Center tunnel / chassis reinforcements

Dr.Jeff

True Classic
I recall some discussions about finding cracks in the center tunnel, around the area of the shift selector. Mine has a couple there also. A few people have made reinforcing plates, but I cannot find examples of them now. Anyone have anything to show, or info about this to share?

Here is where my cracks are:
002.JPG


Interesting how all three of them are around that one hole. And more interesting is I see no reason for that hole. The others allow specific access to components below, but I see no reason for this particular hole. So I'm tempted to just weld a patch over it, including the surrounding cracks. Think of any reason why that hole should not be covered permanently?

Appreciate seeing examples of what others have done here.
 
Yep... those cutouts are for the rear window defrost and the magical "..." whatever switch. If you ask us kids doing the MWB K20 swap, we end up cutting that entire area out and bolting on a plate for the new shifter setup.

Regardless, remember that the tunnel is a structural tube providing essential structure for twist (the outer sections under the door are also essential too, especially for banana flex).

Is this an early (pre '79) X1/9 or later one with power windows, tall dash etc. ?
 
I recall some discussions about finding cracks in the center tunnel, around the area of the shift selector. Mine has a couple there also. A few people have made reinforcing plates, but I cannot find examples of them now. Anyone have anything to show, or info about this to share?

Here is where my cracks are:
View attachment 46647

Interesting how all three of them are around that one hole. And more interesting is I see no reason for that hole. The others allow specific access to components below, but I see no reason for this particular hole. So I'm tempted to just weld a patch over it, including the surrounding cracks. Think of any reason why that hole should not be covered permanently?

Appreciate seeing examples of what others have done here.

What ever you do, remember to drill a very small hole at the end of the crack to keep it from continuing to grow. I brazed mine.
 
Yep... those cutouts are for the rear window defrost and the magical "..." whatever switch. If you ask us kids doing the MWB K20 swap, we end up cutting that entire area out and bolting on a plate for the new shifter setup.

Regardless, remember that the tunnel is a structural tube providing essential structure for twist (the outer sections under the door are also essential too, especially for banana flex).

Is this an early (pre '79) X1/9 or later one with power windows, tall dash etc. ?
Sorry, I should have specified - this is a '79 without power windows. In fact the '79 does not have any switches down there. That's why the reason for the cutouts wasn't obvious. But it should have been, as I also have later X's with switches there. 🦧

The square hole toward the passenger side is useful to help access things inside the tunnel, but the drivers side is nowhere near anything under there. And of course the long rectangular hole is needed to get the shift rod up far enough to access the pivot bolt to the shift selector.
 
I think the holes are for power window switches.
Thanks, you are correct. ;) See my comments in post #5.

I'm debating on a few options to repair and/or strengthen the area. Note my comments in post #5 about the functionality of these holes on my '79:

Option 1 would be to drill and weld up the cracks, then weld in a "repair" plate over the area where they exist. Something like the red lines (in pic below).

Option 2 would also include the drill/welding of cracks, but rather than welding in a patch I'd add a removable plate to reinforce both sides around that area. Similar to the green lines in pic.

Option 3 is like option 2 but also covers the big hole for the shift selector. Although the added thickness might interfere with the mounting of the selector? See the yellow lines for an idea of it.

Option 4 might be a combination of any of those. For example #1 and #3.

A solid patch (#1) should extend a bit beyond the existing cracks rather than just fill the hole. Any removable reinforcement plates (#2-4) would extend far enough (e.g. over both sides of the tunnel and far enough back) to add strength to the area (difficult to show that with my "stick" line drawing). And they would have sufficient attachment/anchor points to disperse the load/stress.

The plates shouldn't need to be too much thicker than the stock sheet metal, maybe 18 gauge for the patch and 16 gauge for the removable ones. The added layer will provide enough support, this is a street-only car. Which is why I'm not sure anything more than a "repair" (option 1) is needed?

Thoughts? Here's the drawing....

001 - Copy.JPG
 
IMG_2327.jpg


Since I run without a tunnel cover, I needed a cosmetic solution. Just a simple plate with those two sheet metal screws at the back and the two shifter bolts at the front. My tunnel also had cracks and I did some pretty horrible welding to fix them.
 
Looking back through some photos I saved a long time ago I found these. Sorry I don't recall whose car this is nor what thread they were in, so I don't have any further info beyond what is seens here:

tunnel1.jpg

tunnel2.jpg

tunnel3.jpg

tunnel4.jpg


This is along the lines of my option #3 earlier. However on my X the cracks extend down the side of the tunnel, so I'd make the cover plate three sided to wrap around the tunnel sides some. This plate appears to be aluminum. I think I'll use steel, but much thinner. Also if you look at the third pic it gives a great representation of why that long rectangular hole is very helpful when dealing with the shifter.


My tunnel also had cracks
Carl, roughly where were your cracks located? Of the examples I've seen they are usually on the drivers side and around the square hole. Was that where yours were? I wonder why this specific area is weaker or has more stress?
 
Here's a wild idea. I've always liked the classic "shifter gate" as seen on traditional Ferraris and such....
6060488968_9abfac51f8_b.jpg


Years ago you could get something like this as an accessory for the early water-cooled VW's. It was only cosmetic, replacing the stock shift boot and surround, but the shifter lever motion did follow the pattern cut into the polished stainless plate.

With a larger metal plate added as a reinforcement to the X's tunnel (e.g. option 3), some extensions could easily be added to raise a platform higher up on the shift lever. Kind of like on this X (this was one of the first Honda K20 swaps):
f2eba24c31de0b24bf8b8787d74a76e1 - Copy.jpg


That platform could allow a "gate" cover to be added. :D
 
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Found another interesting picture of center tunnel mods. Is this @darwoodious build? Sorry I don't remember:

_X_kAnZw - Copy.jpeg


Reinforcements like this over the stock tunnel would definitely add strength and rigidity to the whole thing. And it would provide for a really nice custom center console to be built; with incorporated arm rest, cup holders (if desired), USB ports, and/or a custom shift lever cover (perhaps like in my post # 9).
 
Is this @darwoodious build?
Nope, not me. This is a RHD model so an Aussie or UK'er.

Reinforcements like this over the stock tunnel would definitely add strength and rigidity to the whole thing. And it would provide for a really nice custom center console to be built; with incorporated arm rest, cup holders (if desired), USB ports, and/or a custom shift lever cover
I wonder how well that worked out for the builder of that modded exe. This is race car territory where the shifter is super high and no room for elbows to slouch down (hands on the wheel at all times).
 
Nope, not me. This is a RHD model so an Aussie or UK'er.


I wonder how well that worked out for the builder of that modded exe. This is race car territory where the shifter is super high and no room for elbows to slouch down (hands on the wheel at all times).
Ha, I completely missed the RHD aspect.

If I built a custom center console with a reinforcing framework, it would not be as high as that one appears to be, and I would shape it differently. Although it looks like he also cut down some of the stock tunnel(?), so maybe the bars aren't as high up as they seem? However having the shifter a bit higher with a shorter lever would be nice to me.

For the overall height compared to the seat height, maybe something more along these lines:
961326a5f23448113c8e31de07007fa0.jpg
 
Here's a wild idea. I've always liked the classic "shifter gate" as seen on traditional Ferraris and such....
View attachment 46667

Years ago you could get something like this as an accessory for the early water-cooled VW's. It was only cosmetic, replacing the stock shift boot and surround, but the shifter lever motion did follow the pattern cut into the polished stainless plate.

With a larger metal plate added as a reinforcement to the X's tunnel (e.g. option 3), some extensions could easily be added to raise a platform higher up on the shift lever. Kind of like on this X (this was one of the first Honda K20 swaps):
View attachment 46668

That platform could allow a "gate" cover to be added. :D

I doubt that a shifter gate would work with a standard linkage as it is too "floppy" by nature of the long shifter rod. Gates like this would be more appropriate in cars where the shifter is directly connected to the transmission.
 
Yes, my cracks were at the corners of the rectangular opening on both passenger and driver side. Same thing on my previous red X. These start at very sharp corners on relatively thin metal, I wonder if it's just vibration based rather than chassis flex.

I removed the cooling pipe tunnel when I first started working on the car, the cracks were there before this mod. I have not noticed any flexing or ovaling of the mounting holes since I installed this plate.
 
I doubt that a shifter gate would work with a standard linkage as it is too "floppy" by nature of the long shifter rod. Gates like this would be more appropriate in cars where the shifter is directly connected to the transmission.
I agree with the standard linkage comment too. Before I cut out the "fingers" of the gate I tried to get it to work to no avail. I just ended up with a big aluminum covered hole as that was the only thing I could get to work - 308 interior .
 
I doubt that a shifter gate would work with a standard linkage as it is too "floppy" by nature of the long shifter rod. Gates like this would be more appropriate in cars where the shifter is directly connected to the transmission.
The Ferrari 308 has a similarly long shifter rod, and the gated shifter works only because of the moderately bizarre way that the shifter rod is supported: it passes through the engine oil sump. The bushings and seals constrain it to rotate and slide forwards and backwards, but not to flop around sideways.
 
Yes, my cracks were at the corners of the rectangular opening on both passenger and driver side. Same thing on my previous red X. These start at very sharp corners on relatively thin metal, I wonder if it's just vibration based rather than chassis flex.

I removed the cooling pipe tunnel when I first started working on the car, the cracks were there before this mod. I have not noticed any flexing or ovaling of the mounting holes since I installed this plate.
So yours were on both sides of the tunnel, interesting. The others that I've seen mentioned were only on the drivers side and in the middle of the tunnel - not to the passengers side. But naturally they can occur anywhere eventually.

However all cracks seem to be starting from those rectangular holes where switches can fit. That is a single layer section, opposed to some surrounding areas that are doubled. I imagine those holes were not in the early chassis(?), I've never had a early X so don't know. But if those two holes weren't there, did those cars also crack? Just curious.
 
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I agree with the standard linkage comment too. Before I cut out the "fingers" of the gate I tried to get it to work to no avail. I just ended up with a big aluminum covered hole as that was the only thing I could get to work - 308 interior .
Clark, looking at your link I realize it was your car that the pics came from (that I posted previously with the reinforcement plate). ;) It's been too long and I could not remember what car that was. I'd also forgotten your experimenting with a shifter gate.


I doubt that a shifter gate would work with a standard linkage as it is too "floppy" by nature of the long shifter rod. Gates like this would be more appropriate in cars where the shifter is directly connected to the transmission.
I agree with you guys about this. However on the early VW application the accessory shift gate worked fairly well. And that is a very similar shift linkage arrangement to the X. One difference though, the VW has a support bushing midway along the long shaft (between the selector and the trans linkage). And that might make the difference, along the lines of what @EricH was saying; "the (308) gated shifter works only because of the moderately bizarre way that the shifter rod is supported: it passes through the engine oil sump. The bushings and seals constrain it to rotate and slide forwards and backwards, but not to flop around sideways."

I've been wondering if that same VW support bushing can be added to the X's shaft near the rear of the tunnel. Rather than the rubber boot being the only thing keeping the shaft in place, the bushing would eliminate all that slop. This is what the VW item looks like:
Gear-Shift-Rod-Support-BracketBush-For-VW-Golf.jpg

It is sort of like a monoball or heim joint, the soft bushing in the middle allows the shaft to slide through it and rotate, as well as pivot about it a bit, while supporting it from flopping around.

Even if the idea of adding a gate isn't attempted (which I likely won't do due to time factors), the VW support bushing may be a good idea to improve the X's shifter feel.
 
I finally got around to making a support reinforcement for the center tunnel. As I began working on the area I realized there are two more cracks beginning to form on the opposite side than I first reported. Here's where all of the cracks are:
5002.JPG


I decided to take multiple approaches to remedy this; weld the cracks, weld in a reinforcing rod (1/4" solid round stock) on the inside edge of the large opening, weld in a patch to cover the unneeded open area, and make the reinforcement plate extend well beyond this area where the cracks are. The reason for that last item being longer is due to something I realized about the chassis construction. Most of the tunnel is already double layer thickness. There are reinforcing plates welded on the inside of the tunnel at the rear, middle and front sections, with gaps in between them. Unfortunately there are also extra holes in the sheet metal where those gaps exist, making the areas very weak:
The green arrows are where double layers exist from the factory. The red arrows are where no double layer exists, and where there's holes, making the areas weaker....
031.JPG


In the above pic the leftmost and middle holes (red arrows on left and center) don't seem to crack like the larger front hole (right red arrow) does. But I figured it would be easy to extend my reinforcement plate to at least cover the middle hole (center red arrow) as well as the large front one.

Here is where I welded in the round stock reinforcement inside the top corner:
032.JPG


After this I added a patch over part of that large hole, but forgot to take a pic.

This is the cover plate I made:
040.JPG


And how it fits over the tunnel (need to get more hardware and add a finish paint coat to everything):
036.JPG


The shifter will sandwich the plate toward the front, and the park brake mechanism will sandwich it toward the rear. It extends beyond the double wall sections on each end, making the entire tunnel doubled - except that little hole toward the very rear bulkhead (the leftmost red arrow in the second pic), but I'm not going to worry about that.

I wanted the plate to wrap around from the top of the tunnel and down the sides part way. Additional anchor bolts will go along the lower edges:
038.JPG


The plate is made of the same thickness metal as the factory tunnel, equaling the double layers from the factory. As with the plates made by others, it needs to be removable to access things inside the tunnel.

Then on to redesigning the wire harness/electrical system....that is a huge job.
 
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Chris Obert is parting out a car in FS&W and in his thread posted this pic of the section of the floor he salvaged from the car (a wreck). Shows a view of the structure that one does not normally see.

1621847942928.png
 
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