1974 911 Brake Body and Wheel Upgrade

sharpshooter677 · 02-05-2009, 03:54 PM

I have a 1974 911 with an 85 3.2. Its brake system is in desperate need of help. I will probably need to replace the whole system so am considering a boxster brake kit conversion. So I figure I will upgrade my wheels at the same time to allow more room, and also might as well go for the wide body kit to accommodating the wheels. What wheel size would fit or be appropriate, and with this in mind, what are some alternatives to fiber glass or welding steel flares. I have seen before RSR wide body kits with what looks like straight up bolt on flares. This car is somewhat of a daily, but mainly for fun. I do like the RSR style body but am going to keep the impact bumpers, so the car would probably end up being Turbo look car. Any info, advice, or wutever is much appreciated. Thanks

zotman72 · 02-05-2009, 04:57 PM

I would not recommend going with the installation of later model 911 OEM vaccum unit, power brake conversion. I was mandated to that on my PCA club racer when I took my '74S to euro SC spec. The engine was 930/10 euro spec 3.0, similar output to your 3.2. The conversion job was a major PITA and afterwards braking was unsafe, as my left front wheel would lock up under hard braking. I did the conversion right too, SC pedal cluster, SC Vaccum booster and MC, vaccum line run to the booster and with new custom brake lines made. I past PCA club racing scrutineer inspection but the car was unsafe. I was quite PO too.
If you have 3.5" spacing on your struts, then your existing brakes should be up for the task of slowing down your car. IF not, get the 3.5 struts and SC or Carrera brakes install. Your existing MC can drive these calipers sufficiently. YMMV.

TRE Cup · TRE Cup's Garage

Standard 74 911 had the M caliper mounted on 3" struts. I can see where you can overpower the brakes and fade them out , with hard use. A good inexpensive alternative is the change over to 3.5" struts, 84-89 Carrera calipers and discs front /rear. If in good condition, you can keep the 19 mm master cylinder and have a nice progressive feel the the brakes. Stainless flex lines and a good quality fluid/ pad choice will round out the package.

Next step in terms of cost is the front/rear boxster conversion- which has worked well for racers in PRC. YES, the mass of the 84-89 discs does not yield a huge increase in braking, but again for a budget upgrade, you may want to consider it

Wheels- The availability of 15" tires in iroc rsr (turbo width body) or even full width rsr, are not street legal and extremely expensive on $$ per mileage wear. With the iroc RSR, you can choose 225 and 245 x 16's and that will seem skinny if i read what you are really after. So that leaves 17" rims. The wider Fuchs look ones can be Lindsey, TRE, or Zuffenhaus. With Zuffenhaus probably being the best $$ value going right now

If you decide to fit 17's then you have room to install larger diameter rotors that are thicker. This allows you a wider choice of calipers, including "Big Reds" / 993 TT, which imho front/rear are overkill. A great choice ($$ and performance) would be the secondhand 3.3 turbo set front/rear. You will have to have the back calipers machined to mount on the rear arms. And you should get your brake system decided before ordering rims. The offsets will be determined by what you choose,

Since you are in the valley, you are welcome to come by our shop near van nuys airport and see some conversions that may help your decisions on width and set up

sharpshooter677 · 02-06-2009, 10:22 PM

Hmm.. Thanks guys both good advice... TRE Cup, yeah planning on swinging by hopefully soon. Thanks again.

Larry_Ratcliff · 02-07-2009, 05:49 AM

I agree 100% with what TRE cup said. However, I think the best bang for the buck are the S4 calipers. These are known as S4's because they originally came out on the 928 S4's. However, I believe they are the same specification as the 944 turbo calipers.

These are the largest caliper you can run under a 16" wheel (wont fit 15's like the 930 brakes will) . They are radial mount so adapters can be had at a reasonable price.

I picked up a set with adapters and large 2 piece rotors for 850. Then I got a set of 944 turbo rears for 350. I am still investigating which rotor I am going to run on the rear but I think that I will be into the whole setup for less than you could buy front turbo calipers...

I am going to upgrade the master cylinder to 23 mm.

I did put the turbo calipers and rotors on my 74 911 (the S4 set up is actually going on my 914) I have been happy with the turbo calipers and rotors I just felt like going with S4's this time due to less cost for more brake is the better way to go... You could leave your body work stock on your 74 and run 944 turbo fuchs with those brakes ...

944 turbo fuch's are 7 and 8 x 16. They will fit your narrow body work and would allow for plenty of rubber for your 3.2 engine...

wowzer911 · 02-07-2009, 08:17 AM

I love the manual brake feel, but if I had a 3.2 under the hood, I'd definitely upgrade to power brakes.

Flieger · Flieger's Garage

Hi Afshin,

You have good plans- Turbo brakes, wide tires,wheels and flares- an RSR is an extreme machine.

May advice is to go with what Dave Bouzaglou at TRE www.tremotorsports.com as well as Tony and Marco at TLG Auto www.tlgauto.com say.

You should save your money up and do the whole thing at once. Remember- its a system. In the meantime, your stock brakes are good. New fluid, good street pads like Porterfield R4-S and some stainless brake lines are a good place to start.

After brakes, do suspension- go to TRE, TLG, and Elephant Racing for new rubber bushings ao that your torsion bars don't rub and get damaged. If you lighten the car, the stock spring rates are fine as long as you get new dampers matched to the car. Get a good corner balance and alignment. Beyond that, tires make all the difference. The elephant racing website has a system to walk you through their levels of upgrades, like PolyBronze bushings, available though Pelican.

It is fun to plans these upgrades but is best to save and do them all at once so the cars' systems stay balanced and you do not need to repeat the expensive corner balance and alignment.

Oh, make sure you run Brad Penn 20W50 oil, available through LN Engineering at www.lnengineering.com. Charles Navarro there contributes lots of knowledge to the board- search for the "ultimate motor oil thread" I just put some in today during an oil change.

All the Best on your project!

sharpshooter677 · 02-07-2009, 09:32 PM

Hmm? S4 setup. Thats a smart idea. Like TRE Cup put it, most likley with a widebody conversion similar to RSR, 16 rears would might even seem alittle too slim. Both Big Reds and 993 or 996 TT setup would be out of the budget, also the 930s are rare, expensive, and according to Larry not as poweful. So I think since definetly wider wheels will be in the equation, Ill be able to fit an S4 system that seems to sound like the best bet when considering both performance and budget, again according to larry.

Max, good points. I have thought of the same problems. Saving up and completing the car at one time would make for a sound, well balanced, and properly modified machine.

Larry_Ratcliff · 02-07-2009, 09:57 PM

Quote:

Originally Posted by sharpshooter677

Hmm? S4 setup. Thats a smart idea. Like TRE Cup put it, most likley with a widebody conversion similar to RSR, 16 rears would might even seem alittle too slim. Both Big Reds and 993 or 996 TT setup would be out of the budget, also the 930s are rare, expensive, and according to Larry not as poweful. So I think since definetly wider wheels will be in the equation, Ill be able to fit an S4 system that seems to sound like the best bet when considering both performance and budget, again according to larry.

Max, good points. I have thought of the same problems. Saving up and completing the car at one time would make for a sound, well balanced, and properly modified machine.

you can upgrade the wheels, tires and brakes with my suggestions too... then upgrade the body and even bigger wheels and tires when the budget allows.

BTW there is an excellent article on this board somewhere that outlines the progression of brake upgrades... It starts off something like late carrera brakes-> 930's -> S4's -> 993 twin turbos...

Larry_Ratcliff · 02-07-2009, 10:02 PM

BTW here is the business end of my 74:

3.6, RS body work, turbo brakes (but if I knew then what I know now it would have S4's) 17" Lindsay racing 3 piece fuchs... and a little more

sharpshooter677 · 02-08-2009, 05:18 PM

wow..very impressive, what sway bar are you using, are you happy with it?

Larry_Ratcliff · 02-08-2009, 10:03 PM

Quote:

Originally Posted by sharpshooter677

wow..very impressive, what sway bar are you using, are you happy with it?

Racers group sways. If I remember right I think Patrick motorsports had to modify them ... but other than that I like them a lot.

Facey · Facey's Garage

Quote:

Originally Posted by Larry Ratcliff

BTW here is the business end of my 74:

3.6, RS body work, turbo brakes (but if I knew then what I know now it would have S4's) 17" Lindsay racing 3 piece fuchs... and a little more

what tires are those?? the thread looks alot like mine... lol..

TunersGroup · 06:07 PM

Quote:

Originally Posted by Larry Ratcliff

I think the best bang for the buck are the S4 calipers. These are known as S4's because they originally came out on the 928 S4's. However, I believe they are the same specification as the 944 turbo calipers.

These are the largest caliper you can run under a 16" wheel (wont fit 15's like the 930 brakes will) . They are radial mount so adapters can be had at a reasonable price.

GT3 calipers can also fit under some models of 16" Fuchs.

Here are some photos of a friend of mine's car with GT3 calipers on the front of his '71 911 ...

Shown above is the front of the Supercharged 911, with 17 inch custom wheels clearing these calipers. The supercharged 911 also runs a set of 16 inch Fuch wheels on track days, and the same brake setup fits under those 16 inch wheels.

Here is a photo of it with 16" Fuchs fitted ...

As it is a complete custom setup developed by my friend, with a hat and caliper adapter of his own design, I can't publish the exact combination of which model of Fuchs he uses without his permission, but needless to say, these photos prove it can be done. And the car stops like no other early 911 I have ever seen - modern Porsche braking performance in a lightweight early shell.

You can find some more info about the brake setup of that car on our site at ...

http://www.tunersgroup.com/porsche_brakes.html

As you can see in the photos below, the car has a completely custom supercharger setup - it's an absolute weapon ...

There are some videos of the supercharged 911 hunting GT3's at ...

http://www.tunersgroup.com/Videos/Supercharged_911.html

- Adam

Bill Verburg · Bill Verburg's Garage

Larry very clean, nicely done. If that's a 3.6 you relly need some bigger headers, you will be amazed at how they will wake up that engine.

As to brakes
anything bigger than the 930s is a total waste for most 911's unless you've relly got something special under the hood.

JMHO, but 930 or the new Zuffinhaus 917 are a sweet spot.

Yes, 993/928S4 on 930 rotors is great too and probably a bit cheaper but you need to be more selective wrt wheels. 993 front and 928S4 are essentially the same caliper, to use the S4 on a 911 the bleeds and feed are swapped and you use 930 304x32(f) and 309x28(r) rotors w/ 993(or 965) rear calipers and you do need a 23.8mm m/c

I've got 993RS on both my 911 and 993, for the street 911 they are overkill for the track 993 they are comforting.

Larry_Ratcliff · 02-09-2009, 06:16 AM

Quote:

Originally Posted by Bill Verburg

Larry very clean, nicely done. If that's a 3.6 you relly need some bigger headers, you will be amazed at how they will wake up that engine.

As to brakes
anything bigger than the 930s is a total waste for most 911's unless you've relly got something special under the hood.

JMHO, but 930 or the new Zuffinhaus 917 are a sweet spot.

Yes, 993/928S4 on 930 rotors is great too and probably a bit cheaper but you need to be more selective wrt wheels. 993 front and 928S4 are essentially the same caliper, to use the S4 on a 911 the bleeds and feed are swapped and you use 930 304x32(f) and 309x28(r) rotors w/ 993(or 965) rear calipers and you do need a 23.8mm m/c

I've got 993RS on both my 911 and 993, for the street 911 they are overkill for the track 993 they are comforting.

Hey Bill,

One of these days I will put some B&B 1.75" exhaust on there... It runs pretty well with this set up but I am sure it could benefit from some better breathing.

I would not argue with you at all about the 930 brakes being enough brake ... I would argue that the 993 brakes are a fraction of the cost for more brake though. 930 brakes are pretty tough to find too. I think it took me close to a year to find the ones on my 74. Agreed that wheel selection becomes more limited. However, I am pretty sure they will clear all later model 16" fuchs.

I actually think you wrote the brake page I was referring to in this post...

Bill Verburg · Bill Verburg's Garage

A lot of us used SSI at first, I used them for the first year I had my first 3.6 because that was what I had on the original 3.0, similar situation w/ the oil cooler. 1 3/4" headerss and adequate cooling make all the difference in the world.

There are a lot more 993 calipers floating around loose than 928S4 and the 993 rears are the ones you want to match 993 or 928S4 fronts, 965 rears are even better because they need less work to fit on the 28mm rotors.

It's interesting to see the latter bigger monobloks being used. I was never a fan of the Boxsters because of the rotors they are used w/. The biggest concern w/ the bigger monobloks is that they want 34x330mm rotors, using them on 32mm rotors presents some potential problems w/ hyperextension, but as long as the pads are maintained at at least 50% thickness that won't be a concern