I acquired a 1977 Porsche 924 al holbert body kit. Im swapping into a 07k. The car already had 83 or 84 944 suspension and brakes.This is a fully fledged racecar so comfort is of no concern. i hopefully will be in the 450whp range at around 2100 pounds. I don’t have a huge budget and I’m only 17 so I don’t know to many of the Porsche lingo. I just got done fabricating the cage and now I’m onto the brakes and suspension.

My options for brakes I’m running brake cooling on each option. My hometown track is cmp
1-stock 84 944 brakes with nice pads and ss brake lines.
2- wilwood calipers front and back with everything the same as 1
3- stock 86 turbo brakes
4- 86 turbo big brake kit for the front Volvo 240 rear calipers.
5-86 turbo spindles and hubs with another rotor as the cayenne or a corvette.
there is a guy near me selling a set of 86 turbo hubs and spindles for 200 I think I could talk him down.just looking for new ideas or opinions on each setup.im running aftermarket wilwood pedals so adjustability of the bias will not be a problem.

The suspension setup I was planning for
koni coilovers(not sure what spring rate)
camber Plates
koni yellows in the rear
29 or 30 mm torsion bars
bigger front and rear sway bars I have a 23mm for the front now I got for free.
strut tower brace
new bushings all around
new ball joints and tie rod ends

i think this covers about everything I’m just looking for advice or opinions on every setup because I’m torn between every one . I don’t mind spending extra to do everything right. I just don’t want to go and overspend on something that will never be needed. Like I said comfort is no issue I just want the best option for going around a track as it possibly can. I love reading through this forum and it’s my first post if any of you have anything for sale you think might help I would love to save anywhere I can.

i appreciate any advice or opinions thanks!

 

I'm not sure what CMP is. Canadian Motorsport Park (Mosport)?

Most of your questions depend on if you'll be running downforce, however, none of the brakes in your list will adequately stop a car with that power repeatedly at track loads, no matter how much air they get. They'll simply overheat.

Your brake setup should ultimately be determined by what size wheels you are running. If you are running 18" wheels, your brake choices are essentially unlimited. As you go to smaller wheels, you are more and more limited.

The most economic solution for brakes would be a 17Z or 18Z Brembo up front (six piston), with floating rotors to match the wheel size, and rears to match the front based on bias/preference/master cylinder. That family of calipers was also used on lots of cars in the 2000s, from Cadillacs to Porsche GT2s. That said, they are not a racing caliper so do have some pitfalls, namely the ceramic insulator pucks. Not to mention the melted dust boots, aluminum non-ventilated pistons, and lack of knockback springs. I think some versions were made without ceramic insulators. The most economical motorsport caliper is probably a set of PFCs off of a 991 Cup car, I believe they have ventilated pistons, knockback springs, no boots, etc., but require 18" wheels.

The other problem is front suspension components. The best spindles (M030) and the best hubs (billet hubs for M030 spindles) would barely be able to cope with the loads on the car at those speeds, especially if you add downforce. There are ways to upgrade it beyond what Porsche designed for the car, but it is a very slippery slope, at which point you may as well tubeframe the front of the car. When Porsche ran 400+ HP in these cars, even with minimal downforce, they used a completely different front hub and upright assembly similar to the 935 (that setup is no longer available).

Spring rates and swaybars depends on if you'll be running downforce.

Ultimately I would recommend cutting the power in half, especially with that weight. Trying to achieve GT3 speeds and GT3 reliability in these cars would cost the price of several GT3s.

 

I agree with French, there is nothing on your list that is suitable for a 450whp/2100lb 924 race car. Start looking at ohlins/motons for suspension and at the low end Brembo sixes on the front brakes. Throw away all your hubs, spindles, sways and front/rear control arms and budget on $15-20k for a custom built system including suitable wheels, brakes and suspension to be competitive.

Curious what series/class are you building for?

 

this reply will be for both I’m still researching lots on the topic. I’ve found a guy who puts 350mm cayenne rotors with 18z calipers on a 944 I’ll have to swap over to late offset hubs and spindles . I’m not running wheel to wheel or any endurance racing. I guess you could say it’s more of a hobby car and if I had to put it in any competitive class I would say it’s more of a time attack build. Wheel size are no issue I was probably going to run a larger 18-20 wheel. I’m thinking that the cayenne 350mm rotors with stainless steel brake lines good fluid good pads and the 18z calipers with some brake ducting should be able to stop the car and stay cool for a while. Like I said this is no endurance car or wheel to wheel. I’m not going to be running for long periods of time. I appreciate all the advice and I’m taking it all in.

cmp is Carolina motorsports park btw I probably should have put that

 

Ah ok, when you stated “race car” then that’s a different animal. So what you are building is a track day car, maybe something for hpde or track days, cool!

You seem to have done your research so just build it and don’t worry too much about the minute details. When you get it on the track deficiencies will reveal themselves.

 

i should have probably used different wording sorry. Right now I think I’ve decided on brakes if you could give me your opinion on this setup.
front is a 350mm cayenne rotor and 18z caliper
rear is boxster s 300mm rotor with 4 piston boxster s calipers.
I think this would be a good base setup and not break the bank don’t you think?

 

Cage looks like a pretty good start - but those door bars are puny. Good selection of tie-in points, though, glad to see that.

I agree with the comments above about your parts list being inadequate, but I have to ask - where do you expect to get that power from? What makes you think you can generate that power? I ask, because that is a significant factor on the budget for the rest - and it would suck to massively over-spec the rest only to not even make that output. You didn't mention your powertrain plans. Though it's just as true that it's even more expensive to build incrementally, only to later have to replace stuff that isn't up to snuff. Just looking for a sanity check here.

But with a limited budget (as is reasonable to expect at your age) - it might be wiser to set a more modest goal that you can reasonably expect to reach, and complete, vs. a half-built pile of very expensive parts without completion.

You can save a lot of money sticking with used, existing Porsche parts, not to mention time fitting, vs. the blingy crap in the catalogs that doesn't work nearly as well (Wilwood, I'm looking at you). High end shocks are lovely - I run Ohlins on my prototype, they're key to going fast in a legit high-downforce car - but for this application I'd suggest you consider a custom-valved set of Bilsteins. We run these on our 924 ITB car, and they're extremely durable and effective, though not adjustable in our application.

So I'd suggest you consider a 3.0L swap (unless you're maybe looking an an SBC?), 951 or so transaxle, and stick with Porsche chassis components underneath, at least hubs brakes etc. Get the car running, get out on track, and learn how much you have to learn.

As for weight - again, do you have a plan to get to that weight? That's very low for a 924/944 chassis, will take some very aggressive work to get there. In the range of 2300-2400 is probably more likely, especially considering you are swapping in heavier than stock components. After ditching the glass hatch, the rest of the bodywork isn't exactly heavy, though it does add up.

 

[QUOTE=924RACR;16890732]Cage looks like a pretty good start - but those door bars are puny. Good selection of tie-in points, though, glad to see that.

I agree with the comments above about your parts list being inadequate, but I have to ask - where do you expect to get that power from? What makes you think you can generate that power? I ask, because that is a significant factor on the budget for the rest - and it would suck to massively over-spec the rest only to not even make that output. You didn't mention your powertrain plans. Though it's just as true that it's even more expensive to build incrementally, only to later have to replace stuff that isn't up to snuff. Just looking for a sanity check here.

But with a limited budget (as is reasonable to expect at your age) - it might be wiser to set a more modest goal that you can reasonably expect to reach, and complete, vs. a half-built pile of very expensive parts without completion.


im swapping in an 07k I’m sure you’ve seen the boost brothers that’s my plan for power.
i should have probably stated about the door bars but I’m waiting to put the rest in because I don’t want to be climbing over a fully caged door test fitting seats and other things like that so I’m saving the rest of those bars for later on. As for the weight it was really an estimate based on everything I’ve been reading on other cars. Which is really hard I’ve read some people are at 2000 lbs and others are at 2300.
The car is completely gutted and is going to stay that way and really anything that doesn’t need to be on the car won’t be. As for power 450 was a high estimate. Mainly because I would rather have an “overbuilt” suspension than an under built one.
this is an early 77 model car I think it’s maybe the 845th 924 to enter the states or something of that nature. I’ve also read the early cars are a little lighter than late cars so i took all this into consideration and it was an estimate at 2100 lbs. the 07k is slightly lighter. I appreciate all the reply’s I remember reading all of your post a long time ago 924racer don’t think that name will ever leave me.
i have a fair amount of experience with cars but this track car thing is really not in my boat from my past experience.
ive restored a 66 mustang with a 408 stroker and some other smaller vehicles.
i pulled my dads 924 out of a sand pit pretty much. It was sitting since before I was born and now I take the car to auto cross.

 

Kudos to you for taking on this project... Awesome to see a 17 year old with ambition, and Skills. Setup a spreadsheet in Excel and list all the parts that you need for this build.. Total is all up and see where you budget is. Having recently built a car by myself I can tell you it was way more expesive than I had anticipated.. I did EVERTHING myself, engine build, cage, paint, wiring ect. Dont forget Dyno time..$$$ (worth the money BTW) A good suspension will run you 5 to 6K alone.
Keep in mind what your goal is for the car, with the o7k in it, that rules out PCA clubracing. (and if you ever want to sell it that narrows your prospective buyer list) My suggestion would be to do it in stages.. Not sure what your planned budget is like but I can tell you im North of 15K (Just parts!) on my build and that doesnt include the price of the orginal car.
Once you get the car done, Each DE will run you about 1K ($500 entry for a 2 day event and $250 a day for everything else) and thats without breaking anything. Consumeables are really the issue.. Tires, Gas, heck a set of brake pads just for the front are $300 Be aware of the pitfalls is all im saying.. Along the way keep your eye on the classifieds.. Good bargans there sometimes... Esp for things you forget about.. Helmet, Hans,Ect. Good Luck!

 

Although it’s old this thread over on Pelican has some good info on a 924 transplant build.

GL

 

For those unfamiliar - the 07K is the engine code for five cylinder used in modern transverse applications by VW/Audi. I would recommend leaving the engine stock or even detune it, as you'll have plenty of teething issues of simply swapping the 07K into this application. Yes, there is a kit available but it hasn't been extensively tested for hundreds of thousands of miles.

Once you strip the shell down like you have, early cars aren't really any lighter. At least I am not aware of any significant amount. Most of the weight comes from everything else - HVAC, seats, electrics, heavier engine and transmission, etc.

Regarding your rollcage, I'm not qualified to really analyze it. However, I do know that recently people have shied away from running bars as far back in the trunk as possible, because you're losing the crash structure that's been designed there. I'm going from memory - so I could be wrong - but I think the current FIA rulebooks prohibit rollcages from extending beyond the front and rear axles.

Upgrading to the best available suspension components would be a five-figure endeavor. Even then, you still haven't upgraded the archaic system whole. Single shear connections, spindles, etc. These components simply aren't engineered for GT3 speeds - certainly not with GT3 reliability. You'd be asking them to go twice as fast as their designed limit, all the while with 30 years of fatigue and 30 years worth of tire advancements in lateral load. The reliability of them plummets to the point of magnafluxing and replacing components at very frequent intervals.

There's an old saying. Pick two: cheap, fast, reliable.

Don't misunderstand, it's very cool what you are trying to accomplish. Just don't get in over your head!

 

I appreciate all the input and advice. I think I figured the brakes out and I’m starting to work on the suspension. In no way am I trying to go out and set lap records and beat gt3s (they have engineers for that). I’m just trying to get input to build a happy medium between all three categories you listed of cheap fast and reliable. I know the car won’t be as fast or reliable as many other cars on the planet.

As for the price I’ve learned to add everything up and double or triple that and that’s what it comes out to lol. I’m not trying to achieve the best suspension just something that won’t throw me around like I’m in a boat but will hold up to all the stress of a track day.

Also I found a nice set of ebc yellow pads near me for a good price do you guys have any experience with these?

 

You are already at an advantage if you are aware of cost 'creep.'

Brake pads are really preference. I don't have any experience with those specifically. There are lots of parameters; cold performance, hot performance, noise, dust, bite, wear, etc. I would avoid making impulse purchases just because they are a good deal, many times you'll change your mind as you progress. There are exceptions of course, such as if you're really sure you're going to use it.

My GT3 comment was based on how many people have the notion they can take an old car, throw a bunch of go-fast stuff at it, and it will be as fast as a GT3 and never break. This couldn't be further from the truth. 90% of aftermarket parts are garbage; designed to look good in pictures and don't actually perform. My advice is when you're installing critical components that are aftermarket, really take the time to research their construction and reliability.

I would avoid stuffing 450 hp in this car unless you are ready for pain and headaches. Making a good, reliable car with half that power is difficult.