Chassis support during rocker and longitudinal repair

[Todd Simpson]

I've got a pretty solid '71T that needs outer rocker and a little longitudinal work and I'm trying to figure out the best way to support the chassis during repair.

Leaving it on the wheels is a possibility for some of the repair, but eventually I need to patch the area below the torsion tube which means rear wheels off and suspension apart.

Darryl D's repair is similar to what I need to do, though his car was worse than mine. DarrylD's Porsche 912 Project Page - Phase 8: Right Longitudinal Channel Repair

So...a reasonably solid longhood with a welded in full cage. Can I remove the outer rockers, likely patch the jack area and kidney bowls, supported by the torsion tubes in the rear and the pinch seam up near the tie rods? (mid rise lift.)

Or, should I do the rockers while it's on wheels and then rear torsion area when on a lift? Looks like Darryl used stands on the torsion tube and the front wheels for the whole thing.

Engine is already out.

thanks

[911pcars]

If yours was an unmolested car, I would be careful to perform structural repairs/modifications only on a straight chassis. Merely sitting on tires or on typically-supported jack stands doesn't really ensure there's an absence of chassis twist during sheet metal repairs.

However, your welded full cage has pretty much fixed the chassis into a rigid form already. We will assume the cage was welded on a straight chassis.

What leveling and support fixturing do others recommend short of mounting it on a Celette bench? Just curious.

For reference:
https://porsche356registry.org/article/128

Sherwood

[Todd Simpson]

Thanks Sherwood....bump for any other suggestions. I suspect I am overthinking this...

[Trackrash]

I would think you could support the rear on jack stands supporting the torsion tube and the front on jack stands supporting the front cross beam. You would want to make sure the floor is level and flat. With a coupe I can't imagine you would have any problem unless you started messing with the roof structure. And since you have a cage, I wouldn't worry.

If you are concerned, why not take the basic chassis measurements, as it sits, to make sure you are starting with a straight tub?

[tperazzo]

Originally Posted by Trackrash

I would think you could support the rear on jack stands supporting the torsion tube and the front on jack stands supporting the front cross beam. You would want to make sure the floor is level and flat. With a coupe I can't imagine you would have any problem unless you started messing with the roof structure. And since you have a cage, I wouldn't worry.

If you are concerned, why not take the basic chassis measurements, as it sits, to make sure you are starting with a straight tub?

Agree, a lot can be done with a good tram guage and a spirit level. That's what I did when I was working on my suspension pan, but I would do the same thing when working on the sides.

Link to video for details:
https://youtu.be/RHk3--W7V0w

start around 7:15 for the level and measure technique.

[Tom '74 911]

I am biased, but also lucky to have access to one of these:



W/out a bench, I'd create as stable & level a platform as possible and make sure to take lots of measurements before & during to make sure nothing moves. I've had good success using laser levels to establish baselines. Lots of significantly involved welding and rust repair projects happen w/out Celette benches - Pelican's pages are littered with them - and most turn out just fine... Lots of measuring and verifying along the way...

Also, you mention that the car is fully caged... that's going to help keep everything locked in place too.

Good luck!

Tom

[Shaun @ Tru6]

Todd, without the use of a Celette, I would remove front and rear suspension and put the car on a triangulated dolly such that the rear is supporting the torsion bar tube and the front is supporting the front of the floor or the steering rack crossmember. Even without the cage, as a coupe, you can safely do all of your cutting and welding.

[Mike Billings]

I welded cross beams across the door jams before removing rockers. No biggie to cut them out later.