Another front pan job starting...

tabasco · 06-21-2010, 08:22 PM

I started a front pan job on my '76 Carrera 3.0
It's ugly inside, as expected.

What do you recommend to drill the plug welds ?
I used a plug weld cutter, but it's easy to overdrill, and go through both layers.
Those things cut fast !
To remove the pan itself, I'll have to do a better job.
Should I use a regular drill bit ?
And then drill the body, leaving those holes for future plug welds ?

-Guillaume

911mnypt · 08:36 PM

I used a regular 1/4 drill bit and drilled out each spot weld. Filled them back in when we welded the pan back in.

tabasco · 06-22-2010, 05:07 AM

Nice job ! That's a lot of holes...
Thanks for the answer.

Is that the restoration design pan ? How did it fit ?

-Guillaume

911mnypt · 06-22-2010, 05:29 AM

Quote:

Originally Posted by tabasco

Nice job ! That's a lot of holes...
Thanks for the answer.

Is that the restoration design pan ? How did it fit ?

-Guillaume

I found the pan and top support through EBAY...Restoration Design was a little too expensive. The pan fit just fine...take a lot of measurement though.

BK911 · BK911's Garage

How do you plan to weld the ends? I've seen butt welds, 1/8" overlap, and butt welds with a reinforcement plate on top. I have done a few of these and have always overlapped. I like the butt weld idea because it looks cleaner. However, I saw on one of those gear head shows on spike that butt welds are not that strong. They recommened a slightly bigger gap, and putting in a small reinforcment plate on top. So it looks like a butt weld from the bottom, but each end is actually welded to the reinforcement plate.

What do the experts do?

tabasco · 06-22-2010, 08:18 AM

Good question. I was thinking butt weld but if there's a better idea...

I guess it also depends on where you cut the original pan. If it's in the front, closer to the suspension points, it may put more stress on the welds than if it's further in the back.

-Guillaume

Flieger · Flieger's Garage

Quote:

Originally Posted by BK911

How do you plan to weld the ends? I've seen butt welds, 1/8" overlap, and butt welds with a reinforcement plate on top. I have done a few of these and have always overlapped. I like the butt weld idea because it looks cleaner. However, I saw on one of those gear head shows on spike that butt welds are not that strong. They recommened a slightly bigger gap, and putting in a small reinforcment plate on top. So it looks like a butt weld from the bottom, but each end is actually welded to the reinforcement plate.

What do the experts do?

I like that idea. Do three welds. But weld on bottom, with full penetration to the middle of the reinforcement plate on the other side. Then weld both ends of the reinforcement plate to the pan or body metal below it.

Oldporsche · 06-22-2010, 11:54 AM

Welding from the bottom offers several advantages. It's easier to cover up. You can use a "weld thru" primer and follow up with a rust converter. The disadvantage is that you are welding overhead if the car is not inverted on a rotisserie. A narrow backing piece used on the bottom will allow you to have a grove to fill from the top. This would give you good penetration and probably be an easier weld to finish nicely. A plain lap weld will work. I have done that myself. I used a 1/2' lap am spot welded through it.

tabasco · 07-03-2010, 01:07 PM

Got some more work done in this area, I thought I would share some pics.

I made a jig while my original pan was still in place, to precisely locate the A-arms bolts.

I didn't really like the idea of using the A-arms to position the new pan, as the A-arms have quite a bit of play with their (worn) bushings.

I removed the front section first, and cut the pan in 3 pieces to make it easier.

Then I worked on the sides.
A cheap $2.99 autozone blade tool turned out to be perfect to work on the spot welds once drilled.

Now the pan is off the car !

I'll have to clean everything, take care of the rust, and I may also replace the front section of the left tank support.
There's some rust in there too, and it should be easy to remove this piece at this stage.
Still debating the issue.

-Guillaume

WinRice · 07-03-2010, 02:18 PM

I'm just finishing up the same job and can add a few things to look out for:

1. I had to replace the front half of the left side longitudinal, but I left it in place to help align the pan, then removed it once the pan was tacked in. I figured out where the cut should be, but only made a small cut up through the bottom flange so I could easily complete the cut once the pan was tacked in without damaging the new pan.

2. Check the location of the weld nuts for the front a-arm mounts. I used a St*ddard pan and the front weld nut of the 3 nut group on the right side was moved sideways 1/4" off. So I used the spot weld drill to remove the whole bracket and relocate it.

3. Also check to see if you have plenty of factory spot welds holding the weld nut brackets to the pan. If not, add weld. Easier to do with the pan out and upside down.

4. Check how square the weld nuts are to the a-arm brackets before welding in the reinforcing plates. It seems when they attach the weld nuts they aren't very square to the flange of the bracket, so I mounted up my a-arms and used a small piece of pipe on the top, slid over the weld nut, to tweek the weld nuts for a square fit to the bracket. Then weld in the small reinforcing plates.

5. Test fit the front tank support with the tank in place, then mark it. It's surprising how far off the support was when I thought it was aligned when the tank was out.

I hope this makes sense.

tabasco · 07-03-2010, 06:17 PM

Thanks for the tips.

I have the same pan, from St*ddard, and realized today the A-arm nuts are not at the right place either. :-(

Rather than fixing it myself like you did, I think I want them to fix it.
I want something straight from factory.
I'll probably ask for a refund and get one from Dansk instead.
More $$$ but I hope it will be better.
From what I can see trying to bolt the A-arm covers, and with the jig I made, there are several pieces which are off. It's not just one element.

And while I admire you for fixing the pan yourself, that does not help others.
St*ddard has to know there is a problem.
Or maybe they should sell their pan with the brackets not welded yet !

If I had known your issues with the bolts location before, I would have bought a Dansk pan in the first place.

We'll see what they say on tuesday. In the meantime, I'm kinda stuck for this weekend.

BTW, what did you do with the holes in the pan (3 drain holes + hook) ?
Did you weld them ?

-Guillaume

WinRice · 07:42 PM

Quote:

Originally Posted by tabasco

If I had known your issues with the bolts location before, I would have bought a Dansk pan in the first place.

BTW, what did you do with the holes in the pan (3 drain holes + hook) ?
Did you weld them ?

I've seen where others have stated that the St*ddard pan is a Dansk, not sure what to believe. I wouldn't have fixed it, except for the time and effort to return it and get another one.

The hook holes are gone on my car, I put in a 935 oil cooler duct.

Leave the 3 drain holes in the crossmember as they are and use the proper plugs, which are one valves to let moisture out. 911's have several of these along the tub, so it's better to replace all of them.

abisel · 07-04-2010, 05:02 AM

You jig is a very good idea. It will keep the front A-arm mountings square with the rear cross-member mounting. Be sure to measure two or three times before you weld. Measure front to rear, left front to right rear, etc. And don't forget to install the reinforcements above the A-arm mounts. I have seen several pan replacement jobs where they did not install the reinforcements.

tabasco · 07-04-2010, 09:12 AM

Quote:

Originally Posted by WinRice

The hook holes are gone on my car, I put in a 935 oil cooler duct.

Do you have pics of the oil cooler duct ?
Did you fabricate it yourself ?

-Guillaume

tabasco · 07-04-2010, 09:20 AM

Quote:

Originally Posted by abisel

You jig is a very good idea. It will keep the front A-arm mountings square with the rear cross-member mounting. Be sure to measure two or three times before you weld. Measure front to rear, left front to right rear, etc. And don't forget to install the reinforcements above the A-arm mounts. I have seen several pan replacement jobs where they did not install the reinforcements.

Yes, I have the reinforcements.
The jig should locate the A-arm mounts in the 3 dimensions, but I'll see when I got the pan in if it actually works.

May I ask where your pan came from (and which brand), and if you had to modify it ?

Did you add more welds to the brackets like WinRice did, or are all those plug welds stock ?

-Guillaume

abisel · 07-04-2010, 10:52 AM

Quote:

Originally Posted by tabasco

May I ask where your pan came from (and which brand), and if you had to modify it ?

Did you add more welds to the brackets like WinRice did, or are all those plug welds stock ?

My buid is different. I started with a full pan from Porsche and went from there. All of my replacement sheetmetal is Porsche. The only original part of my 73 is the front firewall, trunk floor and dash. All else was damaged in a rear end collision.

The A-arm brackets welded to the underside of the pan are assembled by Porsche so the spot welds you saw are factory, but I plan to do some seam welding once I can get the car on a rotisserie and flip it over.

Most all of my welding is with a resistive spot welder.

tabasco · 07-04-2010, 03:15 PM

Quote:

Originally Posted by abisel

My buid is different. I started with a full pan from Porsche and went from there. All of my replacement sheetmetal is Porsche. The only original part of my 73 is the front firewall, trunk floor and dash. All else was damaged in a rear end collision.

The A-arm brackets welded to the underside of the pan are assembled by Porsche so the spot welds you saw are factory, but I plan to do some seam welding once I can get the car on a rotisserie and flip it over.

Most all of my welding is with a resistive spot welder.

Wow ! That's quite a project, which would deserve a thread !

abisel · 07-04-2010, 03:44 PM

tabasco,

Thanks.

I don't want to steal from this thread but I do have pictures posted in other threads.

RSR replica pictures

Rear Shock Reinforcement

I have a whole butt load of pictures that I may put into a "How to build an RSR from scratch" thread. We shall see.

WinRice · 07-05-2010, 09:12 AM

Quote:

Originally Posted by tabasco

Do you have pics of the oil cooler duct ?
Did you fabricate it yourself ?

I used the Elephant racing duct, but cut a triangle out of each side and reduced the width to 24" so it fit my cooler better.

The plates above the duct on each side are reinforcements that serve two purposes. I'll weld the upper cooler mounts to them, but also through-bolt the brackets from the inside to attach a 935 style x-brace.

I'll be running a ERP 935 front suspension, so I added additional reinforcment on the front weld nuts. (just tacked, not fully welded yet)

WinRice · 07-05-2010, 09:24 AM

Quote:

Originally Posted by abisel

I don't want to steal from this thread but I do have pictures posted in other threads.

I have a whole butt load of pictures that I may put into a "How to build an RSR from scratch" thread. We shall see.

Sweet!

Forget using old tubs, just get a box of Porsche panels and build one! Heck of a project!