List differences of the 86 EFI 5.0 boosters and 87-93's

[Cobra Jet]

Can someone please tell me what differences, if any at all there are between the 1986 5.0 brake booster and master cylinder and the 1987-1993 5.0 brake booster/master cylinders?

Are the 87-93's a direct fit/replacement? Any differences?

I know the front brakes on the 87-93's were upgraded over the 86-prior Mustangs, but the rears remained as drums (excluding the 1993 Cobra). So, would dropping in a 87-93 brake booster/master cylinder combo WORK, or would I run into modification issues?

I plan on upgrading my front brakes (calipers/rotors) on my 85 GT vert to those of the 87-93 design, this is why I am asking. My original booster/master cylinder is SHOT, so I need to replace it anyway, this is also another reason I am asking too... :)

[Evil86lx]

I'm not sure about the booster...

But the master cyl's are different.. The newer one's use different line's/ports for the brake line's..

The best way that I have found is to use a SVO/lincoln master cyl when upgrading to the bigger front brake's.

Their are a million different way's to do it so I'm sure someone else wil jump in here and correct me if I'm wrong.

kyle

[Coupester]

The boosters are the same on 85-93 HO's.

Chris

[slickshift]

You can use the same master cyl. and booster
But you need '87 spindles (calipers, rotors, and hoses)

[FoxChassis]

Correct. The caliper's piston is the same diameter (60 mm). If you upgrade the caliper to one with a larger piston (73 mm), you'll likely need a different master cylinder. If you upgrade to rear disc, you will need a different master cylinder and a different booster.

[Coupester]

If you upgrade to rear disc, you will need a different master cylinder and a different booster.


Not necessarily true.

SVO's had rear discs and had the same boosters. So did 93 Cobras.

As long as you are not upgrading to Cobra/ Baer/ Brembo brakes, the stock 85-93 HO booster will be fine!

[frankiesaysrelax]

If you upgrade to rear disc, you will need a different master cylinder and a different booster.


Not necessarily true.

SVO's had rear discs and had the same boosters. So did 93 Cobras.

As long as you are not upgrading to Cobra/ Baer/ Brembo brakes, the stock 85-93 HO booster will be fine!

What about earlier GT boosters? Are they ok for rear discs? Are the '85 up boosters considered and upgrade?

[foureyedfool]

I just did a v8 conversion on a 86 4cyl coupe using the drivetrain and brakes from a 88 gt .The master cyl and booster will work fine but you will need the 87-93 hardlines coming out of the master cylinder.I am going to swap over to the 88 gt brakes as soon as I get a chance but right now I am running the smaller front discs with a 88 gt brake booster and master cylinder.The only reason I did this was because the pads and rotors on my 88 gt parts car were shot and I couldnt see buying new ones until the smaller ones needed replacing.So yes to answer your ? it will work fine but you will have to have the hardlines off the 87- up car for it to bolt right on.

[FoxChassis]

My '86 GT has its stock steel ("hard") brake lines in place even with '87-'93 front brakes (upgraded to 73 mm calipers).

[Cobra Jet]

Well, I have expierence with converting to 5 lug - as I had done the complete conversion on my prior 90 LX 5.0 coupe.

However, I just ripped everything out and replaced everything with the 5-lug components, proper SN95 1994 spindles, 94-current Cobra front calipers, 13" front rotors and the rear was a complete Baer Racing disc brake conversion.

At the moment, I cannot remember the bore size of the master cylinder I had used or the year Mustang proportioning valve. The brake booster was an actual 1994-95 Cobra brake booster sourced out from Auto Zone (it was special ordered). I also used a Baer Racing 2nd proportioning valve on the passenger side hardlines (under the hood).

If I remember correctly as well, I believe I did change my hardlines on the coupe - well, the driver's side hardline so that it would mate correctly to the master cylinder.

~~~

Not to get off track, but the reason I was asking or starting this thread is I was not familiar with any differences between the 1986 5.0 EFI brake booster/master cylinder/proportioning valve/front brake hardlines - as opposed to the latter 87-93 components...

I have to remove the old booster/master cylinder anyhow since it's all garbage, so while in there, I thought I could upgrade. At this point in time though, I just ordered a brand new brake booster/master cylinder combo for another 86 EFI... I was not sure if the boosters were the same, or if the master cylinders were the same, etc....

It seems the concensus is the boosters are the same, but the master cylinders, brake proportioning valve and/or front hardlines may vary. I suppose I could always swap out the master cylinder/brake proportioning valve later and if need be, switch the brake hardlines in the front...?

I'll have to look into it further, as I have 2 sets of hardlines, but I am not sure which model years they are from.

[foureyedfool]

i just remebered I changed my prop. valve also that may be the reason I had to change the hard lines.I know the hard line leading to the rear would have worked but the one for the front drivers side wouldnt .Hope I didnt confuse you ,kinda hard to explain haha. I can get you some pics if you need em,haha if you were local you could come buy and pick up the old booster and m/c its just sitiing there in my parts car. One other problem I ran into was the plug on the master cylinder that reads the low brake fluid.I had to change it over to the 87- up plug .The 86 plug was totally different.Hope this helps!

Bill