Chassis REINFORCEMENT is it good??

[Taz69]

Ok guys here is the question. We are talking street car.. I had 2 M3 CSls 03 and I had 2 111Rs 04.. I built them all the way full suspension full weight reduction the whole 9 yards just no down force. I used Deep Forest as the test track.. I want all the tuners input here this is just what I found. I went .2 to .3 seconds faster on the cars WITHOUT the chassis reinforcement. I even tried to change the springs and everything on the cars with the reinforcement but could never make them any quicker that the cars without??? Why is this. Am I wrong? What have most of you "professional" tuners discovered when tuneing street cars.. I do all my testing and racing online so I need input from guys that have also tested online. Since you CANT take it back off I want others opinions before I add it to any of my other cars. No bashing and no one answer is correct I just want to know what everyones personal experience has been.. Thanks guys let the discussion begin. All cars were bought new so old age on the chassis wasnt an issue..

 

[JackWilson]

Keeping it simple.
With Chassis Reinforcement will increase understeer - FACT!

 

[XDesperado67]

It varies on a car by car basis. For me most cars seem to handle better without, but a few have shown improvement with it on.

It's for reasons like this that I prefer to have at least 2 copies of any car I'm tuning, that way if I make a modification that can't be undone and encounter issues I'll have a clean backup on hand.

 

[VTiRoj]

Keeping it simple.
With Chassis Reinforcement will increase understeer - FACT!

Yep. The complex answer would be that the Chassis Reinforcement increases a car's tendency to understeer, but also make it easier to drive and more controllable because the additional stiffness to the car's body improves grip. In cars like the BMW M3 and Toyota GT86, the Chassis Reinforcement serves no purpose since they already have brilliant handling. An RUF Yellowbird however could do with Chassis Reinforcement to help with its oversteer problems.

 

[Vol Jbolaz]

I think a more complex answer would be that chassis reinforcement helps transfer mass better since there is less body flex. This extra weight on the front end during braking and extra weight on the outside during cornering can cause a suspension that is not properly set up to exhibit understeer.

Reinforcement is neither bad nor good. You just have to understand that it will cause less body flex and more weight transfer. Some cars need this. Others don't.

 

[DigitalBaka]

I may be wrong (good chance!) but doesn't a stiffer body translate to less weight transfer? Or does that apply only to springs and dampers?

Overall it seems like the reinforcement would be good for a car that tends to oversteer even when tuned "well". Would this help the older cars with "skinny tire syndrome"?

 

[Vol Jbolaz]

I may be wrong (good chance!) but doesn't a stiffer body translate to less weight transfer?

I could be wrong, but it is my understanding that when a car moves it bends slightly. The body acts like a spring, carrying some of that weight in the bent members and not transferring it completely.

Think of it like this. Use a heavy solid stick and push your friend with it. Then use something less rigid, like a length of PVC pipe. The pipe will bend and less of your force will be transferred to your friend. You'll have to push harder to knock him off his feet.

p.s. With stiffer springs, more of the transferred weight is transferred to the tire. The more the spring can give, the more energy it will absorb on its own. The more energy put onto the tires puts more strain on the contact patch, causing it to break traction easier. Mind you, you do want stiffer springs. You want some weight to transfer onto the front wheels. You want them to force the car to turn. If you don't transfer enough weight, you'll get understeer simply because the front wheels don't have traction (this is why some people may let off or tap the brakes to have the front tires "bite in"). If you transfer too much weight you'll get understeer because the front tires can't offer enough traction for the load they are carrying (this is why FFs understeer so badly, the engine weight is on the front tires).

Again, I could be completely wrong.

 

[DigitalBaka]

I'll see if I can explain how I am looking at it. Going at it from a purely lateral perspective; obviously there is weight transfer longitudinally but I'll ignore that for now.

I have car X with 1000lbs over the front axle. When cornering without any reinforcement the body roll shifts the weight over to 750/250 L/R hypothetically. If I add a chassis brace/tower brace, the car corners flatter which, to me, should transfer less weight the same way stiffer springs and dampers do, say 650/350.

Of course I'm no expert and I could be totally wrong.

 

[Vol Jbolaz]

I'll see if I can explain how I am looking at it. Going at it from a purely lateral perspective; obviously there is weight transfer longitudinally but I'll ignore that for now.

I have car X with 1000lbs over the front axle. When cornering without any reinforcement the body roll shifts the weight over to 750/250 L/R hypothetically. If I add a chassis brace/tower brace, the car corners flatter which, to me, should transfer less weight the same way stiffer springs and dampers do, say 650/350.

Of course I'm no expert and I could be totally wrong.

I don't know. I've not looked at a car with stock springs but braced. I would expect the bracing to, by itself, not affect how flat it corners.

I could be wrong.

In university, I switched from Mechanical/Aerospace Engineering to Computer Science, so my knowledge is limited at best.

 

[XDesperado67]

I may be wrong (good chance!) but doesn't a stiffer body translate to less weight transfer? Or does that apply only to springs and dampers?

Overall it seems like the reinforcement would be good for a car that tends to oversteer even when tuned "well". Would this help the older cars with "skinny tire syndrome"?

The cars I've found it to help have all been older cars. Don't think it has as much to do with the so called "skinny tires" as the fact that many of these older cars had much less rigid chassis that allowed excessive body flex. One of the things I look for in a cars handling is its behavior in quick direction changes, like on an autocross slalom or some of the series of quick corners on certain tracks. On cars its aided for me they would turn in crisply on the first corner but start to lag a bit with the turn in on second as the body took longer to flex than the suspension. This delayed the weight transfer and often the car once into that second change of direction wants to oversteer sometimes very badly as the weight transfer occurs well into the turn and then won't unload in time to straighten out. With the chassis rigidity you get less body flex allowing for the suspension to better handle the weight transfer and reducing the chance of the car overloading one corner.

With most of the newer cars they have a rigid enough structure as is and making it stiffer will just inhibit the desired weight transfer.

 

[VillanUK]

Funny this topic came up. I have just installed a set on my GTO and straight away lost the benifit of using the rear slide to get round bends and now the car is bouncing around corners, im kicking my self tbh. So as i cannot reverse it, should i soften the springs or just accept i buggered the car up lol

 

[CSLACR]

I'll see if I can explain how I am looking at it. Going at it from a purely lateral perspective; obviously there is weight transfer longitudinally but I'll ignore that for now.

I have car X with 1000lbs over the front axle. When cornering without any reinforcement the body roll shifts the weight over to 750/250 L/R hypothetically. If I add a chassis brace/tower brace, the car corners flatter which, to me, should transfer less weight the same way stiffer springs and dampers do, say 650/350.

Of course I'm no expert and I could be totally wrong.

I don't believe you can do anything to truly "stop" or hinder weight transfer at all. Except maybe lowering, that could potentially reduce weight transfer, but even then I'm not sure it does.

What good suspension does is manage weight transfer well, in all scenarios.

I'll be another to say I could be wrong, but I'm pretty sure cornering speed = weight transfer, and it's a set amount.

Chassis flex is generally considered a bad thing, but increasing chassis stiffness does bring on more under-steer, so you always need to re-tune the ride to cope with the improved chassis.

All that aside, when I'm playing GT5, I use chassis rigidity on loose cars only, never on cars that have stable back ends.

 

[DigitalBaka]

Seems like there is some sound logic behind everything here. I will delve into it some more and see what I can find out. We know GT5 doesn't exactly mirror the real world but it might be worth checking some actual tuning forums and numbers to see what the effect is supposed to be.

So then I think consensus is that on something like the RUFs or Alpines or the "slidey" cars it would help but on a car like an Evo there would not be any noticeable benefit. Would that be an accurate conclusion from the discussion thus far?

 

[XDesperado67]

@DigitalBaka on cars with 4wd and FFs it would most likely result in even more understeer to try and dial out with the suspension. Doesn't mean it can't help improve the handling of some of them, just that your initially going to have more understeer.

Back when I first started tuning cars I was slapping the reinforcement on all my cars. The original "Pocket Monster" had it on it making for a rock solid platform that forced the suspension to really work. Car ended up very grippy with throttle off oversteer which isn't common in a FF.

 

[CloneHead]

Hmmm - Interesting.
I think improvement it wold depend on the car's suspension. Say, a big old muscle car with leaf spings wobbles about a lot, whereas a smaller lightweight car, like a Caterham is quite stiff from the beginning. (If my memory serves me correctly.)

I think I would leave it off a car, if it handles well already.

I'll have to test it tomorrow - Cobra will be the weapon of choice. Small, wobbles and understeers like a b***

 

[elric718]

From what I have seen, it seems to be of some use on very light (or very lightened) cars. I can't see the point of using on heavier cars, as you should be able achieve whatever you like with the other settings.

 

[CloneHead]

Well, having tested with a newly bought Cobra on the Nordschleife, it seems that the new one without Rigid improvement understeers a bit less. (as stated above.)
But the one with improvement is more stable, and therefore easier to keep off the grass.
I get better laptimes, from driving on the grey bit.

 

[esoxhntr]

http://www.turnfast.com/tech_handling/handling_weightxfr

suspension, chassis stiffness has zero impact on the amount of weight transferred.

the only thing you can do to change the weight transfer is to lower the center of gravity (possible in gt5), change the weight distribution (possible in gt5), change the wheelbase (gap between the front and rear wheels) and track (width of car) the latter two you cannot do in gt5.

suspension/stiffness can alter the RATE at which weight is transferred but not the amount transferred.

 

[Taz69]

CloneHead what had the faster lap time WITH or WITHOUT chassis reinforcement???

 

[CloneHead]

I had faster laptimes WITH the reinforcement.
But I think it depends on the car. It might have a negative effect on a car that's stiff already.

 

[jakobstrikea]

It varies on a car by car basis. For me most cars seem to handle better without, but a few have shown improvement with it on.

It's for reasons like this that I prefer to have at least 2 copies of any car I'm tuning, that way if I make a modification that can't be undone and encounter issues I'll have a clean backup on hand.

Right on target!

 

[ElusiveYeti]

All I can tell you is I put this on my tempest and it ruined my car. It used to handle just fine and did powerslides like a beast. Now since I used chassis reinforcement it won't hardly turn at all, you have to fight the car to make it turn.

 

[Johnnypenso]

All this talk of chassis stiffness and weight transfer and real world technical terms is great but this is GT5 not real life. Chassis reinforcement is simply a change in the programming of the car that supposedly mimics what happens in real life, but since there is no chassis flex or weight transfer because there is no weight or chassis just 1 and 0's, the effect of it and how really works in the game is dependent on how it is programmed. And based on trial and error it seems to induce some understeer on most of the cars I tried it on without decreasing lap times so I gave up even using it anymore and would not recommend it on any but the most wild and out of control cars like the Yellowbird. But even then I'd tune it side by side with and unreinforced chassis just to be safe.

 

[Highlandor]

It's not just "car by car" basis it can also be track related to.

I found cars with chassis stiffness / rigidity (whatever you wanna call the 20,000cr option) were alot more stable around the (*******) Ring at Cape Ring.

I use this rigidity on cas like the McLaren F1 '94 (585pp racing hards) and Lotus Esprit '02 (530pp sports soft) online "racecars" and they felt so much better, not just around the ring, but generally too.

Agreed, that cars that feel great as stock, I think adding this option isn't worth it, unless you got loads of copies of that car (and the tme) to spend in doing accurate tests, and where you see improvement - go for it.

Definately isn't age related though, modern cars can benefit from rigisity too - it's down to what car your driving on what track with what regulations / rules you got to "play with".

Take each situation individually.

Being extremely general and broad here - MR & RR road cars on low(er) grip tyres with high(er) pp are likely to benefit from this more as these tend to be the "loosest" cars generally and subsequently need all the help they can't get to become stable - so you can then run a less radical setup and car is bascally better / faster.

i.e. Yellowbird, BTR, Esprit '02, Evora, Cizeta, McLaren F1 '94 etc etc