Brake Upgrades for a 4 lug, what's available Options

[zach914v8]

PM'd Bruce, his hubs are still in development.

I think if you can find your plans (fingers crossed) I have a guy in mind that can whip me up a set quick. Eric at kitcarchassis.com made my boxster S adapter plate to lS engine. Back when this was almost in the works a couple years ago I called him a mentioned these hubs. He was down to machine me a set.

That could be a option, or maybe see how this custom bug shop deal plays out. The shop is in So Cal. Its is... http://www.coolrydescustoms.com/

The owner seems like a cool dude, when I can reach him. 5 lug for me is a bit of a bummer, but it gives me a reason to buy some Z06 corvette wheels, which I always thought would look awesome on my car.

Interesting times here... stay tuned...

EDIT: Bruce PM'd me again to tell me that they had an issue with the first run, but he is underway with building these. So if that is the case, I would love to pay Bruce for a set and be done with this nightmare... lol

[bdstone914]

Some progress made. First samples had issues due to machine leveling. Plan is to make four and five lug. I only had three sets of five lug hubs. I think there is going to be a better market for 4 lug rotors wuth BMW 320i calipers modified for use with vented rotors.

[tomh]

What is wrong with your current brakes that you are trying to fix?

For stopping power--
Upgrade #1 == tires. Brakes stop the wheels; tires stop the car.
Upgrade #2 == rebuilding the brake system. Most of us have old and tired parts in our brake system. Refreshing the system will go a long way to improving the stopping distance in that case.

--DD

Excellent answer
That's what I did

[zach914v8]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

[mepstein]

I wouldn't have the patience you guys do. If I wasn't satisfied with my 4 lug brakes, I would upgrade to 5 lug. Yes it's going to be more expensive than waiting for a magic 4 lug conversion hub but you will have almost unlimited options to how big you want to go with off the shelf, bolt on parts.

Not only do big brakes give you ultimate stopping power but set up correctly, they provide modulation so different pressure on the pedal gives you different pressure to the pads. Something that doesn't always happen when you have to apply maximum pressure to lock up the brakes.

[stugray]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

If you are maxing out your brakes from one drag racing pass you are doing something seriously wrong.
That would barely give them a workout compared to how I abuse my stock brakes on the track.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

[zach914v8]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

If you are maxing out your brakes from one drag racing pass you are doing something seriously wrong.
That would barely give them a workout compared to how I abuse my stock brakes on the track.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

It was more than one pass. I was tuning with nitrous, and finally got the car in the 11's. The brakes went south at about the fourth pass, scared myself a bit. A brake upgrade has been on the list since then.

[anderssj]

. . . BMW 320i calipers modified for use with vented rotors.

(IMG:style_emoticons/default/idea.gif)

Would the aluminum Brembo calipers from an old Alfa also fit?

[bdstone914]

. . . BMW 320i calipers modified for use with vented rotors.

(IMG:style_emoticons/default/idea.gif)

Would the aluminum Brembo calipers from an old Alfa also fit?

I think so. i do not have any to test fit.

[stugray]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

If you are maxing out your brakes from one drag racing pass you are doing something seriously wrong.
That would barely give them a workout compared to how I abuse my stock brakes on the track.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

It was more than one pass. I was tuning with nitrous, and finally got the car in the 11's. The brakes went south at about the fourth pass, scared myself a bit. A brake upgrade has been on the list since then.

Then I still say you have something wrong.
Either the brakes are dragging, or you have fronts only working, etc.
One stop from 120 MPH to zero should make the rotors warm to the touch.
Then the time it takes to drive back to the line, restage, and go again and they would be cool to the touch again.
Laps at my track are only about 2.25 minutes so I repeat the 110 MPH to nearly zero every lap, and that is only one corner of 10. My brakes never get to the point of "glowing red hot".

Drag racing over & over as quickly as possible should not overheat these brakes even in 100% stock form.
Unless of course your car has 500 HP, and weighs 4000 lbs.

The physics just doesnt add up.
I'll calculate the energy dissipated and see.

[zach914v8]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

If you are maxing out your brakes from one drag racing pass you are doing something seriously wrong.
That would barely give them a workout compared to how I abuse my stock brakes on the track.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

It was more than one pass. I was tuning with nitrous, and finally got the car in the 11's. The brakes went south at about the fourth pass, scared myself a bit. A brake upgrade has been on the list since then.

Then I still say you have something wrong.
Either the brakes are dragging, or you have fronts only working, etc.
One stop from 120 MPH to zero should make the rotors warm to the touch.
Then the time it takes to drive back to the line, restage, and go again and they would be cool to the touch again.
Laps at my track are only about 2.25 minutes so I repeat the 110 MPH to nearly zero every lap, and that is only one corner of 10. My brakes never get to the point of "glowing red hot".

Drag racing over & over as quickly as possible should not overheat these brakes even in 100% stock form.
Unless of course your car has 500 HP, and weighs 4000 lbs.

The physics just doesnt add up.
I'll calculate the energy dissipated and see.

Maybe the rears were not working? I don't know. I did the nitrous thing back in 2011, then basically right after that I got too busy with other crap and parked the car for a few years. When I got back on it a few months ago the rears were badly locked up and the fronts were draging. I have since rebuilt the rears and put vw fox calipers on the front with brembo pads.

I just always assumed That I was surpassing the ability of the brakes. Now you have me wondering if I have a restriction somewhere in the system?

[stugray]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

If you are maxing out your brakes from one drag racing pass you are doing something seriously wrong.
That would barely give them a workout compared to how I abuse my stock brakes on the track.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

It was more than one pass. I was tuning with nitrous, and finally got the car in the 11's. The brakes went south at about the fourth pass, scared myself a bit. A brake upgrade has been on the list since then.

Then I still say you have something wrong.
Either the brakes are dragging, or you have fronts only working, etc.
One stop from 120 MPH to zero should make the rotors warm to the touch.
Then the time it takes to drive back to the line, restage, and go again and they would be cool to the touch again.
Laps at my track are only about 2.25 minutes so I repeat the 110 MPH to nearly zero every lap, and that is only one corner of 10. My brakes never get to the point of "glowing red hot".

Drag racing over & over as quickly as possible should not overheat these brakes even in 100% stock form.
Unless of course your car has 500 HP, and weighs 4000 lbs.

The physics just doesnt add up.
I'll calculate the energy dissipated and see.

Maybe the rears were not working? I don't know. I did the nitrous thing back in 2011, then basically right after that I got too busy with other crap and parked the car for a few years. When I got back on it a few months ago the rears were badly locked up and the fronts were draging. I have since rebuilt the rears and put vw fox calipers on the front with brembo pads.

I just always assumed That I was surpassing the ability of the brakes. Now you have me wondering if I have a restriction somewhere in the system?

That is what I would suspect.
I was going to add this to my previous post, but too late:

Assuming a 2500 lb (1135kg) car @ 115 MPH (52m/s).
That is: E = ½*M*v^2 = 1534520 Joules or ~1.5 MegaJoules
1.5 MJ = ~1450 BTUs

So to come to a stop from 115 MPH, the brakes would have to dissipate 1450 BTUs essentially instantaneously.

1 BTU = the heat required to raise 1 lb of water by 1 deg F.
Specific heat of Mild steel is .122, so .122 BTUs will raise the temp of 1 pound of steel by 1 deg F.
914 front rotors weigh ~15 lbs each.
Assuming that the kinetic energy of the entire car is absorbed by JUST the front rotors, then we have:
1500 BTUs into 30 lbs of steel = 50 BTUs per lb.
50 BTUs into 1 lb of steel at .122 (BTU/(lb*degF)
50 / .122 = 409 deg F.
So If the 1500 lb car is travelling at 115 MPH, and comes to an abrupt stop using the front brakes ONLY, AND all of the heat goes into the rotors ONLY, then the rotors would increase in temp by ~400 deg F.
The temp of Steel becoming visibly “red hot” is 900 deg F.

In reality, the calipers, pads, and wheels get hot, and a significant amount of heat is dissipated right away via convection.
Therefore “rotors getting red hot by a single drag racing pass is ‘busted’”

Now of course if the heat could not dissipate between runs (and you did repeated runs back to back), then you could certainly overheat them.

[zach914v8]

I think for 90% of the 914's out there, the stock system working correctly is great. It is us, the 10% that have scary fast cars that need more. Its a strange feeling when your at the end of a drag strip trying to slow down from 115 mph and see the end of the road come up fast and your car wont stop. When you get out of the car and see you rotors glowing, you know that you have maxed out your brakes.

If you are maxing out your brakes from one drag racing pass you are doing something seriously wrong.
That would barely give them a workout compared to how I abuse my stock brakes on the track.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

It was more than one pass. I was tuning with nitrous, and finally got the car in the 11's. The brakes went south at about the fourth pass, scared myself a bit. A brake upgrade has been on the list since then.

Then I still say you have something wrong.
Either the brakes are dragging, or you have fronts only working, etc.
One stop from 120 MPH to zero should make the rotors warm to the touch.
Then the time it takes to drive back to the line, restage, and go again and they would be cool to the touch again.
Laps at my track are only about 2.25 minutes so I repeat the 110 MPH to nearly zero every lap, and that is only one corner of 10. My brakes never get to the point of "glowing red hot".

Drag racing over & over as quickly as possible should not overheat these brakes even in 100% stock form.
Unless of course your car has 500 HP, and weighs 4000 lbs.

The physics just doesnt add up.
I'll calculate the energy dissipated and see.

Maybe the rears were not working? I don't know. I did the nitrous thing back in 2011, then basically right after that I got too busy with other crap and parked the car for a few years. When I got back on it a few months ago the rears were badly locked up and the fronts were draging. I have since rebuilt the rears and put vw fox calipers on the front with brembo pads.

I just always assumed That I was surpassing the ability of the brakes. Now you have me wondering if I have a restriction somewhere in the system?

That is what I would suspect.
I was going to add this to my previous post, but too late:

Assuming a 2500 lb (1135kg) car @ 115 MPH (52m/s).
That is: E = ½*M*v^2 = 1534520 Joules or ~1.5 MegaJoules
1.5 MJ = ~1450 BTUs

So to come to a stop from 115 MPH, the brakes would have to dissipate 1450 BTUs essentially instantaneously.

1 BTU = the heat required to raise 1 lb of water by 1 deg F.
Specific heat of Mild steel is .122, so .122 BTUs will raise the temp of 1 pound of steel by 1 deg F.
914 front rotors weigh ~15 lbs each.
Assuming that the kinetic energy of the entire car is absorbed by JUST the front rotors, then we have:
1500 BTUs into 30 lbs of steel = 50 BTUs per lb.
50 BTUs into 1 lb of steel at .122 (BTU/(lb*degF)
50 / .122 = 409 deg F.
So If the 1500 lb car is travelling at 115 MPH, and comes to an abrupt stop using the front brakes ONLY, AND all of the heat goes into the rotors ONLY, then the rotors would increase in temp by ~400 deg F.
The temp of Steel becoming visibly “red hot” is 900 deg F.

In reality, the calipers, pads, and wheels get hot, and a significant amount of heat is dissipated right away via convection.
Therefore “rotors getting red hot by a single drag racing pass is ‘busted’”

Now of course if the heat could not dissipate between runs (and you did repeated runs back to back), then you could certainly overheat them.

Wow, that is good to know. I guess I need to figure out what went wrong here. So by your math I probably don't even need to fuss with vented rotor/billet hubs.

So at what point will these brakes not work? I have a Lm4 5.3 v8 and boxster six speed going in it. I plan on doing the nitrous thing again with the new motor. shooting for low 10's or high 9's with the next setup. Somewhere near 500hp and maybe 135-40mph in the 1/4 mile. If the stock brakes are good for that, I am done chasing the billet hub dragon.

[stugray]

Wow, that is good to know. I guess I need to figure out what went wrong here. So by your math I probably don't even need to fuss with vented rotor/billet hubs.

So at what point will these brakes not work? I have a Lm4 5.3 v8 and boxster six speed going in it. I plan on doing the nitrous thing again with the new motor. shooting for low 10's or high 9's with the next setup. Somewhere near 500hp and maybe 135-40mph in the 1/4 mile. If the stock brakes are good for that, I am done chasing the billet hub dragon.

Well if it was me, I would first do a couple of runs where I measure the temp of the rotors before and immediately following the run (immediately upon coming to a stop) using an IR temp sensor.
Then you would be able to verify the calculations to within a sensible variation and verify that the rears get hot almost as much as the fronts.

If you were having trouble stopping, double check your rear clearances and that the proportioning valve is actuating.

If everything seems to be in working order , then I would upgrade the pads to Porterfields or KFP Golds.

[zach914v8]

Wow, that is good to know. I guess I need to figure out what went wrong here. So by your math I probably don't even need to fuss with vented rotor/billet hubs.

So at what point will these brakes not work? I have a Lm4 5.3 v8 and boxster six speed going in it. I plan on doing the nitrous thing again with the new motor. shooting for low 10's or high 9's with the next setup. Somewhere near 500hp and maybe 135-40mph in the 1/4 mile. If the stock brakes are good for that, I am done chasing the billet hub dragon.

Well if it was me, I would first do a couple of runs where I measure the temp of the rotors before and immediately following the run (immediately upon coming to a stop) using an IR temp sensor.
Then you would be able to verify the calculations to within a sensible variation and verify that the rears get hot almost as much as the fronts.

If you were having trouble stopping, double check your rear clearances and that the proportioning valve is actuating.

If everything seems to be in working order , then I would upgrade the pads to Porterfields or KFP Golds.

This is all great information. That's a good idea with the IR temp reader. I will do this. Thanks for your help.

[Mueller]

The original intent of the 4 lug disc brake kit was NOT for plain jane daily driver vehicles.

It was for guys that tracked their cars and had multiple sets of wheels and tires. If you only have to buy one set of wheels to go to 5 lug not that big of deal.

If you already have lets say 2 or 3 or more sets of rims and tires that are 4 lug, the cost to replicate that setup in 5 lug can get pretty darn expensive.

The 5 lug billet hubs intent was for people that didn't want to swap out their struts for one reason or another.

[stugray]

The original intent of the 4 lug disc brake kit was NOT for plain jane daily driver vehicles.

It was for guys that tracked their cars and had multiple sets of wheels and tires. If you only have to buy one set of wheels to go to 5 lug not that big of deal.

If you already have lets say 2 or 3 or more sets of rims and tires that are 4 lug, the cost to replicate that setup in 5 lug can get pretty darn expensive.

The 5 lug billet hubs intent was for people that didn't want to swap out their struts for one reason or another.

One of the guys I race with says he wished he hadnt changed to 5 lug, because it costs so much more to replace the brakes with the 5 lug setup.
I bet he forgot that the wheel selection (width especially) is much more limited in the 4 lug version.
I have to have custom steel wheels to get up to 7 inches wide in a 4 lug.

[Mueller]

The original intent of the 4 lug disc brake kit was NOT for plain jane daily driver vehicles.

It was for guys that tracked their cars and had multiple sets of wheels and tires. If you only have to buy one set of wheels to go to 5 lug not that big of deal.

If you already have lets say 2 or 3 or more sets of rims and tires that are 4 lug, the cost to replicate that setup in 5 lug can get pretty darn expensive.

The 5 lug billet hubs intent was for people that didn't want to swap out their struts for one reason or another.

One of the guys I race with says he wished he hadnt changed to 5 lug, because it costs so much more to replace the brakes with the 5 lug setup.
I bet he forgot that the wheel selection (width especially) is much more limited in the 4 lug version.
I have to have custom steel wheels to get up to 7 inches wide in a 4 lug.

Brakes should cost the same unless one wants to go with something fancier than stock 911 M (?) calipers.

[jmitro]

bumping this thread as I'm contemplating my options for brakes (vented rotors??) on the car for occasional track use. Car will be close to stock weight, I weigh 175lb, and the engine will be 120hp.

I have brand new solid rotors with PMB 5lug conversion, rebuilt calipers, new pads, lines, proportioning valve, 19mm master cylinder.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

based on your experience, I'm thinking my desire for vented rotors is probably not necessary?

thoughts?

I'm using my stock Boge strut bodies; if I want vented rotors using Porsche calipers and 5lug, I'm assuming the only option is to convert to 911 front struts?

[stugray]

bumping this thread as I'm contemplating my options for brakes (vented rotors??) on the car for occasional track use. Car will be close to stock weight, I weigh 175lb, and the engine will be 120hp.

I have brand new solid rotors with PMB 5lug conversion, rebuilt calipers, new pads, lines, proportioning valve, 19mm master cylinder.

I brake about as hard as I can from 110 MPH (with 215 Hoosiers) on just one of 10 corners at the track, and do that for 20 minutes without stopping.
I have only detected brake fade a few times

based on your experience, I'm thinking my desire for vented rotors is probably not necessary?

thoughts?

I'm using my stock Boge strut bodies; if I want vented rotors using Porsche calipers and 5lug, I'm assuming the only option is to convert to 911 front struts?

I have heard many horror stories about vented rotors cracking on track cars.
There certainly are those that do it, but would it be a benefit for your application?

I would say if have have moderate HP (stock to ~150hp) then you might not need the extra heat dissipation. It also depends on how you drive.