TheSamba.com :: View topic - Bottom Pan Tunnel Sterling/'71 Standard Beetle Frame

Mon Oct 05, 2015 6:08 am

Had a request for this bottom pan tunnel details, for Sterling Kit on "71 Standard Beetle frame. WIP

After cutting into the top tunnel to install custom shifter and Boxster e brake, decided to weld in a half pipe to the bottom of the pan to keep the structure intact. (I hope :)

Found 6 7/8" dia pipe used for emergency sprinkler systems at the local Smith's Iron Works. Turns out that the bottom of the Beetle pan along the tunnel is exactly 6 7/8" wide.

Cut the pipe in half with plasma torch, using angle iron tacked on to use as a guide to make a straight cut.

Prep bottom pan with blind nuts for shifter and e brake brackets in top tunnel

Making nose cone template

Use template to mark cut on extra piece of half pipe.

Welded with MIG 175, ground down welds a bit to make smooth, and some metal reinforced body filler at the cone joint to make it clean.

Mon Oct 05, 2015 6:13 am

Just wondering what the purpose of this was?

Mon Oct 05, 2015 6:34 am

Nice work!

Mon Oct 05, 2015 6:35 am

jspbtown wrote: Just wondering what the purpose of this was?
"After cutting into the top tunnel to install custom shifter and Boxster e brake, decided to weld in a half pipe to the bottom of the pan to keep the structure intact."

For Sterling Kit on '71 Standard Beetle donor frame.
Sterling Kit needs 4 inch dropped seat pans for low roof head room.
The tunnel on bottom serves two purposes, allows access to the top tunnel while retaining structure, and provides protection in case of bad bottom out.
(Also the seat pans are carbon Kevlar epoxy laminated with 21,000 lbs Kevlar webbing strap reinforcement to hopefully save my but if I go off the road and hit a tree stump.)

Mon Oct 05, 2015 6:42 am

I understood that you did it for structure....I wondered by you did a pipe versus a plate.

So access to the top tunnel is accomplished how? Is one end of the pipe opened?

Mon Oct 05, 2015 7:02 am

jspbtown wrote: I understood that you did it for structure....I wondered by you did a pipe versus a plate. So access to the top tunnel is accomplished how? Is one end of the pipe opened?
Top of the tunnel is cut open for the shifter mod (6 inch back) and Boxster side offset E brake, keeps the top of the tunnel clear for arm rest, the seats are really low.
Early shifter, e brake photo

I think tubes are much stronger for the weight compared to using a plate.
Many aircraft fuselages are based on the tube design not only for aerodynamics but for strength to weight.

Also, the half pipe is very close to the original tunnel on top, just adding it to the bottom. This way I don't have to worry about welding in brackets and tie bars in the top tunnel, I can leave it open and then cover with removable carbon panels to finish the interior. If I need to adjust the shifter or E brake, I can just remove the access panel. Works great for the Sterling Kit, but not too good for buggies of course.

Mon Oct 05, 2015 7:06 am

Now I understand..that last picture helps a lot. You basically have lost all the top structure so you basically have flipped it.

On my old Sterling moving the shifter back would have been a great mod. I did move it back 6" on the Avenger and it made all the difference in the world.

Mon Oct 05, 2015 7:16 am

jspbtown wrote: Now I understand..that last picture helps a lot. You basically have lost all the top structure so you basically have flipped it.
On my old Sterling moving the shifter back would have been a great mod. I did move it back 6" on the Avenger and it made all the difference in the world. Wow! Sterling and Avenger? Cool, I found original build instructions for the English version "Nova" and they emphasized moving the shifter back. I was a bit anxious about that and spent some time mocking up the seat and wondering if I should do it. Good to hear that it's worth it, thanks!

Mon Oct 05, 2015 7:30 am

I don't guess the car will be lowered??

Mon Oct 05, 2015 7:52 am

Sterling that I built...oh my....14 years ago (time flies!). No dropped pans and bent shifter to make it more bearable:

More recent Avenger with dropped pans and shifter moved back about 6"

Mon Oct 05, 2015 6:28 pm

MURZI wrote: I don't guess the car will be lowered??

I could extent the lower half body parts to make a lower appearance, like an aero package. The roof is very low giving a flat overall profile.

Mendeola T1 and TT suspension adjustable coil-over shocks should allow for height adjustment, have to be careful because of the 4 inch seat pan and tunnel drop.

Mon Oct 05, 2015 6:36 pm

jspbtown wrote:
More recent Avenger with dropped pans and shifter moved back about 6"

Awesome work, Love the finished, Sterling, Avengers' my dream car, more like a GT40, nice photos Thanks!

Tue Oct 06, 2015 5:23 am

I guess you haven't found our forum yet complete with all the build manuals...

Interesting way to reinforce... but you could have just as easily boxed in the entire floor section, lowering it at the same time and achieved far more head and leg room in the process.

Tue Oct 06, 2015 3:57 pm

Letterman7 wrote: I guess you haven't found our forum yet complete with all the build manuals...

Interesting way to reinforce... but you could have just as easily boxed in the entire floor section, lowering it at the same time and achieved far more head and leg room in the process.

For sure, that's where I found the original Nova build instruction manual, appreciate it very much, thanks. Need to update #667 , waiting to make more progress.

I went with the conventional 4 inch drop seat tubs, but twice as long as the Sterling specs for EV battery storage behind the seats, and epoxy laminated carbon kevlar instead of sheet metal.

The bottom tunnel is safe I think, following the original design, but flipped under instead. If you have a bad bottom out, or hit a tree stump, post or whatever, I'd rather it impact the steel tunnel than crush into the seat pans.
Also will have a full continuous carbon skid plate as part of the aero package.

A full box to replace the tunnel? That sounds great, has someone done that?
What do you mean, far more head and leg room? More than the 4 inch drop original design? More than 4 inch drop might mean you have to raise the suspension just to keep from scraping the road.

Seen some great custom Beetle frames, and was going to get the tubular frame kit, but when ordering, they jacked up the price $4K over what was advertised, so I thought, I'll just restore the original 71 Beetle frame, add Mendeola front and back suspension w/ disk brakes.

Registration was simple too, used original VIN and Replica Kit Makes.

Supposed to be an Electric Vehicle project, so needs strong battery compartments in the frame at the lowest CG possible. Lots of problems, but I'm happy with the frame now.

Tue Oct 06, 2015 4:18 pm

Has anyone ever dropped the entire floorpan, each side, and lowered the pedals too? I imagine with a thin seat bottom your hips would be so low you would be reaching uphill with your feet for the pedals.

Mike T

Tue Oct 06, 2015 5:52 pm

My Avenger had full drop pans. I hung the pedals from the firewall and used a floor mounted gas pedal with cable that ran outside of the tunnel but inside the full length console.

Tue Oct 06, 2015 5:54 pm

On all my cars I've done full pan drops on both sides, front to rear. The driver's side I usually leave a little "sill" to rest my heel on for the pedals, but other than that it's a flat floor front to back. In this particular instance, since the tunnel was already cut, incorporating extra bracing with the drop would have been a piece of cake. And, on two of the cars I've built, the floor was dropped 3 1/2" to 4", depending on what engine was installed at the time. My current car is dropped 3 1/2" and it's very low to the ground - I have touched from time to time on the road over bumps. With the more modern suspension installed front and rear, that should no longer be a problem for low drops.

I didn't know Dave had raised his prices on the tube frames... the company is still in a state of flux. Dave's had it for sale for quite a while.

Wed Oct 07, 2015 1:25 pm

BIGMIKEY wrote: Has anyone ever dropped the entire floorpan, each side, and lowered the pedals too? I imagine with a thin seat bottom your hips would be so low you would be reaching uphill with your feet for the pedals. Mike T
I mocked up the seat and installed the pedals to get an idea of the position.
Felt OK, so I went with the dropped floor plan. Sort of like sitting in a recliner with your legs and feet up on a foot rest.

Ever wanted to drive an F1 car? Sterling appears to be like the F1 but not as extreme.
Formula One cockpit diagram

Wed Oct 07, 2015 1:28 pm

Letterman7 wrote: On all my cars I've done full pan drops on both sides, front to rear. The driver's side I usually leave a little "sill" to rest my heel on for the pedals, but other than that it's a flat floor front to back. In this particular instance, since the tunnel was already cut, incorporating extra bracing with the drop would have been a piece of cake. And, on two of the cars I've built, the floor was dropped 3 1/2" to 4", depending on what engine was installed at the time. My current car is dropped 3 1/2" and it's very low to the ground - I have touched from time to time on the road over bumps. With the more modern suspension installed front and rear, that should no longer be a problem for low drops.

I didn't know Dave had raised his prices on the tube frames... the company is still in a state of flux. Dave's had it for sale for quite a while.
If I ever do this again, I will definitely consider your method, Thanks!

Wed Oct 07, 2015 3:18 pm

How are you going to get out of that once you get in?