GT stiffening kit really no help? Options

[pffft]

I am starting to firm up my chassis to better handle the
abuse my v8 and 930 will dish out.
I have an unistalled roll cage that I may not use because it
is a street car, so if I don't use it I will go with Engman.
I also have had for 15 years an unopened "GT stiffening kit"
There seems to be a lot of thought that it is not worth the
trouble. Is this true? I can get one of Chris' kits with removable
braces, but is there any reason to mix and match the two or should
I go with only CFR stuff? The only rust I have found on the car is a small
hole on top of the long in the hell hole. I'll start digging in there this
weekend to see how bad it is, but the rest of the longs are in great
shape (california cars = good)

patrick

[Eric_Shea]

I like it... all the pieces and then some (meaning extend the long pieces further forward to the jack post).

I think there's a ton of myth behind not liking the factory kit.

[sww914]

It reinforces areas that break. There may be better solutions, but it does reinforce areas that break. If I were building a V-8 car, I would cage it, it just makes the car stronger.

[Richard Casto]

I am building a multipurpose 3.2L widebody track/autocross/street car that will have an 8 point cage, but will not tie to suspension points (no crossing through firewalls). I am on the fence about the GT kit as well. With the cage being a given, how much more will the GT kit add?

[Eric_Shea]

With the cage being a given, how much more will the GT kit add?

The cage will strengthen it quite a bit, even without going to the suspension points.

Here's what I like about the factory kit:

The large piece (that had been poo-pooed previously) spans a section of the inner wheel well which is actually the outer longitudinal. There was rumored to be a section of the outer long underneath that area but there isn't (hence some of the myth stuff). This is the outer long as it extends back to the tranny ladder brace (that thing you see when you pick-up your rear trunk mat). It spans from the shock tower (with another ladder point in the rear engine firewall) to the tranny brace and helps tie the two together. Good idea.

Suspension ear braces. Good idea.

Various Long Braces. Good idea. As mentioned previously, I like the idea of extending them further forward both inside and out. Let's see if we can get Gint to take some pictures of his mods to the factory kit.

All in all a good idea, especially if you're installing a cage that will not tie into the suspension points.

My $.04

[John]

I like my own extended version of the GT kit. I extend mine on the outside past the jack point, and on the inside through the firewall and past the center cross-member in front of the seats. I have some pictures somewhere, but not here at work.

There is a real good discussion of the different cross sections that the GT stiffening kit is intended to strengthen HERE ---->LONGS


I like the GT kit, but I have added to it in my own way. I also like cages and would not want to run on the track without one. I won't put a cage in a street car.

[SirAndy]

there is one piece in particular that has been proven to be useless. the others work, more or less ...


in order to understand why the factory GT kit is not the best possible approach out there, all you need to do is look at the history of the factory backed GT 914s ...

they have internal project numbers close to the factory prototypes. meaning, the GT projects were well underway in '69, even before the first production 914 hit the streets.
the GTs were by no means as well engineered as todays factory racecars. the GT stiffening kit was a quick "bandaid". it worked well enough at the time.

38 years later and a lot has since been proven/disproven.


the piece in question is the inner fender plate. it doesn't work because it's welded on the outside of a hollow U shaped channel. the other side of the channel is what holds the upper shock towers in place. welding a support on the outside is useless as there is no connection to the sheetmetal that actually connects to the shock tower.

(IMG:style_emoticons/default/bye1.gif) Andy

[John]

Here is the area that shows WHY the GT stiffening kit does not tie into the rear shock tower.

The picture is a section view of the Drivers Side Long as it dead-ends into the front of the Drivers side Rear Shock tower. The GT kit welds to the area of the outer long (inside the wheel well) that is spaced AWAY from the shock tower.

I still feel that the stiffening kit does improve the stiffness of the Longitudinal sections of the unit body. Throwing out the kit because it does not effectively tie in the shock towers seems to be counter productive. Utilizing the kit AND welding the shock tower into the Long seems like it would accomplish the task. Some drawbacks to the GT kit is that it does take space inside the wheel well, and the kit does add several pounds.

I still would add the kit, but do some additional welding to tie things together. Like I said before, I extend the kit FORWARD on BOTH sides of the LONGS.

[Jeff Hail]

Eric the site i going to go down again. I just know it.

The longs are actually attached to the rear shock tower. Only on the verticle and about an inch on top. When I installed the inner long I got burn through from the middle on up of the tower. I even had to turn up the voltage because of the heavier sheet.

Easy way to reinforce that area is drill about a dozen resitance welds out and peel open the box. Weld on top, side (verticle) and the botton.

Check out the photos and you will get an idea of the construction.
Area's in red are single wall and green are double.

Notice the last photo with the C-clamp holding the long to the outer wheelhouse. About a 3/8 gap exists on all 914's that the bottom of the long to floor connection. A thin piece of sheetmetal cover's that gap and does nothing for strength. If you slit the long and fold it upward (like folding hospital corners on bed sheets) and weld it to the connector you will increase strength dramatically.

Also look at the photos inside the shock tower. You will see the double wall at the bottom and single midway on up. Notice the burn through?

[Jeff Hail]

Contd

[Jeff Hail]

The GT kits do help this area out a lot. The outer wheelhouse is subject to (cornering stress's) loads that are very high. The trailing arm perch is simply welded to this part and then bridged (poorly) to the inner console.

The factory reinforcement's should have continued higher and wider on both the inner and outer consoles spreading the loads over a larger area.

Personally I think they should have welded 2x4 box (1/8 inch thick) inside the long and ran it all the way to the hinge pillar.

[pffft]

Great information everyone. John, that thread you directed us to is
GREAT and Jeff, thanks for the rest of the pictures.
Eric, I had thought the "if you put the inner fenderwell part on you are just
welding to a cover" bit was gospel, but it SURE looks like that is not true.(!)

Looks like I'm gonna use the gt kit and Chris' ear kit. Not sure about the welding
the longs to shock tower, but as long as I'm in there burning holes
in stuff anyway...

I know there are some strong opinions about cages on the street.
If I am willing to have to crawl over/around the bars, is a padded cage
any more dangerous than any tight hardtopped car?
Not trolling, I just really want to know. I had one in a cj5 and it was never
a problem, but that's a very different set of dimensions.

thanks all,

patrick

[SirAndy]

If I am willing to have to crawl over/around the bars, is a padded cage
any more dangerous than any tight hardtopped car?

get into *any* '70 (at least european) car and look around. your head will be within inches of the side-roof supports and b-pillars that are usually just covered by some vinyl/cloth/flimsy plastic.

i have a friend who rolled over his '74 super beetle. i looked at the wreck the next day and found his eyebrow (yes, the whole eyebrow!) stuck on the passanger(!) side b-pillar!


my point is, a cage with adequate padding is no more dangerous than a similar period car without a cage ...

flame on!
(IMG:style_emoticons/default/popcorn[1].gif) Andy

[Amenson]

If I am willing to have to crawl over/around the bars, is a padded cage
any more dangerous than any tight hardtopped car?

my point is, a cage with adequate padding is no more dangerous than a similar period car without a cage ...

flame on!
(IMG:style_emoticons/default/popcorn[1].gif) Andy

No flames necessary on this topic. A properly padded cage in a street car is not a safety hazard. The Mosler MT900 is DOT Certified and has a full cage. Pictures from the crash test.

(IMG:http://www.moslerauto.com/images/mt900/photo/crashtest/pic_001.jpg)
(IMG:http://www.moslerauto.com/images/mt900/photo/crashtest/pic_003.jpg)

I made the mistake of having this discussion with one of my fiancee's colleagues who consulted on this certification. Luckily it was during a race so he got tired of explaining over the noise of the cars how uninformed I was to have suggested that a cage is not suitable for use on the road. He did offer to supply padding for my cage when I put it in!!

Scott

[John]

The ONLY reason I do not prefer to have a cage in a street car is that I don't like how they make a street car look like a "boy racer/ricer".

My opinion has nothing to do with safety. If I was really concerned with safety on a street car, I would get some real bumpers and probably want to do a full cage including door bars (NASCAR style).....

[Eric_Shea]

Eric, I had thought the "if you put the inner fenderwell part on you are just welding to a cover" bit was gospel, but it SURE looks like that is not true.(!)

In a sense it is but, it does strengthen that area and it does tie it back to where the tranny brace begins. This is the outer portion of the long as it extends past the shock tower and heads to the back. The shock tower does tie in at the bottom (the three corners come together). These joints are often overlooked yet are some of the strongest points. The one thing that hasn't been mentioned here, or shown, are the cracks that have been known to develop in that area with heavy racing. There are pictures here on the site, I'm just too lazy and don't know where to begin the search.

It's going on my car. (IMG:style_emoticons/default/wink.gif)

[Eric_Shea]

i looked at the wreck the next day and found his eyebrow (yes, the whole eyebrow!) stuck on the passanger(!) side b-pillar!

Did you give it back to him? (IMG:style_emoticons/default/biggrin.gif)

I'm with a "PROPERLY" padded cage. Please keep in mind, that does not mean the JPB pool toys (sorry Jean Paul) (IMG:style_emoticons/default/biggrin.gif)

Seriously... one MUST use proper padding.

[Jeff Hail]

i looked at the wreck the next day and found his eyebrow (yes, the whole eyebrow!) stuck on the passanger(!) side b-pillar!

Did you give it back to him? (IMG:style_emoticons/default/biggrin.gif)

I'm with a "PROPERLY" padded cage. Please keep in mind, that does not mean the JPB pool toys (sorry Jean Paul) (IMG:style_emoticons/default/biggrin.gif)

Seriously... one MUST use proper padding.

Eyebrow's??? on the B- Pillar? What the?
I have seen lip kisses on airbags, mascara brushes stuck through sun visors and in eyes(yes eyeballs), toes severed in pedal clusters, hair and face portraits in windshields.........but never an eyebrow?? Then again anything is possible......I thought I have seen it all in my current day job after I left the restoration industry.

Add on to Eric's:
I have to support a properly padded cage is safer in impacts, roll over’s especially. Side impacts are another story. If you are running triple NASCAR side bars with door skins and hollowed out door shells they are by far safer because everything hard is a lot farther away from limbs and torso.

Let’s think about this for a minute. Whether a 30 year old Porsche or even a modern car what do they both have in common? Padded interiors (dash pads, door panels, targa trim, etc). Properly padded cage has the same thing. What’s the difference? Not much, principle is the same, except hard stuff is now closer.

What does make a difference is clearance of the main loop, vertical bars and side bars to the driver and passenger's head, neck, arms and legs. With a cage these are obviously in closer proximity and if not properly padded will hurt you. The other item with an overhead hoop is a helmet. All of the sanctioning bodies specify a distance required from the drivers head. With a 5 point harness the torso is not going to move, only the limbs tend to get loose, nets keep those from getting outside the vehicle. Open wheel cars require arm restraints (tethers)

All the newer FIA approved seats have seat "head wings" for neck protection and can be adapted to a HAN's device. Ok we know race cars are safer now.

On a street car without a helmet. Without a helmet you have even more room over the top of the head to the cage hoop. If no cage or loop the roof may collapse under the cars own weight in a rollover. I want a cage! In a side impact especially in a 914 I want side bars even if they only come up knee high. Why? Those door latches and strikers are weak and a door shell is not what I want in my ribs. 914's do not have a roof. In a side impact the body will splay apart increasing passenger compartment intrusion. Imagine a big fat Ford Excursion, full size pickup or a Big Rig impacting the side of a 914.......I want as much between me and that much kinetic energy as possible. Only a cage will provide that!

Last but not least a cage is part of a system. Structure and restraints. They work together for a purpose. We have all watched race cars hit walls at 200 mph roll seven times and driver's walk away. On the bad side people die even from low speed collisions everyday.

The human body will always be the weak link in a safety system. Bodies flex, bones break, limbs fly, necks stretch with a ten pound pumpkin attached. This is the dark side of a collision. The bright side is safety components.

I will take a properly padded and anchored cage any day. Adding a properly fitted (tight) seatbelt or harness only enhances the "system".