Introduction: Chassis Restoration on a Volkswagen Beetle Volksrod

About: Evil Genius. Diabolical Scary Man. Dark Lord. Lover of Bagpipes and Accordions. Leaver of Lego Brocks on the Carpet in the Dead of Night. Ok, ok. I am really an engineer, I work on ships for a living, usually…

My hotrod has been a labour of love for about seven years now.

I noticed that it required a couple of patches of welding on the front end of the chassis, so set about putting this right.

This resulted in months of hard work, quite a lot of money spent, and a whole plethora of lessons learned and skills acquired. Because, once you start pulling at a thread, things start to unravel!

My hotrod, it seems, was not quite as solid as I had perhaps believed. Please, join me on my journey of personal discovery as you see why my wallet is empty, my hands blistered and sore, and my hair more or less burnt off completely!

Credit to LVH Engines and Restos, without whom many of my Instructables would not be possible!


For this sort of work you will need:

A mop and bucket. This is to mop up your tears of woe as you realise that you are most definitely "gonna need a bigger boat..."

A good quality welder. A gas MIG is my weapon of choice - buy the best you can afford. I can personally recommend the Clarke 151TE and the Sealey Supermig, but digital welders are becoming the thing now. You will struggle using an arc welder for bodywork, you need something far more controlled. For this restoration I used my Sealey.

Welding wire - 0.6mm is plenty for this work, or at a push 0.8mm if you go steady and are careful. Anything over 0.6 is a little too heavy for the intricate work such as bodywork but for a chassis 0.8 is fine.

Buy a brand new fresh spool of welding wire and tips, and a new gas shield. Don't use whatever you had kicking around as you'll be forever fighting with poor welds.

Welding mask - an auto darkening helmet with a grind setting is best here. You really need a good mask, otherwise you will make life hard for yourself.

Bright LED magnetic torch - positioning a good quality light helps a great deal.

Gas - Use Aargon or Aargon/CO2 mix for the best quality welds. I use Aargonshield. Don't bother with CO2, it is cheap but the price difference doesn't make sense in the long run. You want the best welds possible here, it's your chassis!! Please don't skimp, I care about your safety (or rather I care about you blaming me when you hurt yourself after reading something I wrote), but I care even more for the safety of the people you are driving around.

Angle grinder with a large selection of cutting discs, grinding discs and flap wheels.

Some sheet steel - Match the grade you are repairing if you can. I like to work in 2mm for automotive chassis work. It's a nice balance between being easily worked, but forgiving to hot welds.

Body panels - I cannot stress enough how important buying the best quality panels you can here if you aren't making your own from scratch (I made some, and bought others). You can pick cheap floor plans up for a Beetle for less than £100 a side, and prices can get as high as £300 or more. The difference in grade of steel, quality of pressings and accuracy of fit is marked. You do get what you pay for, and while £100 a floor pan can seem like a bargain the hassle involved getting them fitted and the resulting not-quite-right look will leave you feeling like you wasted your time. The one advantage of buying cheap, thin, crappy panels is that you get to re-do it all in a couple of years when it rots out!

Panel beating hammers and dollies

Fire extinguisher - a big topic but use a foam one if you can or water. Using a powder extinguisher in doors will make for interesting toilet visits for a week, and CO2 indoors is dangerous and doesn't work well on hot metal. You need something that will cool as well as smother the fire.

Welding magnets

Assorted drill bits

I also had a pneumatic metal punch which really helped, but drills or a hand punch will do.

You'll need a bunch of other stuff too... But you'll figure that out as you go along!

Step 1: Evaluate and Be Ruthless

When you look at what you have, look hard. A small patch of rot is rarely a small patch of rot.

This chassis looked like it only needed a couple of small patches. But once I started digging I quickly realised it was an absolute mess and a huge job. Years of bodge repairs, paint, and poor repairs and the odd bit of cardboard were cleverly disguised as a reasonably solid looking chassis.

Take a small hammer, screwdriver and Stanley blade, and set about it. Good steel will not be damaged with these tools - if bits start falling off, it needs cutting out. I would strongly recommend media blasting (soda blasting is gentle enough) if you are going full resto. I didn't do this, I went at it with cutting tools until I ran out of rot to cut out. Lots of fun, very noisy!! But please, wear the right PPE, be safe folks!

So the damage... The first picture shows how I got access. This was not a smart way of working on a car, but it was to allow me a clear, quick look to be sure it was even safe to jack up.

The second picture is where the frame head was starting to rot away. This is where the front suspension bolts to the chassis. On mine, this is where a 12" chassis extension bolts on (in grey / zinc coating). The rot was starting to spread! Not good.

Pictures three and four show a stanley knife jammed into the frame head bottom plate, again this is the front of the chassis. This is supposed to be super strong.

So, I cut the framehead bottom plate off with a plasma cutter (an angle grinder would have done nicely too), and this is where I really found issues. The centre tunnel sported a crack at the front end, the "napoleon's hat" (that is the hump you see where the floors end in picture four) was totally rotten, and the floors were looking pretty grim too.

This is where things got really serious, as I decided it best to remove the body from the floor pan to allow better access to repair. In a Bug, this is supposed to be bolted together. On mine, it was bolted, welded, glued, bonded, and bodged. But mostly, it was held together by hopes, dreams and the grace of God and magic. Out with the air chisel (again, a grinder would have done just fine here), and I cut the body from the floors to give what you see in pictures four and five.

Getting to this point meant stripping the interior and wiring harness out. I also removed the front suspension, steering etc. This let me have a really good look - and the chassis needed a major restoration. The body was ok, apart from the lower 3" or so which also needed extensive repair. The body is not covered in this Instructable as the repairs were far more technical, difficult and in-depth. If I get enough requests, I'll upload one about the body repairs too.

So, time to formulate a battle plan!

Step 2: Chop, Chop, and Chop Some More...

The first five pictures here speak far louder than any words I can type. The deeper I dug, the worse things got. I'd cut the floors out completely and put them in the scrap bin, and then started to wonder if this was really worth it.

At this point, I decided to buy a whole new chassis. I drove several hundred miles to collect it, but once I got that home, I found that while all looked well, the floors were aftermarket cheap replacements - there's a HUGE disparity between top quality and budget panels. Budget floors are just not happening for me, they are about 0.7mm thick and poorly pressed and given they are the only thing between my arse and the road, I'd be grateful for good steel! Conversely, you can pick up top quality ones that are 1.2mm thick - slightly thicker than fitted at the factory.

What's more, I decided to get the jetwash on the new chassis to see what was lurking under the paint. What I found was more holes than a tea bag, and the chassis number had been ground off. This meant that I couldn't use it in good conscience (in the UK, it would have been highly suspect just re-stamping the chassis with the number that came on the paperwork I was given with the chassis, and could have resulted in all sorts of legal issues). So, I opted to press on with repairing instead.

I decided the best thing to do was to chop off my destroyed framehead, and take the one from the new chassis as it was not quite as rotten and could be repaired, and weld that in. I cut the tunnel just behind the crack I found, and put the old frame head in the "naughty corner" where I left it to sit and think about how badly it had behaved... and because the scrap bin was too full of Beetle floor...

I then took what was left and, using a blow torch and paint scraper, scraped off all the underseal and loose stuff left on what was left of my chassis. Then I jet washed it, applied de-greaser, and jet washed it again to get it as clean as I could.

Step 3: Just Keep Stichin'

Now that I had cut out all the rot and was left with a short length of useful steel, I set about putting it all back together again.

Refitting a new frame head can feel daunting, any misalignment or bad measurement would have the chassis geometry all wrong.

However, a couple of things to keep in mind:

1) The car is old, and was made in 1972, at a time when the avocado had only just been invented and actual people with actual tools put things together in factories. They probably all had moustaches and long hair, smoked cigars and wore flares. So things won't have been absolutely perfect when it was made, especially if was made on a Friday afternoon and it was Big Nigel's turn to buy the beers at the pub.

2) Because the car is old, and has seen many things, bits of the chassis will not be quite where the mustachio'd avocado munching factory workers put them all those years ago.

So, to get it in the right place, measure, measure, measure some more, but mostly.... Measure. I actually used a technique normally reserved for my work offshore, taking lots of measurements one way, calculating from there what measurements taken another way would be, then measuring it, subtract one from the other (Calculated minus Observed, C-O) and finding where that residual measurement is coming from and eliminating it.

  1. I used a digital spirit level (a regular one will do if you use it right) to take the level of the back of the chassis - I put it across the frame horns where the gearbox bolts on at the rear.
  2. I then cut the donor framehead off, making sure it was cut in such a way as to be a few inches LONGER than the old one (that is, taking more of the centre tunnel with it than what I cut off the old chassis).
  3. Using a grinder, I made several cuts down the bit of tunnel left attached to the frame head to allow it to splay out.
  4. Watching the pressings and shapes that were made to clearance for the foot pedals and clutch cable as a guide, I put the new frame head over the existing tunnel and using a large hammer, bashed it roughly into place.
  5. I then took a level of the framehead by winding in two bolts into the suspension mounts and placing the spirit level across them. Making sure the front and rear mounts were level relative to one another would ensure the geometry of the wheels wound be correct when it was back on the road.
  6. Carefully adjusting and regularly checking front and rear, I tack welded the frame head in place, and marked a little more of the original tunnel I could cut away for a better fit, broke the tacks and trimmed things to fit more snugly. The body has a little adjustment when it gets bolted onto the chassis, so there's a little room for small errors here, but make sure the chassis is the correct length with the framehead in the final position (picture one shows the correct dimensions)
  7. Repeating step six until I had things nice and level, I then tacked for a final time, measured several points from the front to the rear to make sure nothing was twisted and made some very final slight adjustments with my hammer. Once all measurements side to side were within 2mm of one another, I began laying heavy welds.

To weld the centre tunnel, you want your welder really cranked up to deliver a lot of current, with a high wire speed. You are going to move quickly, so that you don't build up too much heat in one spot. But, mostly, you are going to weld no more than an inch or so on any one seam before stopping and welding the same spot on the opposite side, and then letting it cool a little. Even metal of this thickness will warp, and you REALLY don't want that with something this critical. Make little figure-8 shapes with your arc as you weld, and make sure you have a good pool of weld going and that you melt BOTH sides of the joint as you move.

Make sure that you clean BOTH SIDES of any area to be welded VERY well with a flap wheel or a grinding disc. You want to work with shiny metal with not a hint of rust or paint.

Take your time, go steady, and remember that mistakes can be rectified.

After all this work and care, even mine had warped. I had to slit one side of the tunnel and lay in a very thick, hot weld to get it to pull back straight. I then flipped over the chassis, and checked the welds on the inside of the tunnel. Most had penetrated all the way though (picture 6), but those that needed a little extra I hit again along with the edges that were inside the tunnel that I could not get to from the outside.

Step 4: The More Fiddly Welds...

As you could tell from the last step, there was still some metal missing from the donor frame head. I had cut out the rot before moving it over, and this needed to be repaired too.

I used galvanised steel angle of the same thickness as the centre tunnel - this is NOT the most ideal material to use, but it was the only correct gauge angle I could get at the time. This statement is really important:


If you must use this material, remove the galvanised coating from the area you are going to weld thoroughly with a flap wheel. If you weld galvanised coating, you will end up getting attacked by what I can only describe as toxic snow. The fumes are dangerous, and the mess it makes is awful. Please, use mild steel if you at all can.

Now, I used card templates to cut pieces to fit in the gaps. I used one long piece of angle clamped along the centre tunnel to give me a straight edge to work to, and carefully cut out pieces to fit snugly into the gaps. It is tempting to overlap with repairs like this, but it's a little lazy and just creates water traps. It is far better to make a good butt weld here - overlapping is something I did for the frame head for strength. Here, it is not needed.

Taking your time, stitching a little at a time and allowing the metal to cool will ensure a nice, strong, straight end result. Make sure you test your welder on scrap of the same thickness to get the penetration and quality you need. Don't just dive in mob-handed without honing in your welder's settings.

Some people would grind the welds flush. This isn't a problem, but I wanted to leave it to preserve the journey the car has been on and have it "honest". It also lends a little more strength to the weld to not grind flat unless it needs it.

Step 5: Napoleon's Hat!

It was time to weld on the new "Napoleon's Hat" - this one really, REALLY has to be in the right place. It has to be level, and it has to be the correct distance from the rear outriggers, otherwise the body won't fit.

Happily the Napoleon's Hat would only fit properly on one spot. I got the tape measure out and measured. Then I measured again, and then got my friend to measure. Yep, it was 15mm too far back. Seems my heavy welding and splaying of the tunnel had altered the shape of the centre tunnel slightly. So I put the Napoleon's Hat where it should have been, and with the weighted plastic hammer, I gently tapped it. Then I less-than-gently tapped it.

Fast forward...

Sitting exhausted, sweating, my arms so spent they barely had the strength to bring my coffee to my parched trembling lips, the Napoleon's Hat was finally beaten and wedged in the right place. Wedged so firmly, I might add, that it felt as though it didn't need welding at all!
However, once I had recovered my strength, I set about hitting this with a heavy weld. I opted not to seam weld the whole thing for two reasons:

1) It had not left the factory seam welded, rather just with a few stitches.

2) Seam welding here creates a moisture trap, as the Nap's Hat is hollow and water does get in there (just look at the state of mine from the early steps!). I wanted it to breathe.

Hitting it with some very hot welds created a nice, clean, strong bond.

Step 6: While I'm in There...

I realised that now would be the perfect opportunity to do something I had wanted all along... Make it possible to install a bench seat!

I've never, ever seen a Bug with a bench seat before, because the hand brake is between the front seats. Since I had the bottom plate off the centre tunnel at the moment, and I had a whole spare chassis to chop up, I decided to move the hand brake to in front of the gearshift.

I cut off the old hand brake brackets, and selected a point suitably far forward of the gearshift to accommodate a new hand brake bracket. The consideration here is the bowden tubes for the hand brake cables - they need to be extended and made to come around the gear shift rod and clear it well enough to allow the gear shift rod to not be hindered, while at the same time not being so tightly curved as to prevent smooth operation of the hand brake.

I cut a hole in the chassis, and welded the new hand brake bracket in place, and then extended the bowden tubes with steel hydraulic pipe I had kicking around. Nice and simple to do at this point, and it would pay huge dividends later!

Step 7: Button Up the Centre Tunnel...

Now that I was done moving hand brakes around, the time had come to put the centre tunnel to bed.

I cut the rear half of the bottom plate from the donor chassis as this was in OK condition, and cut it to fit what I had cut out of the front of my chassis (the bottom plate is the same width the whole length of the car, so it's not a problem to use the back half on the front here).

Using welding clamps to hold it down, I welded this to the centre tunnel. I used plug welds down the sides (that is, welding a small pool of weld on the top surface to penetrate and weld to the metal behind), and seam welded the joint between rear and front bottom plates.

I bought a framehead bottom plate. Sadly, the only one I could get hold of turned out to be, well... Not great. The thickness of the steel was fine, but the quality of the pressing was very poor. It was obvious that the press did not have the correct tonnage for the gauge of steel, and so it had sprung and warped out of the die it was stamped in. You can see in pics two and three the horrendous gap it left at the front when aligned at the back. This had me shaken for a moment, I became convinced that I had warped my chassis with the welds I had already laid, so set about measuring everything a whole bunch of times before I thought to measure the repair panel. Yep, it was the repair panel at fault. Phew! That was something I could rectify.

To make it fit, I first welded it to the Nap's Hat section to stop it wandering off anywhere. Then, using a butane torch and very short, VERY hot welds and a large hammer, I persuaded the plate that it was in the wrong and that it wanted to fit perfectly after all. It took lots of heat, lots of colourful language, and lots of beating, but it got there in the end and decided the behave its self.

Step 8: Time for New Floors

I bought myself a pair of the very best quality floors I could find. These were not cheap by any stretch of the imagination, but I did get a small discount for buying both sides. These were not the correct year floors for my car, mine required different seat runners. But since I was not installing Bug seats I cared not a jot!

I offered the floors up, and they were very close to fitting. The manufacturer deliberately leaves a little extra on the inner edges to allow for trimming and adjustment, and I had to nibble a little off here and there to get them to sit right.

Patient trimming and checking had the floors sitting nicely, and this is where the air punch paid dividends. Some folk like to stitch weld these, others like to plug weld. I've never met anyone with a spot welder long enough to spot weld these in, but I managed the next best thing. Using the air punch, I made a series of holes, about 1.5" apart, on the inner edges of the floors. I applied some weld-through primer to all the edges, and this allowed me to almost spot weld the floors in place, and make sure that all the welds were spot on. I would NOT recommend seam welding, as the amount of heat would warp the floors and the amount of gas and wire you would use would be frightening!

I then seam welded the fronts of the floors to the Napoleon's Hat, and then added some galvanising spray to all the welds and edges (picture 5).

Step 9: While I'm in There... AGAIN...

While I was doing so much work on the chassis, I decided that the gearbox needed to be adjusted.

Beetles of the earlier era were fitted with "swing axle" suspension. Though not a true swing axle, it was designed such that the axles would move up and down on the gearbox, but the wheels had no articulation on the end of the axle. The result was that the wheel was always perpendicular to the axle. This means in turn that the camber of the back wheels change as the suspension moves up and down.

Because my car sported lowered suspension, I always had negative camber - the bottom of the wheel stuck out more than the top, making the wheels look "wonky" on the back.

I wanted to raise the level of the gearbox by 2.5" to bring my wheels level again. This would also raise the height of the engine, making it look meaner. This is also the most you can move the gearbox upwards without having to take the gearshift rod out of the centre tunnel and mount it on top, which is an ugly modification.

To achieve this, four things need to be done.

Firstly, the front gearbox mount for the gearbox nose cone needs to be cut off and welded into a new position.

Secondly, the rear gearbox cradle needs to be thrown away and a new one made, with the gearbox mounts 2.5" higher up.

Third, the gearbox needs to be pushed forwards slightly to correct the resultant change in toe-in of the back wheels (that is the angle the back tyres point inwards at the front edge of the wheel).

Finally, you need to swap the nosecone of your Bug gearbox for one from a Split Screen T1 van gearbox. They are interchangeable, but the shift rod in the Splitty nosecone exits lower down than the Bug one, which keeps the shifter in the tunnel once the gearbox has been raised.

This is far easier to achieve than you would think. Happily, a standard metric house brick in the UK is just the right thickness. I'm sure a block of wood could be made to suit the purpose too.

Putting a brick between the gearbox and the gearbox cradle moves the bellhouse to the correct position (my first three pics here).

Then, it is simply a case of bolting the front gearbox mount you cut off to the front of the gearbox, offering the gearbox nose up to the hole in the chassis, and pushing it in so that the gearbox mount mates up with the chassis. Mark where it sits, move the gearbox away, and clean the area around the marks.

Then, shave a little off the place the gearbox mount welds to the chassis to make the gearbox sit a few mm close to the front of the car than it did. Not too much, you can adjust the toe-out by adjusting your spring plates later too - you are doing this to compensate for the altered geometry of your suspension with the new gearbox locations.

Offer the gearbox back up and tack the mount in place. Remove the gearbox again, and hit it with a really heavy hot weld. You DO NOT want this breaking off!!

Next up is to make a new cradle. Mine is a little agricultural, I made this with 5mm plate steel and a plasma cutter. It's simply a copy of the original cradle, but with the mounts 2.5" higher up. Mine was done by eye, bolting everything to the gearbox, tacking in place, removing from the gearbox and seam welding. It was only supposed to be a temporary one, I planned to have some steel laser cut later to make a nicer one, but since you can't see it I keep forgetting!

Two points to note here:

1) Mild steel is the correct material for the cradle. Do not use stainless, it is brittle and may crack with the torsional loads the engine puts on it.

2) The gearbox is magnesium alloy. It's hard to ignite, but even harder to extinguish. Be super careful with your welder around it! If it catches fire, raise the alarm, get everyone to safety, walk away and call the fire brigade. You aren't going to tackle it yourself. Chances are, neither are the fire brigade. Just enjoy the show, it's all you can do at this point.

Step 10: Time for Paint!

It was finally time to paint the chassis!

Firstly, apply a liberal dose of seam sealer to every single weld and join. Don't be shy with it, you want to make sure that it really is right in there. I used the stuff that comes in mastic tubes with an applicator gun. Far better than the brush-on variety! You want to apply this like you would bathroom silicone. Wear gloves, apply plenty in a solid bead, and then go over with your finger to push it into the gaps. Only make one pass, don't fiddle around trying to make it look pretty. Believe me, you won't notice once you have painted it!

I used a spit to be able to spin the chassis, this was a godsend as it meant I could work really quickly without having the manhandle the chassis all the time. It was simply two stands with a scaffolding tube that went through the middle of the beetle centre tunnel.

Once that had gone off, I gave the chassis a rub with scotch bright to key the factory transit paint on the new metalwork.

The paint I used is called Raptor - it is a 2K epoxy paint, designed for truck bed linings. However, this stuff is perfect for a chassis as it is extremely tough, sticks to anything and everything, and best of all looks great once laid.
It was painted with a stone chip gun (sometimes called a shutz gun) which came with the kit. I used black, but you can get tintable stuff which you add any 2K paint to so that you can match it to your paint job, if you like.

The surface finish is a nice textured finish that hides a multitude of sins, but looks like it was done in the factory by those guys with the long hair and avocados, though by now those men have probably developed into quite serious balding chaps, the kind who read magazines about maths...

Step 11: Floorpan Complete!

Now was the time to reassemble the floorpan to check suspension geometry, and to make sure the gearbox sat correctly.

Happily, all was well, and all fitted perfectly! Everything measured up properly, the gearbox went in properly without issue, and all four wheels were in the right place. Best of all, nothing was on fire and nobody died!

I hope you enjoyed the read, and that this inspires you to tackle a restoration of your own!


Oh, I mentioned the bench seat and handbrake... I'll write an Instructable about this one day, maybe.

But, the dividends the extra effort paid, here they are... The bench seat I made along with the new hand brake and gear shift.

Enjoy ;-)

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