Moss Motors, Ltd

Howdy, I have a fully restored 61 A with all the go fast stuff added and I've decided to continue setting up the car as a street legal SCCA race car.  My next project is to replace the plywood floor boards with aluminum.  My question is how thick?  I've talked to a Trans-AM race guy and he suggest 3/16".  Anyone know what the MGA racers use?  Thanks, Tom Tompkins

I Don't know what the racers are using, I.m using 1/8 inch diamond plate.

 

Pound for pound, steel is much stronger than aluminum. Don't take chances with your safety, weld in a steel floor.

---

Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Ask these guys.  They race A's and have some beautiful cars.

http://www.vintage31.com/enterMain.html

 

---

1960 MGA
Keep 'em on the road DAILY!

Although expensive, honeycomb sandwich panels (4*8 of honeycomb is $600) from Teklam would do it.

---

59 MGA 1500 -- 3rd in the restoration queue

Tom, I'd advise welding in steel mountings for your seat, then filling the area around them with 1/8" aluminum plate or no less than 18 gauge sheet. You won't be stepping on the rest of the floor so strength there isn't too much of an issue. This will probalby be required for a secure seat mounting my SCCA anyway. You'll want to add some type of insulation aroung the foot well, or you'll certainly get 'hot foot' driving the car. A thin sheet of stainless or aluminum under the floor between it and the exhaust will also act as a heat barrier. Check the area where the floors bolt in frequently, the two different types of metal in close contact will want to set up a galvanic action and cause corrosion pretty quickly, so keep on top of that. If you use the 18 gauge, then if you have access to a bead roller a few well placed beads will help prevent 'tin canning' and add a lot to the strength.

---

'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa
'52 MG TD kit car body project.
'98 Jag XK8

"There is a fine line between a hobby and mental illness"

I repeat, pound for pound, steel is stronger than aluminum. Steel seat mount brackets are a given, but intrusion resistance is also VERY important. The steel floor will be weight placed about as low in the car as you can go. Save weight elsewhere, higher up. What is your safety worth? This is being written by someone who has been severly injured in a racing car. Please take care of yourself. You will not become wealthy or famous as a result of racing an MGA.

---

Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Bill, you are correct, the steel would give better cockpit protection. I was just following the original idea of the post, and  going on what I'd seen in  various MGA racers at the Vintage MG Racers meet at Hallett last year. If the 'look' is all that's wanted, why not just keep the wood floor boards and cover the top with a thin sheet of aluminum. That would give you the 'best' of both worlds with minimum modification to the car.

---

'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa
'52 MG TD kit car body project.
'98 Jag XK8

"There is a fine line between a hobby and mental illness"

I'd have to say that either would be stronger than plywood.  Course if you weld in the steel floors, it might be as strong as an MGB hahaha.  I think the pound for pound statement is incorrect.  In some instances, such as structures, steel may be stronger.  But if it was equal on a wieght/strength basis, aircraft would be built out of steel.

---

72 MGB 80 TR8
Pittsburgh PA

Underdog,

I appreciate your thoughts on the subject, and I enjoy your posts very much. This time, however, you have erred.

The pound for pound statement IS correct. Ask any structural engineer, whether he is designing skyscrapers or aircraft. Aluminum is used in aircraft because of weight PLACEMENT issues. And, sorry to say, with airplanes, lightness often has to trump strenght just to attain flight within reasonable parameters of power requirements. Also, there is actually more steel used in aircraft design than you may think. Aluminum is what you SEE when you look at an airplane.

 

 

 

 

---

Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Well I have to admit, I'm certainly no engineer.  And my experiance with aluminum has been mostly beer cans. lol  I used to be really into Drag cars though & have seen many a Camaro ect. that was gutted and all the floorpans/wheel wells replaced with formed aluminum.  But..they do have very substancial roll cages and frame connectors(made of steel by the way) incorporated into the car  that provide safety as well as structural rigidity.   If it was me, I'd check with the sactioning bodies SCCA SVRA ect and see what is legal.  They research accidents and do their best to develop rules that make the cars as safe as possible.  There does become a tradeoff at some point though or else everyone would be raceing armor plated Hummers.  My own thoughts, if it was my car, would be to save the weight where I could with the aluminum and put the steel into a roll cage with side impact bars.  You are right Bill, in that steel is the material of choice in impact protection and major structural components.  I just don't see the chances of an impact occuring at floor level that often. 

---

72 MGB 80 TR8
Pittsburgh PA

Tom,

Check the SCCA's GCR. My vote would be steel welded in and bead rolled

---

"Cogito ergo Zoom"
"Love your freedom? Thank a Veteran"

Gentlemen, I think we're missing the point Tom tried to originally make. It sounds like he's building a 'replica racer' just for the looks , not for competition. In that case, he'll want the looks of the race car, while maintaining all the streetability he can retain for reasonable comfort. Since it's an already restored car, most of the mods shouldn't detract from the original car and should be reversable. I missed this in my comment on the steel seat mounts. Yes, if I was going to bolt my seat to it, then at least 3/16" plate, probably heavier considering my weight.

 

---

'73 Midget (V6)
'59 MGA (I6) under construction
'73 Lotus Europa
'52 MG TD kit car body project.
'98 Jag XK8

"There is a fine line between a hobby and mental illness"

under,

What a concept!  Armor covered Hummer racing!  Oh yeah, they're already doing that.........

With respect to the possibility of impact to the floor, you just haven't been watching enough NASCAR.

I stand by my original statements concerning likely impact (it only has to happen once, not often). I have experienced same. I will say no more on the subject.

---

Motorbill
From Lola to Land Rover, If it's British and has wheels, it's likely I've bloodied me knuckles thereupon

Bill:

I think that if you check a basic structural materials text you will find that pound for pound aluminum is much stronger than steel.  Its used in aircraft because the same structural strength can be achieved at a lower weight.  However, having said that I agree with you that the floor boards should be steel for number of reasons:

1) You can weld it in, thus the floor boards become strength bearing member of the structure.

2) There will be galvanic corrosion problems unless every part is coated with corrosion preventive and dielectric materials are placed between dissimilar metals.

3) Depending upon the grade of aluminum this material can be very soft and malleable when compared to steel.  The stronger grades are less prone to maleability but are more prone to fatigue/stress fractures.

One of the other posts suggested honeycomb, real expensive but super strong, another exotic alternative would be to laminate carbon fiber over a foam core.  Cost a little more than aluminum and requires skills working with epoxy or polyester resins.  Also either of these alternatives will require use  of high tech adhesives to make the floor board part of the structure.  For the average guy steel is the deal