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

sigsterrr said:

Mustang5l5 I did a swap like you mentioned above, but now I have no idea what to do for the brake lines in the front and rear after the factory hard lines. I used stuff from a 97 model. I read to use 94-95 rear brake soft lines due to easy mounting. I’ve done many searches and came up blank. Any advice would be appreciated.

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The 94-95 rear caliper lines bolt to the axle. Then you can use a pair of Weatherhead 7818 adapeter to connect to the factory fox axle hardliness. You may have to bend the lines around slightly for clearance.

There's also this kit if you want to spend a little mone

https://www.maximummotorsports.com/MM-Stainless-Brake-Hose-Package-1994-95-Mustang-rear-P1224.aspx

Along with new rear lines (which i need to buy myself)
https://www.maximummotorsports.com/...d-Lines-1986-93-with-SN95-calipers-P1460.aspx

Yeah...i know it's a bit spendy

Slumone said:

Mustang5L5, That junkyard combo you just posted would give you a ratio of 16.74 as compared to the factory combo which would put the ratio at approximately 14.839. 14 being stiffer than 16. I am just a little confused at what ratio I should be shooting for, 16? How much does the booster choice affect that ratio?

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There really is no ideal target ratio as its going to depend heavily on the end user. Brake feel is highly subjective. I used what Ford developed as a guideline, with some options for tweaking. That "junkyard combo" i suggest is based on a 99-04 V6 Mustang that also comes with a 1.003" bore MC. So that ratio is 17:1 right out of the factory with the larger booster. Might be ideal for a granny driving her v6 to the mall. The v8 models tend to have brake setups a bit firmer.

As for tweaking, well, like i outlined before, if that combo seems a bit "soft", then you can step down and try an MC ratio that's 1/16" larger. In this case, the 94-95 MC. The larger bore MC would firm the pedal up slightly. I've driven a 94GT with the 99PBR's up front and thought the pedal was a tad bit firm, but that subjectiveness is really all dependent on what a person likes.

The booster is a wild card. Leaving the smaller, Fox booster in place can mimic the results of going larger in MC size giving a firmer pedal feel. So something with a higher number ratio can feel pretty firm withe the smaller level of booster assist.

I think i suggest this 10 years ago, but use what the factory did as a guideline, and then tweak from there. Some folk like the firmer pedal, others want to feel the brakes grab with very little effort. However, it's quite dangerous to go to the extremes when tweaking. Too small an MC, and you'll simple run out of stroke before achiving max braking potential, or the brakes will be too grabby and you'll easily lock them up on a quick stab during a panic stop. Go too big, and you might find yourself unable to press the pedal hard enough in a situation to stop quickly.

But that junkyard combo is a great guideline because the parts are common, readily available and easily found at boneyards even if you decide to go for the 94-95 GT/94-98v6 master cylinder and 94-95 booster. You can easily find rebuild kits and caliper components, and should be able to find these items for years to come and not get gouged on them

Slumone said:

I found something that is oddly not mentioned in this thread. What are the pros and cons of Turbocoupe vs 04 GT rears when paired with 04 GT fronts? For reference, my car is 88 LX vert. Based on Mustang5L5’s post from 2009, I assume I would want to go with a 93 Cobra master with the GT rears and a 1 1/16th ie GT/V6 master if I roll the Turbo coupe rears. I have a turbo coupe axle but converting to 5 lug, so either way I will need new axles but I like the concept of vented over solid. I cannot go with the Cobras because the fronts will not fit under my wheel choice.

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The turbocoupe rear setup is VERY similar to the relatively unknown 1991-1992 Lincoln Mark 7 brake setup that came on 91-92 Saleens and the 1993 Cobra R. Everyone things the Cobra R had the same rear disks as the Sn95 cobra, but its not true. It was a smiliar setup using a turbo coupe style 45mm caliper, and a 10.5" vented rotor taken from the 1991 Lincoln Mark 7.

Ford ran a 1" bore MC on the Cobra R with the 38mm version front cobra style PBR's and the 45mm TC rear setup. In fact, the 1994 Cobra was originally supposed to use the 1" bore MC as well with the 38mm rear vargas, but there was a last minute change to the 15/16" bore due to poor cold braking performance, I do not know what Saleen used with it's setups but Lincoln continued to use the 1 1/8" bore MC that it used with the previous 54mm rears.

Swapping out the 38mm's for the 45mm;s is a 40% increase of rear caliper piston surface area at the rear, so likewise you'd have to step up another 1/16" to possible 1/8" in MC bore diameter to compensate (i'd do the math, but strapped for time). It's also a non-factory, heavily rear biased setup and should only be done with a healthy front brake system with nice gripping tires. Based on personal experience, i've always said these fox bodies don't need much brake on the rear if solely being street driven. Performance driving is another story.

Slumone said:

Lastly, at what point should you consider a hydroboost vs a vacuum booster? One cam I still have near the bottom of my list of considerations will net me around 10 inches of vacuum which I imagine is ridiculously low but I am rebuilding the suspension first so I have yet to fully spec out the motor. I kind of want to see how the car feels with the new suspension before I make that decision.

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I wouldn't make that change unless a mechanical situation forces you to. Poor vacuum, or just needing the room in the bay. Low vac will definitely give you a firmer pedal, but you might find it too firm in a panic stop situation. It's a complex swap, but the hydroboost does give you much more assist than a vacuum booster. AFAIK, there is only one MC size, and everything i've posted regarding ratios and matching MC to the brakes goes out the window as there are at least 3 different systems all using the same MC. Hydroboost is just one area i've yet to learn

I tend to use this page as a guide as well as I simply haven't played with enough brake combos out there to offer any advice that is more than just theory.

https://www.maximummotorsports.com/...98-Hydroboost-in-1979-1993-Mustang-P1617.aspx

MM claims that ideal brake bias is around 70-75% front. They also state that the adjustable PV is really more for fine tuning. The 2004 GT setup with standard 38mm rears would be around 72% front bias. I would speculate that adding the larger 45mm rear calipers would drop that below 70%. Might work fine if you have a really light front end on your car, or a heavy rear.

Here's a bias calculator if you want to try plugging some numbers. At work right now so couldn't spend the time to calculate it up myself

http://www.tceperformanceproducts.com/bias-calculator/

As for the rear rotors solid vs vented, I would always say thay if you do plan on using your brakes for multiple, repeated stops that will generate heat, go with the vented rotors. For street driving, the solid rotors are fine. 1-2 heavy stops an then they usually have plenty of time to cool. The repeated stops is what causes the brakes to heat up, and pad material to transfer giving you the pulsating rotor issues. Again..look at what the factory did. You average V6 (and GT to a point)grocery getter got solid rotors for putting around town. Cobras were expected to be purchases by a population that skewed more towards performance, so they got vented.

I used a Raybestos MC and located a m-2300-k booster that the person chose not to install. When I opened the box, I found it was a reman that Ford used in the kit.