My Beetle Restoration

Tag: tunnel

Removing Tunnel Bottom Plate

by on Apr.23, 2018, under Chassis

After considering the pros and cons of removing a section of the tunnel bottom plate, I decided to go ahead and do it. With all of the rust damage that can be seen from outside of the tunnel, I really can't tell if the inside is damaged to the same extent just by looking from the outside. I would expect it to be much less on the top and sides, but the bottom was definitely exposed to water pooling inside of it for many years. Until I take the plate off and look, I will not be able to have an accurate assessment of the damage. Here are some considerations:

Pros: I'll know for sure what damage is there and be able to fully access it to repair it. Areas with rust damage are weaknesses in the structure and must be removed and any rust that is there will just progress and must be stopped. I'll have a better chance of doing that by getting inside and taking a look. Also, large sections of the lip where the floor pans rest on both sides have to be replaced. On the driver's side, it is eaten completely through. Overall, I think it will result in a much better repair when I can get the areas cut out, prepped, and the replacements welded in when having access to the inside. I can also get the inside of that section of the tunnel painted and protected, replace the fuel line, and install seat belt mounting plates.

Cons: The possibility of structural weakness if not properly welded and/or the creation of alignment issues. These are the two biggest downsides to taking the bottom plate off and welding it back on. Of course, any area where the welds are weak are a concern, but so is any unrepaired area with rust damage that is concealed and inaccessible inside of the tunnel. I currently have areas where the rust is a potential weakness and I think as long as I get good weld penetration and good adherence to both parts being welded, structural strength will be achieved. Also, once the bottom plate is removed, the tunnel is very flexible and is easily twisted. This could result in the frame head being in a position where it is not level or tilting. There is going to be a lot welding both for the replacement of the side strips with the floor pan lip and putting the tunnel plate back on and ample chances that those welds will pull the tunnel one way or another. Well on this chassis, so much is going to be replaced and constant checks of alignment and position will have to be made during the rebuilding process anyway. I will just have to check, double-check, and triple-check throughout this process and hope that I can be successful. There are so many areas that are going to have to be replaced on this car with the body as well, so getting this all correct is imperative.

To start taking the bottom plate off, I used a wire wheel in my drill to remove any paint, undercoating, or rust to reveal the spot welds. There are a ton of welds to drill out! My last count was 142.

Important Update: Not knowing what I was doing, I drilled out twice as many spot welds than needed. If you look carefully at the close-up of the spot welds below, there are two types of spot welds - ones that are smooth, dished, and even, and ones where the metal is raised and uneven. The smooth and even ones are the ones that were made using a higher voltage to attach the tunnel bottom plate to the tunnel. These two pieces are thick and the higher voltage melts the metal more, creating a dish in both. The other raised and uneven welds were created when attaching the floor pan to the lip of the tunnel and were created with a lower voltage since the floor pans are thinner. Because of this lower voltage, it doesn't penetrate fully though the tunnel bottom plate and therefore these do not need to be drilled out. An important lesson learned that I will not forget! These were typically alternated, so basically half them were unnecessary.


The area I am going to remove starts with the frame head bottom plate and goes down to where the tunnel starts to flare out to the forks. That area appears to be in great shape, so no need to do anything with it. At the front end of the tunnel bottom plate, it is overlapped by the frame head bottom plate. In its current condition, the overlapped area is just a huge stack of rusted metal that is bulging outward.


The spot weld cutter that I'm using has a pilot to hold the cutter in one place to cut the holes. This works for about three holes and then it starts skating and making deep circular scratches as it skates away. The duller the tip of the pilot gets, the more uncontrollable it becomes. I discovered that if I take a center punch and mark the center of each spot weld and then use a small drill bit around the size of the pilot to drill a shallow hole in each punch mark, the tool is much easier to control and use. It actually saves time in the long run as you are not fighting to keep it on the correct spot and having to stop and restart the cut. Trust me, it's worth the extra effort. It cuts a 3/8-inch hole which is kind of large, but it does a great job of getting the whole spot weld. These are available from Harbor Freight for $5 each.


Next, I made the cross cut at the frame head plate and at the other end of the tunnel plate. Once the cut was made at the frame head end, big chunks of rusted metal just fell off.


And finally, cutting out the spot welds. This took many hours and the good part of one day to accomplish. I started on the driver side at the frame head and would cut out several of them and then gently pry up with a screwdriver to see if the plate was breaking free. I tried very hard not to drill into the lip below it to keep that section intact as much as possible. I would drill down watching the cuttings carefully and looking for rust to appear. Once I saw the rust, I would vacuum the area and look into the hole to see if I was all the way through the plate. This worked well until I got to the middle of the plate. I couldn't see any signs that I missed a spot weld and it just wasn't moving. so I started at the other end thinking that would help, but it was the very same even once it was free on both ends all the way to the middle. I used the screwdriver to attempt to pry it free. No such luck. I decided to take a break and when I was getting up from sitting on my stool, I barely bumped the Napoleon hat with my drill and the whole side popped loose. Of course, the other side was cooperative until I got to the middle and the same thing happened. I started on one end, gave up and started on the other, and got to the middle and it wouldn't break free. In this case, I had a couple of welds that I didn't cut quite deep enough and once I did that, it was completely free. It is amazing how much just part of a couple of spot welds will hold a piece in place! As expected, the top and sides of the inside of the tunnel were in excellent condition looking pretty much the same as they did the day they were initially assembled. The bottom plate itself is in good shape except at the end by the frame head. That end will require a inch or so cut out and a couple of inches added so that it extends to fit underneath the new frame head plate. It's a relief to get the plate off, but I know that I just added many more tasks and many more days of work to an already never-ending list of things to do. Next, I tackle getting the frame head bottom plate off. Should be fun!


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Removing the Frame Head Bottom Plate

by on Apr.27, 2018, under Chassis

Since I'm replacing the Napoleon hat and there is really no room to drill or cut right next to the top of the frame head, I decided to cut off the arms of the Napoleon hat and trim back the bottom plate. This really made it easier to access. I used a wire brush in my drill to remove the undercoating and rust and reveal the spot welds. Once that was done, I did the same as on the tunnel bottom plate and punch-marked the center of the spot welds and drilled pilots for the spot weld cutter.


I then cut out the spot welds and cut out the inside part of the bottom plate, leaving just the strips where the plate was welded to the frame head. I am so glad that I went to the trouble to take the bottom plate off as there is some serious rust inside the frame head that just would not have been seen otherwise. The side of the tunnel underneath the Napoleon hat has deteriorated on both sides and will need patching with solid metal. Also, the tunnel section that extends through the frame head will need patching on both sides as well. Additionally, the frame head will need patching on the bottom portion where it is welded to the bottom plate on both sides. I have to admit, I was initially discouraged and contemplated replacing the entire frame head with a new after-market reproduction. But as I researched doing so, I determined that the effort and expense of removing the current one, patching the tunnel (which I have to do anyway), purchasing a new frame head (that will not match the current one and is constructed of thinner metal), and properly aligning the new frame head just was not the best course of action. With the tunnel bottom plate removed, the tunnel is just too flexible to be able to do any accurate alignment and I would rather take my chances with replacing the areas that absolutely need it and hopefully maintaining the current positioning as far as the angle of the frame head on the front end and where it is positioned on the tunnel. If I can maintain those two things, I will just need to make sure it is level when it is all welded and reassembled. Also, once it is taken off, I lose all of the current reference points and I really need it where it is now to get the new Napoleon hat properly positioned.


One of the things I found amazing and educational was how much the rusted areas have expanded over the years as they progressed, especially where the panels where overlapped. Where two panels, that were each originally around 2 millimeters thick, were overlapped and then rusted severely, their combined thickness grew to around 12 millimeters. In several areas where this happened, the surrounding areas of the panels were raised and bulged, distorting everything attached to it. On panels with nothing around them, they appear to just disintegrate and fall away. In areas where the panels are welded together and very close to other panels, they have expanded greatly.


Getting the remaining strips of the bottom plate off was a real pain. The spot welds are easy enough to cut out, but on the side edges of the frame head where it is welded to the plate it is seam-welded in the middle section for a couple of inches and towards the front for a couple of inches as well. I just had to cut around the seam-welded areas and grind them down. Where the plate meets the front edge of the frame head, it is seam welded all the way across. I was able to use a cutting disc to trim it back fairly close, but the rest had to be ground down. This is a lot of trouble for the side flanges that are going to be replaced, but I want to get it back to its original position to test fit the new bottom plate and to have good references for the areas that are going to be replaced. Once everything was cut and ground away, I just had to place the new bottom plate in position to see what it looks like. Even though its just sitting there, it feels like progress and is encouraging.


Next, I cut way the majority of the bottom plate that was welded to the frame head and ground it down. There are some areas that still need to be ground down, but I will save that until I am preparing and fitting the bottom plate. The next steps are to cut out the rusted areas and weld in patches.


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Protecting Inside Of Tunnel Bottom Plate

by on Nov.17, 2020, under Chassis

I decided to remove all of the factory's protective coating on the inside of the bottom tunnel plate. It was in very good condition with almost no rust damage there, which is surprising as this area was holding water for many years. The only area with damage was at the front end where it connects to the frame head bottom plate. Here, both had either rusted all the way through or had deep pitting.

After the protective coating was removed, I went over the inside area with a wire wheel on a drill. I masked off the sides where it will be welded back on the tunnel, and also masked the damaged area on the front end. The damaged area will be treated with a rust converter and I will make and weld on an extension to replace the rusted-through area. I then sprayed the inside area with Eastwood Matte Black Rust Encapsulator. This should protect it protected for a while. Once it is welded back on to the tunnel and all tunnel repairs are completed, I will recoat the inside of the tunnel again.


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Making Tunnel Rail Replacement Pieces

by on May.10, 2021, under Chassis

After searching for years for something that I could just purchase to use to replace the rusted-out tunnel rails on my chassis, I decided to just make my own. "Tunnel rail" is what I am calling the lip on the bottom of the tunnel where the tunnel bottom plate is welded and also where the floor pans rest on the tunnel. The closet thing I could find is a 15" tunnel section replacement that is made to replace the tunnel inside of frame heads. But they are around $35 each (plus shipping) and I would need at least 5 of those. Not only would this option be costly, but these aftermarket parts are way thinner metal than the original metal and the shape really doesn't match as well. I found that I could get a 12" x 48" x 2mm sheet of steel online for about $45 total, so I decided to purchase that and see if I could find a way bend it and make pieces to use. It came very well packaged and protected.


To bend the sheet metal and match the radius of the lip on the tunnel, I used two 18" long, 3/16" thick x 2" wide mild steel plates set at a 90 degree angle with a 1/4" round steel rod on the outer edge and welded them on the inside edge. This gives me a smooth rounded surface on which to pound the metal into shape. The sheet metal is 2mm thick and will take a lot of force to form it.


After the plates and dowel were welded together, I made a clamping plate, added clamping bolts, and mounted the unit on a 4" x 4" treated post. The post is dense and heavy and gives me something to hold on to when forming the shape. I used a large rawhide mallet to hammer it into shape. It was quite difficult to bend metal this thick without distorting it and to get it flat and even. With a lot of pounding, I was able to get it fairly flat and checked it against a tunnel section I had from a donor frame head. It matched well. The flange is longer than the tunnel flange, but it gives me more leverage to bend and form it and it can later be trimmed once the tunnel bottom plate is welded back on.


The next issue was how to cut the piece off and to get a nice, straight cut. I can't really do that well with an angle grinder with a cut-off wheel, so I decided to try to do this with my chop saw. I have an Evolution Rage 2 chop saw with a 14" multi-material blade that will cut steel, wood, and plastic. And although the blade is 14" in diameter, it doesn't go down far enough into the table to get a 12" long cut as I needed. So I took the clamping mechanism off of the table and attached a 1" x 4" piece of wood to raise the cutting area up and this made the cutting length about 12 1/4" which is sufficient. I then used some steel plate and 2 clamps to clamp the sheet down while cutting. It was a little difficult to make sure that the cuts were square, but I managed to get them close enough. I checked the first one against the tunnel and it matched well. I made another and it was very close to the first one. I made a few more and the results were good. I went ahead and made 12 of them. Good thing I did as I ended up using 11 of them to complete the tunnel.


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Repairing The Tunnel Rail – Passenger Side

by on May.17, 2021, under Chassis

Now that I have the repair pieces made to replace the tunnel rails, it's time to start cutting and welding them in. My plan is to replace the rail from the point that I removed the tunnel bottom plate, all the way to the end in the frame head. I made the pieces long enough on the tunnel side of the pieces to reach past most all of the rust damage. I will have to patch a couple of places where the damage extends upward past them, but these will cover almost all of the damage. I will weld these pieces in on both sides and ground them down on the outside, but leave the welds as is on the inside for strength. They will not be visible and I'm mainly interested in them being strong. I'm starting on the passenger side as it has the least amount of damage and is the least complicated.

The first section took quite a while to do as I tried different things to figure out the best way to do this. I first laid out a replacement piece on top of the rail, marked the length, and cut 1/2 inch or so through the lip down into the tunnel. After that I cut across between those two cuts to remove the lip. I then placed the piece on the tunnel, lined it up with the existing lip on both ends of the cut-out, and clamped it in place. With it clamped, I then used the piece as a guide to cut through the tunnel. I now had a cut-out just a little larger than the size of the piece. I first held the piece in place for welding using panel clamps, but after just a few tacks across the joint, the panel clamps were locked in tight from the shrinkage of the metal when cooling and I could barely get them out. From that point on, I just used vise grip style clamps. The first three sections were pretty much the same and just involved determining and making the cuts and clamping and welding the pieces in.


The fourth section on this side connects to a tube support bracket for the clutch tube, fuel line, and choke tube. I drilled a couple of spot weld holes in the piece to attach it to the support brace. Next, I will replace the same four sections on the driver side.


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Repairing The Tunnel Rail – Driver Side

by on May.22, 2021, under Chassis

Now on to the driver side of the tunnel to replace the tunnel rail. This side is definitely the worst of the two sides. During the two decades that this car sat outside in the elements, water apparently pooled in the floor pans and there must have been water in higher volume and for a longer period of time on the driver side due to the damage. The tunnel on this side was rusted completely through to the inside in one area and this damage will be cut out on the first and second sections being replaced. In the first section, the cut-out for the piece did not extend high enough to include all of the damage, so I had to make two small patches. I welded them in first and ground down and dressed the welds. I then welded in the first section on both sides and ground down and dressed the welds on the outside.


Next I replaced the second and third sections. The third section had a little area that had a little pitting. Rather that patch it, I ground the area down to clean metal and filled it in with weld. I then welded the section in as usual.


The fourth section includes metal that goes in front of the pedal cluster support plate. Part of that support plate was severely rust damaged, so I first cut out for the tunnel rail replacement piece and then cut it out and welded in a replacement piece on the support plate. I had to grind out an area on that new piece to allow for the pedal cluster mount to fit into the tunnel. I checked it with the already powder coated cluster mount and taped it with tape to protect it from scratches. Once satisfied with the clearance, I welded on the new piece. I used a copper bar behind it as I welded it to keep the weld from blowing out on the edges. I ground down the welds on the outside of the support plate and left the ones on the inside. I drilled holes in the tunnel rail replacement piece to weld to the support plate and then welded the fourth section in. I left the area covering the hole for the pedal cluster mount for now.


With the fourth section welded in and the welds ground down and dressed on the outside, I now had four feet of tunnel rail replaced on both sides. Next up is to continue and finish the tunnel rail replacement through the frame head and up to the frame head front plate.


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Completing The Tunnel Rail Repair

by on May.27, 2021, under Chassis

Before I can continue replacing the rest of the tunnel rail, I need to patch a rusted out area on the driver side under where the Napoleon hat mounts. This damage also extends to the metal in front of the pedal cluster support plate. Rather than make a patch, I cut a section out of the tunnel from the first donor frame head. This matched perfectly. I cut out the tunnel to match the patch, drilled out several spot weld holes for the support plate, and welded the patch in on both sides. I then ground down and dressed the welds on the outside of the tunnel.


On the passenger side, I cut out the rest of the tunnel rail out up to the front plate of the frame head. With that area cut out, you can really see the severe rust damage on the frame head. This section is longer than the frame rail pieces that I made, so I had to use part of another one and weld them together. Then I welded the piece in completely on the inside and as much as I could access on the outside. With the frame head in the way, I could only get to about 2/3 of it. I will complete the rest of outside welds when the frame head is removed. I ground down and dressed the welds on the outside on the short section from the last section welded in up to the frame head.


This section of the driver side is shorter than the frame rail pieces that I made, due to the patch under the Napoleon hat and I was able to use the leftover piece from the passenger side. The cut-out on this section also exposes the rust damage to the frame head on this side. Just like on the passenger side, I welded this section completely on the inside of the tunnel and what was accessible on the outside. I will complete the outside as well once the frame head is removed. I also cut out the rest of the hole for the pedal cluster. I had a real sense of accomplishment with getting these 10' of tunnel rail replaced. I have once more section to replace on the curved portion of the driver side, but that will be in another post.


Below are pictures most of the metal cut out to replace the tunnel rail on both sides. I did use some of the better metal to make a couple of patches, this is the bulk of it. Since I took these pictures later, there are pieces included of the curved section that I cut out on the driver side.


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Removing/Repairing Additional Tunnel Bottom Plate Section

by on May.31, 2021, under Chassis

I thought long and hard about removing this additional section of the tunnel bottom plate. I knew it would be a lot more work, but finally decided that I needed to for 2 reasons. The first reason is that I need to replace some more tunnel rail on the driver side. The problem with replacing this section is that it both curves out and down and is way more complicated than the straight sections I already replaced. The second reason is that this section is dented in and I have not come up with a valid method of removing those dents without removing it. I thought about using a slide hammer, but I don't think that I could do a satisfactory job that way. So out came the angle grinder with a cut-off wheel and the spot weld cutter. After cutting out 25 spot welds and one foot-long cut across the tunnel, this section has been removed.


I first tackled the dented areas. The dents were mainly in the raised ridges, so I thought that if I could raise these back up and get them straight again that maybe that would bring the surrounding metal back up with it. I used a body panel hammer with a wide, narrow tip, a big rawhide hammer, and a 4" x 4" scrap of wood to use as an anvil and hammered them back straight. This brought the flat areas around them back up as well. This actually turned out better than I had hoped. Next, the hard part.


I cut a pattern out of cardboard that was the same size as the rail replacement that I was going to use and bent it to match. Then I cut slits in the cardboard so that I could bend it to match the contour of the tunnel rail area. Each time I got the correct bend, I would tape over the cut to hold it in place. I continued this until I had the pattern matching the tunnel. When I was satisfied with the shape, I removed the tape and laid the pattern over the rail replacement. Each place that there was a slit in the cardboard, I scribed a line on the piece to mark where I needed to cut slits in it. I cut the slits one at a time, bent it, checked the fit, and then tack-welded the slit to hold it in place. I did this for all of the cuts. Of course, the welding process distorted the shape a little and I had to re-cut and adjust it a little. I did finally get it to match fairly well.


With the replacement part now ready, I cut the lip off of the tunnel so that I could match up the top flanges and know where to cut the out the rest of the tunnel to match the replacement. I clamped it to the tunnel and used the edge as a guide for the cut-off disk just like I did with the straight areas. I used smaller cut-off wheels so that I could make the curved cut without cutting out too much. I welded it in on both sides and then ground down and dressed the welds on the outside. I placed the bottom plate section on and checked the fit. Some of the spot welds that I cut out were really far in from the edge and miss the lip of the rail. I will probably fill those area in while the plate is still off of the tunnel as that will be much easier when I can get to both sides of the plate and I can also clamp a copper bar behind it and fill them in.


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Repairing Straight Section of Tunnel Bottom Plate

by on Jun.02, 2021, under Chassis

On the frame head end of the tunnel bottom plate, there was severe rust damage and it was actually rusted through. The only way to repair this is to cut out the damaged area and weld a new piece in. As far as I know, there are no repair panels readily available. In fact, I only know of one source in Finland and I don't want to wait that long or spend that much for a complete panel as I really only need a few inches of it replaced. So I decided to just cut out as much of the flat areas out as necessary and retain the raised portions of it, which would be difficult to reproduce. I started with piece of 2mm plate that I had left over after making the piece for the tunnel rails. I used the jig that I made for the tunnel rails to hammer the straight crease on the sides where it is flat and bent the domed area basically by hand. I managed to get it to match closely to the tunnel bottom plate. It took quite a while and was very difficult to match the shape. Once I was satisfied with the shape, I cut the needed flat areas out of the tunnel plate and then cut the new repair piece to match it. It's a bit off in the pictures below, but I did adjust the fit to be more uniform throughout the joint. I welded it on both sides, ground down and dressed the welds on the outside of it. I will trim the excess width off of it later when fitting and welding the tunnel bottom plate back on the tunnel.


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Welding The Tunnel Bottom Plates Together

by on Jun.04, 2021, under Chassis

I decided to weld the straight section of the tunnel bottom plate to the additional bottom plate section that I removed and make them one piece. The reason is that I can get an overall better welded joint as I can weld on both sides. I did that and also added a connecting plate on the wide end. This helps to hold this end in place and also gives me an additional layer to weld to and strengthen that joint. I sprayed the connecting plate and the area under it on the bottom plate with U-POL Weld #2 Copper Weld Through Primer.


Next, I ground down the welds on the outside and then sprayed the inside areas that will not be welded on with Eastwood Matte Black Rust Encapsulator to seal and protect them.


After the rust encapsulator cured, I place the bottom plate back on the tunnel and then checked the fit of the frame head bottom plate with it. At least in this area, the frame head bottom plate fits well. In other areas, not so much. That's a problem for later.


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Making And Installing Seatbelt Mounts on Tunnel

by on Jul.12, 2021, under Chassis

Being a 1960 model, this car did not come with seatbelts and didn't even have seatbelt mounts installed at the factory. I want to install seatbelts in this car, so I am going to add mounts in the factory locations. Since I am working on the chassis now, I need to add mounts on the tunnel. I don't have any information on exactly where these need to be installed, but I found a couple of pictures in the Internet of mid-1960 models with the factory mount locations. With these pictures, I needed to determine these locations by using some reference of a known quantity. I was able to determine that the measurement from the center of the stick shift hole in the tunnel to the center of the emergency brake pivot pin is about 475mm. So on the picture I had, I drew a line from the stick shift center hole to the emergency pivot pin center which according to the image editing software was 517 pixels. I drew another line on the picture from the emergency brake pivot pin center to the center of the bolt on the seatbelt location, which was 232 pixels. So with these measurements I was able to come up with an equation of 517/475 = 232/x. Solving for x gave me 213.15mm. So I rounded up to 214mm. This should get me in the ballpark of the correct location of the two mounts on the tunnel if I use the emergency brake pivot pin center and measure 214mm towards the back of the tunnel.


To make the mounts, I took two 2" x 3" pieces of 3/16" steel, drilled 1/2" holes in the centers, curved them slightly so that they would fit the contour on the inside of the tunnel, and welded two 7/16-20 nuts on them. I then sandblasted them and gave them a coat of copper enriched weld-through primer just to protect the bare metal. Next, I measured 214mm from the emergency brake pivot pin center towards the back of the tunnel and for the location vertically, I just eyed it and guessed. Not a very scientific method, but I think I will be close enough. At those locations, I drilled 1/2" holes in the tunnel for the seatbelt bolts and four holes for spot welds and welded the mounts to it. The driver side was a challenge as the mount location just happened to be right where one of the accelerator tube mounting brackets was welded to the tunnel. So I drilled out the spot weld on that bracket, welded up in the hole I just drilled in the tunnel, and bent the tube out enough to clear the mount. I then welded the bracket to the mount. I'm almost done with the work inside the tunnel. I just need to weld the new frame head front plate to the end of the tunnel and then I can start fitting the frame head bottom plate to the frame head, tunnel bottom plate, and the Napoleon hat.


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