Having Roll Cage and eliminating some Rear Suspension components
 

I currently have a 4 point rear cage and hopefully next weekend the full cage will be complete. So with the cage (mostly the rear) bracing the body of the car are the two braces underneath the rear body needed? There's two. One that's W shaped and then the rear torsion bars.

I feel with the cage bracing the body of the car and the amount of structural support it has the this small components don't serve a purpose and more and I food remove and save weight there and eliminate useless components.

I removed them because I don't feel they are absolutely needed and also it was interfering with the exhaust I was making.
Yes they do serve a purpose to stiffen more the front attachment.
But the front sub-frame attachment already has another brace. (( 2 actually if you include the W brace that act similar to the V ))

The only big difference between the 350z and 370z is the long V brace that goes from the front main of the sub-frame attachment to the rear middle attachment.

EDIT;
It doesn't show on the picture, but the 350z also has a brace that connect both rear attachment together and bolted to the frame.
Similar to the 370z brace that is shown.

But I would keep that W brace for sure !

http://www.the370z.com/members/megan...-370vs350z.jpg

I donno, it's very low, rearward weight, and it can't be all that much. I'd think any extra stiffness would be worth more than a little weight down there. The W-shaped one does seem a little superfluous, but not so sure about anything else.

That's how I feel. There no absolutely needed. Especially cause the cage braces everything bet ohm all doubt. Hell I wrecked this car one time and the cage saved it from being to totaled. Even when on the frame machine the body was 100% on target. Only the body panels were effected.

Does the Doran car have them?

I love saving weight. I won't be running headlights anymore either. Lol

Im sure you've posted it somewhere but what are you weighing in at now? What will you be filling in the headlight hole with? MCA Suspension has carbon fiber replicas on their 370z...in case you need ideas :tiphat:

Oh, so looking at the diagram again (I haven't been under the rear of my car in a while and it's cold outside :P), the W-shaped bracket and the two long arms that run out to it... they're basically aft of the real suspension, right? Now that puts me more in the mindset of "anything aft of the actual suspension is just to hold up the trunk/exhaust, it can't affect handling" right?

the way I see it is, those brace do serve a purpose of avoiding the long threaded bolt that hold the subframe to bent on either side while there is a load from any direction.


this could affect handling such as modifying camber/toe on heavy load.

In my opinion I can deal with removing the V-brace since the forward portion of the sub-frame is already braced by 2 other one like the 350z

is it optimal ? maybe not.
but removing it on my personal car was to have a much better ground clearance for a future flat bottom / diffuser setup which also contributed to the clearance of my custom exhaust ;) *still for sale ! lol *

Not sure. I'll know exactly next month. It should be lite. I don't have to run my car to any sort of spec. I've done done serious things. I bought headlight covers to fill in the hole.
That's my thoughts. If anything it's chassie related but I've already more than reinforced that with a cage.

This should be easier to understand what I meant ...

http://www.the370z.com/members/megan...5-subframe.jpg

I'm not speaking of that bar. Only the W piece and the two bars tied together in a V shape that attaches to the drop down section you cut out on your car.

The bar it looks like your referring to is #6 in your first post. I'd definitely leave that.

yes , we are also talking about those bar


so what is the purpose of those bar...

think about them as a brace to avoid having those long threaded bolt to bent on loading ....

what is that V and W brace do ?
Its holding that screw to bent on load..

I understand that basic operation. But with the cage welded to the body and the subframe secure there's IMO no way those parts are need even in the minimal. The subframe and actual suspension work together up and down, left and right. And with the cage mounted to the furthest outside of the inside of the car the braces were speaking of are within the perimeters of the cage thus IMO opinion pointless. Can't really brace inside of a brace. Is this making sense?

I give up..

your rollbar are not holding the bottom tip of those long screw that hold your sub-frame.

if there is nothing or not enough brace to hold the bottom part of those long screw (see picture) they will bent a little bit which affect your alligment

on the 370z they only added a 3rd brace to do relatively the same job as the 2 other one (on the front part of the subframe which now has the V-Brace on the 370z)

do what you want. im done

another thought.


are you getting solid sub-frame bushing ?

if yes .
why ?

if you give the answer about avoiding movement of the sub-frame because of rubber bushing and to have a firmer handling

then why wouldn't keep at minimum some bracing of the bolt that hold your sub-frame

like I said I can deal with the v-brace removed but I wouldn't take out the W. since its also holding both side of the car together...

Holy sh!t dude. Chill out. It's a discussion. What I'm talking has nothing to do with those two big threaded studs on any level. The two braces I speak of don't come in contact with the direct subframe at all. Everything is stacked not fully bonded as out served a purpose. The pics above don't even show the way it all comes together. There's a couple things missing in the picture to bring it all together. Amazing someone gives up so easily. I thought you were cool? First it's hard to get a full understanding threw words and typing here to get full point across. Fine, I'll never ask your opinion on any crap again. Geez

Like ever other thing here

no hate here,

I just fail to understand your point of view with your rollcage that is infact only stiffen the body.

it has nothing to do with how the sub-frame interact and how it held under the car.

but go ahead and remove those W and v brace and even the rear one which weight like 5-8lbs ... then also those smaller one that connect the W brace & V-brace to the bolt holding the subframe...

from what you kept saying is your rollbar make your body stiff enough that you think about removing those useless parts now...


again those long bolt which hold your subframe will be even less supported if you do remove the W & V together...

but its your car ... you asked our opinion and it was like your mind was pretty much already set to remove them ... I just support the idea about the V-Brace. not the W.


dont worries ,,, it wont bother me if you stop PM me about my opinion , I received quite enough for the pass year that it hasnt served me well in the end ... but anyway I will still always answer to even someone who I dont respect *which isnt you btw... *

http://www.370z.com/Portals/0/Magazi...0W%20brace.jpg

Has anyone had a look at the Nismo RC race car?

The braces are designed to ensure that the studs into which the rear subframe mounts are held in double-shear rather than single shear.

"IF" you are going to remove them, then the race engineer in me would want to periodically inspect the studs for cracks.

Your cage supports the bodyshell but does not directly reinforce the stud into which the subframe mounts.

If you are replacing, or have replaced, all your suspension bushes with solid, then all lateral/longitudinal loads (including shock loads from hitting things - like kerbs) are fed undamped immediately and directly into the subframe and in the absence of the braces, the studs which secure the subframe will see a bending moment which will eventually lead to fatigue in the stud.

Whether this is a fatigue load that is sufficient to warrant any concern I cannot say, but simply observing that the Nissan designers thought that double-shear mounting is required for road-car durability tells me that it is probably worth retaining.

OEM's don't add unnecessary weight to their cars without reason.

I'll simply observe that I have had some suspension breakages in race cars "at speed" over the past 40 years and not one of them was a pleasant experience, personally or financially. Personally, I'd take a guide from the NISMO RC - if they have them, then they are needed.

Hope this helps make a decision - it is up to you at the end of the day.

RB

After putting it all together no doubt you and Megan (cough) are correct. I just was not seeing the real picture. I had one thing in my mind. So the laterial load and effect makes perfect sence. Especially being I have all solid bushings. Just did know I was was going to get the wrath from Z God after two post. Come at me is fine but to totally disregard the topic is not helpful.

While on the roll cage topic...How did you mount your roll cage? Is it bolted in or welded? If it is welded to the frame what is the cage made of?

Thanks in advance.

Click that big journal button. All you want to read is in his thread with pics etc.

not really. I have read all 55 pages. It just shows the roll bar in. Then there is a few pictures and a comment of his buddy welding the cage to the roll bar. I didn't see any mention of how he bonded steal to aluminum.

Omg where does everyone get this? The cars steel. Aluminium cars don't weight 3400lbs. The only thing aluminium is the hood, doors, hatch and bumper beams. His first rear cage is welded to the body, you can see that..

Actually the first install I believe was in the first build.

It's all welded in. The cage is made of steel and meets most road course spec. The size of the bars, the thickness, and angles of the bars.

That is so damn awesome to here! Thanks synolimit I always wondered why are cars were so heavy even considering its a V6. Yes I saw how it was welded in the pics and now I understand how he was able to do it :tiphat:

Awesom build Sphoon been following it for a while. Think you will ever do W2W racing with it?

Spohn have you done a complete write up on your car's weight loss? I think you should

Sent with TapAhoe

Not really. I posted pics from the corner balance. Weighs in at 2831 with full cage and half a tank of gas. Still more saving to bring it under 2800 easily. But I want it off the front of the car.

As somone who has torn this car apart and have had sheetmetal cut out no doubt in my mind why it weighs as much as a small tank. The chassis is massive from huge rails that traverse the car to heavy subframes, to motor and tranny. Its a big car and Nissan has no hesitation over engineering structures and using tons of steel.

Although my car is headed to sub 2600 lb territory soon. I know where all wieght hiding places are for this car now. But not many people are going to be willing to be quite as crazy as me.