Printable Version of Topic

Posted by: mrbubblehead Feb 17 2014, 11:56 AM

I am wondering how strong the center tunnel is. after seam welding and the inner long kit, would it be ok to cut the top off for access panels? they will be replaced with aluminum panels fastened with rivnuts and 5mm screws. im leaving most of shifter sheet metal to keep the shifter solid. you can see from the pictures what i intend to cut out. http://s722.photobucket.com/user/mrbubblehead_photos/media/NCM_0006_zpsf4942f3e.jpg.html
http://s722.photobucket.com/user/mrbubblehead_photos/media/NCM_0005_zps4abe7da3.jpg.html

Posted by: Old Yella Feb 17 2014, 12:20 PM

Aluminium and steel react causing both metals to corrode when in contact with each other.
I've always wondered about Aluminium floor boards and for that reason haven't bought them.

Posted by: bulitt Feb 17 2014, 01:00 PM

Brant simply drilled access holes.

Posted by: CptTripps Feb 17 2014, 01:04 PM

Interesting idea. Looks like you'll lose the post that's needed for the pedal board mount though.

I can't imagine that's one of the most structurally necessary pieces of the 914 puzzle. Never hear that about aluminium and steel. Maybe if you have a rubber grommit in there somehow?

Posted by: mrbubblehead Feb 17 2014, 01:14 PM

ya, thats where my idea came from. at first i thought about doing dimple died holes, to add the strength back, but the more i thought about it i dont want to have to clean out all the crap that fall down in there. thats when i thought about removing more sheet metal and replacing them with aluminum panels.

there are a few reasons for doing this. i want to blast all the rust out of there. i am going to run my wiring harness thru there instead of my fuel lines, so access would be nice. and i want to reinforce the clutch tube. i am trying to get everything done i can think of before paint. there is nothing worse the cutting and welding on fresh paint.

old yella, im not really worried about electrolysis. both surfaces will be painted.

Posted by: mrbubblehead Feb 17 2014, 01:17 PM

capt, i dont use a pedal board.... i know on a beetle the tunnel is the back bone of the pan. that why im concerned. just dont want to make a mistake i will regret down the road.

Posted by: SirAndy Feb 17 2014, 02:13 PM

That seems like a bad idea ...

As for the access holes, can you bend the edges around the holes to give it a bit more strength?
If you look at the stamped holes from the factory, they usually have a few mm deep flange.

With the outer long kit, you'll probably be fine ...

Posted by: worn Feb 17 2014, 02:20 PM

In most cars this is a major part for strength. Porsche thoughts so because they chose to make it a box beam, which provides strength at minimum weight. Your cutouts will have less effect on strength if you roll the edges and make no sharp corners, space them and then find a way to tighten the cover plate down so it cannot slide.
In a wet environment aluminum will fall in love with steel, especially in threads. It makes an oxide that means all the threads go somewhere out of this universe to a thread heaven. Oil will keep it from happening though. I found that you can buy steel flanged tube nuts, drill a hole and tack weld them. I think the major complaint with rivnuts is actually when you cannot get to the back, you have the fastener in place, and they decide to spin . There are precautions you can take that will minimize that.

Nice work.

Posted by: mrbubblehead Feb 17 2014, 02:36 PM

my drawings dont show them, but all of the angles will have a 1" radius where two cuts intersect. there will not be any sharp corners where the cuts are made. the way i figured is that as long as i stay on top of the tunnel and keep off the rolled edge i would be ok. im assuming the strength is in the rolled edge.

as far as rolling the edge of my cuts, thats a great idea, but not sure how to accomplish this.

dont tube nuts need to be welded from the back side? the reason for using rivnuts is, to get access panel as close to flush with the top of the tunnel as possible. and if one should spin, i could either tighten it up or just drill it out and replace it.

Posted by: mrbubblehead Feb 17 2014, 02:37 PM

i havnt used a pedal board in any of my cars in years.....

Posted by: SirAndy Feb 17 2014, 03:58 PM

That doesn't make it any better. They are there for a reason.

Posted by: Cap'n Krusty Feb 17 2014, 04:32 PM

Without the pedal board, what do you use for pedal stops? Gotta have 'em, one to keep the throttle cable from too much strain, the other to keep the clutch cover plate from going over center ......................

The Cap'n

Posted by: mrbubblehead Feb 17 2014, 05:33 PM

a threaded plastic deal on the end of the clutch pedal. and throttle stops on the carbs.

Posted by: SirAndy Feb 17 2014, 05:37 PM

Neither of which will prevent you from stretching the cables.

Like i said, the pedal board is there for a reason ...

Posted by: mrbubblehead Feb 17 2014, 05:40 PM

how do you figure?

Posted by: SirAndy Feb 17 2014, 06:13 PM

Well, first off, i highly doubt Porsche would add a pedal board to 100,000+ cars if they didn't think it was needed. Pesky engineers with their logical stuff.

Besides, without an actual stop at the pedal for the accelerator you will be stretching the cable when you hit the stops on your carbs.

Posted by: mrbubblehead Feb 17 2014, 06:22 PM

im surprised those pesky engineers didnt call for 1/4 steel plate..... why would they use a flimsy laminated piece of wood for such a vital component? i'll take my chances.

thank you all for your concern for the health of my cables.

Posted by: SirAndy Feb 17 2014, 06:43 PM

Getting answers you don't like to questions you didn't ask is a frequent byproduct when posting on a public forum ...

Posted by: mrbubblehead Feb 17 2014, 06:44 PM

i know right...

Posted by: bulitt Feb 17 2014, 06:52 PM

Because its light, and cheap. They used balsa wood in the C5 corvettes.

Posted by: 76-914 Feb 17 2014, 07:18 PM

Use some JB Weld on the rivenuts. Just prep the area's properly and use it judiciously to prevent excess from fouling your threads. It's in my build thread. Another thought is to weld in re-inforcement rings around your cutouts.

Posted by: mrbubblehead Feb 17 2014, 07:19 PM

there. i fixed it...
http://s722.photobucket.com/user/mrbubblehead_photos/media/woodenpedalboard_zps553da79c.jpg.html

now, about cutting that tunnel up. should i or shouldnt i.

or we could argue about all the reasons i should sell this money pit and take up model airplanes.

Posted by: mrbubblehead Feb 17 2014, 07:24 PM

good idea. i have the proper tool for setting rivnuts but a dab of jb weld wouldnt hurt. im not tooooo concerned about using rivnuts. they are easy enuff to replace. especially if i have access panels

Posted by: Garland Feb 17 2014, 07:48 PM

If you need to.

Posted by: nineonefoursix Feb 17 2014, 09:47 PM

Ok, here we go again, if your car has carpet, you need a pedalboard! Simple as that. If not, no flimsy piece of flexible wood is going to stop your heavy assume foot/ leg from damaging cables, ajustment, ect. Cables need to be adjusted correctly to start with. P.s. my race car has never used a pedalboard for 10 plus years, and only driven extremely hard!