center tunnel strength Options

[mrbubblehead]

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. (IMG:http://www.914world.com/bbs2/uploads_offsite/i722.photobucket.com-12492-1392659784.1.jpg)
(IMG:http://www.914world.com/bbs2/uploads_offsite/i722.photobucket.com-12492-1392659784.2.jpg)

[Old Yella]

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.

[bulitt]

Brant simply drilled access holes.

(IMG:http://www.914world.com/bbs2/uploads/post-2-1099418896.jpg)

[CptTripps]

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?

[mrbubblehead]

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.

[mrbubblehead]

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?

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.

[SirAndy]

capt, i dont use a pedal board....

That seems like a bad idea ... (IMG:style_emoticons/default/blink.gif)

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 ...
(IMG:style_emoticons/default/smile.gif)

[worn]

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.

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 (IMG:style_emoticons/default/headbang.gif) . There are precautions you can take that will minimize that.

Nice work.

[mrbubblehead]

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.

[mrbubblehead]

capt, i dont use a pedal board....

That seems like a bad idea ... (IMG:style_emoticons/default/blink.gif)

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 ...
(IMG:style_emoticons/default/smile.gif)

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

[SirAndy]

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

That doesn't make it any better. They are there for a reason.
(IMG:style_emoticons/default/shades.gif)

[Cap'n Krusty]

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

[mrbubblehead]

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

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

[SirAndy]

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

Neither of which will prevent you from stretching the cables.

Like i said, the pedal board is there for a reason ...
(IMG:style_emoticons/default/shades.gif)

[mrbubblehead]

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

Neither of which will prevent you from stretching the cables.

Like i said, the pedal board is there for a reason ...
(IMG:style_emoticons/default/shades.gif)

how do you figure? (IMG:style_emoticons/default/popcorn[1].gif)

[SirAndy]

how do you figure? (IMG:style_emoticons/default/popcorn[1].gif)

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.
(IMG:style_emoticons/default/driving.gif)

[mrbubblehead]

how do you figure? (IMG:style_emoticons/default/popcorn[1].gif)

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.
(IMG:style_emoticons/default/driving.gif)

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.

[SirAndy]

i'll take my chances.

Getting answers you don't like to questions you didn't ask is a frequent byproduct when posting on a public forum ...
(IMG:style_emoticons/default/smile.gif)

[mrbubblehead]

i'll take my chances.

Getting answers you don't like to questions you didn't ask is a frequent byproduct when posting on a public forum ...
(IMG:style_emoticons/default/smile.gif)

i know right... (IMG:style_emoticons/default/beerchug.gif)

[bulitt]

how do you figure? (IMG:style_emoticons/default/popcorn[1].gif)

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.
(IMG:style_emoticons/default/driving.gif)

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.

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