noddy981

Here's a question for you. How come Porsche's GT4 RGT rally cars able to stand up to this rallying abuse? Has Porsche strengthened the underside of the strut tower - as they did with the rear struts on the standard GT4? OR is the standard strut tower strong enough as it is and using different shocks and springs the answer to the abuse these cars take ? Check out at 1.44 and 2.15 seconds typically.

noro

Willing to bet that car has many body strengthening welding done throughout.

Arcanum

Factory built rally cars typically have cages that punch through the bulkhead to the front strut towers to increase stiffness and improve safety.

Porsche may not have gone this far with the R-GT, but it wouldn't surprise me if they had.

Maxi_z

[QUOTE=noddy981;15900634]Here's a question for you. How come Porsche's GT4 RGT rally cars able to stand up to this rallying abuse? Has Porsche strengthened the underside of the strut tower - as they did with the rear struts on the standard GT4? OR is the standard strut tower strong enough as it is and using different shocks and springs the answer to the abuse these cars take ?

Well I tought that it could be a good idea to ask some advice directly to that French team so I just wrote to them

GoKart Mozart

In theory you are correct, but I bet a strut tower brace does help a little. I wouldn't say it prevents the failures, but with the strut towers angled inwards, any upward motion would put some pressure towards the inside, or against the other tower if they are joined, which should spread the load at least a little.

I've been busy getting ready for an upcoming vacation, but when I return I hope to work on an idea that incorporates some of what has already been done, but with an added anchor point and other improvements. Something I noticed, and why the Motorsport plates are maybe not the ultimate solution, is that the top of the strut towers have a slight raised "boss" around the slots, where the strut is mounted. IMHO, whatever plate rests on the top, should be recessed a bit, so that the plates sit on the actual surface main surface, not just those 3 bosses,especially if the plates are not that strong, which the MS plates aren't. I bought a set of them, and they and I can bend them bye hand a bit. That can certainly be improved upon.

Maxi_z

That s also what I think

I would fit a strut tower brace even if it would do not much the only thing is I would not like it to make the opposite effect in some way

For example if for some reason it could be better to leave the chassis flex a little or if it would put some load on the other strut in a wrong angle that could then not be good for the other strut

Maxi_z

Maxi_z

I found on internet those strut bars for anyone interested but of course I don t know at all if it s an improvement or not

Schnell autosports

Wiechers

Ultra racing

The Ultra racing is a more basic type and the strut plates are probably less rigid but the bar it s welded without joints

I also had a look at the replacement chassis stut part numbers from porsche and the part look to be the same even for the 991 gt3 cup (and the price was about 275 usd only) but many sites list it as not available and replaced with another part number (that you then can t find availabe)

Of course it doesn t mean anything but it could be possible that unofficially porsche revised something about the part itself or that maybe they don t list it anymore as a spare part

Anyone got pictures of a few fails on gt3 rs or gt2 rs?

I think I only saw one picture of a gt3 rs online compared to many gt4 and a few standard gt3

Funny that there are no comments at all of any of the specialist tuners

Joe Weinstein

The amount of vertical deflection/displacement required between the top parts bolted to the shock tower and the body of the shock tower for a complete failure is probably less than 0.5 millimeter. No external bracing is going to prevent a failure. To prevent the problem it would take either an impractically heavy static load straight down on the parts bolted to the top of the shock tower, or it would require the wall of the upper shock tower itself where it currently get punched out in shear to be thickened by a significant amount. This thickening could be done on a stock tower if it was lined on the underside by a form-fitting sleeve of new metal which was then bonded to the underside of the shock tower over a wide surface area and somehow strong enough to bear and transmit vertical loads to a wide area much farther down on the shock tower sides. Actually, the vertical load option could be done with something starting out as looking like a thick shock-tower brace, but with a very rigid beam, and in the middle of the beam, half-way between the two shock towers, it would be pulled down by a vertical member that went down from there to below the chassis to distribute the pull over the bottom of the chassis. This vertical bar would have to be pre-tensioned so as to transmit that needed heavy static downward load on both shock-tower tops.

GoKart Mozart

Well worded. The latter part you described, is what I want to do. Like I said before, I have some ideas, but the challenges are ease of manufacture and install, cost and time (right now). But I think it is doable. I really wish I had an old chassis I could experiment with. Part of the challenge is working on a car that is so nice. I hate tearing things apart on it, just to figure $hit out.

993tt

I had a look at the GT3 Cup Cars they run here in Sweden today and I took some pictures.

d00d

That strut tower bracing isn't being used to solve the cast tower's inherent impact weakness, instead it's to reduce steering looseness by more rigidly locating the tower relative to the tub.
Porsche should be working on a recall to retrofit bonded inverted cups like they did with the rear towers.

noro

I don't want to burst anyones bubble in older posts in this thread but strut bars with pivoting ends are USELESS. They do nothing but give you a false sense of rigidity. Most reputable factory strut bars are have fixed ends. Case in point in the photo above from the GT3 cup car.

noddy981

+1

G-forceGT4

Thanks for posting the photos, it's a neat set-up on the Cup cars. The motorsport plates on these race cars are secured in only two locations (albeit solid chassis bars)!