Fox Upgraded Front Brakes, Stock Rear Drums?

[95BlueStallion]

I am piecing together my 5 lug conversion, and have a couple questions for those who have done this. When I had my '95 and put the PBR calipers and 13" rotors on it, everyone suggested a Cobra master cylinder as well. I didnt have the money at the time, and slapped it together without upgrading the MC and ended up really liking the feel. That being said, has anyone upgraded to 5 lug with that same PBR/13" rotor combo up front, and kept the rear drums on a fox? Rear axles and 5 lug drums are cheap and easy to come by, and I have learned through past cars that I dont necessarily need the best of the best of everything. This is a sub 300 horsepower street car, will never see a track of any kind. I just want better than the stock single piston and 10" rotors up front. Anyone tried this first hand?

PS, I will most likely be getting 5 lug 17" pony wheels, so the look of the brakes is less of a concern than whether the combo functions ok. I can always upgrade to rear discs later, but would like to do this a little at a time and tackle the big pitfall first.

 

[billison]

Yup, pretty common. I think if you keep the rear drums it's almost plug and play.

 

[Moosee1955]

Like you said you can update later. I had rear drums on my 85 and 86, and it stopped fine. Besides 70 percent of your brakes are up front. Just be sure you get your rear shoes adjusted right, and you'll be fine.


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[CarMichael Angelo]

When I first read this, I thought that you were asking about keeping the stock booster. Now that I've re-read it......This is my unqualified answer.

A master cylinder is mostly just a reservoir coupled to a hydraulic cylinder as you know. All M/C's have an inherent bore size that is matched to the job of moving X amount of fluid per stroke. Depending on the demand of the brake system when required to move the pads/shoes, a particular MC may be more or less up to that task.

I don't know what you're stock existing MC piston bore size is, but that answer is a google away. A 95 Cobra MC is 15/16"

Your's maybe bigger (like 1"). The bigger the bore in this instance isn't necessarily a good thing however as it relates to effort and pedal feel.

When I first got the red car running, I had manual brakes on it. I had a brand new 1-1/8" bore MC on it. During the first test drive, It took so much effort to try and slow it down, I couldn't get it to stop, and promptly sailed right through the first stop sign I came to. That got changed right away. I ended up w/ a 7/8" bore by the time it was all said and done.

The fact that your brakes are still power assisted will be beneficial if your first test drive is similar to mine, but I'd make sure that I had a MC bore size that is matched to the one that was on the car that had those front brakes originally. The booster will have a better chance of "helping" if it doesn't have to push a massive hydraulic load. Since 80% of the braking is still achieved through the front brakes, keeping the rears drums may not be a bad thing, with one exception.........

Panic stops.

In a panic stop, a properly biased brake system will lock the front brakes first. That way the weight of the car will drag the rear of the car through that skid. If the rears lock before, or too,......then you'll know real fast what the words "Whoopty, Brodie, Cookie, Doughnut, Spin out" mean when applied to car speak.

At the very least....I'd add a brake proportioning valve that replaces the stock prop block. I got mine from Summit It had a adjuster and a brake light switch port built in, and it was pretty reasonable.

90 bones.

 

[General karthief]

I'd like your post there mm but that free ad for wildwood kinda over ran things, brakes are misunderstood and often overlooked. Imagine the days of air shocks and tires bigger than your wheel wells, ahhh, those where the days.

 

[CarMichael Angelo]

I'd like your post there mm but that free ad for wildwood kinda over ran things, brakes are misunderstood and often overlooked. Imagine the days of air shocks and tires bigger than your wheel wells, ahhh, those where the days.

I never endorse a product for the sake of advertising it here.

Maybe this would've been a better picture then?

 

[Mustang5L5]

If you are not changing the rear drums out, then there is no correct MC for that application. Rear cylinders use much less fluid to move due to their small piston surface area. As a result, you cannot install a 4 wheel disk master cylinder and expect good feel.

I pretty much spell out the math on MC selection in the stickied post on ultilmate 5-lug conversion thread at top of forum. But, i'll take a few snippets.

Surface area of front pistons:
87-93 60mm calipers
-2827mm^2
-5654mm^2 for 2 calipers

vs 99-04 Cobra 13"
99-04 COBRA 40.5mm pistons
-1288mm^2 each piston (4 total for front)
-5152mm^2 for 2 calipers

So the surface area of the 99+ cobra PBR's is actually around 9% smaller than the stock fox calipers. So without even touching the MC/booster, you would have a slightly firmer pedal. To be honest, you'll probably never even notice.

The 1993 cobra MC that is a popular item when 5-lug swapping is 46% bigger than the stock MC. With the smaller surface area of the front calipers, you actually want a slightly smaller MC. Not larger. However, 9% difference in the front is negligible. I wouldn't worry about it


The above applies only when you leave the stock rear drums. Rear disk, then you are changing out the MC. I detail this all out here
http://www.stangnet.com/mustang-for...onversion-upgrade-thread.801400/#post-8075734

 

[CarMichael Angelo]

If you are not changing the rear drums out, then there is no correct MC for that application. Rear cylinders use much less fluid to move due to their small piston surface area. As a result, you cannot install a 4 wheel disk master cylinder and expect good feel.

I pretty much spell out the math on MC selection in the stickied post on ultilmate 5-lug conversion thread at top of forum. But, i'll take a few snippets.

Surface area of front pistons:
87-93 60mm calipers
-2827mm^2
-5654mm^2 for 2 calipers

vs 99-04 Cobra 13"
99-04 COBRA 40.5mm pistons
-1288mm^2 each piston (4 total for front)
-5152mm^2 for 2 calipers

So the surface area of the 99+ cobra PBR's is actually around 9% smaller than the stock fox calipers. So without even touching the MC/booster, you would have a slightly firmer pedal. To be honest, you'll probably never even notice.

The 1993 cobra MC that is a popular item when 5-lug swapping is 46% bigger than the stock MC. With the smaller surface area of the front calipers, you actually want a slightly smaller MC. Not larger. However, 9% difference in the front is negligible. I wouldn't worry about it


The above applies only when you leave the stock rear drums. Rear disk, then you are changing out the MC. I detail this all out here
http://www.stangnet.com/mustang-for...onversion-upgrade-thread.801400/#post-8075734

Don't forget that we're talking about Nick,..here. he will "stumble" upon a rear disc brake setup on day,....he will want to do it once right the first time. He doesn't want to be like me, and have to do stuff twice, three , even 4 times to get sht right.

 

[Mustang5L5]

Don't forget that we're talking about Nick,..here. he will "stumble" upon a rear disc brake setup on day,....he will want to do it once right the first time. He doesn't want to be like me, and have to do stuff twice, three , even 4 times to get sht right.

True, but even if he plans to upgrade to rear disk in the future, he still shouldn't change out the MC just now. Squirrel it away (with the booster) and then when he decides to go rear disk, he'll have to install it then.

But at least for now. He can get the spindles, rotors, calipers, lines, balljoint spacer, and passenger side brake line adapter, install all that, and get the front end aligned and continue to drive the car.

He could even gut the prop valve, and install the adjustable prop valve too now.

 

[stangboy]

My car has the same brake setup. 96 Cobra front brakes, steel braided brake lines for the front, stock size 5-lug drums, stock 88 booster and MC. I plan to put an adjustable proportioning valve on also. So let me get this straight, @Mustang5L5 . In order to use the adjustable proportioning valve I have to gut the stock one?

 

[Mustang5L5]

My car has the same brake setup. 96 Cobra front brakes, steel braided brake lines for the front, stock size 5-lug drums, stock 88 booster and MC. I plan to put an adjustable proportioning valve on also. So let me get this straight, @Mustang5L5 . In order to use the adjustable proportioning valve I have to gut the stock one?

Not necessarily, but if you leave the stock prop valve intact, you are reducing pressure to the rear wheels twice. Once through the factory setup, and a second time through the adjustable.

If you wanted to simply install it now to get it out of the way, you could leave it 100% open, so that only the factory one is reducing pressure to the rears. Or you could gut the factory one, and just use the manual one to adjust now, even with rear drums. Your call really.

Also, just a point of information. The 94-98 cobra calipers are slightly smaller than the 99-04 versions. ~4500 mm^2 of surface area. That means while the 99-04 versions are 9% smaller, the 94-98 versions are about 25% smaller (in terms of piston surface area) than the stock fox front calipers. That means you'll probably notice a bit of firmness increase here.

And since I'm tossing out numbers, the 99-04 GT 10.9" setup is 10% larger than the stock fox setup.

 

[stangboy]

Not necessarily, but if you leave the stock prop valve intact, you are reducing pressure to the rear wheels twice. Once through the factory setup, and a second time through the adjustable.

If you wanted to simply install it now to get it out of the way, you could leave it 100% open, so that only the factory one is reducing pressure to the rears. Or you could gut the factory one, and just use the manual one to adjust now, even with rear drums. Your call really.

Also, just a point of information. The 94-98 cobra calipers are slightly smaller than the 99-04 versions. ~4500 mm^2 of surface area. That means while the 99-04 versions are 9% smaller, the 94-98 versions are about 25% smaller (in terms of piston surface area) than the stock fox front calipers. That means you'll probably notice a bit of firmness increase here.

And since I'm tossing out numbers, the 99-04 GT 10.9" setup is 10% larger than the stock fox setup.

Thanks

 

[95BlueStallion]

If you are not changing the rear drums out, then there is no correct MC for that application. Rear cylinders use much less fluid to move due to their small piston surface area. As a result, you cannot install a 4 wheel disk master cylinder and expect good feel.

I pretty much spell out the math on MC selection in the stickied post on ultilmate 5-lug conversion thread at top of forum. But, i'll take a few snippets.

Surface area of front pistons:
87-93 60mm calipers
-2827mm^2
-5654mm^2 for 2 calipers

vs 99-04 Cobra 13"
99-04 COBRA 40.5mm pistons
-1288mm^2 each piston (4 total for front)
-5152mm^2 for 2 calipers

So the surface area of the 99+ cobra PBR's is actually around 9% smaller than the stock fox calipers. So without even touching the MC/booster, you would have a slightly firmer pedal. To be honest, you'll probably never even notice.

The 1993 cobra MC that is a popular item when 5-lug swapping is 46% bigger than the stock MC. With the smaller surface area of the front calipers, you actually want a slightly smaller MC. Not larger. However, 9% difference in the front is negligible. I wouldn't worry about it


The above applies only when you leave the stock rear drums. Rear disk, then you are changing out the MC. I detail this all out here
http://www.stangnet.com/mustang-for...onversion-upgrade-thread.801400/#post-8075734

I'll be honest with ya brother, I hate math. The reason I posted instead of reading through all of the logic, is that I was wondering who had done what I was looking to do, and their personal thoughts on feel and function. Kind of a "seat of the pants" opinion thing. I know there is math and logic behind the most ideal set ups, but I am not the type of guy needing that info. Your cliff notes were perfect! Now I know I am good to keep the stock MC initially, and upgrade to a Cobra MC once I get around to swapping to rear discs, if I decide to even do so later. Thank you sir!

My car has the same brake setup. 96 Cobra front brakes, steel braided brake lines for the front, stock size 5-lug drums, stock 88 booster and MC. I plan to put an adjustable proportioning valve on also. So let me get this straight, @Mustang5L5 . In order to use the adjustable proportioning valve I have to gut the stock one?

This too, is what I was looking for. You have what I want, and you are still alive to say it works just fine. Thank you for chiming in. Its easy to get wrapped up in the "the RIGHT way to do this, the RIGHT way to do that," but not all of us need the most efficiently calculated set up. If I were looking to make this a road course/autocross weekend car, then I would be doing all the reading on the math. Part of the reason I am loving this fox so much is getting in it and NOT having advanced trac/traction control, ABS, tire pressure sensors, etc. I like to get in, whip it sideways, and not have alarms going off or power being cut from me because I forgot to hold down a damn button with my foot on the brake for X seconds.

@madmike1157 , I appreciate the prop valve statement, regardless of which ad it triggers. I will test drive it with the stock PV to start with, and see how it goes from there. Being its not my daily, I am not all that worried about it meeting the expectations of the crash test dummies. Just want to make sure I wasnt gonna bolt all this on, and find out my brake pedal wouldnt budge because my parts were so mismatched.

 

[95BlueStallion]

Yup, pretty common. I think if you keep the rear drums it's almost plug and play.

It absolutely is. I bought 94-95 spindles, 99-04 PBR calipers with brackets for 13" rotors, and MM stainless hoses specifically made for fox hard lines to PBR calipers. In the rear, I just swap axles, and slide on stock sized 5 lug drums. It's gonna be a walk in the park. Now.... which 5 lug wheels do I choose.... I have spent in total, roughly 5 hours trying to decide on wheels. I always loved my stock 2011 GT wheels, except for how narrow they were. That being said, I think I am going to go with @Boosted92LX 's choice of 18" 2010 style GT wheels. 18X9 up front, 18X10 in back.

 

[95BlueStallion]

If you cant tell, my Explorer sold over the weekend, and they paid in cash. While a part of me wanted to splurge it all away on a 5 lug, 4 wheel disc brake kit and wheels, I am going budget friendly 5 lug/PBR front brakes, rear drums, and wheels. I have it all ordered now, and kept it under $2K. I will start a separate thread once everything is here and I start working on the car. I already have a few interior restoration parts, but they are going to wait until spring. I didnt notice until recently that someone painted the upper half of my dash, and not all that well. So I will tackle the interior restoration when the temp is right for painting several things while I have it apart. May end up being another @madmike1157 225 page thread of useless banter, and a little bit of car building.

 

[General karthief]

I'll be honest with ya brother, I hate math. The reason I posted instead of reading through all of the logic, is that I was wondering who had done what I was looking to do, and their personal thoughts on feel and function. Kind of a "seat of the pants" opinion thing. I know there is math and logic behind the most ideal set ups, but I am not the type of guy needing that info. Your cliff notes were perfect! Now I know I am good to keep the stock MC initially, and upgrade to a Cobra MC once I get around to swapping to rear discs, if I decide to even do so later. Thank you sir!



This too, is what I was looking for. You have what I want, and you are still alive to say it works just fine. Thank you for chiming in. Its easy to get wrapped up in the "the RIGHT way to do this, the RIGHT way to do that," but not all of us need the most efficiently calculated set up. If I were looking to make this a road course/autocross weekend car, then I would be doing all the reading on the math. Part of the reason I am loving this fox so much is getting in it and NOT having advanced trac/traction control, ABS, tire pressure sensors, etc. I like to get in, whip it sideways, and not have alarms going off or power being cut from me because I forgot to hold down a damn button with my foot on the brake for X seconds.

@madmike1157 , I appreciate the prop valve statement, regardless of which ad it triggers. I will test drive it with the stock PV to start with, and see how it goes from there. Being its not my daily, I am not all that worried about it meeting the expectations of the crash test dummies. Just want to make sure I wasnt gonna bolt all this on, and find out my brake pedal wouldnt budge because my parts were so mismatched.

All that traction control/abs/tire monitor/lane drift/on coming texter drive'n a prius garbage is for something resembling a person that can drive.
My opinion and not an admission of guilt.

 

[Mustang5L5]

All that traction control/abs/tire monitor/lane drift/on coming texter drive'n a prius garbage is for something resembling a person that can drive.
My opinion and not an admission of guilt.

When I used to autocross my 2003 GT. Abs made it so much more manageable.

I still have plans to add 94-95 abs to my car one day


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[95BlueStallion]

ABS is a thing for a reason. It works, and helps when you want it to. Call me old school, or even dangerous, but I just have a thing for the car doing only what I make it do.

 

[General karthief]

I've read about the advantages of abs in autocross, mostly on higher hp vehicles than I have, not that I would take my junk for a try on the twisties, to ugly even for the parking lot. I'm easily addicted to stuff.

 

[95BlueStallion]

Don't forget that we're talking about Nick,..here. he will "stumble" upon a rear disc brake setup on day,....he will want to do it once right the first time. He doesn't want to be like me, and have to do stuff twice, three , even 4 times to get sht right.

Still have the 2011 stock hood leaning in the garage, and no 2011 to ever put it on again... Just cant haul it off to the dump for some reason. I have basically learned from that 2011 that everything I did to it really did "upgrade" it as advertised, but didnt really make me enjoy it any more than I did before doing the mod. It handled like a dream, but I have straight roads all around me, and no road courses anywhere near me. I never street race, and have basically learned stock or near stock can be quite enjoyable. So with this car, yes, I am trying to think out each mod. Not only from a cost stand point, but whether I will actually notice or enjoy the mod once its done.