Old Stuff: SVO/93 Cobra brake upgrade notes (part 1) - Ford Mustang Forums : Corral.net Mustang Forum
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Old Stuff: SVO/93 Cobra brake upgrade notes (part 1)

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Posted 02-03-2012 at 06:46 PM by That89GTGuy

So, for the sake of getting it written down before I forget, I feel like talking about doing the SVO brake upgrades on my car that I tried in spring 2011. I know there are a lot of useful sites out there, but I feel like maybe I can throw a few things out there via this blog thingy that might help someone with some frustration later down the line.

Ever since I got the 89 GT, I had a feeling the brakes where pretty bad. I tried a few things to make them better like stainless steel brake lines all throughout the car, the Maximum Motorsports "stock" brake upgrade kit, rebuilding the rear drums, high temp brake fluid, usual kind of stuff. The Maximum kit helped stopping distances a bit I would say, but brake fade was still pretty bad, and at least in my car, the distances where not very good (probably my poor mans tires, but still) overall, but the brake fade was really what I was after to fix.

I had read about the 1994 Cobra disk setup with the 13'' duel piston fronts and 11 point something rears, and for about 2 or so years I had planned on getting some of those. Around the time I could finally afford them and felt like everything else was in order, they discontinued them. Everywhere else that carried them still wanted a bazzilion bucks for the kit. I opted out. I looked around on the web, and compiled a list of components that I could use. Here's a quick and dirty idea of what I found would work:

SVO style front brakes: The piston is a good deal bigger, and my calipers where origionals anyways, so that had to be an improvement anyways. They where compatable with the rotor size I already had too which was nice. There, IIRC, where nearly 11'' disks with 73mm pistons, still retaining the same 4 lug setup as stock. Also, keep in mind there are plastic (!) pistoned versions of this caliper. I went with the metal ones. Because they're metal, like me...

Thunderbird Turbocoupe rear brakes: This was probably going to be a big improvement over the old rear drums. About 10'' rear disks with some small calipers, but hey! At least it can breath better than the drums. I chose to keep the stock caliper brackets and longer axles from the Thunderbird on this. More on that later.

A few other things needed to be purchased with all this as well though. I got a new MC from the SVO, adapter lines from Maximum Motorsports, rebent hardline on the rear brakes with adapter fittings to make it all mesh. You also need to remove/gut the stock brake system balancer, and the stock rear brake pressure fitting. I replaced it with a Wilwood adjustable bias valve.

I also got front brake ducts which install to the dust shields from Quantum Motorsports (that company is gone, but I've heard they where bought by someone else... I dunno). Lastly, I picked more aggressive front pads to go along with all this.

To get the rear thunderbird hardware, I got a whole axle from a guy selling one up in Maine. That day was awful for a lot of reasons, but that guy was really nice, and while the axle was rusty as hell, it made for a good core and was in good enough shape to get some stuff from it. Taking it apart is an adventure. If you're taking the same path as me, there are a few things you want to do on the old axle:

1: Do not worry about salvaging the old lines. The fluid junction box is different from the Mustang and uses different threads I believe. Just rip that shizz off and be done with it.

2: Axle/gear oil is the WORST. STUFF. EVER. Do not have anything you like anywhere near the stuff since it will probably stain like a son of a gun and ruin whatever it touches besides metal. Also notice how everything comes apart because it won't be so convenient (assuming the axle you're cannibalizing is not also under a car) to play with when your under the car trying to put stuff in it.

3: The axle to caliper brackets are held on with 4 really freaking hard to remove bolts/nuts. Use penetrating oil often and liberally. Do not try to use some kind of cleaner, since it just makes the nuts come off even harder for some reason. Just leave them nasty and soak them in PB blaster or what have you. I did not reuse mine, since they where so rusty. I'd recommend you do not either. I easily found some exact replacement grade 8 nut and bolts at the local hardware store.

4: The caliper to caliper bracket bolts are just SOBs to take off if your axle is like mine where it has been allowed to rust for a while. I used a 3 or 4ish breaker bar on mine, and it stunk to do by myself. The axle want to spin with it. Get a friend to help, or get an awesome impact wrench. Again, penetrating oil the hell of of the things. One of mine rounded off after the socket broke on it. I recommend Craftsman bolt outs. Work like a charm. I also replaced these bolts. Again, found some great replacement bolts at the local hardware store. Got the highest grade bolts I could buy.

So disassembling the old axle was not really that hard, which was nice. The old axles where actually in pretty darn good shape too. I got some decent gears out of the Thunderbird axle also, so a good score. I really love my low revs at highway speed though, so I kept my old 3.08 gears though. I drive hundreds of miles to events, and I want to burn as little fuel as I can, and also keeping the noise down a bit is nice too.

The dissasembly of the axle in the car was not too bad either. the oil gear oil was pretty nasty, but otherwise it went well. One thing that I will mention though is that I had a torsen rear diff in my car. Because of that, the torsen had 2 large shims in it to keep axle play to a minimum. After removing the stock axles, the shims got stuck together somehow (the oil displacing when the two went together make them stick to one another I think). It was a real pain getting those apart. Keep this in mind when working on your car, if you have them. Other than that though, installation of the Thunderbird axles into my GT was easy as pie. Replacing the diff cover was also easy. But then, I tried to add axle oil...

I used Redline gear oil, 75/90w. Holy crap adding oil sucks. I tried doing gravity feed, and then did NOT work. I then went out and bought a weird fluid extraction thingy that works by hand. It worked, but it was probably one of the messiest things I've ever done. I ruined a good deal of clothes with that stuff. If you ever plan on doing the gear oil in your car, get a good plan going into it that involves forcing the oil in, because you're going to need it. This was probably the single worst part about working on the rear end.

I'll save some of the front end stuff for later. One thing I will say now though is that if you plan on trying to do this, make sure you're getting a good price. You can get most of this stuff from local parts stores if you look around, and you will need to do some shopping. If you can't get some stuff to use as cores, you might be better off just getting a kit, since the kit will include most of what you need without you having to do so much research or shopping. Just something to note. Till next time!
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