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964 C2 - RS spec

jamescharnley

jamescharnley

Active member
I'm sure this has been discussed before, but I have done a search & can't find anything.

I am thinking of buying a LHD C2 with the long term aim of converting it to a track focussed car / RS spec car. I am not trying to produce an exact replica of an RS just a track car that gives the RS experience.

What would need to be changed on the C2 in terms of suspension & engine mods etc for it to perform / give me the same thrill as an RS? [:)]
 
Probably best to steer away a little from the RS spec but keep in tune with the basic idea (lightness and more power) you could
1. remove all the interior sound deadening and carpets and replace with light weight carpet set or leave bare. also remove rear seats and squabs at the same time (if your really commited remove the brackets too).
2. replace front seats with racing type buckets (recaro standard fit but expensive)
3. replace front bonnet with ally or carbon fibre (if your really commited do the same for the doors) Fit plexiglass where legal to do so (side rear etc).
4. fit Bilstein HD front and rear shocks or cup car equivalent, revalved to except carrera cup eibach springs. Also use aftermarket or Porsche top spherical mounts. I would advise against fitting road RS parts as these are not rebuildable and so cant be used to upgrade at a later date.
5. uprate you roll bars to suit. You could use RS bars but there are modifications neccesary. Also you could fit the RS trailing arms whilst carrying out no 6
6. Follow Porsches own guide for strengthening the body with limited seam welding where aproppriate.
7. Fit the RS braking system or an aftermarket equivalent brembo etc you could use the c2 hydraulics or update to the RS system.
8. engine, start with what Porsche did to it's cup cars (single mass flywheel/clutch, cup pipe air box mod and cup chip/dme)Use a 91' on C2 to get an engine with the plastic manifold.
9.use later 993 trans or RS G50/10
10. Mag wheels or alternative to help save unsprung weight coupled to track day tyres or slicks
11. for serious over commitment you could also, fit spherical mounts to the front control arms rear trailing arms and eliminate all remaining rubber bushings with spherical mounts. Have a full roll cage fitted multi point and tied to suspension points etc etc etc.
Fortunately most of this is very much mix and max and could be done , as and when. And most of it is just my personal view or preferance.
 
Sorry if I'm a little ignorant to the year build differences for a 964. So a '91 onwards car would be the best starting point? Having had a brief look about there seem plenty of 89 / 90 about but less later cars.
 
There are subtle differences with early and later cars Porsche doing the usual thing by improving the model gradually over the build period. Early cars 89/90 have an alloy intake manifold. They also do not have a cylinder head gasket and the rear suspension top ick up points are different allowing less choice when modifying. The standard rear brakes are also less suited to a track car. Later cars (i don't know the exact dates of hand) say 91 on have the plastic manifold the later suspension pickup points and the revised rear brakes. There are probably other changes that i have forgotten. All of these things can be got round but obviously it's easier to just start with the right car. The later cars were made in smaller numbers (Porsches lean times) and so are thinner on the ground.
 
James,
This was done to death fairly recently (though I can't remember what the title of the thread was.......). This is essentially what I have done with my car. It can certainly be done in logical stages. IMHO the main areas of contrast between the C2 and the RS are chassis dynamics, braking and power delivery. These aspects are all accentuated by the weight difference between the two.

The logical place to start is to lose weight. Strip the interior and go for race seats. Take off all of the under-body trays. In time you can install a lightweight RS interior and cage if required.
Then turn to the suspension. Bilstein HDs all round - springs subject of much debate, but either way stiffer than stock C2. Couple with RS adjustable anti-roll bars(doesn't require any modification !), front strut brace, and RS geometry set up. Slap on some sticky tyres.
Brakes - install standard 993 calipers front and rear (using 928 S4 discs on front) - or go whole hog and install Big Reds (overkill IMHO), couple with stainless hoses and SRF or Super Blue fluid. Possibly upgrade to 993 master cylinder and 965 Turbo brake proportioning valve (shifts more braking to rear).
Engine-wise an ECU remap should see c.280 bhp if done in conjunction with a decat and cup pipe. Replace the dual mass flywheel with the lightweight RS version which greatly improves throttle response.
There are literally hundreds more differences between the two cars, but I reckon if you do the above you will have a pretty decent approximation of the RS experience without it costing the earth. It is simply not economic to re-create an RS in every respect, but this is a pretty good start.

Jamie
 
James,
Talk to Keith Calder (he's in the members list), he's built a pretty fair RS Rep, there's article about it in 911&PW last year - about march if memory serves.

Tony
 
The thread Jamie was referring to was quite good and covered a lot of the differences between creating a good 964 track car vs building an RS spec car. If you have the funds to invest all in one go, I would seriously consider buying an RS and I think building a decent car with similar performance etc would cost you a similar amount. Plus there are advantages to having a std RS such as residual value, insurance etc that may make more of a difference in the long term.

Would be interested to hear how you get on. You should also try and get out in Jamie's car and a few RSs to see whether the feel can be recreated in a way that you like.
 
ORIGINAL: Yoda

You should also try and get out in Jamie's car and a few RSs to see whether the feel can be recreated in a way that you like.
Click to expand...

Actually, that's a great idea. I'll be at Oulton on the 18th and I'd love for some of you proper RS guys to jump into my car and see what you think. Might go some way to settling the debate. Not having had the pleasure of driving an RS myself I don't really know how close my car is in reality, however on paper I think it should compare reasonably favourably. Anyone game ???

Jamie
 
Jamie - I am up at Oulton and would love a ride. Happy to return the favour but it is my first visit there so will take it quite easily. I know there are a few other RSs going (just one or two) who may be able to provide a more favourable comparison.
 
I would love an RS, but I think that will have to wait. After having a long think about it last night the modd'ed C2 is the best solution for me as I have 2 young daughters who like to join me for the Sunday morning blast into the Dales. My ideal car will be a LHD C2, full sorted suspension, RS spec motor, semi lightweight interior but with the rear seats [:)] . I will probo only 3 -4 trackdays a year.

Just been checking the article on Keith Calders car & I'm impressed.
 
Jamie
my comment on the anti roll bars requiring modification stems back to smething i have read in the past (which i can't find now) one of the bars, can't remember which (though i think it may be the rear bar) has clearance issues (i think!) when set to the extremes of it's setting. It was a vaugue memory and if you have fitted them with no issues then it looks like I got it wrong.
 
Laurence,
I believe the problem is with clearing the front diff housing on the C4. Clearly not an issue on the C2. That said it does run pretty close to the brake servo on the C2. At the moment I am on mid settings front and rear, but I suspect ultimately I will need to go to full soft front and full hard rear, so as yet I'm not sure if that will work.

Jamie
 
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