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Kurai

240Z Chassis prep / reinforcements

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Ok try not to flame me too much guys I have been searching and trolling around the forum trying to learn this or that but just cant seem to find all the answers im looking for or various opinions and not sure which one to go with.

 

So the situation is this I have a newly acquired 1973 240Z and am currently in Afghanistan and plan to get hot and heavy on her when I return home and am doing alot of research and footwork now. The end state plan is to have a 2JZ-GTE/R154 tranny/R230 diff setup to power and drive her along with alot of little extras I am seeing ppl do here lol :D but what Im posting about today is what all can I do to get the suspension and chassis setup like I want it outside of the usual things.

She will be more of a weekend and occasional circuit tracked car (purely for fun and experiance not too worried about competition restrictions or the like).

 

I have read thru alot of the pinned threads and am looking at a stage 3-4 suspension setup as per the pinned thread, but what I cant find is alot of topics on seam/stitch/spot welding as far as where to do such at and to do so to get X result. I already mentioned the power/drivetrain setup but just added info want to run probably the GC coilover and the TTT weld in plates aiming for a 275ish size tire in the rear (with the ZG flares and modded fenders) and plan to also use one of the Kirk racing cages as well.

 

Outside of that and things one the recommended list of suspension mods, where should I look at stitch welding the chassis? Does anyone make a front strut brace for a JZ series swapped 240Z? What other things can I do to reinforce the chassis while it is in the "down to bare metal stage" before she goes to paint? Like polyurethane foam etc etc etc. I wanna set it up for the best possible configuration with as little repeat teardown as possible, she will be a true project so if she has to sit 3 weeks to get something done so be it. I just wanna do it right the first time around.

 

Thanks in advance guys there is alot of information on this site B)

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Yeah I was eyeing those the other day but couldnt find too much information on them other then the description. Like what is the weakness of the OEM design vs this one etc etc etc. Im sure its something common sense that all long time Z owners know but im lost at the weak points of this chassis. lol but they def just got another look lol, the guy that is finishing up the build on my Corolla has done some work with Baddog on their car I think. ;)

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Here's a quick shot of what's happening with my frame rails although I do not know the technical details of it.

 

 

subframe connectors are a good place to add strength.

 

hear is an example of mine

 

this is the back.

IMG_0015.jpg?t=1272691300

 

its a solid peace up to the front.

 

IMG_0010.jpg?t=1272691382

 

 

Hmm now is that the piece that is offered at baddog all welded in or is that somethng that you guys had made? If it was bought how much and from where? I really wanna make sure this Z is up to par as much as possible and not just go slap alot of power on it and then have it twist from under me.

 

Also does anyone have a diagram or anything of where all to stitch weld the chassis at?

 

Oh and a side question what is the usual general condition most you guys find the fuel cell in? pretty good shape or usually not? Just asking because if not ill have a summit cell added as well at the spare tire well like alot of ppl on here have done and was thinking that too (well the frame for it) can probably be modified to help connect the right and left sides of the rear chassis. Try and get everything knocked out in one fair swoop.

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For a street driven S30, here's about as much as you can do to stiffen the chassis:

 

1. Seam Weld (every sheet metal seam overlap.)

2. Bad Dog Subframe Connectors

3. Weld-In Roll Bar.

4. Welded In Rear STB.

5. Triangulated Front STB.

6. Radiator Core Support Reinforcement.

7. Transverse Link Bracing Reinforcement.

8. RT Diff Mount.

9. Tubular Seat Mounts.

10. Box Upper Frame Horns to Firewall/Cowl.

11. Reinforce Pedal Box/Brake MC Mount.

12. Reinforce Front ARB Mount.

13. Reinforce Front Strut Tower to Frame Rail Junction.

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For a street driven S30, here's about as much as you can do to stiffen the chassis:

 

1. Seam Weld (every sheet metal seam overlap.)

2. Bad Dog Subframe Connectors

3. Weld-In Roll Bar.

4. Welded In Rear STB.

5. Triangulated Front STB.

6. Radiator Core Support Reinforcement.

7. Transverse Link Bracing Reinforcement.

8. RT Diff Mount.

9. Tubular Seat Mounts.

10. Box Upper Frame Horns to Firewall/Cowl.

11. Reinforce Pedal Box/Brake MC Mount.

12. Reinforce Front ARB Mount.

13. Reinforce Front Strut Tower to Frame Rail Junction.

 

Ok sweet this list helps alot, I have a couple questions though....

 

1. For the weld in roll bar and weld in rear STB where can i purchase these? Or do they have to be fabricated?

 

2. Will a bolt in cage (that i think you guys offer via kirk racing http://www.betamotorsports.com/products/products.php?cat=7 ) work well with all these reinforcements in a street application or is it overkill? I have it already on my list.

 

3. Where and will a triangular front STB work with a JZ series engine swap?

 

4. What and where can I get 8 and 9?

 

Lastly you wouldnt happen to have pictures of all these areas would you lol, I dont have my Z here and think I know the areas you are talking about but definately am not real familiar with the S30....yet lol. Very good list though def what i wanted to know. B)

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1. For the weld in roll bar and weld in rear STB where can i purchase these? Or do they have to be fabricated?

 

2. Will a bolt in cage (that i think you guys offer via kirk racing http://www.betamotorsports.com/products/products.php?cat=7 ) work well with all these reinforcements in a street application or is it overkill? I have it already on my list.

 

3. Where and will a triangular front STB work with a JZ series engine swap?

 

4. What and where can I get 8 and 9?

 

Lastly you wouldnt happen to have pictures of all these areas would you lol, I dont have my Z here and think I know the areas you are talking about but definately am not real familiar with the S30....yet lol. Very good list though def what i wanted to know. B)

 

For #1 it will have to be custom made because you want th rar braces to go to the strut towers. Neither Kirk nor the Autopower ready made bars do that.

 

For #2, never run a full roll cage on a street car.

 

For #3, a triangulated front STB can be made for the 2Jz install and I've built one for a customer. Its custom.

 

For #4 search this site for the RT Mount and the seat mounts are custom.

 

No pics.

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For #1 it will have to be custom made because you want th rar braces to go to the strut towers. Neither Kirk nor the Autopower ready made bars do that.

 

For #2, never run a full roll cage on a street car.

 

For #3, a triangulated front STB can be made for the 2Jz install and I've built one for a customer. Its custom.

 

For #4 search this site for the RT Mount and the seat mounts are custom.

 

No pics.

 

Oh why oh why do all the best automotive shops always gotta be in california lol.....man so alot of custom work....

 

On #2 what would be a good setup to use for a street driven car, is there any vendor out there that sells one or is this something that im gonna wanna do custom as well?

 

Im still confused on the RT mounts? are these the same thing as the diff mounts offered thru AZC or Modern?

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reinforce the pedal box?! interesting.. how is the pedal box a weak point?!

 

The firewall/pedal box flexes under hard braking. On a race track it makes the braking slightly vague at times (bumpy brake zones).

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Oh why oh why do all the best automotive shops always gotta be in california lol.....man so alot of custom work....

 

On #2 what would be a good setup to use for a street driven car, is there any vendor out there that sells one or is this something that im gonna wanna do custom as well?

 

Im still confused on the RT mounts? are these the same thing as the diff mounts offered thru AZC or Modern?

 

A roll bar is fine for a street car. Again, search this site using RT Diff Mount.

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Lets see some good examples of street car roll bars.

 

Search the site or something. Auto Power roll bar. It is just a hoop with a harness bare through it, then it triangulates to the top of the strut towers. Simple, if you have a tubing bender you could make one. I am going to make one and then put in just a single door bar on each side to protect me from side impact accidents. They scare me.

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For a street driven S30, here's about as much as you can do to stiffen the chassis:

 

1. Seam Weld (every sheet metal seam overlap.)

2. Bad Dog Subframe Connectors

3. Weld-In Roll Bar.

4. Welded In Rear STB.

5. Triangulated Front STB.

6. Radiator Core Support Reinforcement.

7. Transverse Link Bracing Reinforcement.

8. RT Diff Mount.

9. Tubular Seat Mounts.

10. Box Upper Frame Horns to Firewall/Cowl.

11. Reinforce Pedal Box/Brake MC Mount.

12. Reinforce Front ARB Mount.

13. Reinforce Front Strut Tower to Frame Rail Junction.

hmm my car already painted after bare metal strip so missed number 1 and number 2 :( but it is a 76/77 260z (same shell as your 280z 77/78) which do have a stronger shell

3. Done

4. Done

5. Got that sorted

6. ??? More info?

7. ??? More info again - Would I be correct in saying that would be a support bar across/between the rear of the TC rods?

8. Done

9. Looking to doing this when I replace/install aftermarket seat - some time away :(

10. Would this be talking about the pics shown in the attached file? I am getting these bars welded in the next week or so - just need to get car back to the fabricator

11. Done via a Beta Motorsport dual master cylinder setup - I am amazed how much this helped in this area

12. The world is full of too many TLA so what is an ARB Mount?

13. Missed that too :(

 

So I guess that is a fail - only 5 out of 13 not even 50% :(

post-837-12729625186232_thumb.jpg

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6. ??? More info?

7. ??? More info again - Would I be correct in saying that would be a support bar across/between the rear of the TC rods?

8. Done

9. Looking to doing this when I replace/install aftermarket seat - some time away :(

10. Would this be talking about the pics shown in the attached file? I am getting these bars welded in the next week or so - just need to get car back to the fabricator

11. Done via a Beta Motorsport dual master cylinder setup - I am amazed how much this helped in this area

12. The world is full of too many TLA so what is an ARB Mount?

13. Missed that too :(

 

So I guess that is a fail - only 5 out of 13 not even 50% :(

 

6. The radiator core support reinforcement is a bar across the top with gussets to the inner fenders.

7. That's a brace from the mustache bar mounts to the outer ends of the horizontal brace going across the back of the diff.

10. You're idea works.

12. ARB means Anti-Roll Bar.

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7. That's a brace from the mustache bar mounts to the outer ends of the horizontal brace going across the back of the diff.

Is like the pic attached? The red lines is this what you mean (ripped pic from the internet - it was the best I could find showing this area)

10. You're idea works.

Yes that what I thought - take some of the flex out and hidden in side the fender and not in the engine bay for a street car.

post-837-12730545050485_thumb.jpg

Edited by NZeder

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Is like the pic attached? The red lines is this what you mean (ripped pic from the internet - it was the best I could find showing this area)

 

Yes that what I thought - take some of the flex out and hidden in side the fender and not in the engine bay for a street car.

Not sold on this mod. If you have bushings in the mustache bar (even poly), wouldn't they flex and make the added bar basically useless? If you could isolate the brace from the bushings great, but I don't see a good way to do that. If the mustache bar was mounted with aluminum instead of bushings, then I see this working a lot better.

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Not sold on this mod. If you have bushings in the mustache bar (even poly), wouldn't they flex and make the added bar basically useless? If you could isolate the brace from the bushings great, but I don't see a good way to do that. If the mustache bar was mounted with aluminum instead of bushings, then I see this working a lot better.

 

Ideally the additional tansverse link brace as pictured above would mount between the mustache bar (MB) and the chassis. A .083" wall tube whose ID is greater then the OD of the round ends of the MB, notched to clear the bar itself, one end closed with a hole to slip over the mounting studs would work as the chassis mount. This mount could be welded to the chassis or held in place the the MB mounting itself.

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John,

 

this is a very interesting thread.

 

I know your the king of modifications and pictures and documenting everything.. can you post up some pictures or describe in a bit more detail on reinforcing the firewall?!

 

It would take me a while to search through my pics, upload them, and then post the links. None of this is rocket science and if you look at the areas mentioned and think about the loads involved it should be pretty easy to figure out what should be done. As you can see from NZeder's post there is more then one way to solve these problems.

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