Full Version: Brake Conversion Questions
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?
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?
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.
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.
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.
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.
See the club store for information on the hubs.
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.
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.
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.
front side with rotor
back side with rotor
ooops
caliper
caliper
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
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
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.
John,
You had trouble with heat in Mexico? How much cooling do your brakes have? And are you using the vented rotor also?
You had trouble with heat in Mexico? How much cooling do your brakes have? And are you using the vented rotor also?
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...
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...
-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
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
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
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
-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?
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?
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.
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.
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?
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?
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
Why do you need to up grade the brakes in the first place? Is this a race car?
Paul
his second post said he intended to "race" the car. not sure exactly where
| QUOTE (1973914 @ Nov 4 2005, 09:14 AM) |
| his second post said he intended to "race" the car. not sure exactly where |
Oh, must have missed that.
-URY914-
Racing is the plan. The whole thing is to get bigger rotors for the heat factor. A vented rotors with ducting. How I get there is the question of the day. Bigger pads are easy with the BMW option, but I want to go with the bigger rotor and there is where the confusion starts. There just doesn't seem to be a budjet friendly way to do this.
Racing is the plan. The whole thing is to get bigger rotors for the heat factor. A vented rotors with ducting. How I get there is the question of the day. Bigger pads are easy with the BMW option, but I want to go with the bigger rotor and there is where the confusion starts. There just doesn't seem to be a budjet friendly way to do this.
Sorry.. I am working toward the Targa Newfoundland. (2400km race over 5 days) The car classes keep me from loosing to much weight. So bigger brakes are the order of the day.
| QUOTE (ChicagoChris @ Nov 4 2005, 12:13 PM) |
| Sorry.. I am working toward the Targa Newfoundland. (2400km race over 5 days) The car classes keep me from loosing to much weight. So bigger brakes are the order of the day. |
a 5 lug suspension does not get you coil-over springs...
the 914 and 911 front suspension (up to '89) is very similar in basic design, the major diffs are number of splines on torsion bars and the 5 lugs have larger wheel bearings
the billet hubs allow you to bolt on stock 911 rotors and stock 911 calipers, no machining....however since you have '72 struts, they will not fit, I don't have a set of early struts to figure out what would be needed to adapt the billet hubs to those struts.
The only way to put on bigger vented rotors and keep 4 lug is somthing custom, either billet hubs or with Wilwood Racing components...even with the Wilwood stuff, nothing will bolt on, it's all custom, you'll have to machine off the rotor from the front hubs and order the correct hat and rotor...it can be done, just not that easy unless you have the tools to do it...
woah doggy! If you are doing the TN, then you need to go through the whole suspension to make sure your car is up to snuff. A guy in my PCA region (who i think is on the website main page) broke the suspension on his RUF GT3 from the road conditions! This is a very well maintained top of the line car. Anyway, coilovers will kill your budget and can cost as much as an entire street-worthy 914
Yes the TN,
The car is getting a cage and the chassis stiffeners. But I need to decide if there will be a chane of suspension before I fix up mine. Wether I stick with mine, or get the '73, or the 911 is in the air.
The car is getting a cage and the chassis stiffeners. But I need to decide if there will be a chane of suspension before I fix up mine. Wether I stick with mine, or get the '73, or the 911 is in the air.
If I were you I would look into buying an existing car. Building up a car correctly will take you about a year (or more).
You have a lot of decisions to make and right now you're stuck on the front brakes. The TN is a big step. Ever run an autocross?
Paul
You have a lot of decisions to make and right now you're stuck on the front brakes. The TN is a big step. Ever run an autocross?
Paul
-Paul-
The good new is that I am an experienced racer. I ran formula type cars for several years and even ran a 914 for the last few. I plan on running the '07 TN so I am giving my self lots of time. The reason the brakes are a hassel now is that no one seems to have done it the same. Worse yet actual years, cars, and part numbers are not easy to track down. So there is lots of "I did this" with no specifics. And for all the "big brake" talk it seems not many people take it to the vented rotor stage. People get the bigger calipers with no measurable concern for the heat. I want to make it back from the TN in one piece. And to me the brakes are the place to start. Besides most of the other decisions I have made all ready, and these brakes are proving to be the most expensive part.
The good new is that I am an experienced racer. I ran formula type cars for several years and even ran a 914 for the last few. I plan on running the '07 TN so I am giving my self lots of time. The reason the brakes are a hassel now is that no one seems to have done it the same. Worse yet actual years, cars, and part numbers are not easy to track down. So there is lots of "I did this" with no specifics. And for all the "big brake" talk it seems not many people take it to the vented rotor stage. People get the bigger calipers with no measurable concern for the heat. I want to make it back from the TN in one piece. And to me the brakes are the place to start. Besides most of the other decisions I have made all ready, and these brakes are proving to be the most expensive part.
Ok, sorry if I sounded like a smartass. Stick around, there is enough 914 knowledge here to do anything. 
you know that race has always been a dream of mine too! Maybe get a group of 914s up there for '07? Would that not be the best or what?
Should not be that hard to accumulate the parts. The 86 struts I got were about 300 or so. You can get a pair of M calipers for FREE if you ask your local shop, and the rear hub update isnt that expensive either with the machining and pressing not going over $150 really. You do not have to update the torsion bars really if you are staying pretty much stock with the motor. Did you check out the cage specifications on the TN site? They are pretty good!
Should not be that hard to accumulate the parts. The 86 struts I got were about 300 or so. You can get a pair of M calipers for FREE if you ask your local shop, and the rear hub update isnt that expensive either with the machining and pressing not going over $150 really. You do not have to update the torsion bars really if you are staying pretty much stock with the motor. Did you check out the cage specifications on the TN site? They are pretty good!
If you can lock the wheels you have enough pad area. End of story. Going to 320 calipers will make it easier to lock up the front end but that doesn't increase the capacity of your brakes, and makes your car MORE DANGEROUS because it gives you more thermal capacity without more cooling. The function of a well maintained braking system is limited by the ability to dissipate heat - not the ability to stop the wheel.
I was easily able to lock up my stock front brakes with rotors that are well old and grooved, and worn pads.
What you need to add is better brake cooling. The best way to do that is get vented rotors. There are two excellent options for doing this at the front end. Get the new 4 lug hubs and M calipers from this board. Or get a 911 front end.
On the rear it's more complicated - you can either space your existing calipers, or go for some kind of 911 setup. It's more work to upgrade the rear and a lot of the options will lose you your emergency brake. Having said that - modern cars don't have a lot of pad at the rear - so your probably better off keeping your existing calipers and either stock rotors or vented ones.
If your brakes feel bad or unreassuring - find the root cause - change:
* fluid (get speedbleeders and bleed everything out properly.)
* pads
* rotors
* adjust the rear calipers.
If they still feel bad - lose the stock proportioning valve and add a modern type, and adjust properly. The original valve can trap air, which can cause the whole system to feel spongy.
I was easily able to lock up my stock front brakes with rotors that are well old and grooved, and worn pads.
What you need to add is better brake cooling. The best way to do that is get vented rotors. There are two excellent options for doing this at the front end. Get the new 4 lug hubs and M calipers from this board. Or get a 911 front end.
On the rear it's more complicated - you can either space your existing calipers, or go for some kind of 911 setup. It's more work to upgrade the rear and a lot of the options will lose you your emergency brake. Having said that - modern cars don't have a lot of pad at the rear - so your probably better off keeping your existing calipers and either stock rotors or vented ones.
If your brakes feel bad or unreassuring - find the root cause - change:
* fluid (get speedbleeders and bleed everything out properly.)
* pads
* rotors
* adjust the rear calipers.
If they still feel bad - lose the stock proportioning valve and add a modern type, and adjust properly. The original valve can trap air, which can cause the whole system to feel spongy.
A herd of 914 for the TN!!!
Now that is a great idea! I would like nothing better then more company in the Great White North. My goal is '07. My personal situation won't let me do it any sooner. So I make my plans now and would really enjoy more 914's.
Now that is a great idea! I would like nothing better then more company in the Great White North. My goal is '07. My personal situation won't let me do it any sooner. So I make my plans now and would really enjoy more 914's.
I have a couple of local friends, one ran the TN in a 911 a few years ago, the other has an old 914/6 GT. The GT basically uses the 911S brakes on the front and vented 914/6 on the rear. This car was raced hard for many years including IMSA without brake problems. Based on this, I don't think you need to get exotic.
I would recommend a change to 5 bolt suspension to allow easy brake and wheel choices. The /4 suspension does not give you a lot of choices. The 914/4 caliper can be widened to use a vented rotor, and I have the parts available to do it. Go with the new formula for drive shafts and hubs, and your rear end is done. For the front, a change to 911S suspension is a quick and easy swap.
I would recommend a change to 5 bolt suspension to allow easy brake and wheel choices. The /4 suspension does not give you a lot of choices. The 914/4 caliper can be widened to use a vented rotor, and I have the parts available to do it. Go with the new formula for drive shafts and hubs, and your rear end is done. For the front, a change to 911S suspension is a quick and easy swap.
So... what do the rules allow?
My car is a 1972. the 2002 4 piston caliper was a direct bolt on. The pads ride in the same place on the caliper with non of the over hang issues of the 320 pads. The Volvo calipers are very heavy and require a 23 mm master cylinder in order to retain good pedal travel. If you race you understand the principal of adding un-sprung weight.
Works for me...
Works for me...
pics of volvo with vented rotors and the new hubs
zxz
zxz
Guys, both brakes look great. I sent e-mail for further.
-Eric Shea-
The rules allow for lots of different things. Talking to the guys that run the TN, they don't want to disourage anyone. There are classes from new to antique. Most 914's fall in the late classic division and it gets more specific depending on how preped the car is. I can't do stock due to carbs and ignition, so I am preping for modified. There are also open classes for dedicated racers. Go out and recruit a navigator and get ready. For me the big part is getting there. I figure I'll need 2 weeks. One for the race and one for travel to and from.
-Eric Shea-
The rules allow for lots of different things. Talking to the guys that run the TN, they don't want to disourage anyone. There are classes from new to antique. Most 914's fall in the late classic division and it gets more specific depending on how preped the car is. I can't do stock due to carbs and ignition, so I am preping for modified. There are also open classes for dedicated racers. Go out and recruit a navigator and get ready. For me the big part is getting there. I figure I'll need 2 weeks. One for the race and one for travel to and from.
| QUOTE (fiid @ Nov 4 2005, 01:40 PM) |
| If you can lock the wheels you have enough pad area. End of story. Going to 320 calipers will make it easier to lock up the front end but that doesn't increase the capacity of your brakes, and makes your car MORE DANGEROUS because it gives you more thermal capacity without more cooling. The function of a well maintained braking system is limited by the ability to dissipate heat - not the ability to stop the wheel...etc. |
Best advice! Spot on
Good reading:
http://stoptech.com/tech_info/tech_white_papers.shtml
http://www.teamscr.com/techarticles2.html
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.