911 Chassis Fixturing

[scootermcrad]

With a lot of cars surfacing in need of floor and suspension pan replacement, I'm sure I'm not the only one thinking about this and I haven't seen any new discussions on this for awhile.

A recent visit to Zuffenhaus got me thinking more about the need for fixturing. With several types of projects happening in my garage (majority non-Porsche) the need for a frame or heavy table to cover all my needs, is starting to make sense. For my 911 project, I have a long list of projects that will potentially impact the chassis alignment, (front suspension pan, floor pans, torsion bar tube repair/replacement).

For me, a Celette fixture just isn't realistic. Way too much cheese for my bank account. I'm looking for other options, including home-brew setups similar to member Flank's table.

Here's his thread:
http://forums.pelicanparts.com/porsche-911-technical-forum/226188-flanks-71-targa-restro-home-made-chasis-jig-pictures.html



Something like Flank's table would actually work really well for me and the projects I have lined up. Having a small machine shop at home allows me to make some of these things. I would need to figure out the shock tower posts, if I want to go "all the way", which is probably smart.

Another option seems to be Blackhawk style fixturing, which could easily be adaptable. Still some big bucks, and seem to be available right here in our classifieds and other places for $5K. That would be a one time and done deal and would have to turn around and sell them, but the work is done.

http://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/836561-blackhawk-complete-911-fixture-set.html



Welding and fabricating is not an issue and I'm just psycho enough to enjoy making fixtures for things, so I would absolutely entertain something that would work for the 911, a couple other non-911 Porsche projects, and my other fixturing needs. Having all the right dimensions would take care of all that and I could CAD up and have parts laser cut, and what not. Working for a race team, I also have access to surface plates and Romer arms for checking everything (with a box of donuts and a 6-pack or two for bribery).

Anyway, just wanted to bring up the topic again for discussion. Starting to think now about these future repairs. Just getting my ducks in a row.

Let's hear some thoughts or input.
Thanks!
S

[Tom '74 911]

(full disclosure: I have a Celette bench w/p-car fixtures in my home shop)

I think a home brew fixture table would be a great tool to have. A buddy of mine had one in his shop that he used to build a bunch of hot rods & Bonneville cars. It could, ultimately, be more flexible than a Celette bench.

There will definitely be a trade off between stoutness and mobility. Flank's table for instance - stout as heck! But not very mobile... It takes some planning and it's a heavy mother, but I can roll my Celette bench around my shop by myself, which is really nice.

If you've got access to the tools to make the fixtures, and make them accurately, it'd certainly be a cool project! I'd be excited to see what you come up with!

Tom

[scootermcrad]

Originally Posted by Tom '74 911

(full disclosure: I have a Celette bench w/p-car fixtures in my home shop)

I think a home brew fixture table would be a great tool to have. A buddy of mine had one in his shop that he used to build a bunch of hot rods & Bonneville cars. It could, ultimately, be more flexible than a Celette bench.

There will definitely be a trade off between stoutness and mobility. Flank's table for instance - stout as heck! But not very mobile... It takes some planning and it's a heavy mother, but I can roll my Celette bench around my shop by myself, which is really nice.

If you've got access to the tools to make the fixtures, and make them accurately, it'd certainly be a cool project! I'd be excited to see what you come up with!

Tom

Yeah! A heavy mother for sure! I could see some ways to work around that (in my garage) and it seems like that fixture could have been shortened up a bit, overall. How long is your Celette overall from beam tip to beam tip?

I come across structure beams on a regular basis around here for virtually give-away prices, left-over from projects. Less than scrap prices, really. Making the table true and level on a surface plate at work, would work out well and would serve as a good base for any fixtures I want to make for it.

I haven't looked closely enough at the factory P-car diagrams in Flank's post, but there seems to be a lot of dimensional information there that would be useful.

What other important locations (point and angle-wise) would need to be considered besides the following?

* Front suspension pan suspension points
* Rear torsion bar tube and pattern
* Rear trailing arm and trans mounts
* Rear engine mounts
* Front shock towers
* Rear shock towers

What else?

[Shuie]

If you are not a member over at 914world it might be worth it to sign up to check out this thread:

914World.com - The fastest growing online 914 community!

There is a lot of info in there about fixtures for a 914. I believe it was built for a 914/911, but everything in the thread is 914. It might give you some ideas on a chassis fixture/cart that would work well for a 911.

Here are factory pics for front suspension pan fixture that I collected from that thread:









and a few more that I saved off as reference for the cart if I ever decide to build something similar:











And one more of all of the diagonal measurements of the pan



I know it's all 914 stuff, but maybe it will help with some general ideas that you can transpose to a 911 tub. The front fixtures would be almost identical.

[scootermcrad]

Shuie,

Thanks for sharing that stuff! I appreciate it! Definitely some interesting ideas right there!

[Tom '74 911]

I like that 914 cart! I've made a few tub dollies for rolling around & storing stripped tubs, but that one is cool.

I'll try to remember to measure my bench and post back. It's a MUF7 I think.

I think the most difficult part of fabricating the fixture table will be getting it flat and having a (close to) perfect zero plane to start from. Metal plate is never 100% flat and once you introduce heat (welding) all bets are off! And... having a good base/zero-plane to start from will make everything easier, so it'd be worth the time to get it as close to perfect as possible.

I know that nothing in my shop ever seems flat and I never assume that it is if I'm doing something that has critical measurements involved. My floor especially! Shimming seems to be a fact of life in creating flat workspace, so plan accordingly. Building in some leveling screws to the fixture table would be on my list for sure.

In terms of other fixture locating points on a 911, here is a factory Celette set up sheet for reference. Maybe you've seen it already, but I think it's a good place to start. Once you have the zero plan set and good and the chassis mounted squarely to the table, you could use the factory dimension sheets from the workshop manuals to measure any/all necessary point to check for compliance.

I also have a device by Celette called the "Symetro" that attaches to the bench and is like a big gantry type device. It's not 100% square, but good for getting close... Helpful to use when things are tweaked etc...

[scootermcrad]

Originally Posted by Tom '74 911

I like that 914 cart! I've made a few tub dollies for rolling around & storing stripped tubs, but that one is cool.

I'll try to remember to measure my bench and post back. It's a MUF7 I think.

I think the most difficult part of fabricating the fixture table will be getting it flat and having a (close to) perfect zero plane to start from. Metal plate is never 100% flat and once you introduce heat (welding) all bets are off! And... having a good base/zero-plane to start from will make everything easier, so it'd be worth the time to get it as close to perfect as possible.

I know that nothing in my shop ever seems flat and I never assume that it is if I'm doing something that has critical measurements involved. My floor especially! Shimming seems to be a fact of life in creating flat workspace, so plan accordingly. Building in some leveling screws to the fixture table would be on my list for sure.

In terms of other fixture locating points on a 911, here is a factory Celette set up sheet for reference. Maybe you've seen it already, but I think it's a good place to start. Once you have the zero plan set and good and the chassis mounted squarely to the table, you could use the factory dimension sheets from the workshop manuals to measure any/all necessary point to check for compliance.

I also have a device by Celette called the "Symetro" that attaches to the bench and is like a big gantry type device. It's not 100% square, but good for getting close... Helpful to use when things are tweaked etc...

I agree with all of that. It's incredible how much stuff moves when you start welding. Ideally you would have to build a fixture (for the fixture) and then normalize the whole shubang, I suppose. TALL order for a project like this. Maybe a bolt-together deal like Flank's, is good for this reason. Less pulling of lateral members. If each component is true as a stand alone part (i.e. machined flanges, etc.) then maybe that's a good recipe for a home-brew table.

I suppose, what I could do is actually take the whole chassis/tub over to Zuffenhaus and have them check everything on their Celette, and if the car is good how it is, then use that as a guide, in addition to factory dimensions shown. Lots involved with that plan, and building a dolly to truck it "true" is yet another task, I guess. Almost becomes a chicken or the egg, kind of deal.

All just thoughts for now.

I envisioned a base table something like that 914 setup shown earlier, but a little more stout and constructed of heavy web I-beam, similar to the Celette. The ability to shim and or move portions of it to get it true, would really be desirable for sure. The reality of my situation is, I'll set up the table for the 911 project, get it true with the fixturing in place, do the projects, and then tare it down for use much later. Probably store a car body on it for another project, actually.

It's all an argument of money versus time at the end of the day, I guess. I have more time than money. I'm in no rush. If my tub had evidence of being in a wreck, we wouldn't be having this discussion at all.

[Tom '74 911]

Originally Posted by scootermcrad

It's all an argument of money versus time at the end of the day, I guess.

This is exactly what it boils down to and the reason I decided to swallow my checkbook and buy my Celette set-up instead of fabricating my own. I'm a big DIY'er and fan of DIY'ing as much as possible, but at some point, it's not worth reinventing the wheel.

It's all fun to ponder though - and free to do so too!

Tom

[scootermcrad]

Originally Posted by Tom '74 911

This is exactly what it boils down to and the reason I decided to swallow my checkbook and buy my Celette set-up instead of fabricating my own. I'm a big DIY'er and fan of DIY'ing as much as possible, but at some point, it's not worth reinventing the wheel.

It's all fun to ponder though - and free to do so too!

Tom

Yeah... I've definitely become a DIYer out of necessity. I would buy a Celette in a second if my I could swing it, but that's a bit too much dough for my modest (read slim) hobby funds. I by no means will be cutting corners, just looking to be resourceful for my needs.

I think I would lean to purchasing the Blackhawk reproduction fixture sets and see about building the table to support them. Probably makes the best financial sense, and they could be sold when the project is over. I could even CAD them up in SolidWorks (or scan them) so I had good documentation in case I needed a set in the future. In the end, I still have to have a frame table to support them. It won't be Celette, unless I come across one that someone is literally just unloading.

One thing is for sure... Some kind of fixture, is better than no fixture for some of these projects.

[scootermcrad]

Bump for a new day, with some West-coasters just climbing out of bed.

So my main mission here is to properly support my chassis/tub while I do floors, front suspension pan, and the painful task of repairing/replacing my torsion bar tube. if a whole table makes sense so I can do this all at once, than that's what will be done. Once the projects are complete then this table/fixture will be re-purposed for some other chassis projects, so flexibility for future use will be important.

The other option I COULD throw into all this is the option to make this work with my hoop rotisserie, however I believe anything I build for a fixture will be far to heavy to support the weight of the chassis/tub AND the fixture. It was really intended to be used with a body and a transport dolly, of sorts.

Anyway... bumping up for this fine Tuesday with the hopes of some fresh input on this "home brew" flexible fixturing project. I promise I won't beat this to death though.

Thanks for all the helpful input so far! Some great ideas here and definitely helping me answer some of my own questions and bring up things i hadn't thought of.

Cheers!
S

[Fixer]

It's great if you have this equipment and would feel great to use it while welding. But imo a good home built frame or chassis support is all that is usually needed.

Things absolutely do move or are fixed in the wrong place when people weld in haste. I'm dealing with (2) swb cars at the moment in which this is a problem. I 'd much rather work on an untouched rust bucket than a car that has had prior repairs.

Many who do a fine job at restoring these cars and others do not use expensive specific fixture equipment but rather make there own chassis supporting device (as mentioned here) and using available data and common sense to get the job done right and within a reasonable amount of time.

I know many craftsmen who spend so much time in preparation and overthinking that projects sit for years and even decades. My Father i Law is one of these. His auto project go on for decades, i don't think he realizes he's 72.

Anyway i.e., you should be able to use your front suspension to check that your suspension pan is tacked in properly prior to final spot welding in place. (unless everything is gone due to rust) But if a normal front pan replacement, a fixture should not be necessary imho to do the job correctly with a good replacement part.

[scootermcrad]

Originally Posted by The Fixer

It's great if you have this equipment and would feel great to use it while welding. But imo a good home built frame or chassis support is all that is usually needed.

Things absolutely do move or are fixed in the wrong place when people weld in haste. I'm dealing with (2) swb cars at the moment in which this is a problem. I 'd much rather work on an untouched rust bucket than a car that has had prior repairs.

Many who do a fine job at restoring these cars and others do not use expensive specific fixture equipment but rather make there own chassis supporting device (as mentioned here) and using available data and common sense to get the job done right and within a reasonable amount of time.

I know many craftsmen who spend so much time in preparation and overthinking that projects sit for years and even decades. My Father i Law is one of these. His auto project go on for decades, i don't think he realizes he's 72.

Anyway i.e., you should be able to use your front suspension to check that your suspension pan is tacked in properly prior to final spot welding in place. (unless everything is gone due to rust) But if a normal front pan replacement, a fixture should not be necessary imho to do the job correctly with a good replacement part.

Thanks for the response.

The front pan is mostly intact. Just the usual rust, primarily from the top down (tank support down). The suspension should all be in it's proper place, assuming things haven't been bumped in some way. The unfortunate part is the front latch panel was replaced with a later one at some point (probably to do a slant nose kit or an IROC build), but they left all the early (1970 T) stuff in place. i also believe it was changed long before rust was ever a problem, so it would have been on the road with that change long enough to know if they did damage to the geometry of the suspension pan. The front latch panel will be put back to a long hood configuration as well.

I see most people don't use a fixture for these repairs. Some of which are done without much of ANY kind of bracing, which blows me away, but that's where i figure the more I can do to make it all come together without issues, the better. And really my main concern is the torsion bar tube repair/replacement. I want to make sure that nothing gets out of wack, since i may be doing a lot of cutting into structural members to make these repairs. Won't know until I get in there.

[Willem Fick]

I've been harking after a home built jig for some time. Recently (finally) got a hold of some original chassis blueprints as well as some inspiration. The design so far:

[Willem Fick]

Right so the start of a 911 chassis jig that I showed last sort-of evolved a bit, leading to a final design that looked like this:



Contracted the manufacture out to a local engineering shop, and roughly US$2000 later, this is what we have:





Key features include retractable leg assemblies that allow the jig to be leveled, and removable castor wheels that can be used to move the jig around when the legs are fully retracted. In addition the jig is re-configurable so that the drive-train can be instaled or removed with the chassis mounted in place.

An additional feature is that is has been made a generic as possible, which means that we can now whenever we need just design a couple of posts, bolt them on, and then extend the capability of the jig to include other Porsche's, notably a 356 Cabriolet "D" that is awaiting restoration!

With the jig now done a and dusted (short of painting it in a Martini livery), I have now moved on to my next Porsche related fixture, namely the daddy of all rotisseries:



It features a rolling hoop type mechanism, but as s the case with the jig, allows for it to be reconfigured for other Porsche's.

[nathanbs]

Cool beans. Have you seen the hexagonal "rotisserie" fixtures that Rod Emery designed and utilizes? No wheels as one man can literally tip the car onto any one of the sides of the hexagonal hoops by himself and slide the whole thing around assuming that you have a smooth concrete floor. I was pretty impressed by its simplicity and it hardly takes up more room than a car. Worth looking into to

[Willem Fick]

Nathan, I've seem the "octisseries", but I really need someting that can remain absolutely stationary, as I have very limited space.

[nathanbs]

Originally Posted by Willem Fick

Nathan, I've seem the "octisseries", but I really need someting that can remain absolutely stationary, as I have very limited space.

Oops octagon yeah that makes a lot more sense. Yeah smart and interesting on limited space. Never thought of that. Sure it takes up more space but is perfectly confined within that space.

[Tom '74 911]

Impressive jig. Neat piece of manufacturing and a deal @ $2K. Definitely take the time to verify that it's square & level.

The rotisserie will be great too. I've seen one like that before...

(Not mine)

[Tremelune]

Are you planning to do many cars or just a few? How much does it cost to have a reasonably straight car put on a Cilette and made perfectly straight?

My car will one day see paint, and I'd like to make sure the chassis is absolutely 100% before spraying.

[Willem Fick]

What is a jig if it doesn't have a glossy coat of paint!



We are planning on doing multiple cars done, so costwise this was a great investment. Problem as I mentioned is that guys around here (if they have the correct fixtures for their Celette) typically want to do all the other work too, and thos is not something we like to farm out.