Van Diemen Floor Pan

[Ray Rivard]

Does anyone have a source for Van Diemen (RF99) floor pans? Mine is "experienced" and I'm trying to find an aluminum (or aluminium) replacement part.

[reidhazelton]

Does anyone have a source for Van Diemen (RF99) floor pans? Mine is "experienced" and I'm trying to find an aluminum (or aluminium) replacement part.

Those are typically made as one-offs. I don't know of a commercially made one. Take the experienced one off, flatten it as much as you can, and use it as a template by laying it over a fresh sheet of aluminum. Copy the shape and the rivet holes.

[Rick Kirchner]

what year? I believe I have a drawing for 90-96

[cjsmith]

Contact Brad at Primus racing. I got one from him last year. It had all of the rivert holes in the pan and they were countersunk. He also carrys the rivets if you don't want to search for them. Remenber to use the correct glue to bond it the frame. Lots of good advice in threads on Apex on the process.

[BeerBudgetRacing]

I bought one 4x8 sheet of .090 from a supplier for 2 for different cars.
Cut an outline with a circular saw and trimmed with a router.

There is a long thread about 'doing better floors' which include tips such as using the old one as a template to drill the holes, adding steel strips inside for more rivet and gluing area, and using angle pieces along the sides to more easily repair crash damage and to prevent the floor from being torn off.

I think Lathrop had a bunch of posts on it.

Digest this:
https://www.apexspeed.com/features/bellypan/

and this
https://www.apexspeed.com/forums/sho...light=bellypan

and this
https://www.apexspeed.com/forums/sho...light=bellypan

and search "bellypan" for more threads because most reference the first link above.

[tlracer]

The various threads on here have a massive amount of information about making & replacing a floorpan. It doesn't have to be as dauting as it might sound at first, just take your time and as the old saying goes - measure twice, cut once.

If you're copying the rivet holes over from the old one, a couple of tips from experience:

1) Check the size of the old rivets carefully - I've had chassis where previous owners have gone up one size in places. It's important to identify these and drill accordingly. Make sure to use the correct size drill for fitting whichever size rivet(s) your using.

2) Buy a bunch of Cleco clips in the rivet sizes you are going to be using. Drill the first new hole then Cleco it and progress like that, adding Clecos as you work to keep the two part aligned. It will help enormously to keep the old pan flat on the new metal and avoid finding holes aren't where they need to be because something's moved slightly!

[Spengo]

Has anyone tried using sendcutsend or a similar service to make one? That's always my first thought when I want a flat piece of aluminum in a specific shape with some holes in it.

[Rick Kirchner]

I would NOT use a pan with holes placed from a drawing. The assembly processes of these cars is not that precise, things will be off - at least for the pre-98 chassis - maybe VD came up with better manufacturing processes for the later ones. On my car they appeared to be laid out manually.

If your holes are for an oversized rivet, it was probably replaced by someone with aviation expertise, because that's the way its done in that industry, with rivets that are more precise. The racing industry uses AVEX rivets that are extremely tolerant of hole size variation and misalignment, much more so than aviation rivets.

Once oversize rivets have been used, try to avoid going up another size, as eventually it becomes difficult to get the countersink in thinner panels without breaking out.

I wish I'd known about not needing to go to bigger sizes when I re-tubbed my FSV 25 years ago - but I was taught by aviation guys.

A key part of not making this worse is to properly drill out the old rivet. Make an appropriate punch to tap the stem down a bit, then use a bit that's undersized a few thou to drill the head off. Then use another punch to drive the remains of the rivet out of the bottom piece of structure. Try not to drill that far down if possible. Judicious use of a propane torch on the hole can breakdown any epoxy that's making removal difficult.

When match drilling the new pan by using the old one as a template it helps to have some alignment holes that are not the rivet holes themselves. I always put drain holes in the front corners of each floor compartment, so after some aligning and clamping, I drill those first and then put screws through them to securely align the parts. You can then remove clamps, etc and have less stuff in your way and the parts will not move in relation to one another.

I use a large tophat drill bushing to help hold a transfer punch as tight and as perpendicular as possible. After removing the old floor/template, I then use another bushing to do the same with the drill, and I usually drill a few thousandths undersize with a cobalt bit and an air drill, not an electric drill. Then I place the new pan on with an abundance of clecos and drill to final size swapping the clecos around as I go.

If you want to be really anal about it, there will be a "bump" wherever the tubes have been brazed together. If you are using a thick enough pan (say, at least 1/8) then you could mill the areas under those joints so the pan actually lays flat across the entire surface.

As far as getting the pan made, I would look for a sheet metal job shop that is NOT a HVAC shop. HVAC is not particularly precise. Ask for a recommendation from where you buy the metal - they will know. In my case I found a couple of guys that made stuff for the dairy industry (light fixtures, troughs, etc) and took them the aluminum and a drawing. I was surprised (and somewhat horrified) to watch them lay it out with a tape measure and mark it with a soapstone in front of me, and then bang it out on a stomp shear in less than 5 minutes - and it was accurate within 1/16", so there's something to be said about old craftsmen that know their equipment. You could also lay it out yourself with long straight edges, blueing, and a scribe.

[Lotus7]

A multi-piece floor, with accurate butt joints at a couple of lateral floor tubes makes future repair MUCH less tedious and expensive.

(yes, it's marginally less stiff...)

[Ray Rivard]

I would NOT use a pan with holes placed from a drawing. The assembly processes of these cars is not that precise, things will be off - at least for the pre-98 chassis - maybe VD came up with better manufacturing processes for the later ones. On my car they appeared to be laid out manually.

If your holes are for an oversized rivet, it was probably replaced by someone with aviation expertise, because that's the way its done in that industry, with rivets that are more precise. The racing industry uses AVEX rivets that are extremely tolerant of hole size variation and misalignment, much more so than aviation rivets.

Once oversize rivets have been used, try to avoid going up another size, as eventually it becomes difficult to get the countersink in thinner panels without breaking out.

I wish I'd known about not needing to go to bigger sizes when I re-tubbed my FSV 25 years ago - but I was taught by aviation guys.

A key part of not making this worse is to properly drill out the old rivet. Make an appropriate punch to tap the stem down a bit, then use a bit that's undersized a few thou to drill the head off. Then use another punch to drive the remains of the rivet out of the bottom piece of structure. Try not to drill that far down if possible. Judicious use of a propane torch on the hole can breakdown any epoxy that's making removal difficult.

When match drilling the new pan by using the old one as a template it helps to have some alignment holes that are not the rivet holes themselves. I always put drain holes in the front corners of each floor compartment, so after some aligning and clamping, I drill those first and then put screws through them to securely align the parts. You can then remove clamps, etc and have less stuff in your way and the parts will not move in relation to one another.

I use a large tophat drill bushing to help hold a transfer punch as tight and as perpendicular as possible. After removing the old floor/template, I then use another bushing to do the same with the drill, and I usually drill a few thousandths undersize with a cobalt bit and an air drill, not an electric drill. Then I place the new pan on with an abundance of clecos and drill to final size swapping the clecos around as I go.

If you want to be really anal about it, there will be a "bump" wherever the tubes have been brazed together. If you are using a thick enough pan (say, at least 1/8) then you could mill the areas under those joints so the pan actually lays flat across the entire surface.

As far as getting the pan made, I would look for a sheet metal job shop that is NOT a HVAC shop. HVAC is not particularly precise. Ask for a recommendation from where you buy the metal - they will know. In my case I found a couple of guys that made stuff for the dairy industry (light fixtures, troughs, etc) and took them the aluminum and a drawing. I was surprised (and somewhat horrified) to watch them lay it out with a tape measure and mark it with a soapstone in front of me, and then bang it out on a stomp shear in less than 5 minutes - and it was accurate within 1/16", so there's something to be said about old craftsmen that know their equipment. You could also lay it out yourself with long straight edges, blueing, and a scribe.

Thanks for such an informative response! ....and thanks everyone for helping out. This is a wealth of knowledge that I'll really be able to use. I really appreciate all the help. Also, for those who DMd or texted me, I appreciate all that feedback too. This really is a great community!