Structural Reinforcement - Page 10

Travis Neff · 01-10-2007, 07:13 PM

Question for you 911 guys. What differences between 1969 and 1989 are there for the inner longs? Coupe, Targa & Cab? My first thought is that they are all the same through these years, but I am not 100% sure.

911pcars · 01-10-2007, 09:23 PM

Quote:

Originally posted by Travis Neff
There are no kits for 911's. This particular kit was 18G steel and could be made DIY. I will send PM to the guy who makes the kit to see what he thinks.

Take a look at my post on the second page of this thread. A company called Eurotek can provide the pieces for your 911 targa or coupe.

Structural Reinforcement

Sherwood

randywebb · 01-10-2007, 10:34 PM

As DG624 pointed out, we need to know if these things can make a coupe stiffer to the point that the effect can be felt.

Also, someone once posted (maybe on this thread, maybe on another one) that stiffness was not something you'd feel on a street car. But if this were true, manufacturers wouldn't go to such trouble to make modern cars stiffer -- and they do.

Walt Fricke · 01-11-2007, 07:55 PM

Travis

The 911 longitudinals are formed from stamped and welded together pieces of sheet metal. The Targa/Cab longitudinal has an extra length of sheet metal welded into the assembly.

The A pillar is similarly formed, and the Targa/Cab A has one more layer of sheet metal in it.

Targas/cabs also have an additional layer of sheet metal in the "kick panels."

At some point they were, I think, also given an additional stiffener inside the cockpit to the lower B pillar.

And precisely how these things might have changed over what years I can't say. For instance, the early Targas had a separate steel bar bolted crosswise under the dash (my '68 race car has the attachments at each side). At some point Porsche quit doing that, either because they determined it was doing no good, or because they added some extra sheet metal somewhere.

When I get them suitable for prime time, I'll post some pictures I took when my car had a new front end added by cutting the old front off part way up the A pillars and roughly through where the shift lever is, exposing the layered construction.

Walt Fricke

randywebb · 01-11-2007, 08:14 PM

Thx Walt. I count at least 4 things done to stiffen the cabs and targas from your post.

The pics will be a great asset...

randywebb · 01-11-2007, 09:07 PM

Besides the above added sheet metal in targas and cabs, I've started a thread specifically to explore anything we can find on sheet metal or welding changes to later years of the coupes:
http://forums.pelicanparts.com/porsche-911-technical-forum/324403-added-sheet-metal-later-coupe-bodies.html#post3032992

Also, that thread is for driving experiences in the different years that might amplify rdane's comments re how much stiffer the later coupe felt.

I thought a more specific thread would be better than just dumping a lot of thoughts into this one. We can then summarize the threads separately and finally create a new thread with the bottom line in it (like the summary thread JO did on Black Booty II).

911teo · 01-12-2007, 06:18 AM

At Zuffenhaus (the shop working on my car) they are backdating a 964 C2 to RSR. They are obviously still working on my car (74 tub).

I will go tomorrow and take pictures of both cars to see the differences.

My car has been modified pretty bad, but you can still see where and how Porsche reinforced the later models.

There are extra welds everywhere in the front and the metal itself seems to be thicker.

Any particular angles you guys are interested in?
Both car should be completely stripped, so that will give us a direct comparison.
Let me know.

randywebb · 01-12-2007, 01:07 PM

I'd say pics of anything that was changed...

rdane · rdane's Garage

Quote:

Originally posted by TRE Cup
The only roll bar they had was a simple ST style hoop with diagonal and Penske installed harness bar near the base of the back Y. These were bolted in to the welded in plates on the main hoop and the rear seat hinge pins. No B pillar attachments

Quote:

Originally posted by randywebb
Anyone have measurements - or driving impressions - from seam welding?

FWIW we seam welded the rain gutters from the dash board to the end of the drip rail. That stiffened the car up enough to notice. Then we added one of TRE's RSR roll bars and bolted it to the B pillars as well as to the rear seat belt holes and the welded in side plates. That added even more to the planted feel of the car. Between the two I think the bar made the biggest differnece and was a good bit cheaper to do even after welding on the tabs to bolt it to the B pillar. Makes the roll bar more like a a king kong harness bar for adding any stiffness.

Put both mods together though and the car feels a lot more solid.

Adding a harness bar bolted to the B pillars of the '72 didn't seem to offer anything you would notice. Doing the same to the '79 was something you would notice.

randywebb · 01-12-2007, 02:48 PM

Thx - we're on a no bar thread tho. As per thread-starter Sherwood's injunction, bars are barred.

911pcars · 02:59 PM

For the purpose of this thread, we should consider installing a roll bar or cage as "cheating". We know adding tube structure will help the rigidity of any chassis, but let's concentrate on what it takes to stiffen the basic unibody without obvious structural members.

However, it's good to know what also doesn't seem to work (harness bar).

Regards,
Sherwood

PS: or..... uh, I concur with Randy

Wrecked944 · 02-12-2007, 10:17 AM

Here is a link to a guy who designed his own race car using some pricey software and posted the results of his structural analysis to the web. Not Porsche related but pretty cool (actually the whole design/build blog is really cool).

http://dpcars.net/dp1test/index.htm

randywebb · 02-12-2007, 11:02 AM

A recent thread indicated that the wt. of a bare 964 was very little more than that of the earlier 911 tub. One feature is that the 964 has a larger center tunnel welded in -- it serves a similar function to the backbone on the dpcars.net web page noted above.

911teo · 02-12-2007, 12:10 PM

I owe you guys pics of my car (74 911) vs 964 to see the differences in the welds up front... I haven't been able to have them side by side yet. Sorry.

blue72s · 02-12-2007, 05:04 PM

Quote:

Originally posted by randywebb
One feature is that the 964 has a larger center tunnel welded in -- it serves a similar function to the backbone on the dpcars.net web page noted above.

I think only the C4, not C2, has a larger center tunnel.

randywebb · 03-16-2007, 11:25 AM

The spot welds on the unit body are 1.5" apart (I erred in giving a value of 3" on another thread). This is for a 1971 coupe belonging to a friend.

There is more on increasing the stiffness of the unit body in this thread:
Shaved gutters: What exactly is the water concern?

boba · 03-16-2007, 11:55 AM

I just saw this thread and not to cut off Matto I have some pics of his car and the mentioned 964 on my computer. These are not same angle and area but may provide some insight untill Matto can get some same area/same angle pics. First 964 just back from bake off.

Now Matteo's 74

boba · 03-16-2007, 11:58 AM

Sorry posted the same pic twice, here is the other one.

troy jones · 03-16-2007, 05:23 PM

I haven't tried this but it might be worth checkink out it's on ebay. I havn't figured out how to provide links, but here's the item # Item number: 180066648910

island911 · 03-16-2007, 05:31 PM

Quote:

Originally posted by troy jones
I haven't tried this but it might be worth checkink out it's on ebay. I havn't figured out how to provide links, but here's the item # Item number: 180066648910

so that people don't need to search for the laugh...

My favorite line: The cross floor bar kit will maintain a stiffer center of gravity and a locking motion in your chassis. The overall suspension and handling will increase by 15%.