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Back in the dark ages when only the wizards knew about this, we had to have the tunnel of our 69 VW Convertible cut open to fix the now infamous flappy snappy clutch cable guide that had separated itself from the car.    Brings back memories - like the engraving bit

BTW I'm not That old, when we got that old bug it was an antique in it's own right thus the mysterious and unique failures to attend to    

Baloney - You are TOO that old!   Thanks to the anonymity of "Social Media", you could be some old 600 pound stay-at-home guy named "Virgil" with an internet connection.  

   

I had that same clutch tube separation happen and ended up cutting a rectangular hole in the passenger side of the tunnel for access to apply my usual terrible (but strong) weld to the tube and hanger.  Mine wasn't nearly as far over the top of the tunnel or as fancy-looking as what @IaM-Ray showed (and I wasn't installing a hydraulic clutch), but it's functional and covered with carpet so, Who cares?  Nobody's ever gonna see it but me, it removes with six screws and now it's super-easy to change the clutch cable every fifteen years!

I took the rectangular piece out and pop riveted a 3/4" wide strip on all four sides drilled with two holes each and then used sheet metal screws to attach it back to the tunnel.

Last edited by Gordon Nichols

billthecat01

Have you guys actually looked at the heft of the CMC body sub-frame members?

2" X 3" X 1/4" thick Box frame members with a cross frame member (the Napoleon Hat) 12" in front of the tunnel opening.

I'm not particularly worried about pan flexing.

Besides.....  It's a 3"H X 6" W opening with the rest of the tunnel intact (and that tunnel is only 1/16" thick sheet metal).  I would expect to see a small ripple or crease in the tunnel near that opening by now, like when I had the carpet out to re-do the seats.  I saw nothing and an OCD engineer would see something like that.

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  • billthecat01
Last edited by Gordon Nichols

i'll buy that, el Gordo... but the front and rear suspension doesn't attach to the sub-frame - it attaches to the backbone. The subframe kinda/sorta attaches to the Napoleon's hat and area by the rear torsion tube, and along the pan edges pretty far away from anything. Lots and lots of pan cars have subframes that miss actually riding on the backbone in the rear, and all of them rely on hardware to attach at the Napoleon's hat.

Again, I'm not saying you shouldn't cut the tunnel for any reason, but I am saying I'd weld it back if it were me. My mom has screws and plates holding her backbone together, and I can guarantee you it isn't as good as never having been broken in the first place.

Years ago at my friend's VW shop in NJ we had this discussion so we had a running clapped out VW pan fiberglass buggy , I cut a 3" x 5" three sided opening on the passenger side at the cable area bent it down which is no an easy task considering gauge of the tunnel metal, bent it back into place with the cut off wheel margins remaining on the sides... then took in to  a construction site and ran it hard over hills turns etc. Back at the shop the opening margins were the same and that was w/o screwing or welding it back in place.  IMHO no real issue doing an access panel as the tunnel aka Backbone is very strong.

I remember that Ernie Sachs, one of my mechanical designers at EMC, visited my house when I had just welded the pan back together (Like, it was still smoking when he walked in).  Ernie did all of the flow calcs for my engine/induction/exhaust as an exercise to see what the CAD package we had bought would do.  We used it to design all of our mechanical assemblies and to simulate the airflow across computer boards to find and eliminate hot spots

While he was not impressed with my welding prowess (He said his sister could weld better)    he was impressed with the backbone of the pan (it happened to be upside down when he visited) and he commented that a lot of the torsional rigidity came from the "X" members stamped into the bottom of the tunnel, and that piece is much thicker (2 layers) than the rest of the tunnel.  He went into this long explanation about resisting or absorbing stress by different parts of the frame and how they acted together as a unit with the floor boards and side heater tubes in the outer parts of the body.  It was a very cool description of what was going on.  I just wish I could remember it all, but he paid 4 years and a lotta bucks to the Worcester Polytechnic Institute to know what he was talking about.  He's now the "New Product Engineering Guy" for Medtronic Corp.  

So you cut the tunnel and install one of those access panels (either welded or rivets or sheet metal screws). So, you're driving along and WHAM!!! a meteor falls out of the sky and strikes your Speedster right smack on that patch job you just did on the tunnel...

OR...you are trying to outrun a carload of Medellin Cartel assassins out to eradicate you (mistaken identity, of course) and you fly over an elevated train-crossing getting massive air and landing hard on the front wheels...

OR...you are loading your car onto a container ship with the lift straps on the front and rear of the car then lifted a hundred feet into the air, suspended over the harbor and dropped on the ship...

Well, when you find yourself in any of these (or similar scenarios) you may be wondering "...I hope my tunnel modification will hold out...".

Until then, drive on with the peace-of-mind knowing that because of your  tunnel modification, you will be able to do a roadside replacement of your clutch or throttle cable with ease!

I'm not jumping on the "big hole in the backbone is OK" wagon.

It's not. VW designed the pan for a certain load/twist range. If it were my car I'd weld the piece back in. Period. If it were OK, VW would have put the access panel there already, like for the shifter access in the back.

But I don't putt around to get groceries, and well, don't own a pan-based Speedster.

It's your car, do what you want. But I wouldn't advocate that this is OK for others to do based on some anecdotal junkyard testing OR a mechanical-design guy giving his blessing.

My friend Mike is completely doing up a Lotus Elan. He's doing some really amazing work restoring this thing. His fiberglass repairs are better than the original parts. He could have repaired the steel backbone chassis, it had crash damage in a few spots and a big crack. He elected to purchase a new backbone rather than risk the old one maybe cracking in the same or different spot. Did you ever hear of metal fatigue?

Now, a VW is probably made a whole lot better and is more durable than any Lotus. Both are old and from the 60s, but I still wouldn't chance it. Weld it.

Last edited by DannyP

Well, OK then!

^ - wait a minute, did I just get in the last word? I'm guessing not...

You all must know that I don't take myself too seriously, and once in a while I can't resist lobbing a meatball over the plate to have it knocked out of the park, because...sometimes it's just too easy!

I made it home after 12 months of combat in the jungles of Vietnam without any .50 calibre bullets exploding my head, so I'll take my chances with a tunnel access.

Last edited by MusbJim
@MusbJim posted:

Well, OK then!

^ - wait a minute, did I just get in the last word? I'm guessing not...

You all must know that I don't take myself too seriously, and once in a while I can't resist lobbing a meatball over the plate to have it knocked out of the park, because...sometimes it's just too easy!

I made it home after 12 months of combat in the jungles of Vietnam without any .50 calibre bullets exploding my head, so I'll take my chances with a tunnel access.

You weren't a Tunnel Rat, were you, Brother?

@DannyP posted:

@MusbJim My comments were definitely NOT aimed at you. I knew that your tongue was firmly planted in cheek...

No worries, my brutha! I know you have everyone's best interest in mind when you share tech info and all the other amazing advice stored in that noggin of yours.

Remember when Jake Raby (formerly Massive Type IV) used to openly participate on this forum, he took every opportunity to espouse his beyond-compare expertise (on the other hand, he was brilliant, and moved on to Porsche magnificence). One time when someone mentioned they were going to try to TIG weld something on their Speedster, Jake didn't hesitate to mention that he once did a masterful TIG weld repair in a parking lot (or some such amazing scenario). And he claimed he was only 13 when  he did it!

Well, not to be outdone, of course I replied that I was the one that invented TIG welding....when I was 12. BWAAAAA HAAAAA!!!

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