964 to RSR conversion question

[chancecasey]

Anybody do this, and notice something funny with the front bumper? I'm trying to fit the RSR widebody bumper on the front of my 964, and the bottom of the bumper is a good 2+ inches from the bottom of the front pan of the car. Further, the forward indentation of the front "wall" of the car, to store the jack, interferes with the bottom edge of the bumper as well, so I think I have to cut the bumper.

Wondering if anybody noticed this and what they did, or maybe I just have a really OFF front bumper that is 2+ inches too short from top to bottom.

[mjshira]

chance

This is probably would get more replies over on Rennlist. Geoffrey did this, search there and you should find it. BTW the heater is working great, thanks, it was around 35 today so I was glad to have defrost and heat.

[boba]

Check this thread, may be more than you are looking to do.

http://66.236.61.177/showthread.php?t=318580&highlight=zuffenhaus

[chancecasey]

Yeah I remember that thread - didn't think to look at the pictures but they obviously grafted an entirely new front metal end to the tub and that's a different bumper than what I've got. That is a little beyond the tools and time I've got on hand. So maybe this is a common thing to deal with. If so, that's cool I'll work something out. Just wanted to make sure the bumper I have wasn't way off by being too "short" top-to-bottom-wise.

James - glad the heater is doing the job!

[eimkeith]

Your bumper is normal. The 964 trunk is deeper than the rest, and will protrude below the bumper like you are experiencing.

[jester911]

Porsche Doc did this conversion. I believe his car was in Excellence a while back but he posts here as well. Here is the car he built for sale.
Fs C4RSR

[chancecasey]

Although he has a different bumper (mine is the 74 IROC RSR or "widebody", not sure), I noticed he has a splitter that *appears* to extend downward of the bumper by a couple of inches. This would be perfect but I don't see it in the catalogs for the widebody version, only the narrow version. Doh.

[TRE Cup]

chance
there is no extension for the bottom of the 74 iroc bumper (like a 73 rsr can )
Option 1 is to customize the iroc front bumper . you can extend the face bar section about 1/2-3/4 of an inch and do the same for the lower section. This will give you back 1-1.5 inches. Mind you this is a lot of work and will distort the rsr look a little
option 2 is to section and cut down the bottom of front trunk section on the tub. As it does not serve to mount the front suspension , like earlier chassis, you can angle the cut so it "ramps" the bottom of the car. This can be done a lot easier than modding the bumper and will lend you the correct look you are after

[TRE Cup]

while you are at it, you can also install one of our RSR oil panels to center mount a cooler !

[chancecasey]

That's a good idea - I am playing with the idea of losing my stock 964 oil cooler and going with the one designed to fit in the bumper - though that is more time and $$$ and I'd be cutting up the front of the tub to do it. But if I did, modding the trunk to "sweep up" to the bumper would be a realitively easy "while I'm in there" thing to do.

My only concern is functionality - it is a race car and having the bottom of the bumper (or splitter) 2 inches higher than it *should* be, and stuffing that extra air under the car, might not be so great. It would be interesting to know if the increased 964 *height* dimension in front (compared to earlier tubs) means the bottom of the front is lower, top is higher, or both, in relation to the rest of the car.

[KevinP73]

Example,

[chancecasey]

P.S. Nice "plug", Dave!

[chancecasey]

I guess used Setrab STD172's are about as easy to find as hen's teeth, huh?

[TRE Cup]

aero issues are easily mitigated: get a carrera rubber lower lip and "hide" it on the back edge of the iroc underside. Or find some similar flanged rubber/ flexible plastic material to do the same. If you look at the underside of the ruf yellowbird front bumper, you will see what i mean. Add a splitter to the iroc too, and realize more downforce

a 964 has more "depth" than the 911; the upper bumper height is the same, its what hangs down that is different

[chancecasey]

wow - that is great info! Thanks Dave!

[Bill Verburg]

There were several different versions of lip used on real 3.8RSR
v1


v2

[mjshira]

man, that RSR 964 looks really awesome!

[chancecasey]

Yeah, my scruffier-than-Scruffy will not be worthy!

I did a little measuring - and the rear of the trunk floor pan is about 1 inch higher than the passenger compartment floor pan. The front of the trunk floor pan is about 1/2 inch higher than that, and 4 inches below the bottom of the IROC RSR bumper.

The lowest part of the steering rack assembly is about 1 inch lower than the passenger floor pan.

[MyTurbo3.6]

I have added a set of the factory widebody fenders and front bumper cover to a C4...it is a direct bolt on with no modifications. Additionaly, the factory front lip spoilers simply attach to the bumper cover undertrays with longer screws. If you are using factory parts, they should bolt right up without modification.

I also added two oil coolers behind the front bumper grill area...didn't need to modify the trunk area.

[TRE Cup]

Chance is discussing doing this to his 964, not making a 3.8 RSR look