Brake Conversion Questions, 240DL, 320i, 2002tii...I am so confused Options

[ChicagoChris]

Where do I begin? So much talk about brakes and I am nocloser to a solution. I went with the 2002tii brakes from 1972 on limited information and got burned. The posting says they are a bolt-on to the early 914's so I tried them. No good. The bolt spacing on them is almost a 1/2 inch different. Did I get the wrong year? And does someone have the dimentions from the BMW 320i rotors so I can order a custom vented hat/rotor for my 1972 914 2.0? (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)

[davep]

Did you read any of the threads on brakes here? There is many hours worth of reading on what can be done, and the quirks over the years. Do you know what front suspension you have in your car?

[john rogers]

If you really need some better brakes then the first choice is the BMW 320i calipers on the front, stock rear and loose the prop valve and add a 19MM or 23MM master cylinder. A better solution is a set of the 4 bolt alloy hubs and use the M calipers and vented rotors and the rear the same as the first choice. The Volvo calipers are bigger but I found them a little too soft feeling for my taste on the race car and they pretty much require a 23MMK m/c.

[ChicagoChris]

Yes I did read the threas on brake conversions and while there are many people talking no one is saying very much. The 320 is the most common and seems like a good option. I was really leaning toward the Volvo or the 2002tii because of the extra pad. There is scattered info on the 240 and the 2002tii seems more like urban legand, scattered sightings with no proof.

John...Where have you been racing? I am doing this because I intend to race this car and the extra pad is too much to resist. Did you get a bigger rotor with the new calipers? Or are you running the stock rotor? What master cylinder were you using? What pad? I just can’t wrap my head around a 4-pot caliper not being better then the 1-pot 320. What else have you done to keep the 320 from fading late in the race? If they work with no fade then that may be the way to go.

[DanT]

Use M calipers and the magical Billet hubs. They are very nice and allow the use of a very inexpensive SC rotor. Also you don't have to replace bearings every time you need to change rotors. (2 pieces) This is a tried and true caliper that bolts directly onto the stock 914 struts.
See the club store for information on the hubs.

[john rogers]

As noted, I use the M calipers which have a smaller pad than the BMW but allow use of the vented rotor which finally bcame to a head when doing the street races in Mexico. I had the brakes boil since the straights were pretty short and there was no time for cooling those solid rotors. It was a little scarry since the pedal did not want to get better until after a few laps of slower driving.

[DanT]

Here is a pic of my hubs...I have not mounted them yet because the car is in the body shop for a complete repaint.
My car will be DE/TT/AX. I wanted to use an M caliper for several reasons. I could get them easy. My pca region has always required Porsche parts in less modified classes.
The availability of the billet hubs also allowed me to retain my 4 bolt arrangement front and rear. I like the idea of the car remaining looking stock (sleeper)
As far a actual dimensions you would have to check with Brad or Mike Mueller.
I know they bolt up to SC rotors with M calipers on stock struts and everything works and lines up.
For some folks going to other car makes for parts is acceptable....more power to them...
I just want to keep my car as much Porsche as possible.

[DanT]

front side with rotor

[DanT]

back side with rotor

[DanT]

ooops
caliper

[stock93]

John Rogers,
What exactly is the 23mm master cylinder out of? Is it a direct bolt in? I searched and asked this question a while back and no one could give me a straight answer besides "something mercedes."

John

[dmenche914]

The stock calipers up front are just fine, never been able not to lock them up once I put on some of the pricey racing type pads, i got Porterfield brand fronts (near $100 a set) these pads are excellent, i could not need any more stopping power, cause the tires would break free next (wide sticky tires too boot) So go get some of the good fancy Porterfield pads, and use the stock system, it works great. Once you lock up the wheels, all the extra caliper wont make any more difference. Since i can rapidly lock them up with my good pads I don't think I will gain much if anything by different calipers.

[ChicagoChris]

John,
You had trouble with heat in Mexico? How much cooling do your brakes have? And are you using the vented rotor also?

[1973914]

Just a quick comment as this has been hashed out soo many times...

If you are upgrading the calipers and the size of the pads, you should also upgrade the rotor. Both are heat sinks, which once overheated lose their capacity to apply friction and thus stopping power. Larger pads just heat up the rotors quicker and your brake fade will come on sooner. The ability to lock up the brakes means nothing, as i bet that same system with a hot stickier tire or slick would not be able to do that. Truth is, when you lock em your ability to slow the car is decreased from that of pre-lock state.

Anyway, all I am saying is go with whatever you want, just make sure you are adhering to the proper physics of the system in question. When I found that the stock system was no longer effective was in enduros of an hour or so, or abusive 30 minutes sessions where I was trying to lay down successive hot laps. There would be fade at the end of these kinds of sessions.

For four lug, your first best bet is to make sure your stock system is in top shape. Once that is done, try some cooling options such as ducts in the front with hose directed at the rotors. Or, try picking up a set of 993 brake cooling channels. They are at your local dealer for about $15 each. Mount those with zip ties or other creative measures on your front arms. I have these ready to mount in just a few days from now. This will go a long way to keeping the heat down. Excess heat is the enemy of braking.

Just my lowly opinion with a smattering of fact... (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif)

[ChicagoChris]

-dmenche914- Thanks for the reply on the stock brakes. My current system is in great shape and I can lok them up too. My purpose in this is to get vented rotors. The heat build up gets to be to much for the stock at some point.


Dan (Almaden Valley) - Are you using the "billet" setup with a vented rotor? What parts (exactly) are you using in the upgrade? I don't have lots of 911 knowlage and parts with cars and years would be helpful.

Thanks

[1973914]

Chris - are you staying 4 lug or going to 5? If going to 5 there are some very fine options for braking (the best reason to go to 5 lug).

I am using carrera rotors all around with Boxster fronts and carrera rear calipers, with a 19mm MC and no prop valve. Brake fade is not a problem (IMG:http://www.914world.com/bbs2/html/emoticons/smilie_pokal.gif)

[ChicagoChris]

-1973914-
At the current time I am looking to stay with the 4 bolt. The 5 is the way to go but the cost goes way up. Front suspension, brakes, wheels, tires, flares. It gets expensive quick. If I can stick with the 4 bolt I would like too. But right now it looks like I would need a new front equipment anyway. (from 72 to the 73) to fit the "billet" hubs. So anything is possible right now. What year parts did you use? And are they a "bolt on" or was machining involved?

[1973914]

The struts were replaced with 86 Carrera units. The main thing is to use struts with 3.5" spacing on the ears so that you can use the newer calipers.

I went ahead and replaced the torsion tubes as well to get the wider range and availability of torsion bars, but you can still use the 914 ones - they are the same except for the splines.

For calipers I went with the boxster fronts, because they offer a very large pad compared to the "S" or "M" calipers and are brand new. This requires an adapter, and the kit runs about a grand (ouch). No machining needed. You will likewise not need machinging for either of the above calipers. Do not see the point of going to M 911 calipers in front, as they are basically the same size as stock 914...

The rears were a touch more complicated. I had the 4-lug hubs re-drilled and had the 5 studs pressed in. Have a competent shop do this. This allows me to use stock components all the way back to the tranny. I needed to add 2 washers to space the rear M Wide (87-89) caliper for the vented rear rotors to fit. No machining needed.

In order to balance the ratio - simply buy a "T" fitting (porsche makes the part) and replace the rear slave.

Most of these parts are pretty easy to source and not overly expensive. If you are racing the car, nothing beats taking your time and making sure you have the right components. Also, no need to flare if you are going with 15x6 wheels, so that is not a given.

[ChicagoChris]

OK then,

Help me this this then... I was under the impression that the 5-bolt conversion changed you to the coil-over springs. Your way maintaines the tortion bars. What version have I been looking at? And what years had the 3.5 bolt spacing vs not? What is the pattern on the hubs when done? (5x..?) Or are all Porsche 5 patters the same with the 914 being left behind?

[URY914]

It maybe too late for this question, but here goes...

Why do you need to up grade the brakes in the first place? Is this a race car?

Paul (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)