The ins and outs of chassis strengthening

[PIMPIN] · Aug 2, 2011

What are everyone's thoughts regarding chassis strengthening? Would you say that your Skyline already is perfect from factory meaning its not too stiff that road use is unbearable yet able to handle any extra power not to mention extreme driving? By that I mean it absorbs the forces acting against it without flexing, at least not noticeably.

We see advertisements for all types of products from chassis foam to all types of bars. Have any of you installed any of these products in your Skyline? And if so, what made you do it? What difference has that product made to the car both in terms of handling as well as comfort? Do you regret that decision or was it the best thing you've ever done?

Personally, I'm not against chassis strengthening but there are certain products or modifications I'd probably never do. One of which is the use of chassis foam which is injected into various points and then expands and hardens within the hollow points of the structure. I believe the chassis, designed by engineers, needs to flex and the flexing occurs at such minute levels we definitely don't know its happening. But once you introduce this rigidity where its not engineered to be, how safe is that really?

Take the example of the human spine. It definitely isn't straight, and the reason why its curved is to allow the proper distribution of weight, give us flexibility and mobility yet allowing the skeleton to support the weight of the body while protecting the spinal cord and whatever wiring harnesses inside. So its very much like a chassis isn't it? What happens when the spine is straight? Well it then becomes inflexible and weight is therefore wrongly distributed, placing strain on the lower back and even back of the thighs. Don't worry Prof Nain, this isn't Google'd or Wiki'd but rather based on my own spine. :proud:

So let us now discuss chassis strengthening and hopefully add more information so that in future, this forum can become a knowledge base for all things Skyline related. :burnout:

Disclaimer: For the sake of this discussion, chassis strengthening will encompass both modifications made to strengthen the chassis as well as body of the car with the goal of improving handling by introducing rigidity into the overall structure of the car.

gobiz2 · Aug 2, 2011

Got one legendary car that had spot welds all over... it's a 4 door skyline.
The owner says he uses it to go pasar...but the pasar that he goes to is so far away... like in Lukut, Bentong, Mersing... :biggrin:

shark79 · Aug 2, 2011

spot weld,roll cage are proven through years of racing...foam hmm..what about rusting ?
that 4 door skyline very the dangerous wan.....

[PIMPIN] · Aug 2, 2011

I was thinking if we could keep the discussion centred on cars used primarily on the road where comfort is still a factor. But if there are those who do drive spot welded Skylines and/or ones equipped with rollcages then by all means, your input is invaluable.

In addition, I was hoping to introduce the subject of reinforced bars such as the ones made by everyone from Do-Luck to Ultra Racing. These are the types of strengthing I would consider. However, given the fact that Do-Luck tells you what the bar is made of and you can tell where the mounting points are, couldn't Ultra Racing replicate the exact same thing? Logically it should work the same.

Aside from Ultra Racing, who are the local alternatives?

Thanks in advance!

devious17 · Aug 3, 2011

In complementing chassis reinforcement, the dynamics of vehicles would add to the breath and depth in the discussion.

The dynamics includes and not limited to suspension, weight transfer and weight to power distribution.

suspension - spring, damping, roll center, travel, CG.
weight - lateral, longitudinal.
roll center - kenedy theorem, roll axis.

beatnik · Aug 3, 2011

While strengthening seems to be the ultimate goal, the materials used and the construction also need to be considered. For example, a solid steel front strut bar may be the most rigid; it does not crumple when sh1t happens. If the car is hit on one side, the force is transferred to the other, which will result in a deformed chassis. That may cause more harm than good. Some might scoff at aluminium constructed strut bars, but a well designed (i.e. tubular design) is rigid enough at the same time will crumple at the hinges when the car is hit. I disagree to those who said solid steel is the holy grail of chassis strengthening. Not to mention it is heavy too.. Put whatever bars available for your car and you’ll end up adding another 10-20kg. :rofl:

After all, you get what you pay for.

Chassis foaming? I have heard nothing but praises with the result, but it is not something that I would do. If it is so good why don’t manufacturers pre-fill the chassis with it? Cost? The foams aren’t that expensive.

turbolover · Aug 3, 2011

One thing for sure is that when you strengthen the chassis you get sh*t ride. Uncomfortable from my experience.

Tai Thye · Aug 3, 2011

I installed full set Ultra Racing............handling so pro compare b4, but very heavy the car :bawling:

Temujin · Aug 3, 2011

I'm not a race driver so I can't say much about handling and stuff.

I do feel a difference between having the front and rear struf bars but can't comment much on other chassis strengthening as I've never done any more than what I've mentioned.

I guess it would make a hell lot of a difference for those competing in drift and other motorsport events but I'm quite happy driving my car the way it is on the highway and up touge.

I suppose having a rollcage would not only stiffen the car (for better handling perhaps) but also it could save lives (as per last Sunday's drive).

Suspensions are a different matter but that is another story (a very subjective one at that too)..

[PIMPIN] · Aug 3, 2011

I think everyone has missed the questions in the first couple of paragraphs of my initial post. It's ok, I do realize my posts are long-winded and hard to follow if you're not paying attention but I make no apologies hahah.

For me, my Skyline was a good compromise from factory whereby the chassis can and has been proven to handle double or even triple the standard power output. Even in my situation where my car is substantially heavier than the average BNR34, the car still feels nimble and is able to change directions quickly. In short, it doesn't feel like a car that weighs 1600kg from factory. One of the reasons for this is the structure of the car itself. If you have removed the back seats before, note the huge bar or should I say beam even running across the width of the car. That I feel contributes a lot to the rigidity of the chassis.

I've done no chassis strengthening modifications whatsoever aside from replacing the front strut bar with an ARC item. However, the difference would probably be next to none. I have yet to find a reason to do anything more just yet.

Well that's my approach. I'd be very interested to hear from others, the more specific the better if possible and not meant to be kept secret that is.

Thanks

---------- Post added at 11:42 AM ---------- 6 hour anti-bump limit - Previous post was at 11:38 AM ----------

If I could touch on rollcages very briefly. When I was studying in Perth, cars were only allowed rollcages under very strict circumstances. For example, a coupe like the Skyline could legally have a half cage fitted but can never carry passengers in the rear, meaning it'll be legal as a 2 seater only. The reasoning behind this is simple. Should you be involved in an accident and your car had come to rest in a position where access by emergency rescue teams is severely limited, you could die by the time they are able to free you from the wreckage since it won't be as easy to cut through. Add to that a car that is slowly going up in flames and you'll see the potential danger is quite significant as well.

ftzone · Aug 3, 2011

imho, some sports-car manufacturer did not include the extra strut bars due to cost and also to maintain the comfortable feel for daily use such as the 4 door skyline. not all sport cars owners bring their rides to the tracks right? therefore making it an option for owners to upgrade if required. just like the stock coilovers which don't make you feel like travelling on the moon surface.. if you like racing and drive fast there is always an option to upgrade for improved handling instead of being comfortable.
i personally felt the improvements of my car handling @ the tracks when i installed the lower arm bars, anti roll bar and fender bars. (of course not a skyline as i can't afford one) even my lap times were improved. however sacrificing some comfort level on public roads.

Veloc · Aug 3, 2011

Oh crap... Sorry I didn't see this if for skyline... Deleted post!

Alchemis · Aug 3, 2011

in general point of view, under braces is actually over kill. depending on what you need. i used to drive an old car ... mazda RX7 FD3S... i'm the legendary 777 :P

under braces could help the car because of the material fatique over time. the twist gets more and more as years goes by. because i drive like a bull. normal braces is a stock for the car. changing to other brand of braces will not help other than emptying your pocket for something unnecessary.

previously i've tightened the lower arms with additional braces. the damping of the car feels tighter and more accurate in term of steering, feels more direct. the center brace, they don't do any help. as the mounting point is not any heavy stress point. thus i took out the brace and left it. as for the rear, the suspension arms were tightened only. the rest is still stock... stock front tower strut and stock rear tower strut. it's good enough... the next stage will only be a roll cage either half of full.

[PIMPIN] · Aug 3, 2011

Veloc said:
Oh crap... Sorry I didn't see this if for skyline... Deleted post!

No, actually all opinions are welcome here. It's just that I for one don't really read the other sections of the forums which is why I chose to start this thread here. Chassis strengthening in principle would work the same way regardless of what brand of car you drive so please feel free to join in.

devious17 · Aug 3, 2011

Temujin said:
Suspensions are a different matter but that is another story (a very subjective one at that too)..

I believe chassis tuning includes suspension, cant have one without the other. A simple fender bar makes a differences on my drift setup car depending on the diameter and material of the reinforcement employed.

I had to have the front fender bar cause the chassis was old and prone to cracks, I had one pair installed on both sides and the car was under steering more than usual. I reduced the tire pressure a little and that helped a bit but resulting in inconsistent grip. Back to the pits, inflated the front tires and tweaked the bump and rebound rates and behold! the car was back to its old manners minus the chassis cracking worry.

Just to share.

Veloc · Aug 3, 2011

I think there are ups and downs...

For those foam stuff... I haven't try these, but personally I think these are rubbish. Sound insulation, heat insulation, chassis strengthening all in one. Too gimicky. I mean come to think of it, it might do a little bit of all that is mentioned, but never good at it. Because it tries to do all. Don't tell me the strengthening will be good than steel/aluminium bars. And don't tell em the sound insulation will be better than a full, multi layer sound deadening mats.

For the bars, I believe these are good but depends on what the driver wants. I've tried one on my wira last time. Just a front and back strut bar. Surely the handling is nice. Cornering is crisp. But going over a bump, because the bar links the 2 strut tower together, the car loose some independence in suspension causing more jarring movement.

I also got testimonies when a person using strut bars, got into and accident. Because it ties two sides together, the other side is also slightly dented from the impact.

So, really depends on what the driver wants... But for foam, o0o.

alpina · Aug 4, 2011

Car designers spent a lot of time to develop their car bodies in the event of a crash, many cars are designed with a crumple zones and chassis strengthening may interfere with it.
You may possibly end up with some of your strengthening bars injuring or killing you in an accident. A roll cage on the other hand is designed to strengthen the safety cell in your car in the event of an accident.

Newt · Aug 4, 2011

Hi, can't help but notice this thread :-)

I'm a noob, so my opinion is mostly rubbish i suppose... but this is me just talking from experience...

I drive a very old car (well, my brother's car actually :-p) an RX-7 FC3s, dating from 1987 (yes, it's ancient X-p)... at first, being a noob and all, i never really took notice in body flexing and chassis rigidity and stuff, but then, after taking the car to several consecutive open track days at Sepang, all the high G corners really undermined the chassis rigidity...

The chassis started to twist and turn up to the point where even i would notice it :-p the downside of it all is that it disconnects me from the feel of the suspension, how good are the tires holding the road, how much load is the suspension being subjected etc... So naturally the car became far more unpredictable on the limit...

It became far more obvious on downhill touge runs where car stability and weight control is of priority.. it became so bad, that even my friend's Neo could leave me in the dust on a downhill run :-p

That was when we decided that we needed to re-strengthen our chassis... note the word re-strengthen :-p because i do believe that stock performance car chassis are superb, but overtime, they tend to lose their rigidity and initial stiffness...

So at first we pluck in a full bolt-on roll cage :-p and the feel of the car became SUPERB!! It was many folds better than before... i became connected again to the suspensions and the tires.. the car became so manageable, that i eventually overcooked a corner and crash it X-p well, that may not be a good thing, but the fact of the matter was that by strengthening the chassis, i felt the difference, so much so that it gave me SO much confidence, that i felt i could get the car out of any sort of mess i.e. catch any slides through the turns.. unfortunately i failed to take into consideration the speed and inertia of it all X-p

Anyways, after that, our goal was to seek the ultimate in chassis strengthening... :-p since we're stripping down the car, we had it spot welded, anti-rust treated, and all the rust patched up... Then we strapped on a rear strut tower for good measure :-p

The chassis felt great, the car finally reacting to the suspension as it should be... it became more predictable, more manageable on the limit... then we had a power bump, a bigger turbo, wastegate etc etc etc, we came to speeds that are even twisting our bucket seat... >.< that was when we felt that there is not enough rigidity at the rear as we felt the rear twisting in the corners... not that it was as bad as previously, but i'd still prefer more rigidity...

So currently we're now considering the foam option :-p once we've done that up, i'll tell you guys how it feels ^^

My conclusion, it all depends on what you want to achieve actually... stock chassis are great as it is, but after many decades, and many abuse, the chassis will start to soften up and become undermined... that is when i believe chassis strengthening truly comes into the picture (that is if you're not using it for track / drift specific purposes :-P)

Just another side note, as for mass produced car, the chassis are as soft as candy, so strengthening it up really is a plus... my friend's neo handles like a go-kart when he completely strengthens his chassis via strut bars etc...

That's just my 2 cent worth of quite a rubbish opinion from a noob :-p how far it is from the truth, i have no idea... X-p that is my truth anyway...

DarkChild · Aug 4, 2011

Let me stir the hornets nest a little... :biggrin:

by Dino Dalle Carbonare

Ok this will probably have most of you guys scratching your heads, but yes that's a GT-R driving out of the Spoon Sport's Type-One workshop in Tokyo. It's actually my R34, and the reason I brought it over to Ichishima-san was to have it fitted with something that has intrigued me ever since I heard about it a little over a year ago, the Rigid Collar. The constant pursuit of perfection is something every enthusiasts tries to achieve with his prized possession, and when it comes to my car I'm extremely picky with what I fit it with. I think Ichishima is exactly the same, that's why Spoon Sports has made such a name for itself and when he came up with the Rigid Collar he knew it would benefit pretty much every single car out there, therefore decided not to limit himself on providing it only for the Honda community.

And that is indeed a very good move, as these little aluminum 2-piece collars have been attracting all sorts of cars to the Type-One workshop as the application list continues to grow. "Sometimes we get up to 12 cars in one day," as Yamada-san, the person in charge of fitting the collars to the Skyline, tells me. "We get anything from Porsches and BMWs to Subarus and Toyotas." And it seems everyone is so happy with the result, which makes me even more excited about getting these things onto my car. The concept is very simple, basically the Rigid Collars act as guides for the bolts that hold the chassis and subframes together, so that there is perfect alignment between the two holes the bolts are passed through. These holes, to ease assembly, are usually much larger than they should be, which over time allows the subframes to misalign throwing the car's geometry out the window. But enough with the theory part, let's take a look at how they are fitted, pictures will tell the story far better than words can.

So first thing was to place the GT-R on the lift, remove the wheels and lift it up.

The R34 is fitted from factory with a front diffuser, which helps generate front downforce and smooth airflow over the front portion of the car. It looks cool and very racecar-like but it requires to be removed pretty much every time you need to do anything on the car, which is why I have gown to hate this damn part! On top of this it's actually made pretty badly and a few unavoidable scrapes here and there (check out the opening picture to see what I mean!) it will eventually split open along the seam where it has been fused or glued together. I'm currently on my third one, and they aren't cheap!! But enough moaning.

So with the diffuser off, Yamada-san and the Type-One mechanics got to work in undoing the four big bolts that hold the front subframe to the chassis.

Removing the diffuser revealed a greasy mess around the passenger side drive shaft caused by pretty large split in the rubber CV boot. This is currently getting fixed up over at Pentroof.

As all four bolts were loosened up...

...it was time to hold the subframe in place with an hydraulic transmission lift...

...before the bolts began to be loosened further.

This picture perfectly shows the problem the Rigid Collars address. You can see how the subframe has moved around and the bolt is far from centered, not to mention the offset bolt marks left on the subframe.

This is what the rigid collars look like. They can be very different in appearance depending on application or whether they are made for the front or rear subframe.

These are the ones that were to be used on the front. As you can see they are cut down the center and can be split by hand. This is so they can be fitted without removing the subframes from the car, making the fitting procedure far simpler and quicker.

A little copper grease is placed on each half of the collars...

...before they are carefully placed on each side of the exposed threads.

And there you go, all four halves in position on one side of the subframe.

Using the hydraulic gearbox lift the subframe is carefully lifted up into place while checking the collars snap into place.

There you go, perfect alignment obtained. Next step is to fit the bolts back on, tighten them and torque them to factory settings. The washer part of the collar will squash and deform to form a perfect, even and flat seal between the surfaces of the chassis and subframe. If you watch this video you can see this further explained by a few diagrams and animations.

With the front done it was over to the rear, and like the front the rear undercover had to be removed to expose the rear subframe.

Again first step is loosening the bolts...

...which, after 12 years, were pretty tight!

With rubber bushings being used on the rear mounts of the rear subframe the Rigid Collars required are slightly different...

...one regular thin one on the upper part to seal and align the top cup to the chassis...

...and a second bigger one underneath.

The Rigid Collar in place around one of the front rear subframe mounting points.

With the collars in place, all bolts torque checked and front and rear undercovers back on it was time to fit wheels.

I had them rotated to keep front and rear wear as equal as possible. Those Bridgestone RE-11s do wear down quite quickly!

One of the mechanics took the car out for a quick drive to check everything was ok...

...and found the steering needed to be re-centered now that the subframe was aligned properly with the chassis. Even driving the car around you can instantly feel an improvement in the car's dynamics. The first manhole cover I went over I instantly noticed the suspension felt far more compliant when dealing with bumps and steering feel definitely improved off center, where it had always felt a little vague. On the limit is where the changes can really be felt, with the alignment now perfectly squared up, the car feels far more precise and planted through corners while direction changes are more progressive when tire grip eventually begins to let go.

As soon as my car was done this Mazda Axela MPS was lifted up ready to be fitted with the Rigid Collars. Feeling the car come alive and more communicative is extremely rewarding and I am very happy I decided to go for this upgrade. Now the question is, what's next because as we all know this tuning bug never really ends does it!!

Rigid Collar

Spoon Sports

-Dino Dalle Carbonare

SOURCE - SPEEDHUNTERS.COM

V-Spec · Aug 4, 2011

Leo, when you fitting those rigid collars? Hehehe

The price of those little bolts/washers are amazingly high!

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The ins and outs of chassis strengthening

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