Body stiffening braces- sorting the good from the crap

[Sam_Q]

I am looking at various braces that are meant to support the body of my Sprinter and I have noticed theres a hell of alot of crap out there, especially stuff out of japan. I want to hear peoples opions on what works and what doesnt. I will show a few examples and say what i think, I am open to correction though. I want to hear from peoples experience


All the following comments are under the assumption that the braces are solid and relatively free from flex. Also note that this is all for an ae86+t18, so some points are not valid for other models. Many pics shamelessly stolen from T3!


Normal strut brace: good






Tri brace: excellent






rear brace (top of shockers or next to it): useless ballast






rear tri-brace (top of shockers or next to it to some hole): just stupid






rear brace (seat latch mounts): apparently good, doubles up as a good harness mount too.







Fender brace: apparently these are pretty good (thanks to accoustic for the pic)







I am going to try and dig up some off yahoo japan now

[Sam_Q]

rear hatch strut brace: WTF!?






Castor rod brace (goes between the two ends of the castor rod pivots): meant to work but I have no idea how

[Vios-GT_07]

stupid www.freefilehosting.org all my car's pics are in there, now it says files not chmod correctly.. any computer people get it out, drinks on me

anyway i have 5 pieces of braces on my car.. 3 in cabin and 2 under.. (i got a 4 door sedan so it's not hard to imagine).. here goes

1. under car front side, supports cross-member to chassis.. shaped like a equal trapezoid

2. rear sway bar

3. front strut brace, 2 point, like pic in first pic

4. room bar, that's a bar with a hump in between to clear the floor.. it's bolted in between the seatbelt's harness near the floor.

5. rear booth bar, that's a bar that sits across the boot just behind the rear seats.. it's bolted in, and would sit about 3 inches above the shock absorbers? bolted to the shell like a roll-cage thing..

number 4 and 5 holds my race harness so even if it doesn't work it has some functionality

[Sam_Q]

vios I highly recomend photobucket, they never seem to let me down.

I cant make out what you mean by number 1 or 2, I heard the "room bar" is meant to work, so you think it doesnt help much?




Heres a few more I have seen:


Trans Cross member support (goes between the two vacant holes next to the cross member): useless

Panhard rod brace (goes from the body end pivot of the pan-hard to somewere on the body): Dont know about this any, anyone got any comments?

[Ben Wilson]

I have a personal problem with any brace which uses rose joints. It's supposed to be rigid, why put pivot points in it?

[Sam_Q]

thats a good point and one which I agree with, and the argument of adjustment isnt valid because its not hard to incorperate an adjustment into the design without a joint. Joints add money too.

I Iike welding mine in place while its on the car.

[willwal98]

I think that top photo is from http://www.toymods.net/forums/showthread.php?p=405322

good thread to look at also.

[Sam_Q]

top photos right out of my worklog (see signiture), I made it out of 4130 Cro-mo, I am looking to modify it to make it a tri-brace.


I also made that rear brace that allows the seat to still be folded back.

[oldcorollas]

i'm curios as to why the fender brace works?
i've onyl seen them advertised from brands endorsed by dorifto stars, and most of them seem to be flat strip steel with a bend in them.. ie, totally useless

for example this one... anything with that kind of bend in it will just flex like buggery!!


so if you have a strut brace that stops the struts moving inwards (anyone measured how much they actually move normally?), then the fender brace is suppose to stop vertical movement?

[Vios-GT_07]

vios I highly recomend photobucket, they never seem to let me down.

I cant make out what you mean by number 1 or 2, I heard the "room bar" is meant to work, so you think it doesnt help much?

this is number 2, my rear sway bar



and this is what i meant by number 1, the crossmember support thing

http://www.ultraracing.com.my/Bar_Fu...s_page_ENG.htm

(if link does't work, go to www.ultraracing.com.my and it's under the technical link, lower arm bar)

cheers

[RobertoX]

Just from personal experience on my sprinters, in one car I had a cusco copy brace and a rear seat brace (made by Steve-ae86), the other car a cheap front brace (the type that Racespec sells) and the same type of seat brace and I had a rear ‘strut brace’ (between the shock mounts).

The front strut tower brace gives a noticeable difference, a rear ‘strut brace’ (between the shock mounts) is complete rubbish and is just dead weight. The rear seat mount brace made the most difference of them all. The fronts tend to make the car feel more responsive and turn in a bit sharper. The rear also seemed to help turn in and actually made the rear end feel stiffer, as if it had a higher spring rate. It seemed to change the balance of the car slightly towards more oversteer.

If I were to make my own I would probably copy your design Sam, but make it into a tribrace like you said. I agree with your comments about the joints, your front bar looks like it will resist warping of the strut towers better than others (as in one tower moving forward wrt to the other). Shame I can’t weld or anything though

Also, intuitively, those fender braces look like they would be completely useless! I would like to know how they work

I don't think a rear sway bar comes into the 'brace' category... more of a springing medium

[oldcorollas]

they have some good stuff on that site

i would like to see someone use a strain or torsion gauge to actually detect and measure how much chassis distortion is going on..

it's easy to bandy the term "stiffness" around, but a to if these various bars actually make a difference to the amount of car distortion, and if that diffference has a significant effect on the handling etc....

i'm sure there are plenty of testimonials, and paid test drivers are "sure it must be faster", but is there any science to it?

for example, they claim the fender bar will:

Improve handling, stability at high speed and cornering, hence safer driving.
Provide a better braking and stopping performance.
Reduce NVH (Noise, Vibration and Harshness).
Increase stiffness of vehicle front chassis.

really?

and B pillar bars.... ruinning along the floor..... if your car is changing dimensions at those points, there IS SOMETHING WRONG WITH YOUR CAR

[RobertoX]

Reduce NVH? How? by stopping the chassis creaking through too much flex? lol

[Billzilla]

ITri brace: excellent

That's the only one you should be looking at. And even that one isn't very good as the end points are still able to move around as they terminate in mod-air rather than onto something solid.
To make cars still with bars, you need at a minimum a bunch of triangular shapes, and much better still is a bunch of tetrahedrons.
You guys (Oldrolla's excluded) would be blown away as to how much plain steel structures can flex around.

[oldcorollas]

but seriously, it should be easy to rig up a few little tools to measure the amount of flex between the positions these braces bolt on....
if there is flex, they could potentially help.
if there is no flex...well..

so who's up for some measuring

edit: to make bills point, put one jackstand on the far rear corner suspension mount.. then jack up from the diagonally opposite corner.....

not sure how you would induce banana loads.. but still i think meauring is a good way to start to work out what is good or not