real RSR strut brace

[RWebb]

Can anyone tell me if this Al strut brace is an actual Porsche part or just an aftermarket piece?

[onboost]

It's probably not factory.. assume by "Al" you mean aluminum.

Factory bracket pieces would be mild steel.... and in most cases so was the bar though I have seen some in aluminum.... don't believe it to be factory though.

I have one of these and need another.. where did you find it?

Thanks,

[Steve@Rennsport]

Randy:

Thats aftermarket; real RSR ones were steel.

[RWebb]

Thanks.

I saw it on eBay - the ad is over but it said it would be shipped from Germany but a US address in NC was given... no answer to my questions about that or whether it was OEM.

I'm wondering if it would work any better than the typical braces that bolt to the top strut mounts...

[kycarguy 935]

My factory 79 DP car has a very similar unit. The side pieces that get welded to the strut tower are steel and the bar is aluminum with similar reinforced welds on the tubing. I have had the car since 1991 and think its original to the DP935.

Its a timely thread since I have been thinking of restoring the one I have or buying a new one.

[911pcars]

Domestic chassis mounts can be found which are very similar if not exact. The holes must be drilled accurately (or the mounts welded the same) since there's no provision for bar length adjustments (MHO, seems a little restrictive). But, if one must have the look of a genuine RSR bar ........

Sherwood

[myfast911]

i first bid on one of these last year,and was out bid by $ 2.00. he emailed and said he had one more if i wanted it for $76.00.something smelled fishy about it,so i passed.since then the same listing has been popping up. make sure you read his feedback before you buy!something still doesnt seem right about these things.

[andyjboy]

These strut braces are offered regularly on german ebay by different sellers.

I've bought 3 or 4 of them & fitted them to my 2.8 twin-plug & 911R-inspired cars.

Typical price paid was $75-$100 inc shipping (to the UK).

[rusnak]

My knowledge of Porsche racing cars is not that great, so I could be wrong. But didn't the RSR cars have fully triangulated frames with detachable front fenders? If so, this would negate the need for a cross brace. To add to the confusion, Porsche didn't really run the RSRs did they? I mean if a few privateers ran the cars, then what is a "RSR" brace versus an aftermarket one? I'm sorry if I am making it less clear, but I was just thinking, you know?

I think the "RS" cars were more mild and used pressed steel frames, and maybe they had the cross braces. In any event, I recall seeing some pretty rough looking steel ones, not slick aluminum ones on the old racers.

[javadog]

Here's a couple pictures of a '74 RSR.

JR

[RWebb]

this one is painted like the others I've seen - a magnet would prove whether it was the mild steel OEM or an Al add on...

I've seen those crossbraced ones too, rusnack - not sure which cars had what or when

always possible that some RSRs had these & some had Xbracing too...

[javadog]

An RSR didn't have any cross-bracing from the factory. The later, turbocharged cars did. It's possible an owner or two copied the factory's later design and modified an RSR.

JR

[HarryD]

Randy,

While this may not be of concern to you, a welded in bar system like this has the potential to move you to a higher class in may of the racing organizations. This may be one reason you do not see more of them.

[onboost]

Originally Posted by rusnak

My knowledge of Porsche racing cars is not that great, so I could be wrong. But didn't the RSR cars have fully triangulated frames with detachable front fenders? If so, this would negate the need for a cross brace. To add to the confusion, Porsche didn't really run the RSRs did they? I mean if a few privateers ran the cars, then what is a "RSR" brace versus an aftermarket one? I'm sorry if I am making it less clear, but I was just thinking, you know?

I think the "RS" cars were more mild and used pressed steel frames, and maybe they had the cross braces. In any event, I recall seeing some pretty rough looking steel ones, not slick aluminum ones on the old racers.

RSR car were not necessarily fully triangulated.. that is something that varied from car to car/team to team.





Confusion yes, as Porsche did in-fact race the RSRs as well provide them to the privateer teams both here and in Europe.

Both RS and RSR tubs pretty much start out the same as production cars so I'm not sure what is meant by ""RS" cars were more mild and used pressed steel frames" Wouldn't really have anything to do with needing or not needing the strut brace which is merely to add some torsional rigidity between the shock towers.

These braces themselves were all pretty crude looking as you suggest although some did take the liberty to substitute the bar with aluminum. The mounts on the shock towers are always steel.

[rusnak]

Hey JR,

Those are some great pics! Can you post more, preferably of the front strut area under the front fender? I am interested in what chassis reinforcements if any that Porsche may have included. This seems to debunk the myth of upper strut chassis reinforcements on the RSRs.

I did some more reading and it appears that in 1973 the RSRs were undergoing development, and by 1974 had sprouted the more familiar air intakes in front of the rear fenders that differentiated them from the RS. In 1973 the RSR looked a lot like an RS, and I would bet many were misidentified. By 1976, and in Group 4 or Group 5 specs, the 934 started where the RSR left off. The 934s had tubular-reinforced sheet steel frames, and externally looked a lot like the RSRs, and could be mistaken for one. Things get really confused when people refer to the 934, such as the 1976 Jagermeister 934, a "934 RSR". I guess the RSR label covers a period of 911 development from 1973 to 1977 (some people do not include 1973), and turbocharged engine development, more than a single actual racing car. It seems that no one calls the 935 an "RSR" though. I think the reason Porsche exploited the RS/RSR designation was to avoid repeating the 500 unit homologation run each time they wanted to upgrade their racer. They advocated their opinion that the RSR was an evolution of a car that was already homolaged, the 2.7 liter RS.

That all brings me back full circle. If a 934 is an RSR, then what is an RSR strut brace when some of em had tubular frames that negated the need for a strut brace (see picture below)? I guess some RSRs had em and some didn't? Or should the strut brace be called an RS strut brace, since all of the racing RSs all had em? Production RSs were basically a 2.7 911 with factory option M 471, 472, or 491, not including the 500 homologation RSs built at the end of 1972.


Some really interesting pictures and stuff here:
http://www.pbase.com/slidevalve911rsr/911rsr_vintage_photos&page=1
http://www.vpracing.com/The_Cars/the_cars2.html
http://www.early911enthusiast.com/porsche_models/1973_porsche_carrera_rs.html

[onboost]

Nice sites .. a couple of which I'm already familiar with but very cool none the less...

Nice lesson in history albiet with a number of errors which I don't have the time to discuss... however one of the things you fail to address that clouds the picture even more when you speak of RS, RSR, 934 etc.. is whether or not the car was being used for FIA, GTO or GTU.. all of these classification would denote a particular engine size, use or non-use of Turbo, and what body configuration allowed. It's neat to refer back to all the books and websites that address these cars, but not all are complete with hard facts.

The tube frame cars that you continue to speak of would be the 935s... Many 934s were converted to 935's in the early years.. and have been converted back to 934s in recent years. Having had the pleasure to help crew for a local team that owned and raced both, and later being involved in restoration of the 934... I think I can say I've been up close and personal enough to both see a appreciate many of the differences between the two.

Niether of the cars you picture in your post are tube frame cars... they both appear in 934 configuration and are thus turbocharged. And yes that triangulated cross brace appears to be aluminum.

JR: That is a great shot of the cross brace.. I'll take some of mine when I get a chance to put it in!

[juicersr]

Orignal 'factory' turbo rsr strut:


'73 RSR strut:

[911pcars]

What's the purpose of your inquiry? To make it look period-correct or to make the front end more rigid? If it's the former, so far it looks like less is needed, just an "RSR strut bar". If the latter, then you have more work to do with the cross brace.

Sherwood

[RWebb]

Thx Harry & others. As usual with Porsche... the plot thickens.

Sherwood - my query (way up above) is mostly curiosity as to what does a better job - the simple tie braces that anchor to the top of the struts, or the "RSR" type braces which anchor to the welded U channels. I'm sure the Xbrace is stronger still, so will leave it out for now.

[911pcars]

HI Randy,
Thanks for the clarification.

On a track car, the top of the shock insert is usually secured by a spherical bearing that allows only slight rotational movement. Any attempt to establish an anchor point at this location results in stress on the insert and eventual failure - somethings gotta give.

However, since the shock tower metal is fairly rigid, it's a natural place to install a bar mount to bridge and stabilize both sides.

The street-based strut bars that anchor the chassis to the shock insert, like the WeltMeister version, depend on the compliance of the rubber around the insert to allow some movement - but still not theoretically healthy. However, in the case of the WM mount bracket, it can be modified so the insert is free to "float" inside the mount so only the chassis is the anchor point on each end of the horiz. strut bar.

Maybe it comes down to the design of the strut mount bracket that provides more rigidity. Most of the mounts I've seen appear adequate for street use. However, for the track, I'd take a closer look at the options. For example, the RSR mounts look fine, but I'd replace at least one end of the strut bar with a heim joint (rod end) to provide some adjustability and preload options.

Sherwood