TecH Post build your own belly pan After looking at a side view of my little Austin I thought it was missing something the bottom of the body seemed to end too high and it was too straight With a lot of clutter underneath So I decided to build a belly pan to make it neater
I am lucky that I have a few usefull tools in my workshop the only realy specialist one is a bead roller I used to add a bead and make the joggles so the joints were flush but this is not essential I also wanted the belly pan to be easy to remove so to do this I wanted to fasten the whole thing on using rivnuts and bolts A rivnut is a threaded rivet it is placed through the sheet metal and the rivet part is drawn up with the thread either using a bolt and large washer or a special tool which is like a normal rivet tool except it has a thread on the end i chose to use 10/32 unf as they were small and available from aircraft spruce ready drilled for lock wire i used about 75 bolts and rivnuts http://www.aircraftspruce.com/catalog/hapages/rivnuts.php
To start the belly pan it self I measured from the end of the body to the lowest part of the chassis I then added one inch for the belly pan to mount onto the body then made a few trial section up to get the lengths right so the top part sat on the car body and the lower bit was just below the chassis To make the radius on the bottom I clamped a length of three inch diameter tube to the bench with the 18g half hard aluminium sheet underneath and bent it around the tube by hand
the next thing to do after working out a section that fitted to the body and below the chassis was to add ½ inch to each end on the underneath end this ½ inch was for the joggle so the bottom of the belly pan joined flush and on the top side I wanted to roll a bead to make the pan look finished I also had to split the pan up into sections as my bit of tube used for bending was only 36 long this had another advantage as it made bending a lot easier
I started at the front of the car made the first section dont forget these are handed ( I did) I decided to mount the bolts in groups of three so they could be lockwired together I marked out the holes in the pan then drilled 1/8th pilot holes held the pan section in place then drilled through a hole at each end into the car body and held it in place with cleekos ( removable body pins) while the other holes were drilled into the body Each hole in the body was opened up to the correct size for the rivnut and the hole in the pan was opened up to the correct clearance size for a 10/32 bolt ( a little bigger in someplaces)
After all the sides were made and mounted it was time to make the bottom this again was made in sections splitting at the same points as the sides I used some large pieces of stiff art car and using a screwdriver marked around the edge of the joggle the card was then cut on the line and offered up to see how it would fit after a bit of trimming the shape was transferred to metal more marking out 1/8th holes and cleekos as on the sides of the pan I also decided to add beads at the front and down the middle to add stiffness and hopefully stop the panel drumming
As we say in the UK MR Cockup was in town I forgot when the handbrake was used the bellcrank gets lower and fouled on the bottom panel so had to make a hammer form up to make a bulge in the bottom
That looks great! I've always thought those UK specials were special bread of Hot Rod. Would you know of a source for the "Helmet" style cycle fenders (wings) seen on early 1930's Astons & Lagondas?
I now decided it would be easier if the lower panel was riveted together as one so this was done and the whole pan was removed from the car to finish off installing the rivnuts and a bit of final finishing
here then is the final few pics two die pics to compare with the first pic in this post and a couple of detail shots hope you have enjoyed my little tech post any questions class come on hands up ,,,, you in the back row
First off I think you did a great job on your belly panel, really improves the look of your car. Second as a long time A&PIA I hope you used the keyed style of rivnut. Back when i started my airline life the co I worked for flew SA-227 metroliners. Sweringen loved to use rivnuts, We hated them because when it came time to remove an inspection panel, if the screw had seized to the rivnut due to dissimilar metal corrosion the rivenut turned in the parent metal before it let go of the screws threads. When this occured you had to try and drill out the screw, problem was the screw usually turned when you tried to drill it. i notice you are using -3 bolts making any drilling even harder. If I were you I would make sure and use anti-seize the next time you have it removed. Just my experince YMMV.
the belly pan has been finished for a while now and a few mods have been made a hole under the rear axle to let out any oil and somewhere to jack the car up and change wheels i dont use all the bolts to attach the bottom now spaced every 6 inchs apart rather than every 3 a lot less to undo to drop the bottom off the rivnets are unkeyed but havnt had any come loose as i have been using anti seize thanks coupster the car seems a lot less rattly and quieter i think the large piece of aluminium on the bottom and all the fastners have improved the stiffness of the car a bit it is a bit battered on the bottom now after a few trial off road but it has saved the chassis a number of times as rocks that get caught underneath tend to slide through rather than stopping on the crossmembers downside when driving in deep ruts especialy downhill it turns into one giant sledge lots of fun with no control
this was my first time building anything this big the last thing i made was the alumium cockpit cover
Great tech, Ade. Very cool. One question, though.... What on earth are you wearing in that first photo?
Oops In my defence, it's a very small photo (Artiki walks away with his tail firmly between his legs...)
Great Job Ade! I love the A7's! Probably cause my father has an A7 Special as well... Here is an old photo of his... We made our sidescreens at the local TAFE college at a nightschool. I see you've gone for a brooklands exhaust as well! Nice! It's been off the road with a busted clutch for a while, and in the meantime have we finished a few other projects (36 Hillman Minx and 96A Whippet Roadster). Got a question for you though... We are looking for a new alloy head for the A7? You know if anyone in the UK are remanufacturing these? Cheers Stu Brisbane, Australia
brilliant tech good to see some british know how going to good use i am going to use this on my 34 i going to build in future. thanks again tim
[Got a question for you though... We are looking for a new alloy head for the A7? You know if anyone in the UK are remanufacturing these? Cheers Stu that is a very pretty car,,, what is it's history i'm not sure if anyone is redoing heads at the moment but i'll look into it
UK, a tip of the "Ole Top Hat!" Inovative, nice attention to detail and looks good too!" BTW - The sensors you sent are doing the job. Matter of fact they are being used this week! (North of 49 @ Bonneville) Thanks again. Dave
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