Confused about body reinforcement, Body and chassis reinforcement Options

[juicersr]

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

[juicersr]

some pix of the cage/ rollbar


It ties into the longitudinals in with bolts in the front and rear of the longs

[cobra94563]

I think with a cage, you don't need the "long" kit. (I have the long kit)
I can't see where the rear of you cage goes, so not sure if the chassis kit is necessary either. Others can probably answer...

[Zimms]

That is looking good. Nice work.

[juicersr]

Thanks, here's a thread of th build.

http://forums.pelicanparts.com/showthread.php?t=395856

The cage basically ties into the body and rear tranny mounts, which is reinforced by the eye-bolts you see going into the aluminum panel mounted on the rear of the tranny. I'll try to get some better pix over the weekend. I am worried about the hell-hole area, which has rusted away to expose the chassis beam which runs dow the right side of the car. will send pix soon.

[Joe Bob]

I would go with the Engman kit, he will work with you on special mods.

Send me the Patrick stuff and I'll turn it into a boat anchor, if he has your money it's the last support you'll ever get.

[juicersr]

Hmmm, just notices that performance products has a '914 chassis stiffening kit' in their catalogue. Anyone used it?

[iamchappy]

Looks to me you've got it covered as far as stiffening already, the suspension ears are something you should if you haven't already reinforce.

[SirAndy]

I think with a cage, you don't need the "long" kit. (I have the long kit)
I can't see where the rear of you cage goes, so not sure if the chassis kit is necessary either. Others can probably answer...

excuse me, but i don't see a "cage" ... (IMG:style_emoticons/default/rolleyes.gif)

all i see is a roll bar and some tubing going to the rear shock towers, or so it seems ...

the weakest part of the 914 is right in front of the seats and this car does not seem to have any additional support there.

you'll either need to get a full rollcage (that's what i would do) or at least install the engman long kit.

otherwise, as soon as you start to apply torque or lateral Gs, the chassis will twist like a bungie cord ...
(IMG:style_emoticons/default/shades.gif) Andy

[r_towle]

yep, agreed. There was a real scientific study done and printed in the Up Der Fixen Porsche series, book three, last few pages.

The guys put a 914 chassis in a vibration testing lab and found the weakest point was in the longs....drop a string from top of the windshield to the longs....that is the spot that cracks.

McMark has some pics here of the cracks ...good to know that you cannot see them with all the undercoating in place.

If you are racing this car, a cage that ties into the longs at that spot is paramount to keeping the chassis from twisting, cracking and flexing alot.

Looking at your build its really cool.
These chassis's where built with 165/15 tires in mind...not 1 foot wide slicks...that is what will pretzel yours...

Rich

[juicersr]

Chap, Andy, Rich, thanks. I researched this forum before building my 'semi' cage, running the front braces from the roll bar forward to the maximum point on the longs, where they are bolted. The roll bar is bolted just rear of the seats, and then tied in to the rear strut brace, and then back to the tranny mounts and rear of the car. I was hoping this would be adequate to reduce torsional flex. These pix are not great, but all i have at the moment taken from early in the build. Do you think i still need to reinforce the longs?

[juicersr]

I used this pix from a previous thread as a model for tying in to the shock towers


So these 'engman' plates just get welded to the inside of the longs, across the 'weak' point as it crosses the plumb-line droped from the windshield? Will welding some steel plate across the weak spot accomplish the same thing?

[Dave_Darling]

Yes, that's where it goes. No idea if just a small scab plate would be an adequate reinforcement; but it stands to reason that the larger area and longer section of the Engman kit would hold up better and be at least a bit stiffer.

Note that this is only really adding another thickness of metal to the original structure. To really make it stiff, you will need to put something across the door opening above the level of the long--and the higher, the better. (Like the top hoop of a roll cage, for instance. (IMG:style_emoticons/default/wink.gif) )

The Perf Products stiffening kit is the same (more or less) as the Patrick one. As is the kit that we sell.

Brad Mayeur, and others, sell a "clamshell" or outer rocker reinforcement/replacement. It doubles up on the outer wall of the longitudinal, similar to the way the Engman kit doubles up on the inboard wall of it. Harder to install, though, due to the other reinforcements on the outside there.

--DD

[SirAndy]

i've never been a fan of bolt-in cages and rollbars. i think you'll be adding a lot of strength if you weld in good sized scab plates and weld the tubing of the rollbar to that.

as for the longs, i think DD is right, the larger the patch welded on the better. the engman kit ties the whole long together and does a good job in stiffening up that part.

think about it. open the doors on your 914 and look straight through from side to side right about where the front edge of your seat is. there's nothing holding the chassis together at that point besides the longs.

any triangulation there will help the stiffness immensly ...
(IMG:style_emoticons/default/bye1.gif) Andy

PS: keep up the good work! (IMG:style_emoticons/default/beerchug.gif)

here's a pic of my cage being welded in at TC Design. the small door braces you see are just to prevent the car from shrinking while tony was welding the cage.
even thought i didn't opt for the full "race" X-brace on the doors, the amount of stiffness compared to a stock car is amazing ...

[J P Stein]

Yes, amazing.....and no "stiffening kits" here.....unless you wanna count my own.

[r_towle]

JP,
I like the little lower tube supporting the inner suspension.
Did you do anything similar on the outer one?
Adjustable I assuem, and can you post a pic please...

Rich

[J P Stein]

No, I didn't.

It's a good idea, tho. I've never had trouble with either the inner or outer. The inner reinforcement was something I'd been thinking about for some time and finally did this last winter. A failure there would ruin my day. The car has held up remarkably well, considering the abuse it gets...2 drivers, all metal suspension, stiff springs, 10 inch slicks and our gawddamn venue is a rough cob. It held alignment pretty well last season before the inner mod.
Before the tubes to the suspension towers (2 winters ago) I was bending the chassis....or so the alignment changes told me. Also had some minor cracking (if there is such a thing) at the base of the rear towers/longs.

If the outers ever move I have a plan. (IMG:style_emoticons/default/biggrin.gif) Brant has a good set up.

[J P Stein]

A better look during fabrication.
I had the motor out for a rebuild.

[r_towle]

Im talking about a heim jointed tube that will HOLD the alignment...and also make it alot dame easier to change...Im old...the BFH thing is stupid...a nice heim joint tube, fastened to the long further up...I saw that somewhere...maybe brant...dunno..

Rich

[J P Stein]

Ayup, that's what Brant has.

NOTHING will hold alignment if you have rubber...or plastic for that matter....bushings. You may have it in static, but that goes out the window as soon as you accelerate, corner, or brake. The only rubber in the suspenders left on my car are the upper & lower rear shock mounts. Everything else is mono ball or needle bearings.

Old are you? Welcome to the club. (IMG:style_emoticons/default/biggrin.gif)
I'll be 63 in a couple months....God willing & the creek don't rise.