Access panel in floor pan under engine - ideas?

I've decided that I want to add an access panel so I can remove my engine's sump pan without removing the engine.

My desired goals are: easy to remove, will stay secure when in place and not have any fastener heads under the car.

Thus far, my ideas aren't thrilling me.

Has anyone done something similar, or have any suggestions? I'd like for it to be fairly flush (at least the leading edge), but don't feel it needs to be perfect. I have some sturdy rub blocks in the area (which could figure into the access panel's attachment method ...).

TIA.

Why don't you want fastener heads under the car? What about countersunk heads under the car that mount through the access plate to nutplates secured to the pan?

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Originally Posted by RobLav

Why don't you want fastener heads under the car? What about countersunk heads under the car that mount through the access plate to nutplates secured to the pan?

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Maybe I should rethink that. I'm concerned that the fastener heads will get scratched up, plugged with dirt, etc. and may cause problems down the road.

Here's a picture of my dry sump pan sitting on the floor pan, to give you an idea of the area.

Make a pan like our Citations. Mine started out as a 1" thick chunk of aluminum... it's structural - 4 bolts and the sump screws - and it's out.

Don't know Russ... that's a pretty good sized sump there. Is it worth doing it at all? Can't you clean the sump once per year in the offseason when you do all the other maintenance and upgrades?

Using a doubler set with rivnuts.. 3 panels total.. in the end the bottom is perfectly flush. I can get a 4" access panel out for oil changes in minutes.. its perfect.

So what you all are saying is; The belly pan under the engine compartment of an FB isn't adding any structural rigidity to the frame?

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Originally Posted by rickb99

So what you all are saying is; The belly pan under the engine compartment of an FB isn't adding any structural rigidity to the frame?

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It definately is, and this is what I was thinking about while considering Russ's question. I'm not sure the compromise is worth the benefit of accessing the sump pan. Better would be a small hole to drain oil.... (cover it w/ racer's tape)

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Originally Posted by carnut169

It definately is, and this is what I was thinking about while considering Russ's question. I'm not sure the compromise is worth the benefit of accessing the sump pan. Better would be a small hole to drain oil.... (cover it w/ racer's tape)

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If the floor pan is fabbed correctly using a doubler riveted around the opening with nut plates & counter sunk screws installed to hold the panel it will be just as rigid as it is without the opening. Aircraft wings are full of removable inspection access panels.

If I was going to do this I'd rivet a doubler panel 2" wide all around the opening and use floating nut plates riveted to it, and flat head 8-32's into the nut plates to hold the panel on. In a semi-monocoque panel like that, you can often remove a lot of the middle without totally compromising the stiffness that the panel gives to what it's attached to.

But I kind of question why as well. It's nice to think that taking the pan off and looking at the engine guts is a good, handy thing to want to do, but there's rarely anything useful you can do to them without taking the engine out. Usually you would be taking the pan off to confirm that the bearings have left the building and your weekend is pooched, or like that...:thumbsdown:

Thanks for the suggestions and thoughts.

There are several reasons why an access panel will be helpful. Once the engine is in, it's impossible to get a wrench on the two hose ends that attach to the dry sump pan. There are times when I'd like to have access to them without removing the engine.

Recently I had a generator failure that might have sent metal pieces into the pan. It would have been great to drop the pan to see. Also, it would have given me access to my internal scavenge pump to see if it it was affected. Not to mention easier oil draining, inspections, etc.

I took the engine out yesterday. Big job. I didn't find any metal parts. The next time I build a race car (i.e., NEVER! :-), I'll put more thought into making engine R&R easier.

Whew, the pressure is off my peanut brain. Doubler with panel makes sense. Actually if I had been capable of thoroughly digesting Nicholas' post, I would have realized a 'doubler set' was a reinforced panel edge :)

There are lots of things on the bottom of our FC engine I'd like to get too. When we redo our belly pan next winter, we too shall ponder an access panel.

Getting the fastener heads flat aren't a real concern to me. As someone pointed out recently, with the rub strips and skid plates under there a baby butt smooth bottom isn't achievable any way. But the fastener heads getting packed solid with greasy dirt and pebbles is. Fought that battle this winter even with stuff INSIDE the chassis :)

tape over the fastener heads goes a long way to keeping munge out of the allen or phillips holes. I've pretty much given up on flat head and button head allens though. A good phillips works better in most sizes and if torx were readily available I'd use those instead.

We started adding an access panel to the engine compartment floor pan on 88 Reynards, in the late 80's. We formed a rasied lip in the existing floor below the engine, so that the new floor pan insert, would lay flat with the old panel, The 10/32" button head fasteners, screw into floating nut plates in the main pan. We never had much issue with grinding the heads of these fasteners off, unless someone spent too much time riding the crubs. Even if we counter-sunk the fasteners, if that area was damaged by off track driving, the fasteners would still be an issue (as seen by what happens to counter-sunk rivets in that location).
This system has held up on the old Reynards for years. If your engine compartment is 1/2 as ridged, it should work for you too!
Keith
Averill Racing Stuff, Inc.

Thanks, Keith (and everyone).

I decided to do it, started yesterday. I'm about 70% done. Will post pictures later.

I'm follwing Brian's advice in his first paragraph, and ignoring his second paragraph. :-)

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Originally Posted by Brian

If I was going to do this I'd rivet a doubler panel 2" wide all around the opening and use floating nut plates riveted to it, and flat head 8-32's into the nut plates to hold the panel on. In a semi-monocoque panel like that, you can often remove a lot of the middle without totally compromising the stiffness that the panel gives to what it's attached to.

But I kind of question why as well. It's nice to think that taking the pan off and looking at the engine guts is a good, handy thing to want to do, but there's rarely anything useful you can do to them without taking the engine out. Usually you would be taking the pan off to confirm that the bearings have left the building and your weekend is pooched, or like that...:thumbsdown:

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Done, and very happy. Access to the hose fittings were impossible, now a breeze. I'm sure it will come in handy for years.

Clean and totally functional.. same deal I did.. makes working on those impossible AN fittings so easy now..

Even though those rivplates have squashed nutz... use some light blue loctite.. I didnt beleive they could vibrate loose untill they did...

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Originally Posted by Nicholas Belling

Even though those rivplates have squashed nutz... use some light blue loctite.. I didnt beleive they could vibrate loose untill they did...

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Thanks. You're right - I figured it wasn't needed, but I'll benefit from your experience. :-).

Looks great Russ!

The little 3/32" rivits you put the nutplates in with, even if they are solid bucked/squashed rivits, have precious little shear strength. I have spun nut plates off their rivits before, and the pain of getting at the nut plate to hold it so you can undo the bolt is tremendous (hint - if that happens, drill out the rivits and stick a little screw driver or similar through to keep the nut plate from spinning.

Loctite would exacerbate the problem.

Brian

You can solve the vibration problem/damage issues by putting a strip of metal tape over the bolt heads before every event.