Brakes The Ultimate 4-lug/5-lug Brake Conversion/upgrade Thread

mustang33189

Member
Dec 22, 2020
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Richmond VA
The factory MC would support the calipers. Hydroboost is different than vacuum type boosters. Where Ford used a different size for each vacuum brake setup, they only used 1 MC for the differenve brakes with hydroboost. 1” for 96-98 and 1 1/16” for 99-04.

your stock 99-04 calipers actually have less piston surface area than the ATS brembos. So changing to the 43mm rear calipers would still be around what your stock setup was in terms of surface areA. So yes, it would work with the MC

as to it the bias would be correct? I cannot answer that. Do you actually have a front/rear weight bias? Or just making assumptions as to how the vehicles weight has changed? If you are using the rear GT brakes, The bias is probably still fairly front heavy even if you’ve added weight up front. You might want to consider the Ford M-2300-M kit in addition to the 43mm rears. That bias would be pretty close to stock.
I don't have a split weight but i do know I'm around 180lbs heavier than stock. I probably actually have an equal amount added front and back considering the 5.0 coyote is lighter than the 4.6. The blower and supporting equipment probably made up for that. I do have the Cobra rear conversion already so likely it will still be close with the 43mm swap. Thanks for the info!
 
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mustang33189

Member
Dec 22, 2020
7
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Richmond VA
I don't have a split weight but i do know I'm around 180lbs heavier than stock. I probably actually have an equal amount added front and back considering the 5.0 coyote is lighter than the 4.6. The blower and supporting equipment probably made up for that. I do have the Cobra rear conversion already so likely it will still be close with the 43mm swap. Thanks for the info!
With the ATS up front and the 43mm in rear the pedal feel a little softer up top.
Is that because of the extra volume from the 43s? It is definitely worlds of difference over factory cobra brakes...
 

DannyMK2

New Member
Feb 3, 2021
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im looking to do the 5 lug/big brake upgrade to my 92 lx. I've been doing a ton of research and have most of it figured out. only thing i am unsure of if the master cylinder and booster. for reference, i have already bought 94/95 spindles. im planning on using 99-04 cobra/mach1 brakes front and rear (ideally 03-04 if i can get them). my car is supercharged, and it has a comp blower cam. some things im finding in my research is that the cam can have an effect on which MC or booster i should run? is that true? i was originally leaning towards the 93 cobra master cylinder and leaving the stock booster. now im not so sure. is the 94/95 cobra MC a better choice for my application? do i need the 93 cobra booster?
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
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The 15/16" 94-95 Cobra MC would be idea for the 94-98 Cobra calipers with 38mm pistons

With the 40.5mm 99-04 Cobra calipers, you'd really want the 1" bore 1993 Cobra MC.

I would really recommend the 1993 cobra booster, but you can experiment with leaving the stock booster. Don't let fear of doing the swap prevent you from changing the booster. It's not the most terrible thing to get done
 

90sickfox

Wasn't a pretty sight...and I've got big hands
SN Certified Technician
Mar 2, 2015
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The brake booster is a huge improvement. Worth every bit of the money and aggravation. If you get one that's unpainted clean it thoroughly and paint it. They rust pretty quick.
 

limp

wrap a little cheese around it and its a done
Oct 4, 2020
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Some basic questions here for someone who has NEVER worked on a fox body....
Car is an 83 convertible 5 liter.... I will be converting to 5 lug
So my understanding is the 94/95 spindles have the least amount of increase pushing the brake/wheel to the outside of the wheel well?
I can use a new ball joint to NOT having to stack washers or a spacer when using this spindle? What ball joint would that be?
Is it better to have the separate rotor/hub assembly that this changes this too?
Are the stock rotors and calipers (94/95) bigger or better than the original fox body, or does this spindle upgrade allow you to use better/bigger aftermarket rotors/calipers??
Any help to these questions is appreciated....
 

KRUISR

Well-Known Member
Apr 16, 2015
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So my understanding is the 94/95 spindles have the least amount of increase pushing the brake/wheel to the outside of the wheel well?
- 94/95 vs 96-04, yes slightly less push out

What ball joint would that be?
- 94-04 ball joint, they will press into stock Fox control arm

Is it better to have the separate rotor/hub assembly that this changes this too?
- I don't think one is necessarily better than the other. 94-04's all use separate hub and rotor

Are the stock rotors and calipers (94/95) bigger or better than the original fox body, or does this spindle upgrade allow you to use better/bigger aftermarket rotors/calipers??
- Going to a separate hub/rotor set up allows for more brake choices and sizes (for both 4 lug and 5 lug). 94-98 calipers are basically the same as Fox. 99-04 calipers are dual piston on the front and definitely an upgrade over stock Fox calipers. Stock 94-04 rotors are about same size as stock Foxbody. Likely more larger rotor options for 5 lug (but many 4 lug options if interested).

- 94-04 rear discs are definitely an upgrade over Fox drums (even at stock rotor size)
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
35,647
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94-95 spindles push the wheeks out 3mm over stock

96-04 spindkes are 8mm more than stock fox.

the main difference is the tie rod locstion. The 96+ spindles lower the tie rod mount locstion because the 96-04 k-member lowers the steering rack down. The spindles must match the k-member otherwise you have uncorrectable bump steer.

separate hub/rotor setups are better at heat management.

The GT/V6 rotor is essentially the same diameter 10.9” rotor as a 87-93 fox(10” or 9” on pre-87), but the calipers are larger. Fox is 60mm, 94-98 is a single 66mm and 99-04 is dual 44.5mm

the SN95 spindles offer a great foundation for many aftermarket brake setups. Cobra 13” and even Baer 14” setups.
 
Last edited:

Willybill32

But at least it's tight!
Jul 16, 2019
259
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Lexington, KY
Some basic questions here for someone who has NEVER worked on a fox body....
Car is an 83 convertible 5 liter.... I will be converting to 5 lug
So my understanding is the 94/95 spindles have the least amount of increase pushing the brake/wheel to the outside of the wheel well?
I can use a new ball joint to NOT having to stack washers or a spacer when using this spindle? What ball joint would that be?
Is it better to have the separate rotor/hub assembly that this changes this too?
Are the stock rotors and calipers (94/95) bigger or better than the original fox body, or does this spindle upgrade allow you to use better/bigger aftermarket rotors/calipers??
Any help to these questions is appreciated....
‘86 and earlier rotors are smaller in diameter than ‘87 and up. Best to get the larger rotors and matching calipers.
 

Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
35,647
11,647
224
Massachusetts
I understand that I have to upgrade to 87 or newer struts also to do this??

or use spacers between the strut/spindle.

the 79-86 all and 87-93 4cyl spindle ear is wider. Some aftermarket shock companies just make one shock for 79-93 and include a spacer plate
 

limp

wrap a little cheese around it and its a done
Oct 4, 2020
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Florida
So are these 94/95 spindles getting hard to find?? Ebay prices seem high to me?? Can you order New ones from Ford?
 

KRUISR

Well-Known Member
Apr 16, 2015
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Just find a pair in the wreckers. So long as the spindle shaft is not scored, clean the rust off and you are good to go.
 
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Mustang5L5

i'm familiar with penetration
Mod Dude
Feb 18, 2001
35,647
11,647
224
Massachusetts
So are these 94/95 spindles getting hard to find?? Ebay prices seem high to me?? Can you order New ones from Ford?

nope. I believe all the spindkes are discontinued. Used only.

demand is up and supply is finite. Prices only gonna climb
 

limp

wrap a little cheese around it and its a done
Oct 4, 2020
340
141
53
66
Florida
Just find a pair in the wreckers. So long as the spindle shaft is not scored, clean the rust off and you are good to go.
Been trying to, 94/95 cars are getting OLD and going to the crusher.....