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Unread 08-31-2009, 07:43 AM   #1
Julian Allen
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Default The building of a turbo RSR

I'd really like to see this site have more attention, so I thought I would repeat the story of my 968 turbo RSR's build.

A few years ago I put my track time on hold. I had been racing a 951 S, going to 5-6 events a year. The car was tired, and I had two in college at the same time. And then a wedding. And then another wedding. Long and short of it was, there was not cash to keep the car in good form. So, I embarked on upgrades and rebuilds. Until an eBay ad showed two 968 chassis, one a turbo S and one a turbo RS. Seems the cars had been Freisinger's and they found their way into the states. The RS of course had a cage, but it wasn't the newer cage on the red or the white car. And I had some cagey ideas of my own. So, I watched the S closely, and bid to win. I brought it home about eight years ago.

I started by taking lots of pictures. And got lots more from the fellow who bought the RS chassis, as well as Bruce Corwin when he owned the white car. Searched for factory solutions to roll cages in coupes, and made my plans.

I cut out the rear deck, fueling hose covers and the spare tire well. I removed the coil and power steering pump brackets. And the parking brake stuff. And the hood release brackets. The car already came without a lot of undercoating, and a sunroof delete roof. I bought some steel and borrowed an hydraulic bender. Made mockups and patterns, and (a large pile of misbent tubing later) managed to create a cage that looks a lot like the modifed Matter cage you see in RS's 1 & 4, with the braces to the front strut towers and to the rear shock upper mounts. I seam welded, well, nearly everywhere. I built brackets for a dry sump tank in the passenger foot well, and isolated it from the rest of the cockpit. I put in a mount for a fuel cell.

In the 951, rear tire width was always an issue, particularly when the car was lowered and given negative camber, because the tires always rubbed on the inside of the rear wells. I sacrificed the 951 to see how the rear elements were put together, then modified the 968 to accept Kevlar tubs. I added flares like you've seen on the yellow car Kelly-Moss participated in, and, well, can you say 335's in the rear? They're a snug fit, and the final rubber is still quite a ways off, but I now have that flexibility.

The factory RS's have air jacks, so I added the tubes to mount them. Only the factory gave three and I couldn't put the rear one in because I wanted the fuel cell to be a little further back. So I put in four, at the corners of the floor.

In the 951 I successfully used the front "frame" elements as a channel for air to the brakes. Always liked the carbon fiber ductwork you see on 996 and 997 race cars, but that sort of one off work can break the bank! So I inlet a 4" tube ahead of the wheel well, and inside the well forward of the strut. 4" ducting is much more flexible and doesn't kink as much as 3", so I could deliver more air to the front brakes. I used an aluminum "plate" to deliver the air into the center of the rotors, although for the new car I may make this out of stainless.

And then I moved from Florida to Alabama. The project stopped for a couple of years for various reasons. Over the past two years I worked to complete the welding--mounts for this and that, trying to look ahead so I wouldn't get a finish on the car and then sand it off to mount something I forgot. Probably a good thing to have a pause, because some safety features get better (I added mounts for a right sided net).

Finally this year I made arrangements to dip the car--to remove the factory primer and undercoating, as well as clean up some light rust that had appeared in places. I've posted on other forums about my experience, but the short version is NEVER take your car to Wauchula, FL and I'd highly recommend the shop in Allentown, PA. After stripping, it's been well washed, phosphated, and now is powdercoated.

The car, bumper covers, doors, hood, etc, are all at the paint shop now so the outside can all have the same finish.

When it returns to me, I can finally start assembly. My wife says my shop looks like an auto parts place! And, speaking of parts, I would be remiss if I failed to mention the tremendous help I have received from Buddy Kennedy who manages parts at Brumos Porsche. He, and Richard Pittman at PowderTech Plus in Orange Park, FL have provided me with help beyond measure and I gratefully acknowledge their assistance.

Well, that's a start of the tale. More to follow . . .

Last edited by Julian Allen; 01-19-2010 at 05:30 PM..
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Unread 08-31-2009, 02:49 PM   #2
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wow... this is THE most appropriate post ever for the "this thread is worthless without pics"

This sounds far beyond cool! Thanks for sharing and don't be bashful about sharing more!

Regards,
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Unread 09-01-2009, 06:09 PM   #3
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Pictures . . .


Powder before baking
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After baking
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Unread 09-01-2009, 06:44 PM   #4
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Wow, just Wow...
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Unread 09-02-2009, 08:31 AM   #5
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MORE pictures....we need more...
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Unread 09-02-2009, 08:46 AM   #6
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You got my attention
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Unread 09-03-2009, 05:50 AM   #7
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Here's an "overhead" picture of the bracing to the front strut towers.

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And a picture of how the brace goes to the rear top damper mount.

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With the roof off and the car on its side it's easier to see the other cage elements.

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Unread 09-04-2009, 08:54 PM   #8
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One thing I had made was some transmission flanges. The S/RS transmissions had larger flanges, like 928's and 911 turbos, so higher torque and HP could be managed. But, the flanges on a 968 are unique to our transmissions--similar but not quite the same as those from 911 transmissions.

The factory had some, but I was a little late and got, well, the last one. Only one. So, to have the ability to use the larger S/RS I had Quaife make some reproductions. Here's some shots.

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Unread 09-04-2009, 09:00 PM   #9
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very nice stuff
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Unread 09-05-2009, 05:06 PM   #10
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I had always wondered how "traditional" front wheels could have centerlocks. It's fairly straightforward when the front is like the rear with a bolt from the inside and paired ball bearings, but haven't you wondered about the front?

I was able to obtain a set (the factory actually sold them that way in Weissach) of centerlocks for the car.

Here's the front: a modified (billet) hub with outside threads where the hub/grease cap would go, and a screw on cap with an integral stud for the centerlock.

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Here's the hub without the cap so you can see the threads:

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And here's the rear--just like seen on 964/993/996 racers from the factory, with a slightly different center bolt.

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Once the bolt is torqued down, a "locking cone" fits into slots machined in a standard rear hub, keeping the bolt from coming loose when you remove the wheel.

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More to come!
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Unread 09-05-2009, 06:39 PM   #11
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Holy crap, you've got some awesome stuff going on/in the car
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Unread 09-07-2009, 12:57 AM   #12
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Nice project! I guess I came to the 968 after all the cool parts had gone!
Could you past a pic of how the brace connects to the rear top damper mount?
Do you have a special axle to connect to that transmission flange?
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Unread 09-07-2009, 05:08 AM   #13
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The axles are different. The inner CV is I think 102 mm and uses 8 mm bolts. The outer CV and the stub axle are made together, which must allow a larger CV which will still fit inside the trailing arm. That's the way the cup cars and current factory race cars are made also.

These two pictures show the brace from the main hoop down to the top of the "cup" making up the top rear damper mount.

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Click the image to open in full size.

And although this isn't the best shot, it shows how the brace is welded to the cup from below, as well as the cross brace. The cups were seam welded to the chassis also. You may notice there is a bit of the rear side of the cup missing: that's so the fitting for the remote reservoir for the damper will clear the cup.

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Unread 09-07-2009, 07:01 AM   #14
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Thanks for that, so I guess you have a set of those axles as well? I've always been more concerned with the strength of the gearbox, but porsche always does thing for a reason....
Thanks for the pics, I will have to check my own next time I get a chance.
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Unread 09-07-2009, 03:13 PM   #15
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The half shafts are 28 mm rather than the 26 mm of my 951. My bad, the inner CV is 108 mm and the bolts are 10 mm.

Pix:

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