Help Cutting Off the Inner Fender!

[Rodney Nelson]

Hi Everyone,

I have a 1972 911T and as you can see it has a nasty weld job with a front date. I'm backdating my front date.

I have sourced two original inner fenders and I'm ready to start cutting. I have purchased a laser to assist... So, now for the scary part.

It will be tricky, as I will have to line up the cut line on the current fender and then on the donor fender so they match perfectly. Then I have to cut a line as straight as possible. The inside seems like it will be tricky as well, considering the extra inner well supports and around the tank supports and pan areas. A side note, I will be replacing the pan and tank supports as well.

When looking at the pics my current plan is to cut along the vertical laser line in front of the shock tower area and try to line it up repeatably by determining some reference points, that is the problem.

So, here are the questions...

1. How can I make sure my cuts line up on both fenders exactly, I believe I need at least two reference points. The donor inner fender is full length from front latch panel to past the door jamb.

2. What tools do you recommend for the cutting? I want as clean of cuts as possible.

Thank you for your help and suggestions.

[seafeye]

First I’d weld some supports from the shock towers. I wouldn’t be too worried about a straight line as the pieces will have to be grounded to fit.
I’d start with the suspension pan. Get that in the right spot. Then order the front inner fenders. Fuel tank longitudinals. Maybe the fuel tank corner support. And of course battery boxes.
And the latch panel.
I’d cut ahead of the shock towers. I replaced behind and then needed a jig to align everything.
You should be able to avoid needing a jig if you cut ahead. Where your line is.
Once the suspension pan is in the proper spot. You should be able to measure and align the gender pieces. Download the schematics and find the zero plane on your car.

[Rodney Nelson]

Originally Posted by seafeye

First I’d weld some supports from the shock towers. I wouldn’t be too worried about a straight line as the pieces will have to be grounded to fit.
I’d start with the suspension pan. Get that in the right spot. Then order the front inner fenders. Fuel tank longitudinals. Maybe the fuel tank corner support. And of course battery boxes.
And the latch panel.
I’d cut ahead of the shock towers. I replaced behind and then needed a jig to align everything.
You should be able to avoid needing a jig if you cut ahead. Where your line is.
Once the suspension pan is in the proper spot. You should be able to measure and align the gender pieces. Download the schematics and find the zero plane on your car.

Hi Seafeye,

You lost me at Schematics and find the zero plane. Could you please explain and where to find?

Thanks,

Rodney

[sugarwood]

Just go to 2:58
https://www.youtube.com/watch?v=OvN790dQo5g

[seafeye]

I think restoration design has the schematics. You will need to print those out.

[Bob Kontak]

Originally Posted by sugarwood

Just go to 2:58
https://www.youtube.com/watch?v=OvN790dQo5g

Tenacity is critical. LOL.

As far as cutting and I am just talking. I like the fancy Dremel cut off wheels. I have talked about them before. They are a little small and will take time given old 911 steel gauge but they can be controlled. Angle grinder skinny cut off wheels have power but not so much control. May be a compromise to use angle grinder on the straights and dremel in the turns?

Make seafeye your new best friend.

[Rodney Nelson]

Originally Posted by Bob Kontak

Tenacity is critical. LOL.

As far as cutting and I am just talking. I like the fancy Dremel cut off wheels. I have talked about them before. They are a little small and will take time given old 911 steel gauge but they can be controlled. Angle grinder skinny cut off wheels have power but not so much control. May be a compromise to use angle grinder on the straights and dremel in the turns?

Make seafeye your new best friend.

Hi Bob,

I will take your advice and order this dremel set-up. And yes, I'm slowly working on Seafeye, I have been closely following is project on the body / paint forum.

Thanks

Rodney

[jjeffries]

Rodney, in addition to what others have already said, I'd just add to take careful measurements all over, including diagonally, and keep really good notes. Also, be extraordinarily patient and peel the layers of metal one by one, as opposed to cutting through multiple layera of metal at once. I realize this sounds like Captain Obvious speaking, but I'd need to reminded.
I use those Dremel discs BobK recommends and they will have their uses in the project. If you're using an air powered grinder or cut off tool, it bears repeating to use the best discs available, typically available at your local welding supplier. They are more spendy but last longer, cut better and much safer. Speaking of safety, don't skimp there, either. I buggered up my hearing years ago grinding welds with no ear defenders. "What?" Exactly!
Also as BobK says, watch and ask questions of those guys who have done this before. Godspeed when you start cutting! John/CT.

[jpnovak]

You have a difficult path ahead. I assume you are doing both sides. I would start by carefully sectioning the inner impact support and lateral tank support seams. this will effectively separate the fender well section.

I would make a template that bolts to the top fender mounting flange. The bolt holes for the fender are highly uniform and also the curvature must match the hood. Make your first cut to remove the existing panel. But, cut it short.

Then lay up the new panel and the new seam is overlapping the old panel by a few mm. Clamp up the new panel using your template as a reference. Then scribe your line at the overlap seam. Now start at one end and fit the panel. I would start at the bottom using the front pan as a location plane. The two lower flanges should meet. clamp and/or screw and/or cleco them together with a few strategic holes.

Now you can start with an initial cut from the bottom and tack weld in place. Keep cutting, peeling back your thin kerf cut from the overlap, tack welds, panel fit as you move up the seam. Its no different than welding flares or any other section panel. Go slow and you will probably end up with a weld spot every 2" or so. Then stitch it all together. s

Best of luck. It's not easy and certainly time consuming.

[Rodney Nelson]

Originally Posted by jpnovak

You have a difficult path ahead. I assume you are doing both sides. I would start by carefully sectioning the inner impact support and lateral tank support seams. this will effectively separate the fender well section.

I would make a template that bolts to the top fender mounting flange. The bolt holes for the fender are highly uniform and also the curvature must match the hood. Make your first cut to remove the existing panel. But, cut it short.

Then lay up the new panel and the new seam is overlapping the old panel by a few mm. Clamp up the new panel using your template as a reference. Then scribe your line at the overlap seam. Now start at one end and fit the panel. I would start at the bottom using the front pan as a location plane. The two lower flanges should meet. clamp and/or screw and/or cleco them together with a few strategic holes.

Now you can start with an initial cut from the bottom and tack weld in place. Keep cutting, peeling back your thin kerf cut from the overlap, tack welds, panel fit as you move up the seam. Its no different than welding flares or any other section panel. Go slow and you will probably end up with a weld spot every 2" or so. Then stitch it all together. s

Best of luck. It's not easy and certainly time consuming.

Thank you jpnovak, Yes I'm going to be doing both sides. Thank you for your advice!