Just mapping out my work plan for the coming months. One of the tasks being planned is smoothing the firewall in the engine compartment. The plan is to weld a sheet of 18 gauge body sheet metal onto the main area of the firewall – that area found within the big factory seam which measures roughly 54 wide by about 24 tall.

The intent is to simply weld it into place flat against the existing firewall. As you are aware, the stock firewall has stiffening ribs stamped into it. The smooth (18 gauge) cover will not. It will simply be flat. It will lay against the stiffening ribs of the stock firewall behind so generally I’m not worried about it. Except – where I will eventually mount the master cylinder, power booster and hanging pedal assy, I’m worried about possible unevenness in the face of the stock firewall telegraphing through the smooth cover when I tighten down the master cylinder, etc to it.

Any suggestions as to what I should use between the two panels which will;

1. prevent the firewall from puckering around the mstr cyl, etc.
2. will be relatively easy to drill through
3. will take the heat generated in the engine compartment

Do not tell me to simply figure out exactly where the pedal assy, etc will mount and make a spacer identical to the gasket from the pedal assy as I have no seat or steering column in place and won’t for quite some time – so I am unable to predetermine where the mstr cyl-pedal assy will mount…..

One thing that comes to my mind would be to build up that recess between them in the general area with fiberglass. Certainly fire/heat resistant. Easy to drill through later….

Is that your suggestion?

 

Fergie -

I would use plywood. (I know, I know, sounds dumb). But, the temperatures in the engine compartment are not high enough to char or ignite wood, even if it was not covered by metal. Further, I would GLUE the plywood to the firewall and glue the new smooth sheet metal cover to the plywood. All epoxies and panel adhesive will take that much heat. Besides, the glue is really only required to hold everything until you get the MC and other stuff mounted with thru-bolts.

That sure would be a great heat insulator too. BTW, have you thought about using a polished piece of stainless? Cool, man!

My 2 cents...

 

I'll give the plywood some thought. If I start this over the winter months, I have a better chance of the glue drying than I would with fiber glass...

SS ?! Sorry, this thing's being built on the ferguson budget, not the Randy Jack budget....

(Actually, I prefer the ability to go body coloured rather than flashy. I guess cause I'm old and conservative.....)

AX - you must have an opinion on this. The technical question, not the old and conservative part)

Thanks,

 

Fergie,

Ditto on what Randy said. I think if you used some thin plywood you'd be in good shape. You could just cut the rough shapes to fill in the areas around the ribs and then weld in your cover piece. I think that if you left yourself a small gap around the edges and just welded it in in small sections of tack welds you wouldn't have to worry about setting it ablaze.
Have you thought about how to secure it in the middle? Maybe drill a couple of small holes where the ribs are and make a few spot welds through to the ribs?

Good luck with it
Bobby

 

Bobby,

I think either my fiberglass or Randy Jack's plywood could be used around those center areas you're worried about too. I'll have to have a look at her...

Yah, If I stay at least an inch away from where I'll be welding it up against the main seam, I should be able to avoid calling the local fire dept...

Yah, this might just work.....

(Ah, the stuff you come up with when a bunch of gurus put their heads together. It's a beautiful thing...)

 

fergie, I went through this about two years ago. I used the shiney SS from midfifty. They sell a mild steel unit also, that costs much less and can be color matched to the cab. I fastened my shiney stuff to the existing fire wall with the left over mondo-sized velcro from my Roddoors interior. I put a piece of the double aluminum bubble wrap insulation inbetween the two. Have you thought about relocating the power brake unit under the cab? I know it's pricey, but it sure makes for a clean firewall! Also, I had to cut out numerous nothes for the steeling column and the two attachment points on the fire wall for the fender-support rods. I bought a harbor freight nibler for $19 on sale. It really produced nice cuts. This would be another good topic for a "how-to article." Good luck, Jag

 

Mondo no like shiney! Mondo like paint!

Nix on the mstr cyl. under the floor too.

Expect to have the Mstr. Cyl., two heater hoses and the steering column through the firewall. Nothing else. All wiring will run out under the firewall.

Yah, I'm planning on getting either that nibbler that's now $99. or the shear (by Chicago Elect) that's $40. (both from Harbour). Got a Chicago Elect. die grinder from them about 18mths ago to use for P & P'ing my heads and intake - very impressed with the quality of it.

Thanks,

 

Ferg, on the subject of the nibbler, I think we are talking about different things. I saw my same model of air nibbler in the HF ad this week for $19. Is there some deluxe unit you are alking about? Jag

 

You can also get the small pnuematic reciprocating saw for fairly cheap from HF. I think they call it a high speed air body saw. Seems to me they were about $20 also

Bobby

 

RMF

If I wait an hour or two aftre you post, I don't have to answer a thing.
Match the plywood to the low areas, attach with gule or counter sunk hardware, where your new flat firewall matches up with the old stiffner ribs attach with counter sunk rivets.
New smooth firewall securely attached and rattle free.

Taa - Daa the (_o_)

 

am I missing something obvious here ????

if you mount the pretty painted sheet flush with the raised ribs, you're going to move the M.C. out from the firewall 'bout 1/4" right ??? so that is going to lower your pedal OR shorten your stroke by that much... might not make a difference... but it might (I'm no brake ex-purt)...

but how bout this... forget the filler piece... when you get ready to mount the M.C.... cut a template the shape of the M.C. face + 1/16" all around... nibble/grind/saw/chew a hole thru the p.p.s. and mount the M.C.flush on the original firewall... it's just recessed a little... no short stroke (you know how embarrassing that can be) no filler piece needed... no problemo

you could do the same with heater hoses, using either the bare hose or if you use one of them slick billet connections do the same..... I personally think it might look a little more custom that way, cuz. pretty cool

So ??? all your cables, things, do-hickeys will exit the cab below the vertical firewall... ??? down in the toe board (that's a tech term for the slanty part of the floorboard)... that's gonna make a heck of a throttle cable bend isn't it OR are you going with the new wiz-bang wireless network throttle controls ???
I've heard that folks can hack into your engine with those if you don't have a...wait... I forgot...(wait for it.......) you already have a FIREWALL !!!!! man, i crack me up sometimes

just a suggestion... but with my IQ I have to keep things simple...

later
cuz john

 

Fiberglass, WHY BAD CHIOCE!!!! have U even seen a fibergalss boat burn.. not pretty.. Even the fire dept on the water will not try to put it out.. Believe it or not but the plywood has a much high flash point then the glass.. Id do the plywood or fireboard before hand abd it will give U more mounting points for the time when U go " Ho where shall I mount this gizmo"

 

Ferg

This is what we did on mine. Took just one afternoon for the firewall. We cut out the center of the firewall where the stiffining ribs were located. Flat bar was welded to the inside of the firewall. We welded bolts to the inside of the firewall plate, drilled holes for those bolt and bolted the corners in and welded the center to the flat bar on the inside. Then we took autobody adhesive and glued a stainless layer to the new smoothed firewall. By the way stainless in a pain to drill. Read expensive drill bit. You will not see the flat bar on the inside when it is covered with a firewall insulator. Now your firewall is smooth and looks right.

The thickness of the firewall will not effect the booster mounting. Just use the mount on the inside to drill the holes for the booster. Hope this helps.

 

This is all good input. Got some great alternatives and issues to think about being thrown on the table here. I'll have to set a spell and let all this sink in.

Thanks gentlemen (and Penn Dick).

The price difference on the nibbler is you're talking air, I'm talking electric (as I don't have a compressor).

Any more ideas, throw them out here.

Thanks,

 

I think JetJock is onto this thing. those ribs point ''out'' from the firewall. If you straightedge the surface of those ribs (going side to side) the firewall cover will not touch the far outer areas on the left and right side. Is this clear?