two Alluminum housed bearings for the bar from McMaster-carr. Il take pics when I have it all mocked-up. Here are some pics of the parts I have and on order. 

i will fabricate the mounting of the bearing to the chassis. 

 

 

[clarkspeed]

Man you get things done before I can even post examples for you! Greg runs a bearing like you selected on all his cars. Those end links should be fine. With the straight arms you may need to mount a little higher to try and keep them close to parallel. I think Greg runs the 30 degree. 

[AydinZ71]

12 minutes ago, clarkspeed said:

Man you get things done before I can even post examples for you! Greg runs a bearing like you selected on all his cars. Those end links should be fine. With the straight arms you may need to mount a little higher to try and keep them close to parallel. I think Greg runs the 30 degree. 

Thanks! I think I enjoy the problem-solving challenge more than anything. Greg definitely helped with the concept as usual. I do need to bend the arms to reach the mounting point on the LCA’s, but il have to find a shop with a press. I don’t have anything that can bend 3/4” thick 6061AL. I plan to mount bar a little closer to the crossmember than the OEm mounting location. 
 

Thanks for your help too Clark! 
 

PS: this stuff ain’t cheap! The bar and arms were a bit over $300. Bearings were $50 a piece and the end links were 80 shipped for the pair. 

Edited January 25, 2022 by AydinZ71

[clarkspeed]

That sounds about right since I just bought the same. I got my bar used on Ebay and built my own bearing bearing holders to save a few bucks. But compared to other options it's really not that bad. I just got my end links and will post on my page.

 

Let me know how you bend the arms. I wasn't sure heating the aluminum would be good..I thought about putting mine in my press but that scares the hell out of me. I was just going to brace them and hit with a sledgehammer. But with my new mount it doesn't look like I will need to.

[AydinZ71]

56 minutes ago, clarkspeed said:

That sounds about right since I just bought the same. I got my bar used on Ebay and built my own bearing bearing holders to save a few bucks. But compared to other options it's really not that bad. I just got my end links and will post on my page.

 

Let me know how you bend the arms. I wasn't sure heating the aluminum would be good..I thought about putting mine in my press but that scares the hell out of me. I was just going to brace them and hit with a sledgehammer. But with my new mount it doesn't look like I will need to.

 

Nice! glad you can avoid bending the arms. Honestly, I know nothing about aluminum metallurgy. Heating and bending mild steel does tend to make it harder and more rigid due to work hardening. I believe mild steel is the most ductile/soft state of steel we work with. You can also hammer the drawn surfaces while hot, which will further case-harden the steel. Heating and bending forged steel will weaken it of course. Will heating and bending 6061AL weaken the material and make it less rigid? No idea... If I had a TIG, i would consider just miter-cutting the bar and welding it back at an angle with a full-penetration weld. 

 

I am going to try to heat the bar with a torch and strike it with my 2lb hammer. Heat dissipates FAST in AL though so i will need to work fast.  If it doesn't budge,  I'm going to find a local shop with a press, mark the bar with a seam line for the bend, and just ask them to bend it to an estimated angle based on my mock-up. 

 

My bearings and end-links will be here by Friday, so we may both be working on it this weekend. 

[rossman]

3 hours ago, AydinZ71 said:

Will heating and bending 6061AL weaken the material and make it less rigid?

I work at an aerospace company who designs aluminum structures on a regular basis.  I can tell you that welding aluminum 6061-T6 will weaken the aluminum in the heat affected zone. We assume an 80% reduction in material strength at the weld and the HAZ directly around it.  It becomes, essentially annealed aluminum. Conservatively, I would assume that heating and bending aluminum to have a similar reduction in strength. As far as stiffness goes, annealed aluminum bends very easily, so I would assume that the stiffness would be affected too.  Anyway, that is my $0.02.

[AydinZ71]

3 minutes ago, rossman said:

I work at an aerospace company who designs aluminum structures on a regular basis.  I can tell you that welding aluminum 6061-T6 will weaken the aluminum in the heat affected zone. We assume an 80% reduction in material strength at the weld and the HAZ directly around it.  It becomes, essentially annealed aluminum. Conservatively, I would assume that heating and bending aluminum to have a similar reduction in strength. As far as stiffness goes, annealed aluminum bends very easily, so I would assume that the stiffness would be affected too.  Anyway, that is my $0.02.

Yeah 😕 that’s what I was afraid of. annealed metal is definitely not what we are going for. Between the two options, it does

sound like bending would be a better option. It’s gotta angle somehow! 

[Alexander240z]

 

On 1/23/2022 at 11:38 AM, AydinZ71 said:

Thanks Clark! So I think I see all the parts I would need. I’m eyeing a 1-1/4” .188 wall 36”. I’m going for the aluminum arms. Now the OEM style bar “arm” has an angle (about 30 deg?) outward so the bar avoids the wheel/tire during steering. Any recommendations on how to bend the AL arm  to accommodate as well? I suppose I could cal them Monday and ask if they can pre-band for me. 
 

meanwhile, I need to re-fabricate the OEM mount location to meet EP anyways, so I went ahead and lengthened the bar. I recognize the welded metal does not meet the stiffness of whatever alloy they used but now the bar makes it across so I can fab the chassis mounts. Just for shits and giggles, I did quench and hammer the weld so it’s harder than mild steel but I’m not going to use it anyways. It might just snap in half. I might want to see that. 

 

I'm curious to see what you make for the sway bar mounts. I've read that the OEM sway bar mount were insufficient due to the nut holding the bot for the mount only being welded to the bottom of the inside of the lower rails. This means its only being held by 3 sides of a "box." A solution to fix this would be welding a nut on the top of the inside of the lower rail and running a bolt all the way though so you have support from the entire "box." May be different for you depending on how you mount them. I'm not sure. 

 

I have this document that I believe I got off this website that goes into detail about the structural analysis of an Early Z chassis. They have a section dedicated to racing and what "deficiencies" are produced by heavy load. 

Analysis of Early Z Chassis - NewZletter - James Lux - 19xx.pdf

[calZ]

43 minutes ago, Alexander240z said:

 

 

I'm curious to see what you make for the sway bar mounts. I've read that the OEM sway bar mount were insufficient due to the nut holding the bot for the mount only being welded to the bottom of the inside of the lower rails. This means its only being held by 3 sides of a "box." A solution to fix this would be welding a nut on the top of the inside of the lower rail and running a bolt all the way though so you have support from the entire "box." May be different for you depending on how you mount them. I'm not sure. 

 

I have this document that I believe I got off this website that goes into detail about the structural analysis of an Early Z chassis. They have a section dedicated to racing and what "deficiencies" are produced by heavy load. 

Analysis of Early Z Chassis - NewZletter - James Lux - 19xx.pdf 624.8 kB · 2 downloads

 

Three sides? Really it's just the one side. The common fix is to just weld a thicker spreader plate over the area. 

[AydinZ71]

@Alexander240z thanks! I’l start by saying only 1/3 of the steel from the area behind the seats to the front tip of the car is OEM metal. Over a year of rust repair, fabrication and reinforcement. Hence, my lower frame rails are now ~2.5” 316SS tubes. The mounts for my engine/steering/suspension crossmember are fabricated out of 14-gauge steel. Attached is a pic of the mount. I’m thinking of adding a 3rd bolt attachment here as well. The OEM design allows the crossmember to “lean”, since it’s only being held on by 2 bolts in a single plane, on each side. 
 

I plan to mount the bearing to some mild steel box tube or angle, and use 14-gauge steel as the mounting surface. I went with the face-mount bearings so I can adjust the height with the steel mounting surface, instead of adding bushing material to a foot-mount bearing. Here is a pic of the bearing. Alluminum housing but still not light. To save some weight and a lot of time, the mounting surface will be welded to the stainless frame rail instead of bolted. 
 

as a matter of fact, I weighed the OEM bar and links (11.5lbs), and it looks like the whole assembly (including mounts) for the new one will be 2-3lbs heavier. I don’t have a lot of tangible experience on how critical a sway bar stiffness and response is to overall road track handling, but I can tell ya this will definitely be solid! 

[AydinZ71]

7 hours ago, calZ said:

 

Three sides? Really it's just the one side. The common fix is to just weld a thicker spreader plate over the area. 

yeah… that makes sense. Once the bolt is torqued, the nut is just squishing whatever amount of steel you have between the mounting surface and the nut inside the frame rail. 

[Alexander240z]

9 hours ago, calZ said:

 

Three sides? Really it's just the one side. The common fix is to just weld a thicker spreader plate over the area. 

Physically yes its being held on by one side of the box. Structurally the bottom plate that the nut is welded to is being held by the 2 lateral sides. One of those lateral sides being held by spot welds. Unfortunately for these cars you have to assume rust is already eating at the spot welds. So the structural integrity might not be fully there. If you weld a spreader plate that encompasses the top section of the rail, that'll work too. This is for a factory situation as in Aydin's case he redid the entire front rail.