Frame rails... Options

[brant]

Mike,

one more thing and then I'll shut up and let Jeroen and others reply....

I don't think that you have too worry tooo much about this area on a street car.

Brad always used to say it was only problematic on cars with around 300# springs...

I talked to AJ, and he kinda reinforced Brads statements.
AJ said that on the HUGE tube frame cars (with Downforce) they have to run Big springs (due to the downforce) and so they go ahead and reinforce those cars....

What I'm trying to say is that on a street car its not a common failure.

brant

[Gint]

I hear ya, but if I want to do it, now is the time.

I don't baby my cars.

This car will see the track, even if it isn't much for the first few years.

It will get Mueller bearings which may necessitate stiffer springs.

It may also get much more motor and some point in the future.

And it could very well see significant track time after the shine of the resto wears a bit.

[Eric_Shea]

Me agrees with Brandt.

Here's what we (Mike and I) discussed over the phone:

I thouhgt the longitudinal was spot welded there. A visual inspection of the tub kinda bears that out. As a "while we're in there" philosophy for a street 914-6 that might get driven hard, I thought that seam welding all the factory GT points like what Brandt has done (both inside and out of the shock tower) would be good. I also thought that one who knows how to weld very well could lay a bead down that line inside the rear shock tower where the longitudinal meets. With proper penetration of the weld it would make it stronger. You can see the spot weld so you can follow the joint, effectively seam welding from the backside.

Either that or not worry about that seam and seam weld all those other areas previously discussed.

Thoughts?

[brant]

I know I said that I'd shut up, but oh well.....

my thoughts:
-probably not totally necessary
-better bearings should acually reduce the effective spring rate...

but if it was mine, I'd do a little bit of it since your there and it hasn't been painted yet.

brant

[Jeroen]

Ok, I'll try and explain best as I can...

In the pic below, the sheetmetal plate marked "A" is basically the outside of the engine bay/reartrunk firewall. With outside, I mean the part that you look at when viewing from the rear trunk.
This piece runs from inner fenderwell to inner fenderwell.

At the seam marked "B" you can see how part "A" bends inward toward the rear window.
It sorta bends over the top of the long and is spotwelded there.
These spotwelds can be seen if you remove the seamsealer around the shock tower.

At the seam marked "C" the long has a small lip (aprox 1/4") that is folded to the inside of the long. This lip is spotwelded to part "A" from the outside (shocktower side).
They must have done that before the shocktower was welded in place.

So basically, part "A" is welded in between the shocktower and the long.

The seamweld I made on top, directly welds the long to the shocktower (because I grinded part A flush there)

Hope this makes sense... If not, shoot some more questions

[Jeroen]

If you wanna keep the firewall in place, like Brant. Doing what he did is a very good option.

In addition (I'm not sure if Brant did this) you can do some extra seamwelds on seam "B"
Seamweld part "A" to the long (from the engine bay) and seamweld part "A" to the top of the shocktower (from the rear trunk)
By doing so, you basically seamweld the top of the long to the top of the shocktower

[hargray2]

So you are referring to all of the area highlighted in yellow plus an area that can't be seen in the picture, which would be just below the letter D, right.

[URY914]

Jeroen,

Isn't the sheet metal on the shock tower a heavier (thicker) gage than other areas?

It seems like it when I tap on it (I know, not real scienific)

Paul

[URY914]

I'm going to cut my firewall out. and I'm going to cut the sheetmetal out that the tranny mounts to. I'm gonna run 1" tubing from the shock towers down to hold the rear od the tranny. (IMG:style_emoticons/default/sawzall-smiley.gif) (IMG:style_emoticons/default/welder.gif)

Paul

[Gint]

Ok, I'll try and explain best as I can...

Thanks my friend. I think we have the info we need now.


One more picture and commentary from another of Jeroen's threads. Just for completeness. This picture will help those like me who originally had trouble envisioning all of this without an actual 914 in the garage to look at. The cutaway of the firewall was especially helpful I thought.

I think this entire thread is a pretty good pictorial and description of the issue.

It's because the crappy connection from the framerails to the shock towers

Look at the picture below... the firewall has been cut out and shows the crappy connection from the framerails to the shock towers (green arrow)

The spotwelded seam from the firewall (blue arrow) is supposed to take care of all the stress... and like you noticed, it won't do a very good job at that...
(IMG:http://www.914world.com/bbs2/uploads/post-2-1065887028.jpg)

[Jeroen]

Isn't the sheet metal on the shock tower a heavier (thicker) gage than other areas?

Not as far as I know. I believe that all the sheetmetal on the car is the same gauge

I have a cool pic of a disected (sp?) shocktower on my home computer.
It shows just how amazingly complex the 914 is
I'll post it when I get home.

[Jeroen]

So you are referring to all of the area highlighted in yellow plus an area that can't be seen in the picture, which would be just below the letter D, right.

Daniel,

The weak spot is seam "B" and "C"
Some aditional welding round the shocktower wouldn't hurt of course...

[davep]

I think a fully dissected set of views would be really helpful. Something to think about at the next sawzall party. Mark up all the pieces the factory used and kind of sequence the build process. Part B is spot welded to Part A along seam X. That would help us visualize the strengths and weaknesses of the construction. Then we can determine various fixes for street, track and race cars. Knowing where all the cavities are helps. I imagine the design engineers had a lot of fun trying to figure out how to build these cars.

[Jeroen]

Here's the disected shocktower pic

This is just on example of how complex the bodystructure of the 914 is
It's just a briliant piece of design, even to today's standards
Then imagine the figured this out in the late sixties. No fancy CAD computers, nothing but a piece of paper and a pencil
When you're at a resto shop, you should take a look at some other cars of similar vintage. They're a joke compared to the ingenuity of the 914

I should have some more pics like this, I'll do a search...

(I can't take credit for this pic)

[URY914]

That is a great shot.

[Jeroen]

Some sawzall pics, courtesy of Mike Mueller

Driver side shocktower

[Jeroen]

drivers side front shoch tower

[Jeroen]

drivers side front shock tower - close up

[Jeroen]

firewall (passenger/engine)

[Jeroen]

rear trunk, x-section of the dogbone, near the tranny mount