Confused about body reinforcement, Body and chassis reinforcement Options

[juicersr]

Thanks for all the input guys. this board rocks! (IMG:style_emoticons/default/beer.gif) I hear what you are saying by way of full tied-in cage, but am headed toward the 'Engman Solution' as i want to maintain the aesthetic look of the 908/3 rollbar for my project.

I feel that with the longs reinforced, in addition to the forward bracing, I will be ok, at least at the present power level.
The car is a long-term project, meaning that as i add power, (3.2-3.6 or turbo motor, i will concurrently 'beef up' the rigidity of the frame. As to how old, just turned the big 40.

[Jeff Hail]

I have been watching this project on both boards and I have to say "it has style".
Love the nose......excellent! The profile of the roof line is perfect in proportion to the rest of the car. The center locks and Panzer wheels just add to it. Just knowing that open motor is right behind the driver sucking cabin air get's my adrenaline going. I salute you. (IMG:style_emoticons/default/aktion035.gif)

My own take on reinforcing the tub........I would install the Engman Kit and
an 8 pt cage. I would also tie the rear rails to the shock towers top and bottom. Easy to do and worth it. Cage tied into the front strut towers.

With what this car will become you will not regret it. Once you go into heavy spring rate country something is going to give. If you are considering a fat displacement torque monster in the future reinforcement is not an option. Better over engineered than under. As far as the outer "GT Kit". Well it can't hurt but I think better way's of strenghtening the outer rail/suspension console area are found. Running a tube from the outer console upward into a cage tube are more effective at controlling "rail roll". Adding tube's on the inner console upward and forward add considerable strength to the control points and minimize camber and toe changes under load.

A lot of debate exists on reinforcing a 914. What many do not understand is these tubs have already experienced about a "couple zillion flex cycles" already in life with a 100,000 miles on the clock. Then we get a hold of one and double or triple the stress's on the tub via our performance modifications. Hummm?

Someone above mentioned look at the inner long directly below the top of the windshield frame. I can't agree more. If you put a straight edge on the inner long about a 8-12 inches behind the front heater tube you will notice a ripple in the sheetmetal. It's usually not much. I have not found a 914 yet that does not have this. It is visably noticeable from the opposite side of the car. This is a result of a life of flex cycles or "the paperclip syndrome" (metal fatigue and work hardening). Some 914's this area cracks. I have even seen it on 911's on both sides that have had hard lives. Especially on the drivers side because of the E-Brake notch on the 914. The notch does not allow energy to travel beyond that point and fatigues to the point of fracture. The passenger side usually does not crack as it has no notch to stop this "flex wave" so energy spreads farther forward all the way up to the front wheelhouse (without cracking) spreading the load futher within the metals elasticity limits. Look at a long span highway bridge and you will picture this better.

With the addition of wide sticky tires and fat displacement motor is going up the lateral and torsion/twist loads on the chassis. This should also be addressed with reinforceing of those suspension areas that want to give/fatigue along with stout longitudinal enhancements. Longs can be strenghtened via truss (cage) or doubleing up (Engman) on the sheetmetal as an added layer. Twist can be controlled with diagonal bars (side to side & diagonally across the chassis). The wider the tire you go the less body roll and camber/toe changes you will want to achieve. Fat wide tires do not like big axis changes.

Bottom line is is the chassis is going to flex no matter what you do to beef it up. How much it it flex's depends on what you intend to do with it both driving and modifying it. The yellow car above has a very well designed cage both for safety and rigidity. I bet if he added a tube going upward from the inner console to the diagonal cage tube would make a huge difference in controlling camber changes during lateral loading. Whoever did that cage knew what he was doing. Well thought out!

(hey Chris! How's my cage coming?)

[juicersr]

Jeff, most excellent points and thanks for the complements!!!!. Your dissertation kinda ties everything together. I have indeed gone over the chassis and notices a few of the 'ripples' you mention. I am ordering the engman plates and will be installing them in the next week or so. I am also planning on tying the front/side rollbar braces into the front shock towers but running tubing forward. Further reinforcement will occur, but i just want to start enjoying the car for a little this summer after working on it for so long. If it looks like chassis flex is still a major issue, so be it, and the hardcore track days will just have to wait until i can reinforce adequately. Thanks to all you guys!!!

[BDog]

Hi guys, am just finishing the exterior part of my 914-6 project, and am a little confused about chassis reinforcement. I have come across two kits that seem to vary quite differently in their layout. One is from patrick motorsports.

http://www.patrickmotorsports.com/part/586/

The other two from engman, a 'long' kit

http://engmanparts.com/innerlong.php
http://engmanparts.com/hellholekit.php

What do i need for adequate reinforcement before adequate track work. I have done a lot of work already to tie the rollbar into the shock towers, and

Got to tell you love the look and the work you have done